Linear contact generating tooth grinding machining method

Abstract

The invention belongs to the field of gear machining, and particularly relates to a line contact generating gear grinding machining method which comprises the steps that a tooth-shaped grinding wheel with the tooth surface being an involute spiral surface is adopted, and corresponding grinding machining parameters are deduced on the basis of line contact meshing grinding between the grinding wheel and the tooth surface of a workpiece and in combination with design parameters of the grinding wheel and a gear; in the machining process, a set crossed axis angle sigma and a set shaft distance a are kept between a grinding wheel and a rotary main shaft of the gear, the grinding wheel is biased, the grinding wheel is kept at a bias distance rho, and the rotating speed omega g of the grinding wheel, the rotating speed omega w of the gear to be machined and the feeding speed f of the grinding wheel are kept in a set proportional relation to complete tooth surface machining of the workpiece. According to the designed generating gear grinding machining method, instantaneous linear contact meshing grinding is achieved, no theoretical machining error exists, the machining precision is high, meanwhile, the limitation of traditional worm grinding wheel gear grinding is broken through, and the generating gear grinding machining method can be applied to grinding machining of inner gears.

Description

Technical Field

[0001] The invention belongs to the technical field of gear processing, and in particular relates to a line contact gear generating grinding processing method. Background Art

[0002] Gear grinding is a process of finely machining the gear tooth profile by grinding. It is usually used as the last step of gear hardening to fully correct various errors before gear grinding and obtain high gear accuracy. Precision grinding using a worm wheel is a commonly used gear grinding method.

[0003] During the processing, the worm grinding wheel and the workpiece are equivalent to a pair of staggered cylindrical gears that are continuously meshed. The two rotate at a fixed ratio to perform the generating motion to complete the involute tooth profile processing, and at the same time, the full tooth width is processed by the axial feed of the workpiece. The principle of worm grinding wheel gear grinding is based on the meshing of staggered cylindrical gears. During the meshing process of staggered cylindrical gears, the instantaneous contact of the two meshing tooth surfaces is point contact, and these instantaneous contact points constitute the meshing contact line on the tooth surface. Since the processing is continuous and graded grinding, the worm grinding wheel has a higher processing efficiency. However, during the grinding process, due to the axial feed of the workpiece, there will be a principle error between the two adjacent meshing contact lines. Therefore, in order to ensure that the workpiece with higher precision is obtained, it is often necessary to perform repeated grinding many times, which increases the processing cycle and production cost. At the same time, due to the limitations of the grinding method and structure, the worm grinding wheel cannot enter the inner gear for grinding, making it unsuitable for the processing of internal gears. These shortcomings limit the development of efficient generating grinding in the industry.

[0004] Therefore, it is necessary to provide an improved technical solution to address the above-mentioned deficiencies in the prior art. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a line contact gear grinding processing method. A processing method for involute cylindrical internal gears and external gears using a toothed grinding wheel with an involute spiral surface is proposed to solve the technical problem that the worm grinding wheel gear grinding in the prior art cannot be applied to internal gear processing.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A line contact gear generating grinding method, wherein the method uses a toothed grinding wheel with an involute spiral surface to process an involute cylindrical gear, and the grinding wheel performs generating grinding on the gear surface to be processed while the grinding wheel is feeding along the axial direction of the gear to be processed;

[0008] During the development grinding process, the grinding wheel rotation axis and the gear rotation axis to be processed are relatively tilted, forming an axis angle ∑ and an axis spacing a that remain unchanged. The common perpendicular line between the grinding wheel rotation axis and the gear rotation axis to be processed is defined as the offset adjustment reference, so that the grinding wheel maintains the offset distance ρ and the grinding wheel speed ω g 、Speed ​​of gear to be processedω w The set proportional relationship is maintained with the grinding wheel feed speed f; a multi-axis linkage controller is used to control the grinding wheel rotation axis, the rotation axis of the gear to be processed and the grinding wheel feed axis. The grinding wheel enters from the top of the gear to be processed and exits from the bottom, and feeds along the axial direction of the gear to be processed to complete the grinding of the tooth surface on one side of the gear to be processed; reverse offset is performed to complete the grinding of the tooth surface on the other side of the gear to be processed.

[0009] Furthermore, the grinding wheel speed ω g 、Speed ​​of gear to be processedω w The relationship with the grinding wheel feed speed f is as follows:

[0010] When the gear to be processed is an external gear, the grinding wheel speed

[0011] When the gear to be processed is an internal gear, the grinding wheel speed

[0012] Among them, r bw is the base circle radius of the involute helical surface of the gear to be machined, β bw is the helix angle of the base circle of the gear to be machined, r bg is the base circle radius of the involute spiral surface of the grinding wheel, β bg is the helix angle of the grinding wheel base circle, ω w is the rotation speed of the gear to be processed, and f is the grinding wheel feed speed.

[0013] Furthermore, the axis intersection angle ∑ is based on the grinding wheel base circle helix angle β bg Helix angle β with the base circle of the gear to be machined bw Sure:

[0014] When the gear to be processed is an external gear, the shaft angle ∑=|β bg +β bw |;

[0015] When the gear to be processed is an internal gear, the shaft angle ∑=|β bg -β bw |.

[0016] Furthermore, the axis spacing a is based on the base circle radius r of the involute spiral surface of the grinding wheel. bg The radius r of the base circle of the involute helical surface of the gear to be processed bw Sure:

[0017] When the gear to be processed is an external gear, the axis spacing a=r bw +rbg ;

[0018] When the gear to be processed is an internal gear, the axis spacing a=r bw -r bg .

[0019] Furthermore, the offset distance ρ is based on the axis intersection angle ∑, the axis spacing a, and the grinding wheel tooth top circle radius r ag The root circle radius rf of the gear to be processed w Sure:

[0020] When the gear to be processed is an external gear, it must meet

[0021] When the gear to be processed is an internal gear, it must meet

[0022] Where θ w ,θ g is an indirect parameter.

[0023] Furthermore, the axis intersection angle Σ ranges from 5° to 40°.

[0024] Furthermore, the normal modulus m of the grinding wheel is ng The normal module m of the gear to be processed nw The same, that is, m ng =m nw .

[0025] Furthermore, the grinding wheel type is a spur gear grinding wheel or a helical gear grinding wheel; the grinding wheel shape is cylindrical or conical; and the gear to be processed is a spur gear or a helical gear.

[0026] The beneficial effects of the present invention are:

[0027] The line contact generation gear grinding method of the present invention is based on the line contact meshing principle of staggered axis involute helical surface. During the processing, line contact meshing grinding is performed, which eliminates theoretical processing errors, has high processing accuracy, and can effectively improve product quality. During the processing, only one pass is required to complete the fine processing of the full tooth width of the single-sided tooth surface, effectively reducing the processing cycle and production costs.

[0028] At the same time, the line contact gear grinding method of the present invention has also broken through the limitations of worm grinding wheel gear grinding. In addition to being applied to the grinding of external gears, it can also be applied to the grinding of internal gears, providing an efficient and continuous solution for the finishing of internal gears. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. Among them:

[0030] Figure 1 It is a schematic diagram of the involute helical line contact engagement between the tooth surface of the grinding wheel of the present invention and the tooth surface of the gear to be processed.

[0031] Figure 2 Schematic diagram of the offset calculation for involute contact generation grinding when machining external gears.

[0032] Figure 3 Schematic diagram of the offset calculation for involute contact generation and grinding when machining internal gears.

[0033] Figure 4 The figure is a schematic diagram of the grinding process of the grinding wheel and the gear to be processed in one embodiment of the present invention.

[0034] Figure 5 It is a schematic structural diagram of a line contact gear generating grinding machine tool according to an embodiment of the present invention.

[0035] In the figure: 1-base, 2-Y-axis slide, 3-X-axis slide, 4-workpiece rotary table, 5-workpiece, 6-grinding wheel, 7-tool spindle, 8-axis angle adjustment rotary table, 9-Z-axis slide. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0037] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0038] The line contact generation gear grinding method of the present invention is designed based on the principle of line contact meshing of staggered axis involute helical surfaces. The present invention adopts a toothed grinding wheel with an involute helical surface as the tooth surface, and the grinding wheel type is a spur gear grinding wheel or a helical gear grinding wheel; the grinding wheel shape is cylindrical or conical; the processing parameters during grinding are calculated from the design parameters of the grinding wheel and the involute cylindrical gear to be processed (hereinafter referred to as the gear to be processed), and the gear to be processed is a spur gear or a helical gear. The design parameters of the grinding wheel include the normal module m ng 、Base circle helix angle β bg , base circle radius r bg , Tip circle radius r ag The design parameters of the gear to be processed include the normal module m nw 、Base circle helix angle β bw , base circle radius r bw , tooth root radius r fw In order to ensure that the grinding wheel and the gear to be processed can continuously mesh and grind during the grinding process, the normal module m of the grinding wheel should be guaranteed.ng Should be consistent with the normal module m of the gear to be processed nw The consistency of m ng =m nw .

[0039] like Figure 1 As shown, in the present invention, the tooth surfaces of the grinding wheel and the gear to be processed are both involute helical surfaces. The involute helical surface is a trajectory surface formed by a straight line on a plane in a fixed space when the plane rolls purely along the base cylindrical surface. Therefore, the involute helical surface is a straight line surface formed by a cluster of straight generatrixes. Any generatrix constituting the involute helical surface forms the same angle with the axis of the base cylinder, and the angle is the base circle helix angle of the involute helical surface. When the two staggered axis involute helical surfaces achieve line contact meshing, the instantaneous contact line is a straight generatrix constituting the involute helical surface of the grinding wheel tooth surface and the gear to be processed tooth surface. Therefore, the angles formed by the instantaneous contact line and the axes of the two involute helical surface base cylinders are the base circle helix angles of the two involute helical surfaces (grinding wheel base circle helix angle β bg and the helix angle β of the base circle of the gear to be machined bw ); Figure 1 The instantaneous contact line of the two involute helical surfaces is schematically drawn in the figure. In order to ensure that the grinding wheel tooth surface and the gear tooth surface to be processed can correctly perform line contact meshing grinding, the meshing contact line should have an angle with the grinding wheel and the rotation axis of the gear to be processed of β and β, respectively. bg and the helix angle β of the base circle of the gear to be machined bw , the calculation formula of the axis angle ∑ between the rotation axis of the grinding wheel and the rotation axis of the gear to be processed is further derived as:

[0040] When machining external gears: shaft angle ∑=|β bg +β bw |;

[0041] When machining internal gears: shaft angle ∑=|β bg -β bw |;

[0042] Grinding wheel base circle helix angle β bg Helix angle β with the base circle of the gear to be machined bw It has a set difference, which stipulates that the helix angle is positive when it is right-handed and negative when it is left-handed.

[0043] Furthermore, in order to avoid interference between the grinding wheel rotating axis and the workpiece during processing, the axis intersection angle ∑ is set in the range of 5° to 40°.

[0044] The instantaneous contact line is a straight generatrix that constitutes the involute helical surface of the grinding wheel tooth surface and the gear to be processed. Therefore, a plane tangent to the grinding wheel and the base cylinder of the gear to be processed can be drawn through the instantaneous contact line. The distances between the plane and the rotation axis of the grinding wheel and the gear to be processed are the base circle radius r of the involute helical surface of the grinding wheel and the base circle radius r of the involute helical surface of the grinding wheel. bgand the base circle radius r of the involute helical surface of the gear to be processed bw .

[0045] Furthermore, the calculation formula for the axis spacing a between the rotation axis of the grinding wheel and the rotation axis of the gear to be processed during grinding is derived as follows:

[0046] When machining external gears: axis spacing a = r bw +r bg ;

[0047] When machining internal gears: axis spacing a = r bw -r bg ;

[0048] Figure 2 and Figure 3 These are schematic diagrams of offset calculation when machining external gears and internal gears respectively.

[0049] In order to avoid the grinding wheel from intruding into the root circle of the gear to be processed during the grinding process, the grinding wheel should be offset relative to the common perpendicular line between the rotation axis of the grinding wheel and the rotation axis of the gear to be processed. The calculation formula of the offset distance ρ is:

[0050] When machining external gears:

[0051] When machining internal gears:

[0052] In the formula, r fw is the root circle radius of the gear to be processed, r ag is the radius of the grinding wheel tooth tip circle, θ w ,θ g is an indirect parameter; the axis spacing a and axis intersection angle ∑ used in this set of equations can be calculated according to the formula provided above and are known numbers.

[0053] When the grinding wheel and the gear to be processed rotate at speeds ω g and ω w When line contact meshing is performed, the relationship between the two is:

[0054] When machining external gears:

[0055] When machining internal gears:

[0056] In order to ensure that the grinding wheel can cover and effectively grind the entire tooth width range of the gear to be processed, it is necessary to add a feed motion to the grinding wheel along the rotation axis of the gear to be processed. At this time, in order to ensure the line contact meshing grinding of the grinding wheel and the gear to be processed, it is necessary to add an additional speed to the grinding wheel. A multi-axis linkage controller is used to control the grinding wheel rotation axis, the gear rotation axis to be processed and the grinding wheel feed axis, so that the grinding wheel speed ω g 、Speed ​​of gear to be processedωw and the grinding wheel feed speed f satisfy the following relationship:

[0057] When machining external gears:

[0058] When machining internal gears:

[0059] Specifically, during the process of the grinding wheel generating and grinding the gear tooth surface to be processed, the rotation axis of the grinding wheel and the rotation axis of the gear to be processed keep the axis intersection angle ∑ and the axis spacing a unchanged, the grinding wheel keeps the offset distance ρ, and the grinding wheel speed ω g 、Speed ​​of gear to be processedω w Keeping the set proportional relationship with the grinding wheel feed speed f, the grinding wheel enters from the top of the gear to be processed and exits from the bottom to complete the grinding of the tooth surface on one side of the gear to be processed, and then reverses to complete the grinding of the tooth surface on the other side of the gear to be processed.

[0060] The workpiece speed, grinding wheel speed, and grinding wheel feed speed are determined by the actual processing and need to satisfy the relationship listed in the formula. In a specific embodiment of a certain internal gear ring processing, the normal module m of the internal gear ring nw is 4mm, the normal pressure angle α is 20°, and the number of teeth is z w =100, the helix angle of the base circle of the gear to be processed β bw is 0°, the radius of the base circle of the involute helical surface of the gear to be processed is r bw is m nw z w cosα / 2=4×100×cos(20°) / 2=187.9385mm, the root circle radius of the gear to be processed r fw 205mm; normal modulus of grinding wheel m ng The radius of the base circle of the spiral surface of the grinding wheel is r bg The radius of the grinding wheel tooth top circle is 81.3719 mm. ag 93mm, grinding wheel base circle helix angle β bg is 18.7472°; set the workpiece speed ω w is 20.5rad / s, and the grinding wheel feed speed f is 6mm / min, then,

[0061] The axis intersection angle ∑ in the processing parameters is: |18.7472°-0°|=18.7472°;

[0062] The axis spacing a is: 187.9385mm-81.3719mm=106.5666mm;

[0063] Offset distance ρ: According to the solution of the equation group of offset distance ρ, the offset distance ρ is 35.9144mm;

[0064] Grinding wheel speed g It is: ((4×100×cos(20°) / 2)×cos(0°) / (81.3719×cos(18.7472)))×20.5+(sin(0) / (81.3719×cos(18.7472))×6)=50.00000841093498rad / s≈50rad / s.

[0065] Since the numerical values ​​listed in this embodiment and the results obtained in each step are rounded off, this may cause a slight deviation in the calculation results; in practical applications, accurate numerical values ​​can be obtained using calculation software such as MATLAB.

[0066] In the present invention, the spur gear grinding wheel can process helical gear workpieces, but cannot process spur gear workpieces; the helical gear grinding wheel can process spur gear or helical gear workpieces; the cylindrical and conical shapes have no effect on the processing limitations. In a specific example, the helical gear grinding wheel is used to process the helical gear, and their positional relationship is as follows: Figure 4 shown.

[0067] In one embodiment, the Figure 5 The machining machine shown implements the above-mentioned line contact gear generating grinding machining method.

[0068] The processing machine tool is a vertical machine tool in which the tool spindle 7 and the workpiece 5 rotation axis are arranged longitudinally, and includes six motion axes, including three linear axes and three rotation axes. The processing base 1 includes a base 1, on which a Y-axis slide 2 is provided. The linear motion of the Y-axis slide 2 in the Y-axis direction is achieved by driving a motor, and is used to control the relative position of the grinding wheel 6 and the workpiece 5 in the Y-axis direction, and adjust the axis distance between the grinding wheel 6 and the workpiece 5. An X-axis slide 3 is provided on the Y-axis slide 2. The linear motion of the X-axis slide 3 in the X-axis direction is achieved by driving a motor, and is used to control the relative position of the grinding wheel 6 and the workpiece 5 in the X-axis direction, and adjust the offset distance of the grinding wheel 6. A workpiece rotating table 4 is provided on the X-axis slide 3 to achieve the rotational motion of the workpiece 5 during the processing. A Z-axis slide 9 is provided on the base 1 above the Y-axis slide 2, and the linear motion of the Z-axis slide 9 in the Z-axis direction is realized by a driving motor, which is used to control the relative position of the grinding wheel 6 and the workpiece 5 in the Z-axis direction, and realize the feeding motion of the grinding wheel 6 during the processing. An axis angle adjustment rotary table 8 is provided on the Z-axis slide 9, which is used to adjust the axis angle between the grinding wheel 6 and the workpiece 5. A tool spindle 7 is provided on the axis angle adjustment rotary table 8, which is used to install the grinding wheel 6 and realize the rotational motion of the grinding wheel 6 during the processing. The processing machine tool adopts a multi-axis linkage controller to control the tool spindle 7, the workpiece rotary table 4 and the Z-axis slide 9, so that the grinding wheel speed, the workpiece speed and the grinding wheel feed speed maintain a set proportional relationship.

[0069] When the processing machine tool adopts the line contact gear grinding processing method of the present invention, based on the grinding processing parameters calculated from the grinding wheel and the design parameters of the gear to be processed, the axis angle ∑, the axis spacing a, the offset direction and the offset distance ρ between the grinding wheel and the workpiece are adjusted to maintain the set grinding wheel speed ω g 、Speed ​​of gear to be processedω w and feed speed f, so that the grinding wheel enters from the gear to be processed, completes the line contact generation grinding of the full tooth width of the tooth surface on one side of the gear to be processed, and then adjusts the offset direction to complete the line contact generation grinding of the full tooth width of the tooth surface on the other side of the workpiece.

[0070] On the basis of the aforementioned processing machine tool, if the axis angle adjustment rotating table is not set on the Z-axis slide, and the tool spindle is directly installed on the Z-axis slide at a specified angle, then in the embodiment of this case, the tool spindle and the workpiece rotary spindle maintain a constant axis angle. This machine tool with the tool spindle installed at a specified angle is specially used for processing when the axis angle is a set value.

[0071] In fact, the processing method of the present invention is not limited to the above-mentioned processing machine tools, and can also be used for grinding processing on existing vertical or horizontal machine tools. The requirement is that the tool spindle must be tiltable, and the minimum linkage requirement is the linkage of the grinding wheel rotation axis, the gear rotation axis to be processed, and the grinding wheel feed axis. For example, a six-axis three-linkage machine tool or a six-axis four-linkage machine tool in the prior art can be used.

[0072] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are within the scope of protection of the pending claims of the present invention.

Claims

1. A line contact gear generating grinding method, characterized in that: The method uses a toothed grinding wheel with an involute spiral surface to machine an involute cylindrical gear. When the grinding wheel is fed along the axial direction of the gear to be machined, the grinding wheel performs a generating grinding process on the tooth surface of the gear to be machined. During the development grinding process, the grinding wheel rotation axis and the gear rotation axis to be processed are relatively tilted, forming an axis angle ∑ and an axis spacing a that remain unchanged. The common perpendicular line between the grinding wheel rotation axis and the gear rotation axis to be processed is defined as the offset adjustment reference, so that the grinding wheel maintains the offset distance ρ and the grinding wheel speed ω g 、Speed ​​of gear to be processedω w The set proportional relationship is maintained with the grinding wheel feed speed f; a multi-axis linkage controller is used to control the grinding wheel rotation axis, the rotation axis of the gear to be processed and the grinding wheel feed axis. The grinding wheel enters from the top of the gear to be processed and exits from the bottom, and feeds along the axial direction of the gear to be processed to complete the grinding of the tooth surface on one side of the gear to be processed; reverse offset is performed to complete the grinding of the tooth surface on the other side of the gear to be processed.

2. The line contact generating gear grinding method according to claim 1, characterized in that: When the gear to be processed is an external gear, the grinding wheel speed When the gear to be processed is an internal gear, the grinding wheel speed Among them, r bw is the base circle radius of the involute helical surface of the gear to be machined, β bw is the helix angle of the base circle of the gear to be machined, r bg is the base circle radius of the involute spiral surface of the grinding wheel, β bg is the helix angle of the grinding wheel base circle, ω w is the rotation speed of the gear to be processed, and f is the grinding wheel feed speed.

3. The line contact generating gear grinding method according to claim 1, characterized in that: The axis intersection angle ∑ is based on the grinding wheel base circle helix angle β bg Helix angle β with the base circle of the gear to be machined bw Sure: When the gear to be processed is an external gear, the shaft angle ∑=|β bg +β bw |; When the gear to be processed is an internal gear, the shaft angle ∑=|β bg -β bw |.

4. The line contact generating gear grinding method according to claim 1, characterized in that: The axis spacing a is based on the base circle radius r of the grinding wheel spiral surface bg The radius r of the base circle of the involute helical surface of the gear to be processed bw Sure: When the gear to be processed is an external gear, the axis spacing a=r bw +r bg ; When the gear to be processed is an internal gear, the axis spacing a=r bw -r bg .

5. The line contact generating gear grinding method according to claim 1, characterized in that: The offset distance ρ is based on the axis angle ∑, the axis spacing a, and the grinding wheel tooth top circle radius r ag The radius of the tooth root circle of the gear to be processed is r fw Sure: When the gear to be processed is an external gear, it must meet When the gear to be processed is an internal gear, it must meet Where θ w ,θ g is an indirect parameter.

6. The line contact generating gear grinding method according to claim 1, characterized in that: The axis intersection angle ∑ ranges from 5° to 40°.

7. The line contact generating gear grinding method according to claim 1, characterized in that: The normal modulus of the grinding wheel is m ng The normal module m of the gear to be processed nw The same, that is, m ng =m nw .

8. The line contact generating gear grinding method according to claim 1, characterized in that: The grinding wheel type is a spur gear grinding wheel or a helical gear grinding wheel; the grinding wheel shape is cylindrical or conical; the gear to be processed is a spur gear or a helical gear.

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