A design method for multi-layer gear hobbing tools

Abstract

This invention relates to a design method for a multi-layer gear hobbing tool, belonging to the field of tool design technology, and solves the technical problems of low efficiency caused by the need for multiple machining operations in existing gear hobbing processes. The solution is as follows: a design method for a multi-layer gear hobbing tool, comprising the following steps: 1) Inputting parameters; 2) Calculating and obtaining the envelope diagram of the workpiece to be machined: obtaining the envelope diagram of the workpiece to be machined and the parametric equations of the involute surface based on the necessary and sufficient conditions for forming the tooth profile of the workpiece and the motion transformation matrix; 3) Designing a three-dimensional tool model: determining the number of teeth of the tool based on the gear hobbing cutting principle using gear design software, and designing a three-dimensional tool model; 4) Designing a multi-layer gear hobbing tool: simulating the cutting of the workpiece using the three-dimensional tool model, and designing the multi-layer gear hobbing tool; 5) Machining with the multi-layer gear hobbing tool: finding the reference point and adjusting the feed rate to complete the machining in one pass. Compared with the prior art, this invention has the advantages of completing the machining of the workpiece in one pass and high efficiency.

Description

Technical Field

[0001] This invention belongs to the field of cutting tool design technology, and specifically relates to a design method for a multi-layer gear hobbing tool. Background Technology

[0002] Gear hobbing, also known as gear turning, is a machining process based on the meshing principle of helical gears on two intersecting axes in space. It involves the generating motion of the tool and the workpiece to machine gears. Its advantages include high efficiency, high precision, high flexibility, and low cost. It can complete multiple operations in a single setup, making it particularly suitable for machining internal gears, gears with interference profiles, and hardened tooth surfaces. However, due to the influence of machine tool performance, cutting tools, workpiece material, and cutting parameters, gear hobbing often requires multiple machining operations, resulting in low efficiency. Summary of the Invention

[0003] In order to overcome the shortcomings of existing technologies and solve the technical problems of low efficiency caused by multiple processing steps in existing gear hobbing processes, this invention provides a design method for multi-layer gear hobbing tools.

[0004] The present invention is achieved through the following technical solutions.

[0005] This invention provides a design method for multi-layer gear hobbing tools, comprising the following steps:

[0006] 1) Input parameters:

[0007] Input the gear parameters of the workpiece to be processed into the gear design software;

[0008] 2) Calculate and obtain the envelope diagram of the workpiece to be processed:

[0009] Based on the necessary and sufficient conditions for forming the tooth profile of the workpiece to be processed and the motion transformation matrix, the envelope diagram of the workpiece to be processed and the parametric equations of the involute surface are obtained.

[0010] The necessary and sufficient condition for the tooth profile of the workpiece to be machined is: ,in The parametric equation of the cutting edge curve of a gear hobbing tool in the coordinate system; , where is the vector of the workpiece to be processed in the coordinate system. t is the envelope parameter vector. denoted as the tool helix angle, and s as the axial feed rate; The point of tangency when forming the envelope diagram, i.e., the position where the partial derivative is 0; the cutting edge equation of the gear hobbing tool is... , For a point on the cutting tool, the motion transformation matrix is: ,in For a certain point on the workpiece to be processed, The angle between the axes is equal to the helix angle of the tool. Center distance;

[0011] The parametric equation of the involute surface of the workpiece to be processed is: ,in This refers to the coordinates of the surface at a certain moment when the workpiece is formed into an involute surface, transformed using polar coordinates. The radius of the base circle, For the involute development angle, It is an involute function of the normal pressure angle. The axial pitch is... The angle between the axes is equal to the helix angle of the tool;

[0012] 3) Design the 3D model of the cutting tool:

[0013] Gear design software determines the number of teeth on the tool based on the gear hobbing cutting principle and designs the tool's three-dimensional model.

[0014] 4) Design of multi-layer gear hobbing cutters:

[0015] The cutting parameters of the workpiece are obtained by simulating the cutting of the tool based on the three-dimensional model of the tool. The tool infeed diagram is designed based on the cutting parameters of the tool. The tool axis intersection angle and center distance are calculated based on the tool infeed diagram, and the tool shape is designed to obtain the multi-layer gear hobbing tool.

[0016] 5) Multi-layer gear hobbing tool machining:

[0017] Find the reference point, swing the multi-layer hobbing tool to the axis intersection angle, move the multi-layer hobbing tool to the infeed coordinate point, adjust the feed amount and complete the workpiece to be processed in one pass.

[0018] Furthermore, the workpiece to be processed in step 1) is a straight tooth.

[0019] Furthermore, when the workpiece to be processed is a straight tooth, the workpiece helix angle is 0°, the shaft intersection angle is equal to the tool helix angle, and no differential rotational angular velocity needs to be added to the tool.

[0020] Furthermore, the gear parameters in step 1) include normal module, number of teeth, displacement coefficient, pressure angle, addendum circle coefficient, dedendum circle coefficient, tooth thickness, total depth of cut, tool material, tool cutting speed, and shaft angle.

[0021] The beneficial effects achieved by this invention are as follows: This invention selects spur gears as the workpiece to be processed. Utilizing the theory that spur gears do not require additional differential rotational angular velocity during hobbing, a multi-layer hobbing tool is designed that eliminates the need for multiple passes and allows for one-pass machining of the workpiece. Compared to the single-layer tool used in traditional methods, efficiency is greatly improved. This invention also proposes a multi-layer hobbing tool machining method. In traditional methods, workpiece machining typically involves finding a reference point, swinging the tool to the axis intersection, rotating and moving the tool to the first feed point, performing the first cut, retracting the tool, moving to the second feed point, performing the second cut, and repeating this cycle until machining is complete. However, this invention only requires finding a reference point, swinging the multi-layer hobbing tool to the axis intersection, moving the tool to the feed point, and adjusting the feed rate to complete machining in one pass. This eliminates the need for frequent tool lifting and feeding as in previous methods, saving significant time and improving efficiency.

[0022] Compared with the prior art, the present invention has the advantages of completing the workpiece to be processed in one feed and high efficiency. Attached Figure Description

[0023] Figure 1 This is an envelope diagram of the workpiece to be processed according to an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the feed of a multi-layer gear hobbing tool according to an embodiment of the present invention;

[0025] Figure 3 This is a flowchart illustrating the design of the multi-layer gear hobbing tool of this invention;

[0026] Figure 4 This is a schematic diagram of the hobbing tool structure of the present invention. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0028] like Figures 1 to 4 As shown, a design method for a multi-layer gear hobbing tool includes the following steps:

[0029] 1) Input parameters:

[0030] Input the gear parameters of the workpiece to be processed into the gear design software; the gear parameters include normal module, number of teeth, displacement coefficient, pressure angle, addendum circle coefficient, dedendum circle coefficient, tooth thickness, total depth of cut, tool material, tool cutting speed, and shaft angle.

[0031] Specifically, gear design software includes Kisssoft and self-developed Matlab software. The workpiece to be machined is a spur gear. During the gear hobbing process, machining the gear tooth profile requires maintaining a precise kinematic relationship between the tool and the workpiece. On one hand, to maintain the basic generating relationship between the hobbing tool and the workpiece, a certain tool angular velocity is required. and workpiece angular velocity Maintain a constant ratio On the other hand, the cutting tool performs synchronous linear motion parallel to the workpiece's rotation axis. In the actual machining process of gear hobbing, the existence of the shaft intersection angle causes this synchronous linear motion to disrupt the original correct meshing relationship between the gear hobbing tool and the workpiece. In order to maintain the correct meshing relationship, an additional differential rotational angular velocity needs to be added to the tool. ,in , The helix angle of the workpiece. The normal module of the workpiece. The number of teeth on the cutting tool; thus, we obtain , The number of teeth on the workpiece. The axial angle satisfies... However, when the workpiece to be machined is a straight tooth, the helix angle of the workpiece... Since the angle is 0°, the axis intersection angle is equal to the tool helix angle, and no additional differential rotational angular velocity needs to be added to the tool. Based on the fact that spur gears do not require additional differential rotational angular velocity, a tool that does not require multiple passes is designed.

[0032] 2) Calculate and obtain the envelope diagram of the workpiece to be processed:

[0033] Based on the necessary and sufficient conditions for forming the tooth profile of the workpiece to be processed and the motion transformation matrix, the envelope diagram of the workpiece to be processed and the parametric equations of the involute surface are obtained. The envelope diagram is as follows: Figure 1 As shown, Figure 1 To obtain the tooth profile of the workpiece as seen from the back face of the tool; the necessary and sufficient condition for the tooth profile of the workpiece to be machined is: ,in The parametric equation of the cutting edge curve of a gear hobbing tool in the coordinate system; , where is the vector of the workpiece to be processed in the coordinate system. t is the envelope parameter vector. denoted as the tool helix angle, and s as the axial feed rate; The point of tangency when forming the envelope diagram, i.e., the position where the partial derivative is 0; the cutting edge equation of the gear hobbing tool is... , For a point on the cutting tool, the motion transformation matrix is: ,in For a point on the workpiece to be processed, the motion transformation matrix represents the relationship between a point on the cutting tool and a point on the workpiece through motion transformation. The angle between the axes is equal to the helix angle of the tool. The center distance is; the center distance satisfies , Let be the pitch circle radius of the workpiece to be processed; the parametric equation of the involute surface of the workpiece to be processed is: ,in This refers to the coordinates of the surface at a certain moment when the workpiece is formed into an involute surface, transformed using polar coordinates. The radius of the base circle, For the involute development angle, It is an involute function of the normal pressure angle. The axial pitch is... The angle between the axes is equal to the helix angle of the tool.

[0034] 3) Design the 3D model of the cutting tool:

[0035] Gear design software determines the number of teeth on the tool based on the gear hobbing cutting principle and designs the tool's three-dimensional model.

[0036] Specifically, gear design software analyzes the tool diameter, linear velocity, and tool material based on the hobbing cutting principle to calculate the number of teeth and helix angle. Different tool materials correspond to different linear velocities. For example, the linear velocity of S390 is generally 220-300 m / min. Different linear velocities result in different choices of the number of teeth. The gear design software designs a three-dimensional model of the tool based on the parameters.

[0037] 4) Design of multi-layer gear hobbing cutters:

[0038] The cutting parameters of the workpiece are obtained by simulating the cutting of the tool based on the three-dimensional model of the tool. The tool infeed diagram is designed based on the cutting parameters of the tool. The tool axis intersection angle and center distance are calculated based on the tool infeed diagram, and the tool shape is designed to obtain the multi-layer gear hobbing tool.

[0039] Specifically, cutting parameters include the optimal cutting range of tool linear velocity, depth of cut, feed rate, and tool feed diagram. Figure 2 As shown, Figure 2 The diagram shows the radial depth of cut for each pass. Based on the tool feed rate and the tool feed diagram, the tool outline is designed in reverse engineering. The tool's outer contour, rake angle, clearance angle, number of layers, and other details are designed, ultimately resulting in a multi-layer gear hobbing tool. Figure 4 The diagram shows the structure of a multi-layer gear hobbing tool.

[0040] 5) Multi-layer gear hobbing tool machining:

[0041] Find the reference point, swing the multi-layer hobbing tool to the axis intersection angle, move the multi-layer hobbing tool to the infeed coordinate point, adjust the feed amount and complete the workpiece to be processed in one pass.

[0042] The multi-layer gear hobbing tool designed in this invention only requires finding a reference point when machining the workpiece. The multi-layer gear hobbing tool swings to the axis intersection angle, moves to the infeed coordinate point, and the feed rate is adjusted to complete the machining of the workpiece in one pass. This eliminates the need for frequent tool lifting and feeding as in previous methods, saving a lot of time and improving efficiency.

[0043] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, modifications can still be made to the embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A design method for a multi-layer gear hobbing tool, characterized in that: Includes the following steps: 1) Input parameters: Input the gear parameters of the workpiece to be processed into the gear design software; 2) Calculate and obtain the envelope diagram of the workpiece to be processed: Based on the necessary and sufficient conditions for forming the tooth profile of the workpiece to be processed and the motion transformation matrix, the envelope diagram of the workpiece to be processed and the parametric equations of the involute surface are obtained. The necessary and sufficient condition for the tooth profile of the workpiece to be machined is: ,in The parametric equation of the cutting edge curve of a gear hobbing tool in the coordinate system; , where is the vector of the workpiece to be processed in the coordinate system. t is the envelope parameter vector. denoted as the tool helix angle, and s as the axial feed rate; The point of tangency when forming the envelope diagram, i.e., the position where the partial derivative is 0; the cutting edge equation of the gear hobbing tool is... , For a point on the cutting tool, the motion transformation matrix is: ,in For a certain point on the workpiece to be processed, The angle between the axes is equal to the helix angle of the tool. Center distance; The parametric equation of the involute surface of the workpiece to be processed is: ,in This refers to the coordinates of the surface at a certain moment when the workpiece is formed into an involute surface, transformed using polar coordinates. The radius of the base circle, For the involute development angle, It is an involute function of the normal pressure angle. The axial pitch is... The angle between the axes is equal to the helix angle of the tool; 3) Design the 3D model of the cutting tool: Gear design software determines the number of teeth on the tool based on the gear hobbing cutting principle and designs the tool's three-dimensional model. 4) Design of multi-layer gear hobbing cutters: The cutting parameters of the workpiece are obtained by simulating the cutting of the tool based on the three-dimensional model of the tool. The tool infeed diagram is designed based on the cutting parameters of the tool. The tool axis intersection angle and center distance are calculated based on the tool infeed diagram, and the tool shape is designed to obtain the multi-layer gear hobbing tool. 5) Multi-layer gear hobbing tool machining: Find the reference point, swing the multi-layer hobbing tool to the axis intersection angle, move the multi-layer hobbing tool to the infeed coordinate point, adjust the feed amount and complete the workpiece to be processed in one pass.

2. The design method of a multi-layer gear hobbing tool according to claim 1, characterized in that: The workpiece to be processed in step 1) is a straight tooth.

3. The design method of a multi-layer gear hobbing tool according to claim 2, characterized in that: When the workpiece to be processed is a straight tooth, the workpiece helix angle is 0°, the shaft intersection angle is equal to the tool helix angle, and no additional differential rotational angular velocity is required on the tool.

4. The design method of a multi-layer gear hobbing tool according to claim 1, characterized in that: The gear parameters in step 1) include normal module, number of teeth, displacement coefficient, pressure angle, addendum circle coefficient, dedendum circle coefficient, tooth thickness, total depth of cut, tool material, tool cutting speed, and shaft angle.

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