A method for continuous generating spiral cylindrical gears

Abstract

This invention discloses a continuous generating method for spiral cylindrical gears. By setting the initial positions of the disc milling cutter and the gear blank, and coordinating the rotation and feed motions during the cutting process, continuous generating machining is achieved without tool retraction, saving time and greatly improving machining efficiency. Furthermore, this invention enables the machining of gears with different modules and numbers of teeth by changing and adjusting the disc milling cutter inserts, facilitating tool standardization.

Description

Technical Field

[0001] This invention relates to the field of gear transmission technology, and in particular to a method for the continuous generating process of spiral cylindrical gears. Background Technology

[0002] Spiral cylindrical gears possess advantages such as circular tooth profile, smooth transmission, high load-bearing capacity, and balanced axial force, making them highly suitable for high-speed, heavy-duty transmission equipment. However, their tooth surface forming is complex, requiring high precision in machining methods and equipment, and for a long time, stable and efficient manufacturing methods have been lacking. Traditional gear machining often focuses on involute tooth profiles, employing conventional generating processes such as hobbing and shaping, making it difficult to directly achieve the composite forming of circular arc tooth lines and circular arc tooth profiles.

[0003] Early machining of spiral cylindrical gears mostly employed the contouring method, which used a customized template device to control the tool trajectory, causing the tool to move along a preset arc path. The tooth shape was achieved by relying on the mechanical template for forced constraint. This method has a simple structure, but the template manufacturing error is large, the adjustment cycle is long, and the versatility is poor. Different modules, tooth widths, and arc radii all require the replacement of special templates, making it difficult to guarantee machining accuracy and consistency. It is only suitable for small-batch, low-precision applications.

[0004] As high-end equipment demands increasingly higher transmission performance, indexing milling solutions based on dedicated gear milling machines have emerged. These solutions employ an arc-shaped cutter head to cut teeth one by one, utilizing the relative position of the cutter's rotation radius and the workpiece to form the arc tooth profile. While this method improves processing efficiency, it suffers from significant indexing errors and tooth direction deviations, and the tooth surface is prone to tool marks. Furthermore, the transmission stability and strength are insufficient to meet the requirements for high-precision applications.

[0005] Some studies have used shaped grinding wheels to improve tooth surface accuracy, but this method suffers from problems such as difficulty in dressing the grinding wheel, low processing efficiency, and high manufacturing costs. It is mostly used for small-batch precision grinding and cannot meet the needs of mass production. Currently, the machining of spiral cylindrical gears still generally suffers from high specialization, poor process compatibility, and difficulty in balancing accuracy and efficiency, which restricts its widespread application in high-end equipment. Therefore, a stable, reliable, and versatile high-precision generating machining method is urgently needed.

[0006] Existing patent application number 201010231318.2 describes a machining method for spiral cylindrical gears that uses a tooth-by-tooth indexing method. After each tooth groove is cut, the machine tool must perform an indexing action and allow the tool to idle before proceeding to the next tooth groove. This intermittent machining method results in excessively long non-cutting idle travel time, leading to low machining efficiency and failing to meet the requirements of modern manufacturing for high-efficiency production.

[0007] The continuous generating machining method is based on the generating principle. By controlling the precise linkage between the tool and the workpiece, it simulates the continuous meshing process of a hypothetical arc-shaped rack and gear. The tool does not need to retract or index during machining, eliminating idle travel time and enabling continuous cutting of the gear workpiece, thus significantly improving machining efficiency. Summary of the Invention

[0008] The purpose of this invention is to address the technical deficiencies in the prior art by providing a continuous generating method for spiral cylindrical gears.

[0009] The technical solution adopted to achieve the purpose of this invention is: A method for continuous generating of spiral cylindrical gears includes the following steps: Step 1: Install the disc milling cutter and the gear blank in the initial position. At this time, the spindle of the disc milling cutter is perpendicular to the spindle of the gear blank. The horizontal distance between the spindle of the disc milling cutter and the spindle of the gear blank is the rolling radius of the disc milling cutter, and the vertical distance between the spindle of the disc milling cutter and the spindle of the gear blank is the nominal radius of the disc milling cutter. Step 2: Drive both the disc milling cutter and the gear blank to rotate clockwise, with a fixed speed ratio between them; Step 3: The disc milling cutter moves along its axial direction to approach the gear blank and cuts the gear blank. After completing at least one revolution of cutting, the disc milling cutter continues to move along its axial direction until the distance between the tip of the disc milling cutter and the center of the gear blank is equal to the radius of the tooth root circle of the gear blank, thus completing the machining of the gear blank and forming an arc-tooth cylindrical gear.

[0010] In the above technical solution, the module of the spiral cylindrical gear is controlled by adjusting the number of cutting blades of the disc milling cutter.

[0011] In the above technical solution, the rotational speed of the disc milling cutter and the rotational speed of the gear blank satisfy the following formula: ; in, Let be the angular velocity of the milling cutter. The angular velocity of the gear blank. The gear pitch circle radius, This is the radius of the milling cutter.

[0012] In the above technical solution, the toolpath trajectory of the disc milling cutter is in the production rack coordinate system. S 1 （O 1 ,X 1 ,Y 1 ） The parametric equations are as follows: ; in, X 1 represents the x-coordinate of the toolpath trajectory of the disc milling cutter.Y 1 represents the ordinate of the toolpath trajectory of the disc milling cutter. for M The distance from the point to the center of the milling cutter's roll circle. M Point as O With 0 as the center, R b A point outside the circle rounded by a disc milling cutter with radius [radius]. Origin of coordinates O 1 to O A distance of 0; The roll angle for the milling cutter.

[0013] In the above technical solution, the tooth surface of the spiral cylindrical gear Determined by the following formula: ; in: M 2f Let be the transformation matrix from the disc milling cutter coordinate system to the gear blank. For the tooth surface of the milling cutter.

[0014] In the above technical solution, the transformation matrix M 2f Determined by the following formula: ; in: This refers to the rotation angle during the meshing process between the gear and the imaginary gear rack.

[0015] In the above technical solution, the tooth surface of the milling cutter Determined by the following formula: ; in: The pressure angle of the disc milling cutter insert. The nominal radius of the disc milling cutter head. u As variables, H 1 and H Both 2 are intermediate variables.

[0016] In the above technical solution, intermediate variables H 1 and H 2. Calculated using the following formula: ; ; ; ; ; ; in,A , B and C All are intermediate variables.

[0017] In the above technical solution, the disc milling cutter includes a disc shank, a cutter head disposed on the disc shank, and a plurality of inserts disposed on the end face of the cutter head and evenly arranged along its circumference. The inserts include inner inserts and outer inserts, which are used to process the inner and outer tooth surfaces of the gear blank, respectively.

[0018] In the above technical solution, during the cutting process, the inner and outer blades cut simultaneously, and the entire gear machining is completed in one pass.

[0019] In the above technical solution, the position of the cutting tool can be adjusted in the radial and circumferential directions of the cutter head. After machining, the tooth profile, tooth direction and tooth thickness are detected. If they do not meet the specified requirements, fine cutting can be performed by adjusting the feed speed of the disc milling cutter, the radial position of the cutting tool (used to finely adjust the position of the tooth profile and the contact area of ​​the disc milling cutter), and the circumferential position of the cutting tool (used to control the tooth thickness and backlash of the spiral cylindrical gear).

[0020] In the above technical solution, the nominal diameter of the cutter head D m Tooth width of gear blank b The following relationship exists: ; in, k This is the nominal diameter coefficient of the disc milling cutter. k =2.5~3.5.

[0021] In the above technical solution, spiral cylindrical gears with different numbers of teeth and modules are machined by changing the inserts of the disc milling cutter. The number of insert pairs... Z b With the base circle radius of the gear blank R b Gear module m Calculate using the following formula: ; In the above technical solution, the module m =1~10, the tip circle diameter of the spiral cylindrical gear D a <800mm.

[0022] In the above technical solution, the pressure angle of the milling cutter insert is... α =18~22°.

[0023] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention achieves continuous generating machining by setting the initial positions of the disc milling cutter and the gear blank, and coordinating the rotation and feed motions during the cutting process. There is no tool retraction action, saving time and greatly improving machining efficiency. 2. This invention enables the machining of gears with different modules and numbers of teeth by changing and adjusting the inserts of the disc milling cutter, which facilitates the standardization of cutting tools; 3. This invention can improve machining efficiency and achieve roughing by increasing the feed speed of the disc milling cutter; and can perform fine cutting by decreasing the feed speed of the disc milling cutter, adjusting the radial position of the insert (for fine-tuning the position of the tooth profile and the contact area between the disc milling cutter) and adjusting the circumferential position of the insert (for controlling the tooth thickness and backlash of the spiral cylindrical gear), which is beneficial to improving tooth profile accuracy and machining reliability. Attached Figure Description

[0024] Figure 1 The toolpath trajectory of the disc milling cutter of the present invention is shown below. M It is the position after the disc milling cutter has rolled through an angle θ. O 0 Let be the origin of the machine tool coordinate system. O 1 Let the origin of the gear rack coordinate system be the origin. O t Let the origin of the milling cutter's coordinate system be the initial position of the milling cutter. O 0 coincide.

[0025] Figure 2 This is a schematic diagram of the overall structure of a disc milling cutter.

[0026] Figure 3 The images show the side and front views of the disc milling cutter and gear blank in their initial positions.

[0027] Figure 4 It is a spiral cylindrical gear.

[0028] Wherein, 1: disc milling cutter, 1.1: disc shank, 1.2: cutter head, 1.3: inner insert, 1.4: outer insert, 2: gear blank. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0030] like Figure 3 As shown, a method for continuous generating spiral cylindrical gears includes the following steps: Step 1: Install the disc milling cutter 1 and the gear blank 2 on the machine tool. Use a tool setting device to determine the initial position of the disc milling cutter 1 and the gear blank 2. At this time, the spindle of the disc milling cutter 1 is perpendicular to the spindle of the cylindrical gear blank. The horizontal distance between the spindle of the disc milling cutter 1 and the spindle of the gear blank 2 is the base circle radius L2 of the disc milling cutter 1. The vertical distance between the spindle of the disc milling cutter 1 and the spindle of the gear blank is the nominal radius L1 of the disc milling cutter 1. The base circle radius of the gear blank 2 is equal to the base circle radius L2 of the disc milling cutter 1. Step 2: Activate continuous machining mode. The disc milling cutter 1 feeds along its axial direction towards the gear blank 2 to cut it. After completing at least one revolution of cutting, the disc milling cutter 1 continues to feed until the distance between the tip of the disc milling cutter 1 and the center of the gear blank 2 is equal to the radius of the tooth root circle. The gear blank 2 is processed to form a spiral cylindrical gear (such as...). Figure 4 (as shown) Step 3: After machining is completed, check the tooth profile, tooth direction and tooth thickness. If they do not meet the specified requirements, fine cutting can be performed by adjusting the feed speed of the disc milling cutter, the radial position of the insert (used to finely adjust the position of the tooth profile and the contact area of ​​the disc milling cutter), and the circumferential position of the insert (used to control the tooth thickness and backlash of the spiral cylindrical gear).

[0031] Furthermore, the rotational speed of the disc milling cutter and the rotational speed of the gear blank satisfy the following formula: ; in, Let be the angular velocity of the milling cutter. The angular velocity of the gear blank. The gear pitch circle radius, This is the radius of the milling cutter.

[0032] Furthermore, such as Figure 1 As shown, the tooth profile of the spiral cylindrical gear is generated based on a hypothetical production rack, and the geometry of the production rack is generated by the toolpath trajectory of the disc milling cutter 1. If the base circle of the disc milling cutter 1 rolls purely along the center line of the production rack, the trajectory of a fixed point M outside the base circle of the spiral cylindrical gear constitutes the rack tooth profile. The toolpath trajectory of the disc milling cutter 1 in the coordinate system... S 1 （O 1 ,X 1 ,Y 1 ） The parametric equations are as follows: ; in, X 1 represents the x-coordinate of the disc milling cutter's toolpath. Y 1 represents the ordinate of the toolpath of the disc milling cutter. Let M be the distance from point M to the center of the milling cutter's roll circle, where M is the distance from point M to the center of the roll circle. O With 0 as the center,R b A point outside the circle rounded by a disc milling cutter with radius [radius]. Origin of coordinates O 1 to O A distance of 0; The roll angle for the milling cutter.

[0033] like Figure 4 As shown, the tooth surface of the spiral cylindrical gear Determined by the following formula: ; in: M 2f Let be the transformation matrix from the disc milling cutter coordinate system to the gear blank. For the tooth surface of the milling cutter.

[0034] The transformation matrix M 2f Determined by the following formula: ; in: This refers to the rotation angle during the meshing process between the gear and the imaginary gear rack.

[0035] Disc milling cutter tooth surface Determined by the following formula: ; in: The pressure angle of the disc milling cutter insert. The nominal radius of the disc milling cutter head. u As variables, H 1 and H Both 2 are intermediate variables, and their formulas are as follows: ; ; ; ; ; ; in, A , B and C All are intermediate variables.

[0036] Furthermore, such as Figure 2As shown, the disc milling cutter 1 includes a disc shank 1.1, a cutter head 1.2 disposed at the end of the disc shank 1.1, and a plurality of inserts disposed on the end face of the cutter head 1.2 and evenly arranged along its circumference. The inserts include inner inserts 1.3 and outer inserts 1.4, which are used to process the inner and outer tooth surfaces of the gear blank 2, respectively.

[0037] Furthermore, during the cutting process, the inner insert 1.3 and the outer insert 1.4 cut simultaneously, completing the rough machining of the entire gear in one pass. The position of the inserts can be adjusted radially and circumferentially on the cutter head 1.2. After finishing, the tooth profile, tooth direction, and tooth thickness are inspected. If they do not meet the specified requirements, the radial position of the inserts (used to fine-tune the contact area between the tooth profile and the disc milling cutter 1) and the circumferential position of the inserts (used to control the tooth thickness and backlash of the spiral cylindrical gear) can be adjusted for another cutting.

[0038] Furthermore, for the same module family, only one disc milling cutter 1 is needed, with a cutter head of 1.2 nominal diameter. D m The following relationship exists between the tooth width b of gear blank 2 and the gear blank 2: ; in, k The nominal diameter coefficient for the disc milling cutter is k = 2.5~3.5.

[0039] Furthermore, by changing the inserts of the disc milling cutter, spiral cylindrical gears with different numbers of teeth and modules can be machined, increasing the number of insert pairs. Z b The base circle radius of the gear blank R b Module of gear blank m Calculate using the following formula: ; When processing modules For a spiral cylindrical gear with a diameter of 5mm, number of teeth Z=40, and tooth width b=60mm, the nominal diameter of the milling cutter 1 is 1.2mm. Logarithm of blades The selection should consider both economic efficiency and ease of adjustment to determine the base circle radius of the disc milling cutter. Based on the meshing principle, the motion parameters of the tool and the workpiece are set, and the transmission ratio is calculated: The parameters are shown in Table 1. Table 1 Parameters

[0040] The above description is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for continuous generating of spiral cylindrical gears, characterized in that, Includes the following steps: Step 1: Install the disc milling cutter and the gear blank in the initial position. At this time, the spindle of the disc milling cutter is perpendicular to the spindle of the gear blank. The horizontal distance between the spindle of the disc milling cutter and the spindle of the gear blank is the rolling radius of the disc milling cutter, and the vertical distance between the spindle of the disc milling cutter and the spindle of the gear blank is the nominal radius of the disc milling cutter. Step 2: Drive both the disc milling cutter and the gear blank to rotate clockwise, with a fixed speed ratio between them; Step 3: The disc milling cutter moves along its axial direction to approach the gear blank and cuts the gear blank. After completing at least one revolution of cutting, the disc milling cutter continues to move along its axial direction until the distance between the tip of the disc milling cutter and the center of the gear blank is equal to the radius of the tooth root circle of the gear blank, thus completing the machining of the gear blank and forming an arc-tooth cylindrical gear.

2. The continuous generating process method according to claim 1, characterized in that, In step 2, the rotational speed of the disc milling cutter and the rotational speed of the gear blank satisfy the following formula: ； in, Let be the angular velocity of the milling cutter. Let be the angular velocity of the gear blank. The gear pitch circle radius, This is the radius of the milling cutter.

3. The continuous generating process method according to claim 1, characterized in that, The milling cutter's toolpath trajectory is in the gear rack coordinate system. S 1 （O 1 ,X 1 ,Y 1 ） The parametric equations are as follows: ； in, X 1 represents the x-coordinate of the toolpath trajectory of the disc milling cutter. Y 1 represents the ordinate of the toolpath trajectory of the disc milling cutter. for M The distance from the point to the center of the milling cutter's roll circle. M Point is the origin of the machine tool coordinate system. O With 0 as the center, R b A point outside the circle rounded by a disc milling cutter with radius [radius]. Origin of coordinates O 1 to O A distance of 0; The roll angle for the milling cutter.

4. The continuous generating process method according to claim 1, characterized in that, The tooth surface of the spiral cylindrical gear Determined by the following formula: ； in: M 2f Let be the transformation matrix from the disc milling cutter coordinate system to the gear blank. For the tooth surface of the milling cutter.

5. The continuous generating process method according to claim 4, characterized in that, The transformation matrix M 2f Determined by the following formula: ； in: This refers to the rotation angle during the meshing process between the gear and the imaginary gear rack.

6. The continuous generating process method according to claim 4, characterized in that, Disc milling cutter tooth surface Determined by the following formula: ； in: The pressure angle of the disc milling cutter insert. The nominal radius of the disc milling cutter head. u As variables, H 1 and H Both 2 are intermediate variables, referring to the pressure angle of the milling cutter insert. α =18~22°.

7. The continuous generating process method according to claim 6, characterized in that, intermediate variables H 1 and H 2. Calculated using the following formula: ； ； ； ； ； ； in, A , B and C All are intermediate variables.

8. The continuous generating process method according to claim 1, characterized in that, The disc milling cutter includes a disc shank, a cutter head disposed at the end of the disc shank, and multiple inserts evenly arranged circumferentially on the end face of the cutter head. The inserts include inner inserts and outer inserts, which are used to machine the inner and outer tooth surfaces of the gear blank, respectively. During the cutting process, the inner and outer inserts cut simultaneously, and the entire gear is machined in one pass. The position of the inserts can be adjusted radially and circumferentially on the cutter head. After machining, the tooth profile, tooth direction, and tooth thickness are inspected. If they do not meet the specified requirements, fine cutting can be performed by adjusting the disc milling cutter feed rate, the radial position of the inserts, and the circumferential position of the inserts.

9. The continuous generating process method according to claim 1, characterized in that, nominal diameter of cutter head D m Tooth width of gear blank b The following relationship exists: ； in, k This is the nominal diameter coefficient of the disc milling cutter. k =2.5~3.

5.

10. The continuous generating process method according to claim 1, characterized in that, Machining spiral cylindrical gears with different tooth counts and modules by changing the inserts of the disc milling cutter; insert pair number Z b With the base circle radius of the gear blank R b Gear module m Calculate using the following formula: ； Among them, gear module m =1~10, the tip circle diameter of the spiral cylindrical gear D a <800mm.

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