A bidirectional gear shaping method

Abstract

The application discloses a bidirectional gear shaping method, wherein the gear shaping cutter and the gear shaping part rotate in the same direction to perform gear shaping, and then the gear shaping cutter and the gear shaping part change the rotating direction to perform gear shaping. The application has the advantages of high machining precision and long service life of the gear shaping cutter.

Description

TECHNICAL FIELD

[0001] The present application relates to gear manufacturing technology and gear shaping field, and particularly relates to a bidirectional gear shaping method. BACKGROUND

[0002] At present, the unidirectional gear shaping technology (the rotating direction of the tool and the part does not change during the machining process) is used at home and abroad. With the continuous application and promotion of new materials, the material hardness of the gear shaping machining is higher and higher. If the material is a material with strong toughness (such as titanium alloy, stainless steel, etc.) or a material with high hardness (the hardness is higher than HRC42), the extrusion phenomenon is prone to occur. The steel represented by the third generation of aviation gear steel (15Cr14Co12Mo5Ni2WA) has a core hardness of HRC48-52. When the gear shaping machining is performed, the tool is prone to collapse and melting, the machining resistance is large, the cutting shape is distorted, and the technical parameters of the tooth part are unqualified. SUMMARY

[0003] The present application solves the technical problems of overcoming the deficiencies of the prior art and providing a bidirectional gear shaping method with high machining precision and long service life of the gear shaping tool.

[0004] To solve the above technical problems, the present application adopts the following technical scheme:

[0005] A bidirectional gear shaping method, the gear shaping machining is internal gear machining or external gear machining. When the internal gear machining is performed, the gear shaping tool and the gear shaping part are simultaneously rotated in the same direction to perform the gear shaping machining, and then the rotating directions of the gear shaping tool and the gear shaping part are simultaneously changed to perform the gear shaping machining. When the external gear machining is performed, the gear shaping tool and the gear shaping part are simultaneously rotated in opposite directions to perform the gear shaping machining, and then the rotating directions of the gear shaping tool and the gear shaping part are simultaneously changed to perform the gear shaping machining.

[0006] As a further improvement of the above technical scheme:

[0007] Preferably, when the gear shaping machining is the internal gear machining, the following steps are included:

[0008] S1, when the cutting allowance of the inner hole diameter of the gear shaping part is greater than 0.5mm, the gear shaping tool and the gear shaping part are simultaneously rotated counterclockwise to perform the gear shaping machining;

[0009] S2, when the cutting allowance of the inner hole diameter of the gear shaping part is in the range of 0.05-0.5mm, the gear shaping tool and the gear shaping part are simultaneously rotated clockwise to perform the gear shaping machining;

[0010] S3, when the cutting allowance of the inner hole diameter of the gear shaping part is in the range of 0-0.05mm, the gear shaping tool and the gear shaping part are simultaneously rotated counterclockwise to perform the gear shaping machining.

[0011] The core hardness of the gear-shaping component is HRC 48-52.

[0012] The raw material for the gear-shaped part is 15Cr14Co12Mo5Ni2WA.

[0013] Before simultaneously changing the rotation direction of the gear shaping tool and the gear shaping part, the method further includes: determining whether the cutting force borne by the gear shaping part is greater than the force required for elastic deformation of any one of the tools, tool holders, machine tool spindles, or fixtures; if so, then simultaneously changing the rotation direction of the gear shaping tool and the gear shaping part when machining the gear shaping part; otherwise, simultaneously changing the rotation direction of the gear shaping tool and the gear shaping part when machining the next gear shaping part.

[0014] Preferably, the cutting force borne by the gear-shaping part is calculated according to formula (I):

[0015] f z =A m ×p (Ⅰ)

[0016] In the above formula, Z represents the number of teeth on the workpiece, m represents the module of the workpiece (mm), and p represents the unit cutting force (N / mm). 2 ), F c This is the circumferential feed rate.

[0017] Preferably, when the gear shaping is external gear shaping, it includes the following steps:

[0018] A1. When the machining allowance is greater than 0.5mm, the gear shaping tool and the gear shaping part rotate in opposite directions.

[0019] A2. Second stage: The machining allowance is 0-0.5mm, and the rotation direction of the gear shaping tool and the gear shaping part is changed at the same time to perform gear shaping.

[0020] The principle of this invention is as follows:

[0021] The applicant discovered that during the cutting of hardened teeth, the sharpness of the cutting tool continuously decreased. At a critical point, the tool "slipped" (the actual path of the tool deviated from the theoretical path, and the stress state of the tool changed from uniform stress to unidirectional stress), concentrating the stress at a single point, causing the following technical problems: 1. A sudden and drastic increase in cutting heat led to abnormal tool wear (chipping, burning, thermal melting, and severe unilateral wear, such as...). Figure 2 As shown, one side experiences severe wear, while the other side experiences slight wear, indicating uneven wear at the rake and clearance angles of the gear shaping tool. 2. A large amount of "tool pressure" (the actual amount removed during machining is less than the theoretical amount removed) is generated, leading to distortion of the tooth shape. However, the bidirectional gear shaping method of this invention can extend the time until this critical point is reached, improve tool life, and effectively reduce "tool pressure" to improve cutting accuracy and tooth profile accuracy.

[0022] Compared with the prior art, the advantages of the present invention are as follows:

[0023] The bidirectional gear shaping method of this invention, on the one hand, can fully utilize all the cutting surfaces of the gear shaping tool through alternating cutting in the rotational direction, thereby improving the tool's lifespan; on the other hand, through alternating cutting in the rotational direction, it can minimize the "tool pressure," reduce the tool's wear, correct the damage caused by tool "slippage," correct tooth profile errors, and improve machining accuracy. These are advantages that the unidirectional gear shaping method does not possess. This method solves the technical problem that when machining high-hardness gears, the unidirectional gear shaping method results in much higher tool wear on the side closer to the tool's rotational direction than on the other side, leading to a short tool life and the need to replace the tool after machining 1-2 parts, making it difficult to adapt to gear shaping of high-hardness materials. Attached Figure Description

[0024] Figure 1 This is a flowchart of the gear shaping method of the present invention.

[0025] Figure 2 This is a schematic diagram of the single-sided wear of the gear shaping cutter in a conventional unidirectional gear shaping method.

[0026] Figure 3 This is a schematic diagram of the wear of the bidirectional gear hobbing method of the present invention.

[0027] Figure 4 This is a schematic diagram of the gear-shaping part in Embodiment 1 of the present invention.

[0028] Figure 5 yes Figure 4 Sectional view at point B.

[0029] Figure 6 This is the main view of the toothed component installation in Example 1.

[0030] Figure 7 This is a top view of the gear-mounted component installation in Example 1.

[0031] Figure 8 This is a schematic diagram of the gear-shaping part in Example 2.

[0032] The labels in the diagram represent: 1. Gear part; 11. Inner hole; 12. Gear; 2. Base; 3. Locking part; 4. Support part; 5. Pressure plate; Detailed Implementation

[0033] The present invention will be further described in detail below. Unless otherwise specified, the instruments or materials used in the present invention are commercially available.

[0034] Example 1:

[0035] The material of the gear-shaping part 1 in this embodiment is steel represented by third-generation aerospace gear steel (15Cr14Co12Mo5Ni2WA), with a core hardness of HRC48-52. The inner hole of the core of the gear-shaping part 1 needs to be machined.

[0036] like Figure 1 As shown, a bidirectional gear shaping method is described, where the gear shaping is an internal gear machining process. During internal gear machining, the gear shaping cutter and the gear shaping part first rotate in the same direction for gear shaping, and then the rotation directions of the cutter and the gear shaping part are simultaneously changed for further gear shaping. This gear shaping method, on the one hand, utilizes the entire cutting surface of the gear shaping cutter through alternating rotational cutting, thus improving the cutter's lifespan; on the other hand, it maximizes the elimination of "tool pressure" and corrects tooth profile errors, improving machining accuracy—advantages not found in unidirectional gear shaping methods.

[0037] In this embodiment, "in the same direction" means that when shaping internal teeth, the shaping tool and the shaping part 1 rotate in the same direction. This adds the function of simultaneously changing the rotation direction of the tool and the part during the machining process, which was not available in previous shaping methods. In this embodiment, as... Figure 4 and Figure 5 As shown, the gear-shaping part 1 has an inner hole, located at the middle of the inner wall of the inner hole 11 ( Figure 4 The B-side of the toothed part 1 has internal teeth, which need to be machined. During the machining process, the top surface of the tooth 12 of the toothed part 1 ( Figure 4 The middle surface (A) is the support surface, and the bottom surface of tooth 12 is the fixing surface. Figure 4 (Middle D surface), with the gear part 1 close to the inner wall of the inner hole 11 of the tooth part 12 ( Figure 4 The C-surface is the coarse positioning surface.

[0038] like Figure 6 and 7 As shown, during gear hobbing, the gear part 1 is clamped by a clamping device. The clamping device places the gear part 1 on a base 1. Multiple support members 4 are vertically arranged on the outer circumference of the base 1, and a pressure plate 5 is horizontally arranged above the support members 4. One end of the pressure plate 5 presses against the top surface of the gear part 12, and the pressure plate 5 and the base 1 are locked together by a locking member 3. A rotating platform is provided below the base 1, which can drive the clamping device to rotate when needed.

[0039] In this embodiment, performing reversal machining on the gear shaping part 1 at cutting allowances of 0.5mm, 0.05mm, and 0mm ensures that within 8 parts, the parts are qualified. A schematic diagram of gear shaping tool wear is shown below. Figure 3 As shown, the gear shaping tool wears out evenly. However, if the existing conventional unidirectional gear shaping method is used, that is, the gear shaping tool does not use the reversing method for gear shaping, the gear shaping tool will break when machining the second part.

[0040] Before machining, the inner hole 11 of the gear part 1 has a diameter of 121mm and a tooth root diameter of 125.2mm. The gear machining method in this embodiment is divided into three stages:

[0041] Phase 1: Cutting within an inner diameter range of 121-124.2mm, with the tool and the gear-shaping part 1 rotating counterclockwise simultaneously. During this phase, the tool experiences significant force and undergoes extrusion cutting; therefore, the left-hand side and bottom cutting edge of the tool are the primary wear areas. (This phase is consistent with the classic machining method.)

[0042] Second stage: Cutting within the inner hole range of 124.2-125.2mm. During this stage, the tool and the gear part 1 rotate clockwise simultaneously. At this time, the contact area between the tool and the gear part 1 is large, and the force on the tool is further increased. The right side and bottom cutting edge of the tool are the main wear areas.

[0043] The third stage involves the cutting tool and gear shaping part 1 rotating counterclockwise simultaneously, without feeding in the diametrical direction, to correct the tooth profile and direction errors caused by the pressure cutter. To ensure accuracy, the gear shaping tool needs to be reversed again in the later stages of wear.

[0044] The number of reversals will vary depending on the machining hardness, machining parameters, cutting tool, tool holder diameter, and machine tool rigidity.

[0045] The position and timing of the direction change need to be determined based on the total gear shaping allowance and the magnitude of the force. In this embodiment, based on the machining test of the gear shaping part 1, extrusion is likely to occur when the gear shaping depth is 1 / 2 of the depth of the gear shaping tool (the smaller the tool holder of the gear shaping tool, the earlier the extrusion phenomenon will occur). After extrusion occurs, it is necessary to keep the cutting depth on both sides consistent (principle: when the cutting force is greater than the force required for the elastic deformation of the tool, tool holder, machine tool spindle, and fixture, it is necessary to ensure that the cutting depth before and after the change of direction is consistent. The faster the cutting speed, the greater the cutting force, and the earlier the change of direction will occur). The tool wear rate on one side of the rotation direction is higher than that on the other side. In this embodiment, the total cutting allowance reserved for the gear shaping part 1 is 2.1mm. After uneven wear occurs, keeping the depth of removal before and after the change of direction consistent can maximize the tool life.

[0046] Example 2

[0047] In this embodiment, the bidirectional gear shaping method involves external gear shaping. The gear shaping tool and the gear shaping part 1 first rotate in opposite directions to perform the gear shaping, and then the rotation directions of the gear shaping tool and the gear shaping part 1 are changed simultaneously to perform the gear shaping again.

[0048] In this invention, "reverse" means that when shaping external teeth, the shaping tool and the shaping part 1 rotate in opposite directions. For example, if the shaping part 1 rotates clockwise, it rotates counterclockwise. Conversely, if the shaping tool rotates counterclockwise, the shaping part 1 rotates clockwise. "Same direction" means that when shaping internal teeth, the shaping tool and the shaping part 1 rotate in the same direction. This invention adds the function of simultaneously changing the rotation direction of the tool and the part during the machining process, which was not available in previous shaping methods.

[0049] Gear-shaped part 1, as shown Figure 8 As shown, the outer circumference of the shaft portion of the gear-shaping part 1 ( Figure 8 There is an external tooth at point B in the middle. This external tooth needs to be further machined. Before machining, the diameter of the external tooth is 46.925mm, the tooth root is 43.053mm, and the total machining allowance is 1.936mm.

[0050] The bidirectional tooth-fitting method of this embodiment includes the following steps:

[0051] Phase 1: When the machining allowance is 0-1.73mm, the conventional classic machining method is used. The gear shaping tool and the gear shaping part 1 rotate in opposite directions. The gear shaping tool rotates counterclockwise, while the gear shaping part 1 rotates clockwise.

[0052] Second stage: When the machining allowance is 1.73-1.936mm, the gear shaping tool rotates clockwise and the gear shaping part 1 rotates counterclockwise.

[0053] The principle of reversing timing: When the cutting force is greater than the force required for elastic deformation of any one of the tools, tool holders, machine tool spindles, or fixtures, it is necessary to reverse the direction to ensure that the cutting depth is consistent before and after.

[0054] In this embodiment, the maximum cutting force is calculated according to equation (1):

[0055] f z =A m ×p (1)

[0056] In the above formula, Z represents the number of teeth on the workpiece, m represents the module of the workpiece (mm), and p represents the unit cutting force (N / mm). 2 ), F c This is the circumferential feed rate.

[0057] When the cutting is complete, the fixture will produce an elastic deformation of 0.067 mm during machining. When the cutting continues to a depth of 1.73 mm, the fixture deformation is 0.02 mm, at which point the machining needs to be reversed.

[0058] Third stage: Shaping stage, the gear shaping tool rotates counterclockwise, and the gear shaping part 1 rotates clockwise.

[0059] When machining the next gear shaping part 1, the rotation direction of the gear shaping tool and the gear shaping part 1 at the start of machining is opposite to that at the start of machining the previous part. That is, at the start of machining, the gear shaping tool rotates clockwise and the gear shaping part 1 rotates counterclockwise to maintain uniform wear of the cutting edge.

[0060] In this embodiment, during processing, the bottom end face of the gear-shaping part 1 is used as the support surface. Figure 8 (Surface A), with the upper end face of the lower gear of the gear-shaping part 1 as the fixed surface ( Figure 8 (D side) The clamping device of Embodiment 1 is used to clamp the gear part 1.

[0061] If there is no opportunity to change direction, when machining the external gear, after machining one gear shaping part 1, the next gear shaping tool can directly change direction throughout the entire process.

[0062] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention, or modify them into equivalent embodiments, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the present invention, should fall within the protection scope of the present invention.

Claims

1. A bidirectional tooth-fitting method, characterized in that: Gear shaping can be either internal gear shaping or external gear shaping. When machining internal gears, the gear shaping tool and the gear shaping part (1) first rotate in the same direction to perform gear shaping, and then the rotation direction of the gear shaping tool and the gear shaping part (1) is changed simultaneously to perform gear shaping again; When machining external teeth, the gear shaping tool and the gear shaping part (1) are first rotated in opposite directions to perform gear shaping, and then the rotation direction of the gear shaping tool and the gear shaping part (1) is changed at the same time to perform gear shaping again; When gear shaping is performed as internal gear shaping, the following steps are included: S1. When the cutting allowance of the inner hole (11) of the gear shaping part (1) is greater than 0.5mm, the gear shaping tool and the gear shaping part (1) rotate counterclockwise at the same time to perform gear shaping. S2. When the cutting allowance of the inner hole (11) of the gear shaping part (1) is within the range of 0.05-0.5mm, the gear shaping tool and the gear shaping part (1) rotate clockwise at the same time to perform gear shaping. S3. When the cutting allowance of the inner hole (11) of the gear shaping part (1) is within the range of 0-0.05mm, the gear shaping tool and the gear shaping part (1) rotate counterclockwise at the same time to perform gear shaping.

2. The bidirectional tooth-fitting method according to claim 1, characterized in that: The core hardness of the gear-shaping component is HRC48-52.

3. The bidirectional tooth-fitting method according to claim 2, characterized in that: The raw material for the gear-shaping part (1) is 15Cr14Co12Mo5Ni2WA.

4. The bidirectional tooth-fitting method according to claim 1, characterized in that: During the internal gear shaping process, the top surface of the tooth (12) of the shaping part (1) is used as the support surface, the bottom surface of the tooth (12) is used as the fixing surface, and the inner wall of the inner hole (11) of the shaping part (1) near the tooth (12) is used as the rough positioning surface.

5. The bidirectional tooth-fitting method according to any one of claims 1 to 4, characterized in that: Before simultaneously changing the rotation direction of the gear shaping cutter and the gear shaping part (1), the following is also included: Determine whether the cutting force borne by the gear shaping part (1) is greater than the force required for elastic deformation of any one of the cutting tool, tool holder, machine tool spindle, or fixture. If so, change the rotation direction of the gear shaping tool and the gear shaping part (1) simultaneously when machining the gear shaping part (1). Otherwise, change the rotation direction of the gear shaping tool and the gear shaping part (1) simultaneously when machining the next gear shaping part (1).

6. The bidirectional tooth-fitting method according to claim 5, characterized in that: The cutting force borne by the gear shaping part (1) is calculated according to formula (Ⅰ): f z =A m ×p(Ⅰ) In the above formula, A m = Z represents the number of teeth on the workpiece, m represents the module of the workpiece (mm), and p represents the unit cutting force (N / mm). 2 ), F c This is the circumferential feed rate.

7. The bidirectional tooth-fitting method according to claim 6, characterized in that: When the gear shaping is an external gear shaping process, it includes the following steps: A1. When the machining allowance is greater than 0.5mm, the gear shaping tool and the gear shaping part (1) rotate in opposite directions to perform gear shaping. A2. Second stage: The machining allowance is 0-0.5mm, and the rotation direction of the gear shaping tool and the gear shaping part (1) is changed at the same time to carry out gear shaping.

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