A non-circular gear generating processing device and method based on a disc-shaped tool

Abstract

The present invention relates to a non-circular gear developing processing device and method based on a disc cutter. The device is derived from the gear shaping process of non-circular gears and uses an involute disc cutter as a processing tool. The gear shaping process is simulated on a horizontal five-axis machining center through the motion synthesis of the machine tool's axes. During the actual processing, after the two rotating shafts at the workpiece end rotate in a corresponding relationship, the disc cutter performs a radial cutting along the non-circular gear to be processed. After multiple movements, the processing of a single tooth surface can be completed. The non-circular gear is then indexed and the next gear tooth is processed. The above movements are repeated to process a complete non-circular gear. This method can realize developing processing on a general-purpose machine tool. Compared with traditional processing methods, the processing tool structure is simpler and easier to trim. The processing parameters of the gear milling machine can be adjusted according to processing needs to improve the meshing performance of the non-circular gear and make the processed non-circular gear more accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of gear processing, and in particular to a non-circular gear generating processing device based on a disc-shaped tool and a method thereof. Background Art

[0002] Gears are transmission components used in machines and instruments to transmit rotational motion and power between two shafts. Non-circular gear mechanisms that can achieve variable transmission ratios have the advantages of compact structure, precise and smooth transmission, and easy dynamic balancing. They are widely used in industrial facilities such as automatic machinery, transportation, instrumentation, pumps, and flow meters. Non-circular face gear transmission mechanisms are also a type of non-circular gear mechanism. Their transmission method uses a non-circular face gear meshing with traditional cylindrical gears. This transmission mechanism not only has the dual functions of combined reduction of two cylindrical gears and combined speed change of two non-circular gears, but also has the outstanding advantages of high efficiency and lightweight compared to ordinary series transmission mechanisms of non-circular gears and circular gears. As a new type of spatial non-circular gear transmission mechanism, it has great application potential in high-end fields such as medical equipment, aerospace, and robotics, which have special requirements for gear transmission space, quality, and performance.

[0003] The processing method of face gears is one of the research directions of many scholars at home and abroad. Among the many known face gear processing methods, most are processing methods for ordinary face gears. For the relatively new non-circular face gears, the existing processing methods are very rare. The invention patent with publication number CN102581387A discloses a face gear processing method. This invention can use disc-shaped tools on existing processing machines to achieve high-precision milling or grinding of face gears. Since this processing method does not require the design of a separate processing machine, this method can greatly reduce the production cost during the face gear processing process. The invention patent with publication number CN112719467A discloses a face gear skiving processing method. This invention method cuts the face gear by means of spatially staggered axial worm transmission between the tool and the workpiece, thereby achieving the face gear skiving processing. This processing method applies the skiving processing method to the processing of face gears, so that the processing of face gears has relatively high production efficiency and processing accuracy. The invention patent with publication number CN113927100A discloses a method for grinding face gears with worm grinding wheels at arbitrary axis intersection angles. This method uses a worm grinding wheel as a processing tool and is performed on a cylindrical gear grinding machine available on the market. This method can be used to process face gears with arbitrary axis intersection angles.

[0004] The above processing methods for face gears each have their own advantages, but because the shape of non-circular face gears is non-circular and the motion relationship between the workpiece and the tool is nonlinear, the above processing methods are not suitable for the processing of non-circular face gears. The existing processing methods that can process non-circular face gears are generally free-form surface processing methods on CNC machine tools, but the efficiency and accuracy of processing non-circular face gears using this processing method are relatively low. Summary of the Invention

[0005] In response to the above problems, the purpose of the present invention is to provide a non-circular gear developing processing device and method based on a disc-shaped tool. In view of the problem that there are no special machine tools for anisotropic tooth surfaces, a technical solution is proposed that can realize developing processing on a universal machine tool with high efficiency and high precision.

[0006] The technical solution adopted in the present invention is as follows:

[0007] The present invention proposes a non-circular gear generating processing device based on a disc-shaped tool, which is a horizontal five-axis machining center, characterized in that: the device includes an L-shaped machine tool bed, a disc-shaped tool, a tool shaft, a slide a, a slide b, a slide c, a workbench and a rotary table; the slide a is connected to the upper end surface of the horizontal side of the L-shaped machine tool bed in a sliding manner along the X-axis direction; the slide b is connected to the upper end surface of the slide a in a sliding manner along the Y-axis direction; the rotary table is arranged between the two sides of the upper end of the slide b and the middle part thereof is rotated by The moving shaft is connected to the rotating pairs on both sides of the upper end of the slide b, and the rotating axis is parallel to the Y axis; the worktable is arranged in the middle of the upper end surface of the turntable, and its center is connected to the rotating pair of the turntable, and the rotating axis is parallel to the Z axis; the slide c is connected to the inner end surface of the vertical side of the L-shaped machine tool bed in a sliding manner along the Z axis; one end of the disc-shaped tool is connected to the rotating pair in the middle of the front end surface of the slide c through the tool axis, and the disc-shaped tool corresponds to the worktable, and the tool axis is parallel to the X axis; during processing, the non-circular gear wheel blank can be installed on the worktable.

[0008] Furthermore, the disc cutter is an involute disc cutter, and its tooth surface is the same as a single tooth surface of a gear shaping cutter.

[0009] A non-circular gear generating method based on a disc-shaped tool. During the processing, each time the disc-shaped tool completes processing of a gear tooth, the non-circular gear wheel blank is indexed and the next gear tooth is processed until a complete non-circular gear is processed. Moreover, in the processing of a single gear tooth, the left and right tooth surfaces are processed separately. When processing a single tooth surface, each time the two rotating axes at the workpiece end rotate in a corresponding relationship, the disc-shaped tool performs a cut along the radial direction of the non-circular gear wheel blank to be processed. After multiple such movements, the processing of a single tooth surface can be completed. The specific steps for processing a single tooth surface of a non-circular gear are as follows:

[0010] a1. Generating motion: Set the angular increment of the workbench rotation axis after each generating motion to Assuming that the movement of each axis of the machine tool after completing the first generating motion is 0, then after completing the i-th generating motion, the movement of the worktable rotation axis, the rotary table rotation axis, the Z axis, and the X axis compared to the first generating motion is:

[0011]

[0012] Where R s is the radius of the virtual gear shaping cutter, is the angle value of the non-circular gear after completing the kth indexing, L is the distance between the axis of the rotary table shaft and the axis of the virtual gear shaping cutter itself, and "±" represents the direction of the worktable shaft. Represents the direction of rotation of the rotating table axis;

[0013] a2. Radial feed motion: After the disc cutter and the non-circular gear wheel blank complete a generating motion, the cutter feeds along the Y-axis of the machine tool to complete a cutting motion in the tooth diameter direction of the non-circular gear. The feed rate of this motion is set to:

[0014] l Y =Y0-l min +2d

[0015] Where, l min is the minimum value of the inner diameter of the wheel blank, Y0 is the distance between the disc cutter and the non-circular gear in the Y-axis direction of the machine tool when in the processing position, and the value of d is usually in the range of 2 to 5 mm;

[0016] a3. Tool retraction motion: After completing one cutting, the tool retracts to prepare for the next cutting. This motion only requires the Z-axis and Y-axis to move. The translational motion of the two axes is:

[0017]

[0018] Where t is the amount of tool lift along the Z axis during the tool retraction process, and D is the difference between the tooth addendum height and the tooth root height of the non-circular gear.

[0019] a4. In order to machine a complete tooth surface, the tool and the wheel blank need to reciprocate between the developing motion → radial feed motion → retraction motion until the complete tooth surface is cut out.

[0020] Furthermore, in step a4, the termination condition of the reciprocating motion between the generating motion → radial feeding motion → tool retraction motion is:

[0021]

[0022] Furthermore, before processing, the position of the non-circular gear wheel blank must be moved to complete tool alignment, and the tool shaft must be turned on to allow the disc-shaped tool to operate at high speed.

[0023] Furthermore, the angle of rotation of the non-circular gear wheel blank is different each time it is indexed, and the angle of rotation of the non-circular gear wheel blank after completing the kth indexing is different. The following relationship is satisfied relative to the position to be processed:

[0024]

[0025] Where n is the number of teeth on the non-circular gear, and 0≤k≤n-1;

[0026] The angle value of the non-circular gear wheel after completing the k+1th indexing is for:

[0027]

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention not only enriches the existing processing types of non-circular gears, but also has a simple processing tool structure and is easy to trim. The processing parameters of the milling machine tool can be adjusted according to processing needs, thereby improving the meshing performance of the non-circular gears and making the processed non-circular gears more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a structural schematic diagram of the device of the present invention;

[0031] Figure 2 It is a schematic diagram of the tooth surface profile of the disc tool;

[0032] Figure 3 This is a schematic diagram of the disc cutter and the non-circular gear after completing the first generating motion;

[0033] Figure 4 is a schematic diagram of the disc cutter and the non-circular gear after completing the i-th developing motion;

[0034] Figure 5 It is a schematic diagram of a disc-shaped tool cutting a non-circular gear wheel blank.

[0035] Among them, the figure marks are: 1-disc tool; 2-equivalent gear shaping cutter; 3-non-circular gear wheel blank; 4-L-shaped machine tool bed; 5-slide c; 6-tool axis; 7-worktable; 8-rotating table; 9-slide b; 10-slide a. DETAILED DESCRIPTION

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] It should be noted that, in the description of the present invention, the terms "up", "down", "top", "bottom", "one side", "the other side", "left", "right", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not mean that the device or element must have a specific orientation, be constructed and operated in a specific orientation.

[0038] See attached Figures 1 to 5 , an embodiment of a non-circular gear generating processing device and method based on a disc-shaped tool proposed by the present invention is given. The device is a horizontal five-axis machining center, specifically comprising a disc-shaped tool 1, an L-shaped machine bed 4, a slide c5, a tool shaft 6, a worktable 7, a rotary table 8, a slide b9 and a slide a10; the slide a10 is connected to the upper end surface of the horizontal side of the L-shaped machine bed 4 in a sliding manner along the X-axis direction; the slide b9 is connected to the upper end surface of the slide a10 in a sliding manner along the Y-axis direction, and the slide b9 has a concave structure; the rotary table 8 is arranged between the two ends of the open side of the slide b9, and the middle part of the rotary table 8 rotates with the two ends of the open side of the slide b through the rotating shaft. The workbench 7 is arranged in the middle of the upper end surface of the rotating table 8, and the center of the workbench 7 is connected to the rotating pair of the rotating table 8 through the rotating axis, and the rotating axis is parallel to the Z axis direction; the slide c5 is connected to the inner end surface of the vertical side of the L-shaped machine tool bed 4 in a sliding manner along the Z axis direction; one end of the disc-shaped tool 1 is connected to the rotating pair in the middle of the inner end surface of the slide c5 through the tool axis 6, and the disc-shaped tool 1 corresponds to the workbench 7, and the tool axis 6 is parallel to the X axis direction; during processing, the non-circular gear wheel blank 3 can be installed on the workbench 7.

[0039] This device is designed based on the principle of gear shaping. In the present invention, an involute disc tool is used to replace the original gear shaping cutter, and the tooth surface of the disc tool is the same as the single tooth surface of the gear shaping cutter. The non-circular face gear milling process based on the disc tool simulates the process of the gear shaping tool machining non-circular face gears.

[0040] Select the parametric equation as The spiral line is used as the pitch curve of the non-circular gear wheel blank, where R is the base circle radius of the spiral line and e is the eccentricity of the spiral line; the normal distances between the inner diameter curve and the outer diameter curve of the non-circular gear and the pitch curve are R n =5mm and R m=10mm.

[0041] Table 1 System design parameters

[0042]

[0043] A non-circular gear generating method based on a disc-shaped tool comprises the following steps:

[0044] Step 1: Move the non-circular gear wheel blank 3 to complete the tool setting, and move each axis of the device to the position to be processed, turn on the axis A of the tool shaft 6 to make the disc tool 1 run at high speed;

[0045] Step 2: Processing a single gear tooth; To complete the processing of a single tooth surface of a gear tooth, the disc-shaped tool 1 needs to perform multiple cutting movements on the tooth surface. During a certain cutting movement on the tooth surface, the disc-shaped tool 1 and the non-circular gear wheel blank 3 need to perform the following actions: generating, radial feeding, and retracting. These actions are described in detail below.

[0046] a1、Extension movement: such as Figure 3 As shown, after the first generating motion is completed, the rotation amount of the rotation axis C of the workbench 7 and the rotation axis B of the rotating table 8 and the translation amount of the X axis and the Z axis are respectively; l x (1) = 0, l z (1) = 0, and the rotation angle increment of the axis C of the workbench 7 after each completion of the unfolding movement is Then, after the i-th developing motion is completed, the position between the disc cutter 1 and the non-circular gear wheel blank 3 changes to Figure 4 The positional relationship shown in FIG, the movement of the rotation axis of the workbench 7, the rotation axis of the rotating table 8, the Z axis, and the X axis compared to the first generating movement is:

[0047]

[0048] Where R s is the radius of the equivalent gear shaping cutter 2, which is equivalent to the gear shaping cutter used in gear shaping of non-circular gears. s =60mm, is the angle value of the non-circular gear wheel blank 3 after completing the kth indexing. L is the distance between the axis of the rotating shaft B of the rotating table 8 and the axis of the rotating shaft of the virtual gear shaping cutter itself, L = 186.25 mm. "±" represents the direction of rotation of the rotating shaft C of the workbench 7. Represents the direction of rotation of the rotating axis B of the rotating table 8;

[0049] It can be concluded that after completing the i+1th unfolding motion, the motion increments of the C-axis, B-axis, Z-axis, and X-axis compared to the i-th unfolding motion are:

[0050]

[0051] a2. Radial feed motion: such as Figure 5 As shown in the figure, after the disc cutter 1 and the non-circular gear wheel blank 3 complete a generating motion, the cutter needs to be fed along the Y-axis direction of the machine tool to complete a cutting motion in the tooth diameter direction of the non-circular gear. The feed rate of this motion can be set as:

[0052] l Y =Y0-l min +2d

[0053] Where, l min is the minimum value of the inner diameter of the wheel blank, l min =104.47mm, Y0 is the distance between the disc cutter and the non-circular gear in the Y-axis direction of the machine tool when the disc cutter is in the processing position. Usually, the value of d ranges from 2 to 5mm. In the calculation process, the value of d is 5mm.

[0054] a3. Tool retraction: After completing one cut, the tool needs to be retracted to prepare for the next cut. This movement only requires the Z and Y axes of the machine tool to move. The translational motion of the two axes is:

[0055]

[0056] Where t is the amount of tool lift along the Z axis during the tool retraction process, D is the difference between the tooth addendum height and the tooth root height of the non-circular gear, D = 6.75 mm;

[0057] a4. After completing one retraction motion, the next generating motion begins between the non-circular gear wheel blank 3 and the disc cutter 1. Generally speaking, the cutter and the gear reciprocate between generating motion → radial feed motion → retraction motion until a complete tooth surface is cut. The end condition of this reciprocating motion is:

[0058]

[0059] After completing the machining of a single gear tooth, the movement of the B-axis, Z-axis, and X-axis returns to zero, and the movement of the C-axis remains unchanged;

[0060] Step 3: After completing the processing of a single gear tooth, the non-circular gear wheel blank 3 needs to be indexed in order to complete the processing of the next gear tooth; after completing the kth indexing, the angle of rotation of the non-circular gear wheel blank 3 is The following relationship is satisfied relative to the position to be processed:

[0061]

[0062] Where n is the number of teeth on the non-circular gear, n=89, and 0≤k≤n-1;

[0063] The angle value of the non-circular gear wheel after completing the k+1th indexing is for:

[0064]

[0065] Step 4: To complete the processing of the entire non-circular gear, it is necessary to repeat between steps 2 and 3. When k=n, the processing is completed, the tool shaft 6 stops rotating, and the axes of the machine tool move to the initial position, and the processing is completed.

[0066] In summary, the method employed in the present invention for machining non-circular gears is based on the principles of gear shaping. This method simulates the process of machining non-circular gears using a gear shaping cutter on a horizontal five-axis machine tool through the relative motion between the non-circular gear and a disc-shaped cutter. Without accounting for any errors, the gear shaping process and the non-circular gear machined using this method are identical. Compared to gear shaping, the proposed method utilizes a simpler tool structure, is easier to trim, and can adjust the machining parameters of the horizontal five-axis machine tool according to machining requirements, improving the meshing performance of non-circular gears. This method has promising application prospects.

[0067] Matters not fully described in the present invention are known in the art.

[0068] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A method for generating a non-circular gear using a disc-shaped tool, wherein the processing device is a horizontal five-axis machining center, characterized in that: The device comprises an L-shaped machine tool bed, a disc-shaped tool, a tool shaft, a slide a, a slide b, a slide c, a workbench and a rotary table; the slide a is slidably connected to the upper end surface of the horizontal side of the L-shaped machine tool bed along the X-axis direction; the slide b is slidably connected to the upper end surface of the slide a along the Y-axis direction; the rotary table is arranged between the two sides of the upper end of the slide b and the middle part thereof is connected to the rotary pairs on both sides of the upper end of the slide b through a rotary shaft, and the rotary shaft is parallel to the Y-axis; the workbench is arranged in the middle of the upper end surface of the rotary table, the center of which is connected to the rotary pair of the rotary table, and the rotary shaft is parallel to the Z-axis; the slide c is slidably connected to the inner end surface of the vertical side of the L-shaped machine tool bed along the Z-axis direction; one end of the disc-shaped tool is connected to the rotary pair in the middle of the front end surface of the slide c through the tool shaft and the disc-shaped tool corresponds to the workbench, and the tool shaft is parallel to the X-axis; during processing, the non-circular gear wheel blank can be mounted on the workbench; During the machining process, each time the disc cutter completes machining of a gear tooth, the non-circular gear wheel blank is indexed and the next gear tooth is machined until a complete non-circular gear is machined. Moreover, in the machining of a single gear tooth, the left and right tooth surfaces must be machined separately. When machining a single tooth surface, each time the two rotating axes at the workpiece end rotate in a corresponding relationship, the disc cutter performs a cut along the radial direction of the non-circular gear wheel blank to be machined. After multiple movements, the machining of a single tooth surface can be completed. The specific steps for machining a single tooth surface of a non-circular gear are as follows: a1. Generating motion: Assume that the angular increment of the table rotation axis after each generating motion is Δφ, and the motion of each axis of the machine tool after the first generating motion is 0. Then, after the i-th generating motion is completed, the motion of the table rotation axis, the rotary table rotation axis, the Z axis, and the X axis compared to the first generating motion is: Where Rs is the radius of the virtual gear shaping cutter, φk is the angle of rotation of the non-circular gear after completing the kth indexing, L is the distance between the axis of the rotary table shaft and the axis of the virtual gear shaping cutter itself, "±" represents the direction of rotation of the worktable shaft, and "∓" represents the direction of rotation of the rotary table shaft. a2. Radial feed motion: After the disc cutter and the non-circular gear wheel blank complete a generating motion, the cutter feeds along the Y-axis of the machine tool to complete a cutting motion in the tooth diameter direction of the non-circular gear. The feed rate of this motion is set to: Where lmin is the minimum inner diameter of the wheel blank, Y0 is the distance between the disc cutter and the non-circular gear in the Y-axis direction of the machine tool when in the processing position, and d is usually in the range of 2~5 mm. a3. Tool retraction motion: After completing one cutting, the tool retracts to prepare for the next cutting. This motion only requires the Z-axis and Y-axis to move. The translational motion of the two axes is: Where t is the amount of tool lift along the Z axis during the tool retraction process, and D is the difference between the tooth addendum height and the tooth root height of the non-circular gear. a4. In order to machine a complete tooth surface, the tool and the wheel blank need to reciprocate between the developing motion → radial feed motion → retraction motion until the complete tooth surface is cut out.

2. The processing method according to claim 1, characterized in that: The disc cutter is an involute disc cutter, and its tooth surface is the same as a single tooth surface of a gear shaping cutter.

3. The processing method according to claim 1, characterized in that: In step a4, the termination condition of the reciprocating motion among the generating motion → radial feeding motion → tool retraction motion is: 。 4. The processing method according to claim 3, characterized in that: Before processing, the position of the non-circular gear wheel blank must be moved to complete the tool setting, and the tool shaft must be turned on to make the disc tool run at high speed.

5. The processing method according to claim 4, characterized in that: The angle of rotation of the non-circular gear wheel blank is different each time it is indexed, and the angle φk of rotation of the non-circular gear wheel blank after completing the kth indexing satisfies the following relationship relative to the position to be processed: Where n is the number of teeth on the non-circular gear, and 0≤k≤n-1; Then the angle value Δφk of the non-circular gear wheel blank after completing the k+1th indexing is: 。

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