D-shaped hole micro gear machining method and tooling

Abstract

The application provides a D-shaped hole micro gear machining method and tooling. A shaft gear blank is first machined according to a shaft gear machining process, then the tooth part is machined by hobbing, then a preformed hole is machined by using an electric pulse machining center, then a D-shaped hole is machined by slow wire cutting, and finally a plurality of D-shaped hole micro gear single pieces are obtained by slow wire cutting. The tooling is composed of a clamping block and a top pin. A block body through hole for concentrically clamping the shaft gear blank is formed in the center of the square clamping block body, and symmetrical locking pin holes are formed in the square clamping block. The locking pin holes are screwed with the top pin to lock the position of the long light shaft section. The application solves the technical problems of the existing D-shaped hole micro gear machining, such as inconvenience and low efficiency. The process is good, the operation is convenient, the machining efficiency is high, and the application is suitable for promotion.

Description

Technical Field

[0001] This invention belongs to the field of work transport gear manufacturing technology, specifically relating to a D-type hole micro gear processing method and tooling. Background Technology

[0002] With social development and progress, small gears, especially those with D-shaped holes, have been widely used in many industrial fields such as precision instruments, watches, and small-scale planetary reducers due to their space and structural limitations. Among them, the sun gear in a planetary reducer is a typical example of this small gear component. The D-shaped hole of the sun gear is connected to the motor shaft (D-shaped shaft) to realize rotational motion to achieve high-speed rotation of the motor, and finally achieves low-speed output through planetary reduction.

[0003] Taking the sun gear of a common planetary reducer as shown in Figures 1(a) and 1(b) as an example, this sun gear has a module m=0.25, number of teeth z=20, inner hole type D, and thickness L0=1.5. +0.1 mm. This part cannot be machined using a mandrel according to the gear machining process because the D-shaped hole is too small. Therefore, the following technical solution is proposed. Summary of the Invention

[0004] The technical problem solved by this invention is to provide a method and tooling for machining D-type hole micro gears, which adopts the process steps of making shaft gear blanks, making gears, making pre-made holes, making D-type holes, and cutting, thereby solving the technical problems of inconvenience and low efficiency in machining D-type hole micro gears under the prior art.

[0005] The technical solution adopted in this invention is as follows: a method for machining D-type hole micro gears, which involves first machining a shaft gear blank according to the shaft gear machining process, then machining the gear part using a gear hobbing process, then machining a pre-made hole using an electrical pulse machining center, then machining the D-type hole using a slow wire EDM, and finally machining multiple D-type hole micro gear individual pieces using a slow wire EDM.

[0006] The above technical solution further includes the following steps:

[0007] S1. Shaft and gear blank: The shaft and gear blank is composed of a short optical shaft section, an intermediate optical shaft section, and a long optical shaft section, which are coaxially integrally formed. The diameters of the long and short optical shaft sections are equal and smaller than the diameter of the intermediate optical shaft section. The diameter of the intermediate optical shaft section matches the diameter of the D-type hole micro gear. The axial length of the intermediate optical shaft section matches the thickness of multiple D-type hole micro gears. The axial length of the short optical shaft section is smaller than the axial length of the intermediate optical shaft section. The length of the long optical shaft section is greater than the axial length of the intermediate optical shaft section.

[0008] S2. Gear manufacturing: The teeth of the D-type hole micro gear are obtained by machining the intermediate optical shaft section using a gear hobbing process.

[0009] S3. Shorten: Shorten the short optical axis segment so that the axial length of the shortened short optical axis segment is ≤2mm.

[0010] S4. Pre-drilling holes: Use an electric pulse machining center to pre-drill axially through holes, ensuring that the center of the pre-drilled hole is not concentric with the center of the shaft gear blank.

[0011] S5. Making D-shaped holes: Clamp and press the D-shaped hole micro gear machining fixture onto the platen of the slow wire EDM machine using a flat-jaw vise. Use the D-shaped hole micro gear machining fixture to clamp the long optical shaft section, and then use slow wire EDM to make D-shaped holes after threading the wire.

[0012] S6. Slitting: The D-type hole micro gear machining fixture clamped with flat-jaw pliers and the shaft gear blank clamped by the D-type hole micro gear machining fixture are rotated together by 90°. After the short optical shaft section is removed by slow wire EDM, multiple D-type hole micro gear individual pieces are obtained by slow wire EDM slitting.

[0013] In the above technical solution, further: the module m of the D-type hole micro gear is ≤0.3mm, the number of teeth Z is ≤20, the inner diameter is ≤3mm and is a D-type hole, and the gear width L0(1.5+0.1)≤2mm.

[0014] In the above technical solution, further: the short optical axis segment and the long optical axis segment serve as the clamping and positioning references during step S2 for tooth making, step S4 for pre-drilling holes, step S5 for D-type holes, and step S6 for cutting; the outer diameter tolerance grade accuracy requirement of the short optical axis segment and the long optical axis segment is not lower than h7.

[0015] Furthermore, in the above technical solution, the precision requirement for the teeth is no less than level 6.

[0016] In the above technical solution, the preferred method is: the diameter of the pre-made hole is φ0.3~0.5mm; the eccentricity between the center of the pre-made hole and the center of the shaft gear blank is 0.5mm.

[0017] This invention also claims protection for a D-type hole micro gear machining fixture, which can be used to machine D-type hole micro gears using any method. The D-type hole micro gear machining fixture consists of a clamping block and a set screw. The clamping block has a square structure and a through hole in its center. The through hole concentrically positions and clamps the long optical shaft section of the gear blank. With the center of the through hole as the axis of symmetry, the clamping block has an axisymmetric locking screw hole. The center line of the locking screw hole is perpendicular to the center line of the through hole. The locking screw hole is screwed with a set screw, which is used to lock the position of the long optical shaft section. The inner shaft end face of the long optical shaft section is tightly fitted to the clamping block.

[0018] In the above technical solution, furthermore: the tooling is subjected to quenching treatment to improve its hardness.

[0019] Advantages of this invention compared to existing technologies:

[0020] 1. This invention has good processability, is easy to operate, has high processing efficiency, and is suitable for widespread application.

[0021] 2. This invention can process five finished products instead of the traditional method of processing only one part at a time, which improves efficiency and saves costs. The minimum hole diameter that can be processed by the traditional method is 2mm, while the minimum hole diameter that can be processed by this invention is 1mm. It increases the processing stability of D-type hole micro gears and is suitable for the processing of micro gears and small gears in watches, with a wide range of applications.

[0022] 3. This invention uses forging and other processes to prepare the blank, ensuring that the gear shaft has high strength and rigidity, providing a solid foundation for subsequent processing; gear hobbing is a continuous process with no idle stroke, resulting in high production efficiency and making it easy to ensure that the processed gear has a precise tooth pitch, suitable for processing gears requiring small cumulative error adjustment; the EDM machine tool has μm-level machining accuracy, suitable for high-precision small workpiece processing; the surface finish can reach 0.1Ra, meeting the high surface quality requirements of micro gears; the slow wire EDM machining has a high precision level, generally reaching 0.001mm or even higher, ensuring product accuracy; during the slitting process, the slow wire EDM can maintain high precision, ensuring that each micro gear meets the design requirements; the processes are closely connected and the flow is smooth, improving production efficiency.

[0023] 4. The short and long optical axis segments of this invention serve as clamping and positioning bases, enabling precise clamping and positioning and control of machining accuracy. This helps reduce scrap rates, improve product quality and production efficiency. By using a unified positioning datum and tolerance level requirements, the quality remains stable and consistent, improving product consistency and reliability.

[0024] 5. The electro-pulse machining center of this invention has high-precision machining capabilities, ensuring that the diameter, depth, and positional accuracy of the pre-made holes meet design requirements. This high-precision machining helps reduce error accumulation in subsequent machining processes and improves overall machining accuracy. The electro-pulse machining center allows for flexible adjustment of the pre-made hole's position, ensuring it is not concentric with the center of the gear blank. This flexibility helps meet specific design requirements. Setting the pre-made hole to be concentric with the center of the gear blank can reduce stress concentration to some extent, which helps extend the service life of the gear and reduce failures such as cracks and fractures caused by stress concentration.

[0025] 6. The tooling of this invention has a simple structure, is easy to clamp, and has a precise and stable fit; the tooling is hardened to improve its hardness, will not wear out, can be reused, improves the economic efficiency of the tooling, and reduces production costs. Attached Figure Description

[0026] Figure 1(a) is a cross-sectional view of the sun gear of a common planetary reducer.

[0027] Figure 1(b) is a front view of the process diagram of the sun gear in a common planetary reducer;

[0028] Figure 2 This is a front view of the shaft gear blank of the present invention;

[0029] Figure 3 This is a front view of the shaft gear blank after gear making in step 2 of the present invention;

[0030] Figure 4(a) is a front sectional view of the shaft gear blank after being shortened in step 3 of the present invention;

[0031] Figure 4(b) is a side view of the shaft gear blank after being shortened in step 3 of the present invention;

[0032] Figure 5(a) is a front sectional view of the shaft gear blank after the pre-drilled hole is made in step 4 of the present invention;

[0033] Figure 5(b) is a side view of the shaft gear blank after the pre-drilled hole is made in step 4 of the present invention;

[0034] Figure 6(a) is a front view of the tooling block for machining D-type hole micro gears according to the present invention;

[0035] Figure 6(b) is a cross-sectional view of the tooling block for machining D-type hole micro gears;

[0036] Figure 7(a) is a cross-sectional view of the tooling of the present invention clamping the shaft gear blank;

[0037] Figure 7(b) is a schematic diagram of Figure 7(a) of the present invention along direction A;

[0038] Figure 8(a) is a front sectional view of the shaft gear blank after making the D-shaped hole in step 5 of the present invention;

[0039] Figure 8(b) is a side view of the shaft gear blank after the D-shaped hole is made in step 5 of the present invention;

[0040] Figure 9(a) is a front sectional view of the tooling clamping shaft gear blank after the short optical shaft section is removed in step 6 of the present invention.

[0041] Figure 9(b) is a left view of Figure 9(a) of the present invention;

[0042] Figure 10 This is an overview of the flowchart of the method of the present invention;

[0043] In the diagram: 1-shaft gear blank, 101-short optical shaft section, 102-intermediate optical shaft section, 103-long optical shaft section, 2-tooth section, 3-prefabricated hole, 4-D-type hole, 5-D-type hole micro gear, 6-D-type hole micro gear machining fixture, 601-clamping block, 6011-block through hole, 6012-locking screw hole, 602-set screw. Detailed Implementation

[0044] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings 1-10. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0045] It should be noted that the module m of the D-type hole micro gear 5 to be processed in this invention is ≤0.3mm, the number of teeth Z is ≤20, the inner hole diameter is ≤3mm and it is a D-type hole, and the gear width L0(1.5+0.1)≤2mm.

[0046] The following description uses the machining process requirements of the sun gear of a common planetary reducer, as shown in Figures 1(a) and 1(b), as an example:

[0047] A method for machining D-type hole micro gears involves first machining a shaft gear blank 1 using shaft gear machining technology, then machining the gear part 2 using gear hobbing technology, then machining a pre-made hole 3 using an electrical pulse machining center, then machining a D-type hole 4 using wire EDM, and finally machining multiple D-type hole micro gears 5 individually using wire EDM.

[0048] It should be noted that: Forging and other processes are used to prepare the blank, ensuring the gear shaft possesses high strength and rigidity, providing a solid foundation for subsequent machining. Gear hobbing is a continuous process with no idle stroke, resulting in high production efficiency. It easily ensures that the machined gear has a precise tooth pitch, making it suitable for machining gears requiring minimal cumulative error adjustment. EDM machines offer μm-level machining accuracy, suitable for high-precision machining of small workpieces; surface finish can reach 0.1Ra, meeting the high surface quality requirements of micro gears. Wire EDM offers high precision, typically reaching 0.001mm or even higher, ensuring the accuracy of the D-hole 4. During the slitting process, wire EDM maintains high precision, ensuring that each micro gear 5 meets design requirements. The close connection between each process and the smooth flow improve production efficiency.

[0049] In the above embodiments, the following steps are further included (e.g.) Figure 10 (as shown)

[0050] (like Figure 2(As shown) S1. Shaft and gear blank: The shaft and gear blank 1 is composed of a short optical shaft section 101, an intermediate optical shaft section 102, and a long optical shaft section 103, which are coaxially integrally formed. The long and short optical shaft sections 101 and 103 have the same diameter, and their diameters are smaller than the diameter of the intermediate optical shaft section 102. The diameter of the intermediate optical shaft section 102 matches the diameter of the D-type hole micro gear 5. The axial length of the intermediate optical shaft section 102 matches the thickness of multiple D-type hole micro gears 5. The axial length of the short optical shaft section 101 is smaller than the axial length of the intermediate optical shaft section 102. The length of the long optical shaft section 103 is greater than the axial length of the intermediate optical shaft section 102.

[0051] It should be noted that the short optical shaft section 101, the intermediate optical shaft section 102, and the long optical shaft section 103 are coaxially integrally formed, ensuring the integrity and coaxiality of the shaft gear blank, which is beneficial for the precision control of subsequent machining and assembly. The standardized dimensions of each part of the shaft gear blank facilitate subsequent machining. The design of the short optical shaft section 101 and the long optical shaft section 103 provides convenient positioning and clamping points for subsequent machining and assembly, helping to ensure the accuracy of machining and assembly.

[0052] In the above embodiments, further: the short optical axis segment 101 and the long optical axis segment 103 serve as the clamping and positioning references during step S2 (tooth making), step S4 (pre-drilling), step S5 (D-shaped hole making), and step S6 (splitting); the outer diameter tolerance grade accuracy requirement of the short optical axis segment 101 and the long optical axis segment 103 is not lower than h7 (e.g., Figure 2 (As shown).

[0053] It should be noted that using the short optical axis segment 101 and the long optical axis segment 103 as clamping and positioning datums ensures precise positioning in subsequent machining steps such as gear making (S2), pre-drilled hole making (S4), D-shaped hole making (S5), and splitting (S6). This helps reduce machining errors and improve overall machining accuracy. Since the short optical axis segment 101, the intermediate optical axis segment 102, and the long optical axis segment 103 are coaxially integrally formed, using them as positioning datums ensures coaxiality between different parts during machining, further improving machining accuracy. Using standardized short optical axis segments 101 and 103 as positioning datums simplifies the clamping process, reduces clamping and adjustment time, and thus improves machining efficiency. Precise clamping and positioning, along with machining accuracy control, helps reduce scrap rates and improve product quality and production efficiency. Using unified positioning datums and tolerance requirements ensures consistent quality and improves product consistency and reliability.

[0054] Specifically: the thickness L0 of the D-shaped hole micro gear 5 is 1.5mm, and the intermediate optical axis section 102 is designed to be 10mm (5×1.5 mm + wire diameter of 0.25mm during cutting + discharge amount) to ensure that five D-shaped hole micro gears 5 are obtained after the cutting in step 6; the outer circle of the short optical axis section 101 and the long optical axis section 103 is φ3h7 ( 0 -0.01 The lengths of the short optical axis segment 101 and the long optical axis segment 103 should not be too long to avoid the tooth precision not meeting the requirements. The short optical axis segment 101 is 8mm long, the long optical axis segment 103 is 12mm long, and the intermediate optical axis segment 102 is 10mm long.

[0055] (like Figure 3 (As shown) S2, Gear manufacturing: The intermediate optical shaft section 102 is machined using a gear hobbing process to obtain the tooth portion 2 of the D-shaped hole micro gear 5. In the above embodiment, furthermore, the precision requirement of the tooth portion 2 is not lower than grade 6.

[0056] It should be noted that the precision requirement for tooth section 2 is no less than grade 6, meaning that key dimensions such as tooth pitch and tooth profile are precisely controlled. High-precision teeth reduce vibration and noise during meshing, improving the smoothness of the transmission system. The high surface finish of high-precision teeth reduces friction and wear during meshing. A precision requirement of grade 6 allows the teeth to withstand greater loads, increasing the gear's load-bearing capacity. The precision requirement of grade 6 for tooth section 2 meets the design requirements of many high-precision transmission systems. Gear hobbing is characterized by high efficiency and continuous cutting, enabling the rapid production of high-precision teeth. This helps improve production efficiency, reduce manufacturing costs, and meet the market's large demand for high-precision micro gears.

[0057] (As shown in Figures 4(a) and 4(b)) S3, Shortening: Shorten the short optical axis segment 101 so that the axial length of the shortened short optical axis segment 101 is ≤2mm. That is, the remaining length L of the short optical axis segment 101. 00 =2mm, the purpose of cutting it short is to: reduce the depth of the pre-made hole in step S4, and reduce the difficulty of subsequent manufacturing processes; in addition, the remaining length L of the short optical axis section 101 00 The 2mm diameter also serves to align the center of the micro gear 5 during the subsequent step S5 when creating the D-shaped hole 4, ensuring that the cut D-shaped hole 4 coincides with the center of the micro gear 5, i.e., coaxiality. Cutting the short optical shaft segment 101 reduces the depth of the pre-drilled hole in the subsequent step S4. Shallower pre-drilled holes are easier to machine, reducing problems such as tool wear, prolonged machining time, and decreased machining accuracy that may result from excessive hole depth, thus helping to improve overall machining efficiency and shorten the production cycle.

[0058] (As shown in Figure 5(a) and Figure 5(b)) S4. Making pre-drilled holes: Using an electric pulse machining center, an axially penetrating pre-drilled hole 3 is made, and the center of the pre-drilled hole 3 is not concentric with the center of the shaft gear blank 1.

[0059] The EDM machining center possesses high-precision machining capabilities, ensuring that the diameter, depth, and positional accuracy of the pre-drilled hole 3 meet design requirements. This high-precision machining helps reduce error accumulation in subsequent machining processes and improves overall machining accuracy. The EDM machining center allows for flexible adjustment of the position of the pre-drilled hole 3, ensuring it is not concentric with the center of the gear blank 1. This flexibility helps meet specific design requirements. Setting the pre-drilled hole 3 to be concentric with the center of the gear blank 1 can reduce stress concentration to some extent, which helps extend the gear's service life and reduce failures such as cracks and fractures caused by stress concentration. Setting the pre-drilled hole 3 as axially continuous simplifies subsequent machining processes. For example, when machining a D-shaped hole in a later step, positioning and cutting operations are more convenient.

[0060] In the above embodiments, preferably, the diameter of the pre-drilled hole 3 is φ0.3~0.5mm (as shown in Figure 5); the eccentricity between the center of the pre-drilled hole 3 and the center of the shaft gear blank 1 is 0.5mm. The size of the eccentricity and the size of the pre-drilled hole are designed based on the size of the D-type hole 4 to ensure that the processing is convenient and feasible.

[0061] It should be noted that the diameter of the pre-drilled hole 3 is set within the range of φ0.3~0.5mm. This size range is neither too large nor too small, ensuring precise cutting operations. Simultaneously, this size range helps reduce error accumulation during processing, improving overall machining accuracy. The 0.5mm eccentricity design creates a certain offset between the pre-drilled hole 3 and the center of the shaft gear blank 1. This offset can serve as a positioning reference when machining the D-shaped hole 4, facilitating precise determination of the position and shape of the D-shaped hole 4. Furthermore, since the pre-drilled hole 3 already exists, cutting resistance is reduced and cutting efficiency is improved when cutting the D-shaped hole 4. The reasonable design of the pre-drilled hole 3 and the eccentricity setting enhance the structural stability of the shaft gear blank 1.

[0062] S5. Making D-shaped holes: Clamp and press the D-shaped hole micro gear machining fixture 6 onto the platen of the slow wire EDM machine using a flat-jaw vise. Use the D-shaped hole micro gear machining fixture 6 as shown in Figures 6(a) and 6(b) to clamp the long optical shaft section 103 (as shown in Figures 7(a) and 7(b)). After threading the wire, use slow wire EDM to cut the D-shaped hole 4 (as shown in Figures 8(a) and 8(b)). The D-shaped hole 4 obtained is guaranteed to be φ2.5. +0.1 mm, 0.5 +0.01 mm dimension requirements.

[0063] It should be noted that the slow wire EDM technology has high-precision machining capabilities, ensuring that the size of the D-type hole 4 meets the φ2.5 standard. +0.1 mm, 0.5 +0.01 The stringent mm-level requirements of this high-precision machining process help reduce error accumulation in subsequent processes and improve accuracy. Using slow-wire EDM technology to process the D-shaped hole 4 ensures consistency in the dimensions and shape of the D-shaped hole 4, thereby improving the overall quality and reliability of the product. Slow-wire EDM technology can adapt to the machining of various complex shapes. During processing, the machining parameters of the slow-wire EDM machine, such as cutting speed and electrode wire tension, can be adjusted according to actual needs to optimize the machining effect and improve processing efficiency. Slow-wire EDM technology has high-efficiency machining capabilities, enabling the machining of the D-shaped hole 4 in a short time. This high efficiency helps shorten the production cycle and improve overall production efficiency. Although the initial investment in a slow-wire EDM machine is relatively large, its high precision, high efficiency, and wide adaptability can significantly reduce costs in subsequent machining and assembly processes. Slow-wire EDM technology uses a non-contact machining method, reducing machining errors caused by mechanical friction and wear. At the same time, this technology also has automatic detection and compensation functions, which can further reduce machining errors and improve product quality. High-precision machining of the D-hole 4 helps improve the stability and reliability of the transmission system. By ensuring the dimensional and shape accuracy of the D-hole 4, transmission failures and damage caused by assembly errors can be reduced, extending the product's service life.

[0064] S6. Separation: The D-type hole micro gear machining fixture 6, clamped by flat-jaw pliers, and the shaft gear blank 1 clamped by the D-type hole micro gear machining fixture 6 are rotated together by 90°. After the short optical shaft section 101 is removed by slow wire EDM (as shown in Figure 9(a) and Figure 9(b)), multiple D-type hole micro gears 5 are produced by slow wire EDM separation. The length of each D-type hole micro gear 5 is required to be L0=1.5mm, that is, the machining of the D-type hole micro gear parts is completed. Flat-jaw pliers are used in conjunction to avoid repeated clamping during the clamping process and to avoid errors caused by multiple clamping.

[0065] It should be noted that using slow wire EDM technology for slitting can achieve a high degree of automation. By programming and controlling the machining path and parameters, batch processing can be achieved, further improving production efficiency. Slow wire EDM technology produces lower surface roughness, resulting in smoother machined surfaces for individual D-hole micro gears. Compared to traditional machining methods, slow wire EDM technology does not generate a heat-affected zone, thus avoiding machining errors caused by thermal deformation. This is crucial for ensuring the machining accuracy and shape stability of the gears.

[0066] This invention also claims protection for a D-type hole micro gear machining fixture 6, which uses any of the methods described above to machine D-type hole micro gears (as shown in Figure 6). The D-type hole micro gear machining fixture 6 consists of a clamping block 601 and a set screw 602. The clamping block 601 has a square structure and a through hole 6011 at its center. The through hole 6011 concentrically positions and clamps the long optical shaft section 103 of the gear blank 1. With the center of the through hole 6011 as the axis of symmetry, the clamping block 601 has an axisymmetric locking screw hole 6012. The center line of the locking screw hole 6012 is perpendicular to the center line of the through hole 6011. The locking screw hole 6012 is screwed into the set screw 602, which is used to lock the position of the long optical shaft section 103. The inner shaft end face of the long optical shaft section 103 is tightly attached to the clamping block 601 to increase stability.

[0067] Specifically: When using the D-type hole micro gear machining fixture 6 to clamp the long optical shaft section 103, the block through hole 6011φ3H6 in the D-type hole micro gear machining fixture 6 and the outer circle φ3h7 of the long optical shaft section 103 are in a small clearance fit to ensure the coaxiality of the fixture and the shaft gear blank 1. This fit precision design facilitates quick positioning of the fixture and the shaft gear blank 1 to ensure that they are coaxial and concentric. The 2-M2 locking screw hole 6012 allows for the installation of two set screws 602 after the shaft gear blank 1 and the fixture are coaxial, thereby ensuring that the shaft gear blank 1 and the fixture are axially tightened and do not move.

[0068] It should be noted that the clamping block 601 has a through hole 6011 at its center. This through hole 6011 is used for concentric positioning and clamping of the long optical shaft section 103 of the shaft gear blank 1. This design ensures the precise position of the shaft gear blank during machining, helping to reduce machining errors and improve machining accuracy. With the center of the through hole 6011 as the axis of symmetry, the clamping block 601 has an axisily symmetrical locking screw hole 6012. This design allows the set screw 602 to uniformly and stably lock the position of the long optical shaft section 103, further improving the stability and accuracy of clamping. The locking screw hole 6012 is screwed into the set screw 602, which is used to lock the position of the long optical shaft section 103. This locking method is not only simple and effective, but also ensures that the shaft gear blank 1 will not move or wobble during machining, thereby improving machining stability. The inner end face of the long shaft section 103 is tightly fitted to the clamping block 601. This design further increases the stability of the clamping. The tight fit between the shaft end face and the clamping block effectively prevents the shaft gear blank from loosening or shifting during processing. The fixture has a simple and clear structure and is easy to operate. Workers can quickly complete the clamping and positioning of the shaft gear blank, thereby improving production efficiency.

[0069] In the above embodiments, furthermore: the tooling undergoes quenching treatment to improve its hardness, preventing wear and allowing for reuse. Quenching is an important heat treatment process that rapidly cools a high-temperature workpiece, causing a phase transformation on its surface or throughout, resulting in a high-hardness structure. For tooling, quenching treatment significantly improves its hardness, enhancing its resistance to external forces. Because quenching treatment increases the tooling's hardness, it makes it more wear-resistant. During processing, friction and wear between the tooling and the workpiece are effectively reduced, thus extending the tooling's service life. The quenched tooling, due to its increased hardness and wear resistance, can be reused multiple times without frequent replacement. This helps improve the economic efficiency of the tooling and reduce production costs.

[0070] From the above description, it can be seen that: the present invention prepares the blank through forging and other processes, ensuring that the gear shaft has high strength and rigidity, providing a solid foundation for subsequent processing; gear hobbing is a continuous process with no idle stroke, resulting in high production efficiency and making it easy to ensure that the processed gear has a precise tooth pitch, suitable for processing gears with small cumulative error requirements; the EDM machine tool has a machining accuracy at the μm level, suitable for high-precision small workpiece processing; the surface finish can reach 0.1Ra, meeting the high surface quality requirements of micro gears; the slow wire EDM machining has a high precision level, generally reaching 0.001mm or even higher, ensuring the accuracy of the D-shaped hole; during the slitting process, the slow wire EDM can maintain high precision, ensuring that each micro gear meets the design requirements; the connection between each process is tight and the process is smooth, improving production efficiency.

[0071] The short optical axis segment 101 and the long optical axis segment 103 of this invention serve as clamping and positioning references. By using a unified positioning reference and tolerance level requirement, the quality is stable and consistent, thereby improving the consistency and reliability of the product.

[0072] The electric pulse machining center of this invention has high-precision machining capabilities, which helps to reduce the accumulation of errors in subsequent machining processes and improve the overall machining accuracy. The electric pulse machining center can flexibly adjust the position of the pre-made hole to meet specific design requirements. The pre-made hole is not concentric with the center of the shaft gear blank, which can reduce stress concentration to a certain extent. This helps to extend the service life of the gear and reduce failures such as cracks and fractures caused by stress concentration.

[0073] The tooling of this invention has a simple structure, is easy to clamp, and has a precise and stable fit. The tooling is hardened to improve its hardness, does not wear, can be reused, improves the economic efficiency of the tooling, and reduces production costs.

[0074] In summary, this invention has good manufacturability, is easy to operate, and has high processing efficiency, making it suitable for widespread application. Compared to the traditional method of processing only one part at a time, this invention can process five finished products, improving efficiency and saving costs. It is applicable to the processing of micro gears and small gears in watches, and has a wide range of applications.

[0075] The various embodiments in this specification are described in a related manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0076] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications and equivalent substitutions made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A method for machining D-type bore micro gears, characterized in that: First, a shaft gear blank (1) is processed according to the shaft gear processing technology. Then, the gear part (2) is made by hobbing. Next, a pre-made hole (3) is made by using an electric pulse machining center. Then, a D-shaped hole (4) is made by slow wire EDM. Finally, multiple D-shaped hole micro gears (5) are made by slow wire EDM. Includes the following steps: S1. Shaft gear blank: The shaft gear blank (1) is composed of a short optical shaft section (101), an intermediate optical shaft section (102), and a long optical shaft section (103) formed coaxially. The long and short optical shaft sections (103, 101) have the same diameter and the diameter is smaller than that of the intermediate optical shaft section (102). The diameter of the intermediate optical shaft section (102) matches the diameter of the D-type hole micro gear (5). The axial length of the intermediate optical shaft section (102) matches the thickness of multiple D-type hole micro gears (5). The axial length of the short optical shaft section (101) is smaller than that of the intermediate optical shaft section (102). The length of the long optical shaft section (103) is greater than that of the intermediate optical shaft section (102). S2. Gear making: The teeth (2) of the D-type hole micro gear (5) are made by machining the intermediate optical shaft section (102) using the gear hobbing process. S3. Shorten: Shorten the short optical axis segment (101) and make the axial length of the short optical axis segment (101) ≤ 2mm; S4. Pre-drilling the pre-drilled hole: Use an electric pulse machining center to make an axially penetrating pre-drilled hole (3), and make the center of the pre-drilled hole (3) not concentric with the center of the shaft gear blank (1); S5. Making D-shaped holes: Clamp the D-shaped hole micro gear machining fixture (6) onto the plate of the slow wire EDM machine with a flat-jaw pliers. Use the D-shaped hole micro gear machining fixture (6) to clamp the long optical shaft section (103). After threading the wire, use slow wire EDM to make D-shaped holes (4). S6. Slitting: The D-type hole micro gear machining fixture (6) clamped with flat-jaw pliers and the shaft gear blank (1) clamped by the D-type hole micro gear machining fixture (6) are rotated together by 90°. After the short optical shaft section (101) is cut off by slow wire EDM, multiple D-type hole micro gears (5) are obtained by slow wire EDM slitting.

2. The method according to claim 1, characterized in that: The D-type bore micro gear (5) has a module m ≤ 0.3 mm, a number of teeth Z ≤ 20, an inner diameter ≤ 3 mm and is a D-type bore, and a gear width L0 (1.5 mm). +0.1 ≤2mm.

3. The method according to claim 1, characterized in that: The short optical axis segment (101) and the long optical axis segment (103) serve as the clamping and positioning references during step S2 (tooth making), step S4 (pre-drilled hole making), step S5 (D-shaped hole making), and step S6 (slitting). The outer diameter tolerance grade of the short optical axis segment (101) and the long optical axis segment (103) is required to be no less than h7.

4. The method according to claim 1, characterized in that: The precision requirement of the teeth (2) is not lower than level 6.

5. The method according to claim 1, characterized in that: The diameter of the pre-formed hole (3) is 0.3~0.5mm; the eccentricity between the center of the pre-made hole (3) and the center of the shaft gear blank (1) is 0.5mm.

6. A D-hole micro gear machining fixture (6) for machining D-hole micro gears using the method described in any one of claims 1-5, characterized in that: The D-type hole micro gear machining fixture (6) consists of a clamping block (601) and a set screw (602); the clamping block (601) has a square structure and a block through hole (6011) in its center. The block through hole (6011) is used to concentrically position and clamp the long optical shaft section (103) of the shaft gear blank (1); with the center of the block through hole (6011) as the axis of symmetry, the clamping block (601) has an axisymmetric locking screw hole (6012); the center line of the locking screw hole (6012) is perpendicular to the center line of the block through hole (6011); the locking screw hole (6012) is screwed with a matching set screw (602), and the set screw (602) is used to lock the position of the long optical shaft section (103); the inner shaft end face of the long optical shaft section (103) is tightly attached to the clamping block (601).

7. The tooling according to claim 6, characterized in that: The tooling is hardened by quenching.

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