Manufacturing method of self-balancing double-end spiral double-screw with symmetrical mass

Abstract

The invention belongs to the technical field of screw manufacturing, and discloses a manufacturing method of a symmetric-mass self-balancing double-end spiral double-screw, which comprises the following manufacturing steps: S1, designing; s2, material selection treatment; s3, numerical control machining; s4, rough grinding; s5, heat treatment; s6, accurate grinding; and S7, warehousing. According to the double-end screw manufactured through the manufacturing method, the geometrical shape of the rotating face is not completely symmetrical, the mass is symmetrical, no matter which combination form is adopted in the direction of the rotating shaft, the spiral body formed by double-end spirals forms the variable-pitch screw, the mass is symmetrically distributed relative to the rotating shaft on the micro-units arranged in the axial direction, and therefore the variable-pitch screw is formed. The mass center is located on the rotation axis, the rotor can be automatically balanced when rotating, and the rotor balance problem of the screw can be solved.

Description

Technical Field

[0001] The invention belongs to the technical field of screw manufacturing, and in particular relates to a method for manufacturing a mass-symmetrical self-balancing double-head helical twin screw. Background Art

[0002] The screw is the core and key component of a dry twin-screw vacuum pump, and the most common style is a single-head spiral. The mass distribution of this type of screw on the radial section is completely asymmetric and biased to one side. The single-head screw must be dynamically balanced before use. After the deweighting method is used for dynamic balancing, a large number of deweighting balancing holes with considerable depth are left on the end face and the outer cylindrical surface. When the vacuum pump is running, the material in the medium will accumulate in these holes, thereby greatly increasing the imbalance. The vibration caused by the unbalanced rotor damages the machine, greatly reduces reliability, requires frequent maintenance, and has a very high failure rate. The root cause is its poor balancing performance. Summary of the invention

[0003] In view of the problems raised by the above background technology, the purpose of the present invention is to provide a method for manufacturing a quality-symmetrical self-balancing double-headed spiral twin-screw.

[0004] In order to achieve the above technical objectives, the technical solution adopted by the present invention is as follows:

[0005] A method for manufacturing a mass-symmetrical self-balancing double-headed spiral twin-screw, comprising the following manufacturing steps:

[0006] S1. Design:

[0007] The mass-symmetrical cross-section design is adopted to ensure that the mass of the micro-units arranged along the axial direction is symmetrically distributed relative to the rotation axis, and the center of mass is accurately positioned on the rotation axis;

[0008] S2. Material selection and processing:

[0009] Select steel with less deformation tendency after oil quenching and process it on a lathe to the required outer diameter and length;

[0010] S3, CNC machining:

[0011] S3.1. Clamp the steel on the machine tool;

[0012] S3.2, call out the spiral processing program from the system,

[0013] S3.3, adjust the parameters of the spiral processing program so that after processing one circle of uniform pitch line, it will process three circles of equal pitch line immediately;

[0014] S3.4, set the screw machining allowance;

[0015] S3.5, start processing;

[0016] S4, coarse grinding:

[0017] Grind the processed outer circle of the screw until the surface roughness meets the design requirements;

[0018] S5. Heat treatment:

[0019] heat treating the screw;

[0020] S6, fine grinding:

[0021] Grind the outer circle of the heat-treated screw until the surface roughness meets the design requirements;

[0022] S7, Warehouse entry:

[0023] After fine grinding, the entire screw is coated with anti-rust grease, completely wrapped with anti-rust film, and then put into storage.

[0024] It is further defined that in step S3, a plurality of parallel spiral lines are firstly processed on the surface of the screw, and then the screw is reciprocated until the depth of the spiral groove reaches the requirement, thereby reducing the tool pressure and ensuring the processing quality.

[0025] It is further defined that in step S3, the process is interrupted and reset at any spiral position in the spiral processing program, and the restarted processing can be immediately continued from the interruption point as specified by the parameters, which is conducive to the tool replacement and parameter fine-tuning in the middle, ensuring the quality of the finished product and flexible processing.

[0026] It is further defined that in step S3, the helical surface is decomposed into a combination of a concave surface and an inclined surface for processing, and an independent CNC program module is written for each concave surface and inclined surface, each module contains all the instructions and parameters required for processing the specific surface, and each module includes but is not limited to being linked by variable assignment, unconditional transfer and conditional transfer. Because the helical surface is a complex three-dimensional surface, it is difficult to process it directly. The decomposition is to simplify the processing process. Based on the geometric characteristics of the helical surface, the concave surface represents the inwardly concave part of the helical surface, and the inclined surface represents the inclined part of the helical surface. For the decomposed concave surface and inclined surface, independent four-axis machining center CNC machining programs are written for them respectively, and each program module contains all the instructions required for processing the surface, such as tool path, cutting parameters, feed speed, etc. In this way, each surface can be processed independently, which improves the flexibility and maintainability of processing;

[0027] Furthermore, in order to enable the independent modules to work together and complete the processing of the entire spiral surface, they need to be linked in a certain way, including but not limited to the following aspects:

[0028] Variable assignment: In CNC programs, variables are used to store key data in the machining process, such as tool position, cutting depth, etc. By transferring these variables between different modules, the continuity and consistency of the machining process can be achieved;

[0029] Unconditional transfer: In some cases, the program needs to automatically jump to another module after executing one module. The unconditional transfer instruction can achieve this function, which enables the program to execute each module in a predetermined order;

[0030] Conditional transfer: Different from unconditional transfer, conditional transfer instruction determines whether to jump to another module based on whether a certain condition is met. This allows the program to make dynamic adjustments according to actual conditions during the processing, improving the flexibility and adaptability of processing;

[0031] In summary, decomposing the spiral surface into concave surface and inclined surface, writing independent CNC machining program modules for each surface, and then linking these modules through variable assignment, unconditional transfer and conditional transfer is an effective method to realize complex spiral surface machining. This method not only improves the flexibility and maintainability of machining, but also helps to optimize the machining process and improve the machining quality.

[0032] It is further defined that in step S3, the program parameters include left-hand parameters and right-hand parameters, and only the rotation direction of the left-hand parameters and the right-hand parameters changes, while other parameters remain unchanged, so that the matching accuracy of the twin screws produced is higher.

[0033] It is further defined that in step S4, a fine steel abrasive belt is used for grinding. The fine steel abrasive belt has good flexibility and can adapt to workpieces of various shapes and curved surfaces, including complex shapes and irregular parts. Compared with other grinding tools, such as diamond grinding wheels, the fine steel abrasive belt has lower cost and longer service life, which reduces processing costs. The fine steel abrasive belt generates less dust during the grinding process and is easy to collect and treat, meeting environmental protection requirements.

[0034] It is further defined that in step S5, the heat treatment includes preheating, heating, cooling and tempering. Specifically, the preheating temperature is 150-200°C. After keeping warm for 1-2 hours, the oil stains on the surface are removed, and then the screw is heated to 900-950°C and kept warm for 1-2 hours. After that, oil cooling is adopted. Finally, the screw is heated to 200-250°C, kept warm for 2-3 hours, and slowly cooled. Such operation effectively changes the internal structure of the steel, significantly improves the mechanical properties of the steel, and enables the steel parts to obtain the required hardness, wear resistance, toughness and other properties to meet different usage scenarios and requirements.

[0035] It is further defined that in step S6, a silicon carbide grinding wheel is used for grinding. The silicon carbide grinding wheel has fine density and good surface roughness, and can grind a high-precision surface. During the fine grinding process, the silicon carbide grinding wheel can ensure that the workpiece reaches the required dimensional accuracy and shape accuracy, thereby improving the processing quality. Moreover, the silicon carbide grinding wheel has uniform particles, does not release harmful substances during the grinding process, has uniform force and does not break the edge, thereby ensuring the quality of the workpiece surface after grinding. The workpiece surface after fine grinding has low surface roughness and high smoothness, which is conducive to subsequent processes such as polishing. Furthermore, the silicon carbide grinding wheel has high hardness and strong wear resistance, and can maintain stable grinding performance during the fine grinding process, thereby improving grinding efficiency. Moreover, due to the high wear resistance of the silicon carbide grinding wheel, it has a long service life, thereby reducing the number and cost of replacing the grinding wheel, thereby reducing production costs.

[0036] The beneficial effects of the present invention are as follows:

[0037] The rotating surface geometry of the double-headed screw manufactured by the manufacturing method of the present invention is not completely symmetrical but symmetrical in mass. The spiral body formed by the double-headed spiral forms a variable pitch screw no matter what combination form is used along the direction of the rotation axis. The mass of the micro-units arranged along the axial direction is symmetrically distributed relative to the rotation axis, and the center of mass is located on the rotation axis. The rotor will automatically balance when rotating, which can solve the rotor balance problem of the screw. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The present invention can be further illustrated by the non-limiting examples given in the accompanying drawings;

[0039] Figure 1 It is a schematic flow chart of an embodiment of a method for manufacturing a mass-symmetrical self-balancing double-headed spiral twin-screw according to the present invention;

[0040] Figure 2 It is a schematic diagram of parts produced by an embodiment of a method for producing a mass-symmetrical self-balancing double-headed spiral twin-screw according to the present invention; DETAILED DESCRIPTION

[0041] In order to enable those skilled in the art to better understand the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0042] like Figure 1 As shown, a method for manufacturing a mass-symmetrical self-balancing double-headed spiral twin-screw of the present invention comprises the following manufacturing steps:

[0043] S1. Design:

[0044] The mass-symmetrical cross-section design is adopted to ensure that the mass of the micro-units arranged along the axial direction is symmetrically distributed relative to the rotation axis, and the center of mass is accurately positioned on the rotation axis;

[0045] S2. Material selection and processing:

[0046] Select steel with less deformation tendency after oil quenching and process it on a lathe to the required outer diameter and length;

[0047] S3, CNC machining:

[0048] S3.1. Clamp the steel on the machine tool;

[0049] S3.2, call out the spiral processing program from the system,

[0050] S3.3, adjust the parameters of the spiral processing program so that after processing one circle of uniform pitch line, it will process three circles of equal pitch line immediately;

[0051] S3.4, set the screw machining allowance;

[0052] S3.5, start processing;

[0053] S4, coarse grinding:

[0054] Grind the processed outer circle of the screw until the surface roughness meets the design requirements;

[0055] S5. Heat treatment:

[0056] heat treating the screw;

[0057] S6, fine grinding:

[0058] Grind the outer circle of the heat-treated screw until the surface roughness meets the design requirements;

[0059] S7, Warehouse entry:

[0060] After fine grinding, the entire screw is coated with anti-rust grease, completely wrapped with anti-rust film, and then put into storage.

[0061] In the preferred step S3, a number of parallel spiral lines are first processed on the surface of the screw, and then the screw is reciprocated until the depth of the spiral groove reaches the requirement, thereby reducing the tool pressure and ensuring the processing quality. In fact, the processing rhythm can also be considered according to the specific situation. When the quantity required is urgent, the tool consumption cost can be increased, and the pre-processing can be directly turned into shape, thereby improving production efficiency.

[0062] In the preferred step S3, the process is interrupted and reset at any spiral position in the spiral processing program, and the restarted processing can be immediately continued from the interruption point as specified by the parameters, which is conducive to the tool replacement and parameter fine-tuning during the process, ensuring the quality of the finished product and flexible processing. In fact, the parameters of the stop and start points can also be determined according to the specific situation.

[0063] In the preferred step S3, the helical surface is decomposed into a combination of a concave surface and an inclined surface for processing, and an independent CNC program module is written for each concave surface and inclined surface, each module contains all the instructions and parameters required for processing the specific surface, and each module includes but is not limited to being linked by variable assignment, unconditional transfer and conditional transfer. Because the helical surface is a complex three-dimensional surface, it is difficult to process directly. The decomposition is to simplify the processing process. Based on the geometric characteristics of the helical surface, the concave surface represents the inwardly concave part of the helical surface, and the inclined surface represents the inclined part of the helical surface. For the decomposed concave surface and inclined surface, independent four-axis machining center CNC machining programs are written for them respectively. Each program module contains all the instructions required for processing the surface, such as tool path, cutting parameters, feed speed, etc. In this way, each surface can be processed independently, which improves the flexibility and maintainability of processing;

[0064] Furthermore, in order to enable the independent modules to work together and complete the processing of the entire spiral surface, they need to be linked in a certain way, including but not limited to the following aspects:

[0065] Variable assignment: In CNC programs, variables are used to store key data in the machining process, such as tool position, cutting depth, etc. By transferring these variables between different modules, the continuity and consistency of the machining process can be achieved;

[0066] Unconditional transfer: In some cases, the program needs to automatically jump to another module after executing one module. The unconditional transfer instruction can achieve this function, which enables the program to execute each module in a predetermined order;

[0067] Conditional transfer: Different from unconditional transfer, conditional transfer instruction determines whether to jump to another module based on whether a certain condition is met. This allows the program to make dynamic adjustments according to actual conditions during the processing, improving the flexibility and adaptability of processing;

[0068] In summary, decomposing the spiral surface into concave surface and inclined surface, writing independent CNC machining program modules for each surface, and then linking these modules through variable assignment, unconditional transfer and conditional transfer is an effective method to realize complex spiral surface machining. This method not only improves the flexibility and maintainability of machining, but also helps to optimize the machining process and improve the machining quality.

[0069] In the preferred step S3, the program parameters include left-hand parameters and right-hand parameters, and only the rotation direction of the left-hand parameters and the right-hand parameters change, while other parameters remain unchanged, so that the matching accuracy of the twin screws produced is higher.

[0070] In the preferred step S4, a fine steel abrasive belt is used for grinding. The fine steel abrasive belt has good flexibility and can adapt to workpieces of various shapes and curved surfaces, including complex shapes and irregular parts. Compared with other grinding tools, such as diamond grinding wheels, the fine steel abrasive belt has lower cost and longer service life, which reduces processing costs. The fine steel abrasive belt generates less dust during grinding and is easy to collect and treat, meeting environmental protection requirements. In fact, the choice of grinding material can also be considered according to specific circumstances.

[0071] In the preferred step S5, the heat treatment includes preheating, heating, cooling and tempering. Specifically, the preheating temperature is 150-200°C. After keeping warm for 1-2 hours, the oil stains on the surface are removed, and then the screw is heated to 900-950°C and kept warm for 1-2 hours. After that, oil cooling is adopted. Finally, the screw is heated to 200-250°C, kept warm for 2-3 hours, and slowly cooled. Such operation effectively changes the internal structure of the steel, significantly improves the mechanical properties of the steel, and enables the steel parts to obtain the required hardness, wear resistance, toughness and other characteristics to meet different usage scenarios and requirements. In fact, the time and temperature of the heat treatment can also be considered according to the specific situation.

[0072] In the preferred step S6, a silicon carbide grinding wheel is used for grinding. The silicon carbide grinding wheel has fine density and good surface roughness, and can grind a high-precision surface. During the fine grinding process, the silicon carbide grinding wheel can ensure that the workpiece reaches the required dimensional accuracy and shape accuracy, thereby improving the processing quality. Moreover, the silicon carbide grinding wheel has uniform particles, and no harmful substances are released during the grinding process. The force is uniform and there is no edge collapse, thereby ensuring the quality of the surface of the workpiece after grinding. The surface roughness of the workpiece after fine grinding is low and the finish is high, which is conducive to the subsequent processes, such as polishing. Furthermore, the silicon carbide grinding wheel has high hardness and strong wear resistance, and can maintain stable grinding performance during the fine grinding process, thereby improving grinding efficiency. Moreover, due to the high wear resistance of the silicon carbide grinding wheel, it has a long service life, thereby reducing the number and cost of replacing the grinding wheel, thereby reducing the production cost. In fact, the selection of the grinding material can also be considered according to the specific situation.

[0073] In this implementation case, when using a method for making a mass-symmetrical self-balancing double-headed spiral twin-screw, the design scheme is first determined, that is, a mass-symmetrical cross-section design is adopted so that the cross-section of the component is symmetrical in mass distribution. The core purpose is to reduce or eliminate vibration and unbalanced force caused by uneven mass distribution, thereby improving the running stability and service life of the rotating component. The mass of the micro-units arranged along the axial direction is symmetrically distributed relative to the rotation axis. The center of mass is the center point of the mass of the object and also the balance point of the object under the action of gravity. In the mass-symmetrical cross-section design, through precise calculation and adjustment, it is ensured that the center of mass of the entire rotating component is accurately positioned on the rotation axis. This can be achieved by adjusting the mass distribution of the micro-units or adding counterweights. It should be noted that the precise positioning of the center of mass is crucial to the balance of the rotating component. If the center of mass deviates from the rotation axis, unbalanced force will be generated, causing vibration and wear of the component during operation, and may even cause failure;

[0074] After the design scheme is determined, the raw materials are selected. Steel with a small deformation tendency after oil quenching treatment is selected, and it is processed on a lathe to the required outer diameter and length dimensions, such as non-deformation wear-resistant oil steel. This material ensures that the center of mass of each shaft segment of the working rotor is located on the axis of rotation under the high-speed rotation of the screw. In harsh environments, such as chemical and pharmaceutical industries with dust, it can withstand long-term friction and wear, and there will be no rotor imbalance. Then it is processed on a lathe to the required outer diameter and length dimensions;

[0075] Start CNC machining, clamp the material on the machine tool in a top-to-top manner. After clamping, use the coaxiality meter to check the overall coaxiality to ensure that the clamping position will not deviate too much. Then call out the spiral processing program from the system and start tool setting. After tool setting is completed, enter the data into the four-axis machining center and start running the program. The program code includes but is not limited to the following sample code:

[0076] O1234 (Program number)

[0077] G21 (use millimeters)

[0078] G17 (Select XY plane)

[0079] G90 (absolute coordinate programming)

[0080] (Set workpiece coordinate system and tool compensation)

[0081] G54

[0082] T1M6 (select tool 1 and change tool)

[0083] (Move above the starting point to avoid collision)

[0084] G00X0Y0Z10

[0085] (Start spiral processing)

[0086] G01Z0F100 (Move to the Z coordinate of the starting point at a speed of 100 mm / min)

[0087] G02X10Y0I0J-10Z-1F200 (start spiral processing at a speed of 200mm / min, I and J are the offsets of the center of the circle relative to the starting point, and Z-1 means that the Z axis drops 1mm per rotation)

[0088] (Continue spiral processing until the required length or number of turns is reached)

[0089] G02X20Y0I0J-20

[0090] G02X30Y0I0J-30 ...

[0092] (Add more G02 commands as needed until the helical processing is completed)

[0093] (End processing and move to a safe location)

[0094] G00Z10

[0095] G00X0Y0

[0096] M30 (end of program and return to starting point)

[0097] It should be noted that in the code, before the spiral processing, a straight line processing code can be added to make a contact with the entire outer surface of the screw, and its coaxiality can also be further detected;

[0098] like Figure 2 As shown in the figure, on the basis of the spiral processing program, adjust its parameters so that its running trajectory is to process one circle of uniform pitch line, followed by three circles of equal pitch line, which meets the processing requirements, and then set the remaining amount, that is, determine the processing amount in place. When the processing center reaches this point, stop processing, start the four-axis machining center, and start processing;

[0099] It should be pointed out here that because the purpose is to process a double-headed twin screw, after processing the left-handed screw, the program is changed to right-handed, and the left-handed and right-handed switching is done without changing other parameters, and then another screw is processed to ensure the matching accuracy of the two screws;

[0100] The finished screw is subjected to a rough grinding to remove the burrs on the screw spiral surface and ensure its coaxiality again. The removal of burrs can prevent the subsequent heat treatment from being affected, such as the formation of melted hard particles, which in turn affects the quality;

[0101] After the rough grinding is completed, the screw is heat treated. Specifically, it is preheated and kept warm at a temperature of 150-200°C for 1-2 hours. This operation can remove the oil stains on the surface of the screw. At the same time, preheating can balance the overall temperature of the screw, thereby reducing the deformation caused by the temperature gradient during the heat treatment process and ensuring the quality of the screw. Preheating helps to reduce the generation of cracks. By preheating, the hardened parts can be softened, the organizational structure of the screw can be improved, and its plasticity and toughness can be improved to ensure that the screw has stable performance in the subsequent use process. Then the screw is heated to 900-950°C and kept warm at this temperature for 1-2 hours. After this process, the screw has higher hardness, greater strength, and better Good corrosion resistance, and significantly improve the bearing capacity and durability of the screw during use. Heat treatment can refine the grains of the screw, thereby improving its organizational structure, helping to eliminate the deformation and stress generated during cold working, and making the overall performance of the screw more stable. Through heat treatment, the internal stress generated by the screw during cold working can be effectively reduced, which helps to reduce the risk of fracture or bending caused by stress concentration during use of the screw, and significantly improves the comprehensive mechanical properties of the screw, including tensile strength, yield strength ratio, etc., and then use cooling oil for cooling. After complete cooling, start tempering. The tempering temperature is 200-250℃, and the tempering time is 2-3 hours. After tempering is completed, it can be cooled naturally;

[0102] After cooling, the screw is finely ground to achieve the final required roughness, and the overall processing is completed;

[0103] Finally, the finely ground screw is coated with anti-rust grease, completely wrapped with anti-rust film, and then put into storage.

[0104] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A method for manufacturing a mass-symmetrical self-balancing double-headed spiral twin screw, characterized in that: The production steps include: S1. Design: The mass-symmetrical cross-section design is adopted to ensure that the mass of the micro-units arranged along the axial direction is symmetrically distributed relative to the rotation axis, and the center of mass is accurately positioned on the rotation axis; S2. Material selection and processing: Select steel with less deformation tendency after oil quenching and process it on a lathe to the required outer diameter and length; S3, CNC machining: S3.

1. Clamp the steel on the machine tool; S3.2, call out the spiral processing program from the system, S3.3, adjust the parameters of the spiral processing program so that after processing one circle of uniform pitch line, it will process three circles of equal pitch line immediately; S3.4, set the screw machining allowance; S3.5, start processing; S4, coarse grinding: Grind the processed outer circle of the screw until the surface roughness meets the design requirements; S5. Heat treatment: heat treating the screw; S6, fine grinding: Grind the outer circle of the heat-treated screw until the surface roughness meets the design requirements; S7, Warehouse entry: After fine grinding, the entire screw is coated with anti-rust grease, completely wrapped with anti-rust film, and then put into storage.

2. The method for manufacturing a mass-symmetrical self-balancing double-headed spiral twin-screw according to claim 1, characterized in that: In step S3, a plurality of parallel spiral lines are firstly processed on the surface of the screw, and then the screw is reciprocated until the depth of the spiral groove reaches the requirement.

3. The method for manufacturing a mass-symmetrical self-balancing double-headed twin-screw according to claim 2, characterized in that: In step S3, the process is interrupted and reset at any spiral position in the spiral processing program, and the restarted processing can be immediately continued from the interruption point as specified by the parameters.

4. The method for manufacturing a mass-symmetrical self-balancing double-headed spiral twin-screw according to claim 3, characterized in that: In step S3, the spiral surface is decomposed into a combination of a concave surface and an inclined surface for processing, and an independent CNC program module is written for each concave surface and inclined surface. Each module contains all the instructions and parameters required for processing the specific surface. The modules include but are not limited to being linked by variable assignment, unconditional transfer and conditional transfer.

5. The method for manufacturing a mass-symmetrical self-balancing double-headed spiral twin-screw according to claim 4, characterized in that: In step S3, the program parameters include left-hand parameters and right-hand parameters, and only the rotation direction of the left-hand parameters and the right-hand parameters changes, while other parameters remain unchanged.

6. The method for manufacturing a mass-symmetrical self-balancing double-headed twin-screw according to claim 5, characterized in that: In step S4, polishing is performed using a fine steel abrasive belt.

7. The method for manufacturing a mass-symmetrical self-balancing double-headed twin-screw according to claim 6, characterized in that: In step S5, the heat treatment includes preheating, heating, cooling and tempering. Specifically, the preheating temperature is 150-200°C. After keeping warm for 1-2 hours, remove the oil stains on the surface, then heat the screw to 900-950°C, keep warm for 1-2 hours, then use oil cooling, and finally heat the screw to 200-250°C, keep warm for 2-3 hours, and slowly cool.

8. The method for manufacturing a mass-symmetrical self-balancing double-headed twin-screw according to claim 7, characterized in that: In step S6, grinding is performed using a silicon carbide grinding wheel.

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