Abrasive flow machining device for screw polishing and working method

Abstract

The abrasive flow machining device for screw polishing comprises a lathe bed, a charging barrel for loading a screw is arranged on the lathe bed, a power assembly for driving the screw to rotate is arranged at one end of the charging barrel, and a regulation and control structure is arranged at the other end of the charging barrel; the regulation and control structure comprises a regulation and control cylinder communicated with the interior of the charging barrel and a discharging port formed in the regulation and control cylinder, and a spring and a regulation and control plate matched with the spring and used for controlling the size of the discharging port are arranged in the regulation and control cylinder; the charging barrel is connected with a feeding assembly for providing grinding materials into the charging barrel, and the charging barrel is connected with a circulating assembly for circulating the grinding materials; compared with the prior art, the adjusting and controlling plate reciprocates at the discharging port under the action of the spring and the grinding material, so that the size of the discharging port is adjusted, the pressure at the discharging port is automatically adjusted and controlled, the pressure difference between the two ends of the charging barrel is autonomously controlled, uneven stress of a screw rod is avoided, and the polishing effect of the screw rod is improved.

Description

Technical Field

[0001] The invention relates to the technical field of screw polishing processing, and in particular to an abrasive flow processing device and a working method for screw polishing. Background Art

[0002] As the core component of some mechanical equipment, improving the surface quality of the screw is an important research topic in mechanical processing. Abrasive flow machining is widely used in the field of screw surface processing due to its conformal characteristics and high accessibility, but there are also many defects in the abrasive flow machining process. For example, the pressure difference effect in the abrasive flow machining process will lead to inconsistent surface quality of the workpiece, which will affect the performance and service life of the screw.

[0003] The pressure difference effect refers to the significant uneven pressure difference during the processing of parts with a large depth-to-diameter ratio, which leads to certain differences on the surface of the parts. The main reason for the pressure difference effect is the effect of the viscoelasticity of the fluid abrasive on the pressure during the processing and the pressure drop characteristics of the flow field. The effect of the viscoelasticity of the fluid abrasive on the pressure during the processing is mainly reflected in two aspects: 1. The inlet convergence effect. When the viscoelastic fluid enters the small cross-section flow channel from the large cross-section flow channel, the streamlines converge, and the abrasive undergoes shear deformation and tensile deformation at the same time, resulting in pressure loss including viscous energy loss and elastic energy storage; 2. Extrusion expansion phenomenon. The elastic parts of the two deformations produced by the inlet convergence effect cannot be completely relaxed before leaving the processing section. Therefore, when the viscoelastic fluid leaves the processing section, the cross-sectional area of ​​the flow channel changes from small to large, and the partial elastic deformation of the abrasive is restored, resulting in the expansion of the cross-sectional area of ​​the abrasive flow, and the inlet and outlet pressure difference increases with the increase of the expansion ratio. The pressure drop characteristic means that since the abrasive medium itself has a certain viscosity, the contact and friction between the abrasive medium and the workpiece surface during the flow process will cause the loss of internal energy of the fluid.

[0004] Chinese patent application number 202311209898.9 discloses an abrasive flow machining device for screw polishing and a working method thereof. The abrasive flow machining device disclosed above includes a constraint pipe, one end of the constraint pipe is provided with a fixed box and a screw reduction motor, and the other end of the constraint pipe is connected to the convection section pipe; a screw is assembled in the constraint pipe, a forced feeder is installed on the constraint pipe, the constraint pipe and the convection section pipe are slidably installed on a guide rail, an electric cylinder is slidably installed on the guide rail through a bottom plate, and the electric cylinder is connected to the convection section pipe through a piston. Chinese patent application number 201110060318.5 discloses a single-taper screw circulating polishing extruder. The above-disclosed polishing extruder includes a base, a motor arranged on the base, a gearbox connected to the motor, a single screw connected to the gearbox, a heating sleeve with a feed hopper arranged outside the single screw, and a mold fixing sleeve connected to the heating sleeve. Polishing material is filled between the single screw and the heating sleeve. The single screw is a tapered screw. A polishing material circulation pipe is fixedly installed on the base through a support. One end of the polishing sand circulation pipe is connected to the feed hopper, and the other end is connected to the mold fixing sleeve with a mold arranged inside. A polishing material circulation pipe is fixedly installed on the base through a support. One end of the polishing material circulation pipe is connected to the feed hopper, and the other end is connected to the mold fixing sleeve with a mold arranged inside.

[0005] In the above-disclosed prior art, when polishing the screw, the abrasive moves in the constraint pipe. When the abrasive polishes the screw in the constraint pipe, when it moves from the inlet to the outlet of the constraint pipe, uneven force occurs on the surface of the screw, resulting in a pressure difference effect, which leads to different polishing effects at both ends of the screw, thereby affecting the polishing quality of the screw. Summary of the invention

[0006] The present invention aims to overcome the defects in the above-mentioned prior art and provide an abrasive flow processing device and working method for screw polishing which can adaptively control the pressure difference, ensure uniform force on the screw and improve the polishing effect of the screw.

[0007] In order to achieve the above-mentioned invention objectives, the present invention adopts the following technical scheme: an abrasive flow processing device for screw polishing, comprising a bed, a barrel for loading the screw is provided on the bed, a power component for driving the screw to rotate is provided at one end of the barrel, and a regulating structure is provided at the other end of the barrel; the regulating structure comprises a regulating barrel connected to the inside of the barrel and a discharge port formed on the regulating barrel, a spring and a regulating plate cooperating with the spring for controlling the size of the discharge port are provided in the regulating barrel; a feeding component for providing abrasive to the barrel is connected to the barrel, and a circulation component for circulating the abrasive is connected to the barrel.

[0008] As a preferred solution of the present invention, the barrel is suspended on the bed, and a moving component for adjusting the position of the barrel is provided on the bed, and the moving component controls the barrel to move along the axial direction of the barrel.

[0009] As a preferred solution of the present invention, the moving assembly includes a slide rail arranged on the bed and a support seat slidably connected to the slide rail, the support seat is provided with a plurality of fixing parts, and the barrel is fixedly arranged on the plurality of fixing parts.

[0010] As a preferred solution of the present invention, a feed port and a circulation feed port are formed at the end of the barrel, the feed assembly is connected to the feed port, and the circulation assembly is connected to the circulation feed port.

[0011] As a preferred solution of the present invention, the discharge port is formed in the radial direction of the barrel, and the regulating plate is movably arranged in the regulating barrel along the axial direction of the barrel.

[0012] As a preferred embodiment of the present invention, the feeding assembly includes a silo and a connecting port formed at the bottom of the silo, a stirring shaft is provided in the silo, stirring blades are provided on the stirring shaft along the axial direction of the stirring shaft, and a stirring motor is provided on the top of the silo to drive the stirring shaft to rotate.

[0013] As a preferred solution of the present invention, the circulation component includes a screw pump and a screw pump motor for driving the screw pump to operate, and the screw pump is connected to a circulation pipeline.

[0014] As a preferred solution of the present invention, the screw pump is connected to a first connecting pipe connected to the discharge port, and the tail end of the circulation pipeline is provided with a second connecting pipe connected to the circulation feed port.

[0015] As a preferred solution of the present invention, the power assembly includes a power motor and a fixing box for fixing the barrel, and the screw passes through the fixing box and is connected to the output end of the power motor.

[0016] A working method of an abrasive flow machining device for screw polishing comprises the following steps: S1. Install the end of the screw on the power assembly, and install the barrel on the moving assembly. Under the action of the moving assembly, move the barrel to the barrel, realize the sleeve connection of the barrel outside the screw, and set the initial position of the spring of the regulating structure; S2, adding abrasive into the silo of the feeding assembly, and starting the stirring motor, the power motor and the screw pump motor; S3. Driven by the power motor and the screw pump motor, the abrasive of the entire device begins to circulate in one direction, and the regulating structure controls the back pressure of the discharge port through the reciprocating telescopic motion of the spring; S4. After processing, the barrel moves away from the power motor through the moving assembly to completely expose the screw and check whether the screw polishing quality is qualified.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. A regulating structure is provided at the tail end of the barrel. When the abrasive moves in the barrel and polishes the screw, the abrasive at the tail end of the barrel abuts against the regulating plate of the regulating structure. The regulating plate is driven to move under the action of the abrasive flow pressure. At the same time, the regulating plate is connected to the spring. Under the action of the spring and the abrasive, the regulating plate moves back and forth at the discharge port, thereby adjusting the size of the discharge port, realizing automatic regulation of the pressure at the discharge port, and then realizing autonomous control of the pressure difference at both ends of the barrel, avoiding uneven force on the screw and improving the polishing effect of the screw; 2. Furthermore, a circulation assembly is connected at both ends of the barrel. The abrasive coming out of the rear end of the barrel is transported to the end of the barrel through the first connecting pipe, the circulation pipe and the second connecting pipe under the action of the screw pump and the screw pump motor, and re-enters the barrel from the circulation feed port of the barrel to polish the screw, thereby realizing the circulation of the abrasive, saving the use of the abrasive, and thus saving the cost; 3. Furthermore, the barrel is fixed by the fixing parts on the moving assembly, and the movement of the barrel is controlled under the cooperation of the support seat and the slide rail, thereby facilitating the disassembly of the screw and improving the work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 It is a schematic diagram of the structure of the barrel of the present invention; Figure 3 It is a structural schematic diagram of the feeding assembly of the present invention; Figure 4 This is a schematic diagram of the regulatory structure. Figure markings: power assembly 1, power motor 101, fixed box 102, barrel 2, feed port 201, circulation feed port 202, moving assembly 3, support seat 301, slide rail 302, fixing part 303, feeding assembly 4, silo 401, connecting port 4011, stirring motor 402, stirring shaft 403, stirring blade 404, regulating structure 5, regulating barrel 501, discharge port 5011, regulating plate 502, spring 503, circulation assembly 6, screw pump 601, screw pump motor 602, circulation pipeline 603, second connecting pipe 604, first connecting pipe 605, bed 7. DETAILED DESCRIPTION

[0019] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0020] like Figure 1-Figure 4 As shown, an abrasive flow processing device for screw polishing includes a bed 7, on which is provided a barrel 2 for loading the screw, one end of the barrel 2 is provided with a power component 1 for driving the screw to rotate, and the other end of the barrel 2 is provided with a regulating structure 5; the regulating structure 5 includes a regulating barrel 501 connected to the inside of the barrel 2 and a discharge port 5011 formed on the regulating barrel 501, and the regulating barrel 501 is provided with a spring 503 and a regulating plate 502 that cooperates with the spring 503 to control the size of the discharge port 5011; the barrel 2 is connected with a feeding component 4 for providing abrasive to the barrel 2, and the barrel 2 is connected with a circulation component 6 for circulating abrasive.

[0021] Furthermore, the entire device is mounted on the bed 7 by bolts, the power component 1 drives the screw to rotate, the abrasive is added into the barrel 2 through the feeding component 4, the abrasive moves in the barrel 2, and continuously polishes the surface of the screw, and a regulating structure 5 is connected to the tail end of the barrel 2. When the abrasive moves in the barrel 2 and polishes the screw, the abrasive at the tail end of the barrel 2 abuts against the regulating plate 502 of the regulating structure 5, and under the action of pressure, the regulating plate 502 is driven to move along the axial direction of the regulating barrel 501. At the same time, the regulating plate 502 is connected to the spring 503. Under the action of the spring 503 and the abrasive, the regulating plate 502 moves back and forth at the discharge port 5011, thereby adjusting the size of the discharge port 5011, realizing automatic regulation of the pressure at the discharge port 5011, and then realizing autonomous control of the pressure difference at both ends of the barrel 2, avoiding uneven force on the screw, and improving the polishing effect of the screw.

[0022] The barrel 2 is suspended on the bed 7, and a moving component 3 for adjusting the position of the barrel 2 is provided on the bed 7. The moving component 3 controls the movement of the barrel 2 along the axial direction of the barrel 2. Furthermore, the moving component 3 is used to fix the barrel 2 and control the movement of the barrel 2 along the axial direction of the barrel 2, which facilitates the installation and disassembly of the screw.

[0023] Specifically, the moving assembly 3 includes a slide rail 302 arranged on the bed 7 and a support seat 301 slidably connected to the slide rail 302. The support seat 301 is provided with a plurality of fixing parts 303, and the barrel 2 is fixedly arranged on the plurality of fixing parts 303. Furthermore, the slide rail 302 is arranged along the axial direction of the barrel 2, and the support seat 301 is slidably connected to the slide rail 302. The fixing part 303 is used to fix the barrel 2. A plurality of fixing parts 303 are arranged on the support seat 301, and the plurality of fixing parts 303 are distributed along the length direction of the barrel 2. Under the action of the fixing part 303, the barrel 2 is fixed. At the same time, through the plurality of fixing parts 303, the barrel 2 will not shake during the grinding and polishing of the screw, thereby ensuring the stability of the barrel 2. In addition, the fixing part 303 is spliced ​​by two semicircular fixing plates. The barrel 2 is located between the two fixing plates. The two fixing plates are connected by bolts. The barrel 2 is fixed by the two fixing plates, so that it can be suitable for fixing barrels 2 of different diameters.

[0024] A feed port 201 and a circulation feed port 202 are formed at the end of the barrel 2, the feed component 4 is connected to the feed port 201, and the circulation component 6 is connected to the circulation feed port 202. Furthermore, the feed port 201 and the circulation feed port 202 are located at the same end of the barrel 2, the abrasive in the feed component 4 enters the barrel 2 through the feed port 201, and the abrasive in the circulation component 6 enters the barrel 2 through the circulation feed port 202.

[0025] The discharge port 5011 is formed in the radial direction of the barrel 2, and the regulating plate 502 is movably arranged in the regulating barrel 501 along the axial direction of the barrel 2. Furthermore, the regulating barrel 501 is coaxially arranged with the barrel 2, and the regulating plate 502 is located at the discharge port 5011. The regulating plate 502 reciprocates along the axial direction of the regulating barrel 501, thereby realizing the adjustment of the size of the discharge port 5011.

[0026] Furthermore, by adjusting the parameters of the spring 503, namely the stiffness coefficient and the original length of the spring, the spring 503 can perform telescopic motion to apply a certain back pressure to the internal cavities of the regulating cylinder 501 and the barrel 2. The reciprocating motion of the spring 503 controls the gap between the regulating plate 502 and the discharge port 5011, thereby controlling the size of the back pressure. Ultimately, the pressure difference between the discharge port 5011 and the feed port 201 is maintained within the target value, so that the pressure difference flowing through the screw tends to be stable.

[0027] The feeding assembly 4 includes a silo 401 and a connecting port 4011 formed at the bottom of the silo 401. A stirring shaft 403 is provided in the silo 401. A stirring blade 404 is provided on the stirring shaft 403 along the axial direction of the stirring shaft 403. A stirring motor 402 is provided on the top of the silo 401 to drive the stirring shaft 403 to rotate. Furthermore, the inner diameter of the silo 401 gradually decreases from top to bottom, and the stirring shaft 403 is vertically arranged. The stirring motor 402 drives the stirring shaft 403 to rotate, thereby driving the stirring blade 404 to rotate, and then driving the abrasive in the silo 401 to rotate, so that the abrasive continuously enters the barrel 2, thereby increasing the speed at which the abrasive enters the barrel 2, and also avoiding the abrasive from being blocked at the connecting port 401.

[0028] The circulation component 6 includes a screw pump 601 and a screw pump motor 602 for driving the screw pump 601 to operate. The screw pump 601 is connected to a circulation pipe 603. Furthermore, the screw pump 601 is connected to a first connecting pipe 605 connected to the discharge port 5011. The tail end of the circulation pipe 603 is provided with a second connecting pipe 604 connected to the circulation feed port 202. The abrasive enters the first connecting pipe 605 through the discharge port 5011. The screw pump motor 602 drives the screw pump 601 to operate, thereby transporting the abrasive to the circulation pipe 603. At the same time, the abrasive enters the barrel 2 through the second connecting pipe 604 and the circulation feed port 202, thereby realizing the circulation of the abrasive.

[0029] The power assembly 1 includes a power motor 101 and a fixed box 102 for fixing the barrel 2. The screw passes through the fixed box 102 and is connected to the output end of the power motor 101. Furthermore, the power motor 101 is located at the end of the barrel 2. The screw passes through the fixed box 102 and is connected to the power motor 101. The screw is driven to rotate by the power motor 101, and the barrel 2 is installed on the fixed box 102 through a connecting flange.

[0030] A working method of an abrasive flow machining device for screw polishing comprises the following steps: S1, install the end of the screw on the power assembly 1, and install the barrel 2 on the moving assembly 3, move the barrel 2 to the barrel 2 under the action of the moving assembly 3, realize the sleeve connection of the barrel 2 outside the screw, and set the initial position of the spring 503 of the regulating structure 5; Specifically, the screw is installed in the barrel 2 and connected to the power motor 101, the barrel 2 is installed and fixed by the fixing member 303, the barrel 2, the regulating structure 5, the first connecting pipe 605, the screw pump 601, the circulation pipe 603, and the second connecting pipe 604 are connected in sequence; the initial position of the spring 503 of the regulating structure 5 is set.

[0031] S2, adding abrasive into the silo 401 of the feeding assembly 4, starting the stirring motor 402, the power motor 101 and the screw pump motor 602; The stirring motor 402 drives the stirring shaft 403 to rotate, and the stirring blades 404 on the stirring shaft 403 drive the abrasive to continuously enter the barrel 2; the power motor 101 drives the screw to rotate, driving the abrasive to flow through the screw in the positive direction along the barrel 2 to polish the screw. When the abrasive in the barrel 2 enters the regulating barrel 501 of the regulating structure 5, the spring 503 is squeezed by the abrasive pressure at the discharge port 5011 and retracts, and the gap between the regulating plate 502 and the discharge port 5011 increases. When the abrasive enters the screw pump 601, the screw pump motor 602 drives the abrasive back to the barrel 2 in the negative direction through the circulation pipe 603 until all the abrasive completely enters the barrel 2 and fills the cavity of the entire device, completing the loading work.

[0032] S3. Driven by the power motor 101 and the screw pump motor 602, the abrasive of the entire device begins to circulate in one direction, and the regulating structure 5 controls the back pressure of the discharge port 5011 through the reciprocating telescopic motion of the spring 503; The control strategy of the pressure difference uniformity of the abrasive flow field is as follows: the power motor 101 pushes the abrasive into the barrel 2, and the power motor 101 controls the pressure at the feed port 201 to keep it at a constant value. When the abrasive flow is affected by the viscoelastic properties of the fluid abrasive and the pressure drop characteristics of the flow field during the processing, the pressure at the discharge port 5011 drops suddenly, and a pressure difference effect occurs at the inlet and outlet. After the spring 503 is selected according to the target pressure difference value, when the pressure difference exceeds the set value, that is, the discharge port 50 When the pressure at 11 is too small, the spring 503 extends to push the regulating plate 502, thereby reducing the area at the abrasive outlet 5011, reducing the expansion ratio of the abrasive flow, and suppressing the extrusion expansion phenomenon; when the pressure difference is too small, that is, the pressure at the outlet 5011 is too large, the spring 503 retracts and pulls back the regulating plate 502, increasing the area at the abrasive outlet 5011, increasing the expansion ratio of the abrasive flow, and enhancing the extrusion expansion phenomenon, thereby performing real-time regulation of the pressure difference through real-time changes in the area of ​​the outlet 5011.

[0033] S4. After the processing is completed, the barrel 2 is moved away from the power motor 101 through the moving assembly 3 to completely expose the screw to check whether the polishing quality of the screw is qualified.

[0034] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one 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 present invention; therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

[0035] Although the following terms are used more frequently in this article: power assembly 1, power motor 101, fixed box 102, barrel 2, feed port 201, circulation feed port 202, moving assembly 3, support seat 301, slide rail 302, fixing part 303, feeding assembly 4, silo 401, connecting port 4011, stirring motor 402, stirring shaft 403, stirring blade 404, regulating structure 5, regulating barrel 501, discharge port 5011, regulating plate 502, spring 503, circulation assembly 6, screw pump 601, screw pump motor 602, circulation pipeline 603, second connecting pipe 604, first connecting pipe 605, bed 7, etc., the possibility of using other terms is not excluded. These terms are used only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional restrictions is contrary to the spirit of the present invention.

Claims

1. An abrasive flow machining device for screw polishing, characterized in that: The invention comprises a bed (7), wherein a barrel (2) for loading a screw is arranged on the bed (7), a power assembly (1) for driving the screw to rotate is arranged at one end of the barrel (2), and a regulating structure (5) is arranged at the other end of the barrel (2); the regulating structure (5) comprises a regulating barrel (501) connected to the inside of the barrel (2) and a discharge port (5011) formed on the regulating barrel (501), a spring (503) and a regulating plate (502) matched with the spring (503) for controlling the size of the discharge port (5011) are arranged in the regulating barrel (501); a feeding assembly (4) for providing abrasives to the barrel (2) is connected to the barrel (2), and a circulation assembly (6) for circulating abrasives is connected to the barrel (2).

2. An abrasive flow machining device for screw polishing according to claim 1, characterized in that: The barrel (2) is suspended on the bed (7), and a moving assembly (3) for adjusting the position of the barrel (2) is provided on the bed (7). The moving assembly (3) controls the barrel (2) to move along the axial direction of the barrel (2).

3. The abrasive flow machining device for screw polishing according to claim 1, characterized in that: The moving assembly (3) comprises a slide rail (302) arranged on a bed (7) and a support seat (301) slidably connected to the slide rail (302); a plurality of fixing members (303) are arranged on the support seat (301); and the barrel (2) is fixedly arranged on the plurality of fixing members (303).

4. The abrasive flow machining device for screw polishing according to claim 1, characterized in that: The end of the barrel (2) is formed with a feed port (201) and a circulation feed port (202); the feed component (4) is connected to the feed port (201); and the circulation component (6) is connected to the circulation feed port (202).

5. The abrasive flow machining device for screw polishing according to claim 1, characterized in that: The discharge port (5011) is formed in the radial direction of the barrel (2), and the regulating plate (502) is movably arranged in the regulating barrel (501) along the axial direction of the barrel (2).

6. The abrasive flow machining device for screw polishing according to claim 1, characterized in that: The feeding assembly (4) comprises a silo (401) and a connecting port (4011) formed at the bottom of the silo (401); a stirring shaft (403) is arranged in the silo (401); a stirring blade (404) is arranged on the stirring shaft (403) along the axial direction of the stirring shaft (403); and a stirring motor (402) is arranged at the top of the silo (401) to drive the stirring shaft (403) to rotate.

7. The abrasive flow machining device for screw polishing according to claim 4, characterized in that: The circulation component (6) comprises a screw pump (601) and a screw pump motor (602) for driving the screw pump (601) to operate, and a circulation pipeline (603) is connected to the screw pump (601).

8. The abrasive flow machining device for screw polishing according to claim 7, characterized in that: The screw pump (601) is connected to a first connecting pipe (605) in communication with a discharge port (5011), and a second connecting pipe (604) in communication with a circulation feed port (202) is provided at the tail end of the circulation pipeline (603).

9. The abrasive flow machining device for screw polishing according to claim 1, characterized in that: The power assembly (1) comprises a power motor (101) and a fixing box (102) for fixing the barrel (2); the screw passes through the fixing box (102) and is connected to the output end of the power motor (101).

10. A method for operating an abrasive flow machining device for screw polishing, characterized in that: An abrasive flow machining device for screw polishing according to any one of claims 1 to 9, comprising the following steps: S1. Install the end of the screw on the power assembly (1), and install the barrel (2) on the moving assembly (3). Under the action of the moving assembly (3), move the barrel (2) to the barrel (2), so that the barrel (2) is sleeved outside the screw, and set the initial position of the spring (503) of the regulating structure (5); S2, adding abrasive into the silo (401) of the feeding assembly (4), starting the stirring motor (402), the power motor (101) and the screw pump motor (602); S3. Driven by the power motor (101) and the screw pump motor (602), the abrasive of the entire device begins to circulate in one direction, and the regulating structure (5) controls the back pressure of the discharge port (5011) through the reciprocating telescopic motion of the spring (503); S4. After the processing is completed, the barrel (2) is moved away from the power motor (101) through the moving assembly (3) to completely expose the screw and check whether the polishing quality of the screw is qualified.

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