Feeding formula of soft magnetic powder forming part for electromagnetic valve and preparation method of soft magnetic powder forming part

Abstract

The invention relates to the technical field of metal powder injection molding, in particular to a feeding formula of a soft magnetic powder molding part for an electromagnetic valve and a preparation method of the soft magnetic powder molding part for the electromagnetic valve. The binder comprises the following raw materials in percentage by mass: 86% of polyformaldehyde (POM), 5% of polyethylene (PE), 3% of polypropylene (PP), 1.5% of stearic acid, 1.5% of antioxidant and 3% of paraffin, and the soft magnetic powder comprises the following raw material: FeNi50.

Description

Technical Field

[0001] The invention relates to the technical field of metal powder injection molding, in particular to a feeding formula of a soft magnetic powder molding part for an electromagnetic valve and a preparation method thereof. Background Art

[0002] Solenoid valve switches are widely used in the field of automation, and they play an important role in industrial automation control systems. However, there are some technical problems in the existing CNC process for producing solenoid valve switches and other related solenoid valve soft magnetic parts. These problems mainly include the cumbersome production process, low production efficiency, and material waste, which leads to high costs.

[0003] First of all, the production process of CNC technology is usually complicated, which not only includes multiple steps such as programming, setting, processing and post-processing, but also requires precise control and operation in each step. This cumbersome process not only increases production time, but also requires highly skilled operators to operate, further increasing labor costs.

[0004] Secondly, due to the complexity of the CNC process and multi-step operation, the production efficiency is relatively low, and the processing time of each part is long, which cannot meet the needs of large-scale production, which to a certain extent limits the market supply capacity of solenoid valve switches.

[0005] In addition, the CNC process will generate a large amount of material waste during the processing. Since the raw materials are cut into the required shape by cutting processing, a large amount of material is cut away to form waste, resulting in low material utilization. Especially when processing parts with complex shapes, material waste is more serious.

[0006] Therefore, a feeding formula and a preparation method of soft magnetic powder molding parts for electromagnetic valves are proposed. Summary of the invention

[0007] In order to overcome the deficiencies of the prior art, the present invention provides a feeding formula for soft magnetic powder molding parts for solenoid valves and a preparation method thereof.

[0008] To solve the above technical problems, the present invention provides the following technical solutions: a feeding formula for soft magnetic powder molded parts for solenoid valves, comprising the following materials in mass ratio: 9% binder and 91% soft magnetic powder, the binder comprising the following raw materials in mass ratio: 86% polyoxymethylene (POM), 5% polyethylene (PE), 3% polypropylene (PP), 1.5% stearic acid, 1.5% antioxidant and 3% paraffin, the soft magnetic powder comprising the following raw materials: FeN i50.

[0009] A method for preparing a soft magnetic powder molded part for a solenoid valve comprises the following steps:

[0010] S1. Add raw materials into a mixer according to the feeding formula, mix, and then extrude and granulate to obtain MIM raw materials.

[0011] S2. Pour the MIM raw material into an injection molding machine, heat it to the melting temperature, inject the molten raw material into the mold, cool it and shape it, and take it out from the mold after shaping to obtain a green body.

[0012] S3, sending the raw embryo into a degreasing tank to remove part of the binder, and then sending it into a degreasing furnace to remove the remaining binder to obtain a brown embryo.

[0013] S4. The brown blank is sent into a sintering furnace. The sintering temperature is controlled just below the melting point of the metal, so that the metal powder is fused together to form a whole, and a solenoid valve soft magnetic part is obtained.

[0014] S5. Use flat grinding technology to process the flat surface of the solenoid valve soft magnetic parts that need to be sealed.

[0015] As a preferred technical solution of the present invention, the following steps are also included between S4 and S5:

[0016] S4.5. When the solenoid valve soft magnetic parts are bent and deformed during sintering, the solenoid valve soft magnetic parts are placed in a special imitation shaping mold installed on a four-column hydraulic press and shaped with the pressure of the four-column hydraulic press.

[0017] As a preferred technical solution of the present invention, S1 also includes the following steps:

[0018] S101. Before feeding, open the press for 10 minutes to allow the water vapor to evaporate before granulating.

[0019] S102, preheat the mixer to 185-195°C.

[0020] S103, pour in half the mass ratio of soft magnetic powder.

[0021] S104, pour in a binder having a certain mass ratio.

[0022] S105, slow stirring, the specific parameter is 15-20r / min.

[0023] S106. After 20 minutes, add the remaining soft magnetic powder.

[0024] S107, increase the stirring speed, the specific parameter is 25-35r / min, after stirring for 30-40 minutes, the raw material becomes maltose-like, let it stand and observe the state every 10 minutes, lower the set temperature to 160-170℃, open the pressure head to let the water vapor evaporate, use a scraper to scrape off the soft magnetic powder or binder in the dead corner, and then extrude and granulate.

[0025] As a preferred technical solution of the present invention, the mold in S2 is designed to increase a process gap on the flat grinding surface of the green body, and the size of the process gap is larger than the processing amount of flat grinding, so that the burrs produced by flat grinding will not protrude from the process gap.

[0026] As a preferred technical solution of the present invention, the method also includes a flat grinding device, including an electric power control cabinet, a control circuit is arranged in the electric power control cabinet, a rotary worktable is rotatably installed on the table of the electric power control cabinet, a driving mechanism for driving the rotary worktable to rotate with a fixed torque is installed in the electric power control cabinet, a plurality of clamps for clamping the solenoid valve soft magnetic parts are equidistantly installed on the table of the rotary worktable, a clamping groove adapted to the solenoid valve soft magnetic parts is opened on the clamp, a flat grinding component for grinding the sealing surface of the solenoid valve soft magnetic parts is installed on the table of the electric power control cabinet, and the flat grinding component includes a fixed end, a lifting end, and a lower end. The grinding wheel is installed on the transmission shaft of the flat grinding motor, and the grinding depth is adjusted by lifting and lowering the lifting end, the feed amount is adjusted by extending and retracting the pushing end, and the grinding speed is adjusted by controlling the speed of the flat grinding motor. An industrial camera table is installed on one side of the flat grinding component of the table top of the power control cabinet, and an industrial camera is installed on the industrial camera table. A hole is opened in the middle of the rotating workbench and a dust suction pipe is rotatably installed. A number of dust suction holes are opened on the surrounding side of the dust suction pipe. A dust suction device is installed in the power control cabinet and the dust suction end is connected to the dust suction pipe.

[0027] As a preferred technical solution of the present invention, S5 includes the following steps:

[0028] S501. The solenoid valve soft magnetic parts are fixed in the fixture after loading. The rotary table rotates at a fixed torque to make the solenoid valve soft magnetic parts correspond to the flat grinding assembly. The flat grinding motor drives the grinding wheel to rotate. The telescopic motor pushes the flat grinding motor to move toward the solenoid valve soft magnetic parts, so that the grinding wheel can grind the surface of the solenoid valve soft magnetic parts.

[0029] S502. An industrial camera takes a picture of the solenoid valve soft magnetic part after flat grinding. After image processing and analysis, relevant values ​​of the surface roughness, flatness and burr length of the solenoid valve soft magnetic part are obtained.

[0030] S503, setting a threshold for the burr length, and assigning weights to the effects of grinding depth, grinding speed and feed rate on the burr length according to the expert evaluation method; when the burr length reaches the threshold, respectively reducing the parameters of grinding depth, grinding speed and feed rate according to the assigned weight ratio, so that the control circuit adjusts the frequency, height and advancement speed of the flat grinding motor to ensure that the burr does not exceed the process gap.

[0031] S504, setting thresholds for surface roughness and flatness, and when the thresholds are reached, increasing the parameters of grinding depth, grinding speed and feed rate respectively according to the assigned weight ratios.

[0032] S505: When the values ​​of burr length, surface roughness and flatness all reach the threshold, the machine needs to be stopped and the flat grinding assembly and grinding wheel need to be maintained or replaced.

[0033] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0034] 1. Through the design of feeding formula, the solenoid valve soft magnetic parts prepared by MIM can meet the performance requirements of the solenoid valve when in use. By taking advantage of the advantages of MIM preparation, the preparation process is simplified, the labor cost and production time are reduced, and large quantities of solenoid valve soft magnetic parts can be produced at the same time, greatly improving production efficiency.

[0035] 2. By adding the flat grinding process and the setting of process gaps after the traditional steps of preparing the solenoid valve soft magnetic parts by MIM, the surface roughness and flatness required for the sealing of the solenoid valve soft magnetic parts are ensured. At the same time, the post-processing process only requires flat grinding of one surface, which also saves the step of removing burrs, making the process simple and efficient, while reducing the waste of raw materials and helping to reduce costs.

[0036] 3. Through the setting of the flat grinding component and the industrial camera platform, the relevant values ​​of the flat grinding status of the solenoid valve soft magnetic parts can be obtained in real time, and the relevant parameters of the flat grinding component can be set to ensure that the solenoid valve soft magnetic parts reach a qualified and uniform quality level, and the stability information of the flat grinding component and the grinding wheel can be fed back in time to avoid the appearance of large quantities of defective products. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the process of the preparation method of the present invention;

[0038] Figure 2 It is a structural schematic diagram of the flat grinding equipment of the preparation method of the present invention;

[0039] Figure 3 It is a schematic structural diagram of the flat grinding assembly of the present invention.

[0040] Among them: 1. Power control cabinet; 2. Rotating workbench; 3. Clamp; 4. Surface grinding assembly; 41. Fixed table; 42. Linear guide rail 1; 43. Lifting table; 44. Linear guide rail 2; 45. Motor frame; 46. Motor; 47. Screw; 48. Motor frame; 49. Telescopic motor; 5. Industrial camera platform; 6. Dust suction pipe; 7. Surface grinding motor. DETAILED DESCRIPTION

[0041] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below in conjunction with specific embodiments, but the following embodiments are only preferred embodiments of the present invention, not all. Based on the embodiments in the implementation mode, other embodiments obtained by those skilled in the art without creative work all belong to the protection scope of the present invention. The experimental methods in the following embodiments, unless otherwise specified, are conventional methods, and the materials, reagents, etc. used in the following embodiments, unless otherwise specified, can all be obtained from commercial channels.

[0042] Embodiment: Figure 1-3 As shown, a feeding formula for soft magnetic powder molding parts for solenoid valves includes the following materials in mass ratio: 9% binder and 91% soft magnetic powder, the binder includes the following raw materials in mass ratio: 86% polyoxymethylene POM, 5% polyethylene PE, 3% polypropylene PP, 1.5% stearic acid, 1.5% antioxidant and 3% paraffin, and the soft magnetic powder includes the following raw materials: FeN i50.

[0043] A method for preparing a soft magnetic powder molded part for a solenoid valve comprises the following steps:

[0044] S1. Add raw materials into a mixer according to the feeding formula, mix, and then extrude and granulate to obtain MIM raw materials.

[0045] S2. Pour the MIM raw material into an injection molding machine, heat it to the melting temperature, inject the molten raw material into the mold, cool it and shape it, and take it out from the mold after shaping to obtain a green body.

[0046] S3, sending the raw embryo into a degreasing tank to remove part of the binder, and then sending it into a degreasing furnace to remove the remaining binder to obtain a brown embryo.

[0047] S4. The brown blank is sent into a sintering furnace. The sintering temperature is controlled just below the melting point of the metal, so that the metal powder is fused together to form a whole, and a solenoid valve soft magnetic part is obtained.

[0048] S4.5. When the solenoid valve soft magnetic parts are bent and deformed during sintering, they are placed in a special imitation shaping mold installed on a four-column hydraulic press and shaped with the pressure of the four-column hydraulic press to ensure the product size and functional requirements and meet the appearance requirements after assembly.

[0049] S5. The plane of the solenoid valve soft magnetic parts needs to be sealed during use. However, during the shrinkage process of sintering, the surface requirements for sealing cannot be met. Therefore, the flat grinding process is used to process the plane of the solenoid valve soft magnetic parts that need to be sealed. The surface requirements for the solenoid valve soft magnetic parts are flatness 0.02 and roughness Ra0.6, so as to meet the sealing requirements.

[0050] S1 also includes the following steps:

[0051] S101. Before feeding, open the press for 10 minutes to allow the water vapor to evaporate before granulating.

[0052] S102, preheat the mixer to 185-195°C.

[0053] S103, pour in half the mass ratio of soft magnetic powder.

[0054] S104, pour in a binder having a certain mass ratio.

[0055] S105, slow stirring, the specific parameter is 15-20r / min.

[0056] S106. After 20 minutes, add the remaining soft magnetic powder.

[0057] S107, increase the stirring speed, the specific parameter is 25-35r / min, after stirring for 30-40 minutes, the raw material becomes maltose-like, let it stand and observe the state every 10 minutes, lower the set temperature to 160-170℃, open the pressure head to let the water vapor evaporate, use a scraper to scrape off the soft magnetic powder or binder in the dead corner, and then extrude and granulate.

[0058] During the flat grinding process, due to the low hardness of the soft magnetic material, edge burrs will be generated and difficult to remove. In order to avoid this phenomenon from having an adverse effect on actual use, the mold in S2 is designed to increase the process gap on the flat grinding surface of the green body. The size of the process gap is larger than the processing amount of flat grinding, so that the burrs generated by flat grinding will not protrude from the process gap.

[0059] like Figure 2 and Figure 3As shown, the method also includes a flat grinding device, which is characterized in that it includes an electric power control cabinet 1, a control circuit is arranged in the electric power control cabinet 1, a rotary table 2 is rotatably installed on the table top of the electric power control cabinet 1, a driving mechanism for driving the rotary table 2 to rotate with a fixed torque is installed in the electric power control cabinet, the driving mechanism for driving the rotary table 2 to rotate with a fixed torque is an existing well-known technology, usually composed of a motor and a gear set, which will not be described in detail here, a plurality of clamps 3 for clamping the solenoid valve soft magnetic parts are equidistantly installed on the table top of the rotary table 2, a clamping groove adapted to the solenoid valve soft magnetic parts is opened on the clamp 3, and the overall height of the clamping groove is slightly lower than the solenoid valve soft magnetic parts, and a flat grinding component for grinding the sealing surface of the solenoid valve soft magnetic parts is installed on the table top of the electric power control cabinet 1 4, the flat grinding assembly 4 includes a fixed end, a lifting end, a propulsion end and a flat grinding motor 7, the grinding wheel is installed on the transmission shaft of the flat grinding motor 7, the grinding depth is adjusted by lifting and lowering the lifting end, the feed amount is adjusted by telescoping the propulsion end, and the grinding speed is adjusted by speed control of the flat grinding motor 7. Specifically, the fixed end includes a fixed table 41, the fixed table 41 is fixedly installed on the table of the power control cabinet 1, and a linear guide rail 42 is installed on the fixed table 41. The lifting end includes a lifting platform 43, the lifting platform 43 is installed on the moving part of the linear guide rail 42, and the bottom surface of the lifting platform 43 is installed with a linear guide rail 2 44. The propulsion end includes a motor frame 45, and the motor frame 45 is installed on the moving part of the linear guide rail 2 44 The flat grinding motor 7 is installed on the motor frame 45, the fixed table 41 is installed with a motor 46, the transmission shaft of the motor 46 is installed with a screw 47, the screw 47 is threadedly connected with a motor frame 48, the motor frame 48 is installed with a telescopic motor 49, the transmission shaft of the telescopic motor 49 is connected to the motor frame 45, the table of the power control cabinet 1 is installed with an industrial camera table 5 on one side of the flat grinding component 4, the middle of the rotating workbench 2 is opened and a dust suction pipe 6 is rotatably installed, a plurality of dust suction holes are opened on the surrounding side of the dust suction pipe 6, a dust suction device is installed in the power control cabinet 1 and the dust suction end is connected to the dust suction pipe 6, an industrial camera is installed on the industrial camera table 5, and the industrial camera is used to shoot the surface of the solenoid valve soft magnetic parts to obtain the grinding effect and roughness. The length of the edge, the number of industrial cameras can be multiple and the positions and angles can be different, so that the three data of the burr length, surface roughness and flatness of the solenoid valve soft magnetic parts can be obtained after processing. Based on the above industrial cameras, image acquisition cards, computers and other equipment, an embedded machine vision system is formed, which can obtain the surface roughness, flatness and burr length of the solenoid valve soft magnetic parts after polishing by shooting. The specific machine vision system is an existing public technology and will not be described in detail here. It should be noted that the movement amplitude of the equipment and structure of the present application is controlled by setting sensors, and the sensor control method is an existing public technology and will not be described in detail here. In addition, the loading and unloading functions of the present application can be realized by adding a robot or manually, and the present application does not limit it.After grinding, the solenoid valve soft magnetic parts rotate at a fixed moment on the rotary table 2 to correspond to the industrial camera table 5. The industrial camera takes photos of the solenoid valve soft magnetic parts after grinding. According to the photos, it is judged whether the grinding effect and burrs are within a reasonable range. When the burrs are too much or the grinding effect is not good, the control circuit adjusts the frequency, height and propulsion speed of the flat grinding motor to adjust the grinding depth, grinding speed and feed rate to adapt and adjust the best grinding effect, grinding efficiency and burr amount.

[0060] S5 includes the following steps:

[0061] S501, the solenoid valve soft magnetic parts are fixed in the fixture 3 after loading, the rotating worktable 2 rotates at a fixed torque to make the solenoid valve soft magnetic parts correspond to the flat grinding assembly, the flat grinding motor 7 drives the grinding wheel to rotate, and the telescopic motor 49 pushes the flat grinding motor 7 to move toward the solenoid valve soft magnetic parts, so that the grinding wheel can grind the surface of the solenoid valve soft magnetic parts.

[0062] S502. An industrial camera takes a picture of the solenoid valve soft magnetic part after flat grinding. After image processing and analysis, relevant values ​​of the surface roughness, flatness and burr length of the solenoid valve soft magnetic part are obtained.

[0063] S503, setting a threshold for the burr length, and assigning weights to the effects of grinding depth, grinding speed and feed rate on the burr length according to the expert evaluation method; when the burr length reaches the threshold, respectively reducing the parameters of grinding depth, grinding speed and feed rate according to the assigned weight ratio, so that the control circuit adjusts the frequency, height and advancement speed of the flat grinding motor to ensure that the burr does not exceed the process gap.

[0064] S504, setting thresholds for surface roughness and flatness, and when the thresholds are reached, increasing the parameters of grinding depth, grinding speed and feed rate respectively according to the assigned weight ratios.

[0065] S505. When the values ​​of burr length, surface roughness and flatness all reach the threshold value, the machine needs to be stopped, and the flat grinding assembly 4 and the grinding wheel need to be maintained or replaced.

[0066] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto, and various changes can be made within the knowledge scope of technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A feeding formula for soft magnetic powder molding parts for solenoid valves, characterized in that: The material comprises the following materials in proportion by mass: 9% of binder and 91% of soft magnetic powder; The binder includes the following raw materials in mass ratio: 86% of polyoxymethylene (POM), 5% of polyethylene (PE), 3% of polypropylene (PP), 1.5% of stearic acid, 1.5% of antioxidant and 3% of paraffin; The soft magnetic powder includes the following raw materials: FeNi50.

2. A method for preparing soft magnetic powder molded parts for solenoid valves, characterized in that: The steps include: S1, adding raw materials into a mixer according to the feeding formula, mixing, and then extruding and granulating to obtain MIM raw materials; S2, pouring the MIM raw material into an injection molding machine, heating it to the melting temperature, injecting the molten raw material into a mold to cool and shape it, and taking it out from the mold after shaping to obtain a green body; S3, sending the raw embryo into a degreasing tank to remove part of the binder, and then sending it into a degreasing furnace to remove the remaining binder to obtain a brown embryo; S4, sending the brown embryo into the sintering furnace, and controlling the sintering temperature just below the melting point of the metal, so that the metal powder is fused together to form a whole, and the solenoid valve soft magnetic parts are obtained; S5. Use flat grinding technology to process the flat surface of the solenoid valve soft magnetic parts that need to be sealed.

3. The method for preparing a soft magnetic powder molded part for a solenoid valve according to claim 2, characterized in that: The following steps are also included between S4 and S5: S4.

5. When the solenoid valve soft magnetic parts are bent and deformed during sintering, the solenoid valve soft magnetic parts are placed in a special imitation shaping mold installed on a four-column hydraulic press and shaped with the pressure of the four-column hydraulic press.

4. The method for preparing a soft magnetic powder molded part for a solenoid valve according to claim 2, characterized in that: S1 also includes the following steps: S101, before unloading, open the press head for 10 minutes to allow the water vapor to evaporate before granulation; S102, preheat the mixer to 185-195°C; S103, pouring in half the mass ratio of soft magnetic powder; S104, pouring a binder in a mass ratio; S105, slow stirring, the specific parameters are 15-20r / min; S106, after 20 minutes, add the remaining soft magnetic powder; S107, increase the stirring speed, the specific parameter is 25-35r / min, after stirring for 30-40 minutes, the raw material becomes maltose-like, let it stand and observe the state every 10 minutes, lower the set temperature to 160-170℃, open the pressure head to let the water vapor evaporate, use a scraper to scrape off the soft magnetic powder or binder in the dead corner, and then extrude and granulate.

5. The method for preparing a soft magnetic powder molded part for a solenoid valve according to claim 2, characterized in that: The mold in S2 is designed to increase the process gap on the flat grinding surface of the green embryo. The size of the process gap is larger than the processing amount of flat grinding, so that the burrs produced by flat grinding will not protrude from the process gap.

6. A method for preparing a soft magnetic powder molded part for a solenoid valve according to claim 5, the method further comprising a flat grinding device, characterized in that: The invention comprises an electric power control cabinet (1), wherein a control circuit is arranged in the electric power control cabinet (1), a rotary worktable (2) is rotatably mounted on the table of the electric power control cabinet (1), a driving mechanism for driving the rotary worktable (2) to rotate at a fixed moment is installed in the electric power control cabinet, a plurality of clamps (3) for clamping the solenoid valve soft magnetic parts are equidistantly mounted on the table of the rotary worktable (2), a clamping groove adapted to the solenoid valve soft magnetic parts is provided on the clamp (3), and a sealing surface for grinding the solenoid valve soft magnetic parts is installed on the table of the electric power control cabinet (1). The flat grinding assembly (4) comprises a fixed end, a lifting end, a propulsion end and a flat grinding motor (7); the grinding wheel is mounted on a transmission shaft of the flat grinding motor (7); the grinding depth is adjusted by lifting and lowering the lifting end; the feed amount is adjusted by extending and retracting the propulsion end; the grinding speed is adjusted by controlling the rotation speed of the flat grinding motor (7); an industrial camera platform (5) is mounted on the table of the power control cabinet (1) at one side of the flat grinding assembly (4); an industrial camera is mounted on the industrial camera platform (5).

7. The method for preparing a soft magnetic powder molded part for a solenoid valve according to claim 6, characterized in that: A hole is opened in the middle of the rotary workbench (2) and a dust suction pipe (6) is rotatably installed thereon. A plurality of dust suction holes are opened on the peripheral side of the dust suction pipe (6). A dust suction device is installed in the power control cabinet (1) and the dust suction end is connected to the dust suction pipe (6).

8. The method for preparing a soft magnetic powder molded part for a solenoid valve according to claim 7, characterized in that: S5 includes the following steps: S501, the solenoid valve soft magnetic part is fixed in the fixture (3) after loading, the rotary table (2) rotates at a fixed torque to make the solenoid valve soft magnetic part correspond to the flat grinding component, the flat grinding motor (7) drives the grinding wheel to rotate, and the telescopic motor (49) drives the flat grinding motor (7) to move toward the solenoid valve soft magnetic part, so that the grinding wheel can grind the surface of the solenoid valve soft magnetic part; S502, an industrial camera takes a picture of the flat-ground solenoid valve soft magnetic part, and obtains relevant values ​​of the surface roughness, flatness and burr length of the solenoid valve soft magnetic part after image processing and analysis; S503, setting a threshold for the burr length, and assigning weights to the influence of grinding depth, grinding speed and feed rate on the burr length according to the expert evaluation method. When the burr length reaches the threshold, the parameters of grinding depth, grinding speed and feed rate are respectively reduced according to the assigned weight ratio, so that the control circuit adjusts the frequency, height and advancement speed of the flat grinding motor to ensure that the burr does not exceed the process gap. S504, setting thresholds for surface roughness and flatness, and when the thresholds are reached, increasing the parameters of grinding depth, grinding speed, and feed rate respectively according to the assigned weight ratios; S505: When the values ​​of the burr length, surface roughness and flatness all reach the threshold value, the machine needs to be stopped and the flat grinding assembly (4) and the grinding wheel need to be maintained or replaced.

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