CN107322059A - Enveloping worm hob CAD/CAM approach based on universal numerical control milling machine - Google Patents

Abstract

The invention relates to a CAD/CAM method for a toroidal worm gear hob based on a four-axis or more linkage universal numerical control milling machine, which belongs to the design and manufacturing method of the torus worm gear hob. Using the forming principle of the helical surface and side relief surface of the toroidal worm gear hob, the point families on the left and right side helical surfaces, the left and right margin band termination lines, and the left and right relief surfaces of the uniform hob are respectively obtained; the point families are imported into the 3D software The left and right side helical surfaces, the left and right margin band termination lines and the left and right back angle surfaces of the hob are fitted in the middle; the remaining surface structure is established through simple feature commands according to the parameters, and a complete 3D model of the torus worm gear hob is obtained. Import the model into the four-axis or more linkage universal CNC milling machine system, and realize the automatic processing of the hob only through the three processes of rough milling, heat treatment and fine milling. The processing technology of the hob is simplified, and the manufacturing precision of the hob is improved.

Description

CAD/CAM method of toroidal worm gear hob based on general CNC milling machine

technical field

The invention relates to a CAD/CAM method for a toroidal worm gear hob based on a universal numerically controlled milling machine linked by four or more axes, and belongs to the design and manufacturing method of a toroidal worm gear hob.

Background technique

Compared with the cylindrical worm drive, the toroidal worm drive has strong bearing capacity, small size, high transmission efficiency and long service life, and is widely used in high-efficiency and heavy-duty occasions. However, the meshing theory of the toroidal worm drive is complex, and the meshing transmission performance is very sensitive to errors and deformations, requiring high-precision manufacturing. However, the toroidal worm gear hob used in the machining of the toroidal worm gear is a special tool with complex structure and great difficulty in design and manufacture. The processing process of the existing integral toroidal worm gear hob is cumbersome, and it is necessary to use different equipment such as worm CNC machine tools, milling machines, and heat treatment equipment to combine various processes such as turning, grinding, milling, heat treatment, and manual grinding. To manufacture the hob, the workpiece is clamped many times, it is difficult to ensure the accuracy, the process is complicated and the precision of the obtained hob is low. The low precision of the hob leads to low cutting performance of the hobbing worm gear, and the resulting toroidal worm pair has low precision and poor meshing performance, and needs running-in to be used normally. Therefore, it is necessary to find a new method of designing and manufacturing the toroidal worm gear hob that breaks away from the traditional complex and cumbersome processing technology and can improve the accuracy and cutting performance of the hob.

China Agricultural University's 2013 doctoral thesis "Research on Numerical Control Machining Technology of Enveloping Toroidal Worm Gear Hobs" proposed a design method for the turning process of the flank of the hob, and established a hob including the flank of the tooth side Three-dimensional model, and using the milling method to preliminarily discuss the direct forming of the key surface of the hob including the relief surface of the tooth side on a four-axis linkage milling machine, but this method only focuses on the milling of the flank surface of the hob , without considering the back angle of the top of the knife, there is no complete manufacturing process of the hob, and it cannot be used for the hobbing of the worm gear. Chinese patent ZL201410613061.5 "Numerical Control Grinding Method for Side Back Angle Surface of Plane Secondary Enveloping Toroidal Worm Gear Hob" proposes a planar secondary enveloping toroidal worm gear hob rear surface based on four-axis linkage toroidal worm grinding machine Angle surface grinding technology realizes the automatic grinding of the back angle of the hob, and can be ground according to the designed land width and back angle, but it is only the grinding of the back angle. All have not realized the complete design and manufacture of the toroidal worm gear hob based on the general CNC milling machine.

Contents of the invention

The object of the present invention is to provide a method for automatic machining of the toroidal worm gear hob on a universal CNC milling machine with four or more axes linked by only two clamping and one heat treatment process. The technical scheme taken in order to achieve the object of the present invention is as follows:

Torus worm gear hob CAD: Utilize the helicoid forming principle of torus worm gear hob to calculate the three-dimensional coordinate data of the left helicoid point family (1) and the right helicoid point family (2) uniformly distributed on the hob, According to the given number of rows of teeth, rake face and margin width, calculate the three-dimensional coordinates of the left margin end line point family (3) and the right margin end line point family (4) uniformly distributed on each tooth Data, according to the calculation method of the lead angle of the helical surface of the hob and the method of turning the rear face of the hob with the tip of the turning tool and the angle of the rear face, calculate the point family (5) and The three-dimensional coordinate data of the right back angle point family (6) will calculate the three-dimensional coordinate data of the left helicoid point family (1) and the right helicoid point family (2) of the hob, and the left The three-dimensional coordinate data of the point family of the end line of the side margin (3) and the point family of the end line of the right margin (4), the point family of the left relief surface of the tooth (5) and the point family of the side relief surface (6) The 3D coordinate data is imported into the 3D modeling software, and the left helicoid (7) and right helicoid (8) of the hob, the left margin end line (9) and the right margin of the cutter tooth are respectively fitted The end line (10), the left relief surface (11) and the right relief surface (12) of the cutter tooth, and the tooth top torus (13) and tooth root torus of the hob are established according to the relevant parameters of the hob (14), the rake face (15) and the flank face (16) of the cutter tooth, through the cutting of the left helical face (7) by the rake face (15) and the left flank face (11), obtain The left margin surface (17) of the cutter tooth is cut by the rake face (15) and the right flank surface (12) to the right helical surface (8), to obtain the right margin surface ( 18), the rake face (15) is translated in the direction of the flank face (16) by a distance of the land width and intersects with the addendum ring surface (13) to obtain the top margin end line (19) of the cutter tooth, and the addendum The portion of the torus (13) between the rake face (15) and the top margin end line (19) is the top margin surface (20) of the cutter tooth, and the tooth top torus (13) is located at the top edge The portion between the belt end line (19), the left helicoid (7), the right helicoid (8) and the flank (16) turns around the top margin end line (19) to the tooth root annulus (14) After a relief angle, the top relief surface (21) of the cutter tooth is obtained. In this way, the rake surface (15), the left margin surface (17), the left relief surface (11), the top edge Band surface (20), top relief surface (21), right side margin surface (18), right relief surface (12) and flank surface (16) enclose a three-dimensional solid model of cutter tooth, and The three-dimensional solid model of other cutter teeth can be obtained, and thus the three-dimensional solid model of the hob can be obtained (22).

CAM of the toroidal worm gear hob: input the 3D solid model (22) of the toroidal worm gear hob into the CAM software, based on the K-axis linkage general-purpose CNC milling machine, where K is a positive integer, and the value range of K is 4, 5 and 6, The finishing allowance L of the rake face (15), the left margin face (17), the right margin face (18) and the top margin face (20) of a given cutter tooth, where L is in the range of 0.05mm-1.00 Given within the range of mm, compile the NC milling program, rough machine the toroidal worm gear hob on the K-axis linkage general NC milling machine, and then heat treat the torus worm gear hob, make the machining allowance zero, compile the NC program, and then The rake surface (15), the left margin surface (17), the right margin surface (18) and the top margin surface (20) of each tooth of the toroidal worm gear hob on a K-axis linkage universal CNC milling machine Finishing, that is, the finished product of the worm gear hob.

The beneficial effect of the present invention is that: based on CAD/CAM technology, only a general-purpose numerical control milling machine with four or more axes linked can be used to process the toroidal worm gear hob through rough and finish machining and a heat treatment process. This method not only simplifies the processing technology of the hob, but also ensures the position and shape of the cutting edge of each tooth of the hob, the width of the edge, and the angle of the relief angle, thereby obtaining better manufacturing accuracy and Cutting performance of the toroidal worm gear hob.

Description of drawings

Fig. 1 is the flow chart of the design and manufacturing method of the toroidal worm gear hob of the present invention

Fig. 2 is a schematic diagram of the distribution of point families on the key curved surface of the profile of the toroidal worm gear hob of the present invention

Fig. 3 is the schematic diagram of the process of establishing the right helicoid of the hob according to the helicoid point family on the right of the hob in the three-dimensional software in the method of the present invention

Fig. 4 is the schematic diagram of the single cutter tooth three-dimensional solid model of the hob set up in the method of the present invention

Fig. 5 is the three-dimensional model diagram of the toroidal worm gear hob set up in the method of the present invention

Figure 6 is a schematic diagram of the position of the toroidal worm gear hob in the CNC milling machine when the CNC milling program is compiled based on the CAM software

detailed description

Examples of the present invention are described below with reference to the accompanying drawings.

Taking the planar quadratic enveloping toroidal worm gear hob as an example, the relevant parameters are: the center distance of the toroidal worm pair a = 175mm, the hob root arc radius R _f0 = 152.4mm, the hob addendum arc radius R _a0 ＝158mm, the number of rows of cutter teeth N _z ＝6, the chip flutes are straight grooves, evenly distributed in the circumferential direction, the angle between the circumference of each rake face is 60°, and the rake face of a row of cutter teeth passes through the throat of the hob The teeth are thicker. The hob has a total of 31 cutter teeth, the cutter tooth relief angle χ=5°, the edge width l _E =1mm, and the cutter tooth thickness η=15mm.

Figure 2 is a schematic diagram of the distribution of the point family on the contour surface of the toroidal worm gear hob. Using the helicoid forming principle of the toroidal worm gear hob and the given parameters above, the three-dimensional coordinate data of the left helicoid point family (1) and the right helicoid point family (2) uniformly distributed on the hob are calculated, Among them, on the one-sided helical surface, there are 23 points in the tooth height direction and 127 points in the hob axial direction, a total of 23×127=2921 points. Determine the position of each rake face (15) according to the number of rows of given cutter teeth, each rake face (15) is translated to the cutter tooth entity along the normal direction of the rake face by a distance of the land width l _E , and the left side The intersection of the helicoid (7) and the right helicoid (8) results in the termination of the left margin (9) and the termination of the right margin (10), so that the termination of the left margin evenly distributed on each tooth can be calculated The three-dimensional coordinate data of the line point family (3) and the right margin termination line point family (4) each have 17 points. According to the calculation method of the lead angle of the helical surface of the hob and the method of turning the rear face of the hob by the tip of the turning tool, according to the angle χ of the side relief face, the lead angle of the point on the starting line of the relief face and the turning transmission ratio relationship, a series of helical lines on the side relief surface are obtained, and thus the mathematical model of the side relief surface is obtained. Using the mathematical model of the side relief surface, the point family (5) and The three-dimensional coordinate data of the point family (6) on the right relief surface, including 17 points in the tooth height direction, 16 points in the hob tooth length direction, and a total of 17×16=272 points in the relief surface on one side of a single tooth of the hob .

Fig. 3 shows the fitting process diagram of the helicoid (8) on the right side of the hob based on the reverse engineering principle of the modeling software. On the right helicoid point family (2), fit every 127 points along the hob axis into a helical line, a total of 23 helical lines, and then fit the 23 helical lines into the right helicoid ( 8), similarly, the left helicoid (7) can be obtained. On the point family (4) of the right margin end line, 17 points are fitted into a curve along the tooth height direction, that is, the right margin end line (10). Similarly, the left margin end line ( 9). On the point family (6) of the right flank surface of the cutter tooth, every 16 points are fitted into a curve along the tooth length direction, a total of 17 curves, and then 17 curves are fitted into the right relief surface ( 12), in the same way, the left back angle surface (11) can be obtained.

Figure 4 is a schematic diagram of the established three-dimensional solid model of a single tooth of the hob. According to the center distance of the toroidal worm pair a = 175mm, the hob root arc radius R _f0 = 152.4mm, and the hob addendum arc radius R _a0 = 158mm, the hob is established by the command "arc rotation into pieces" The addendum torus (13) and root torus (14). According to the fact that the chip flute is a straight groove, the rake face of the first row of cutter teeth passes through the tooth thickness point of the throat of the hob and the angle between the circumference of each rake face is 60°, and the tooth thickness η of the cutter teeth is 15mm, it is determined by "straight line stretching" Into a sheet" command to establish the rake face (15) and flank face (16) of the cutter tooth. Cut the left helical surface (7) through the rake surface (15) and the left flank surface (11) by the command "Cut sheet", to obtain the left margin surface (17) of the cutter tooth, and pass the front The cutting of the right side helical surface (8) by the knife face (15) and the right flank surface (12) obtains the right side land surface (18) of the knife tooth. Translate the rake face (15) to the flank face (16) by the "translation" command and the "intersect to form a curve" command for a distance of a margin width l _E and intersect the addendum torus (13) to obtain the cutter tooth The top margin end line (19) of the tooth top, the part of the addendum torus (13) between the rake face (15) and the top margin end line (19) is the top margin surface (20) of the cutter tooth.

Terminate the portion of the addendum torus (13) located between the top margin termination line (19), the left helicoid (7), the right helicoid (8) and the flank (16) around the top margin Line (19) turns back angle x=5 ° to dedendum annulus (14), obtains the top relief face (21) of knife tooth. The top relief face (21) is extended by the Extend Surface command to intersect the left relief face (11), right relief face (12) and relief face (16), and trimmed by the Trim Body command Remove the part of the left relief face (11), right relief face (12) and flank face (16) beyond the top relief face (21), so that the rake face (15), flank face ( 16), left margin face (17), left relief face (11), top margin face (20), top relief face (21), right margin face (18) and right relief face The surface (12) has just surrounded a three-dimensional solid model of a cutter tooth, and in the same way, the three-dimensional solid models of other cutter teeth can be obtained, that is, the three-dimensional solid model (22) of the toroidal worm gear hob is obtained.

Figure 6 is a schematic diagram of the position of the toroidal worm gear hob in the CNC milling machine when the CNC milling program is compiled based on the CAM software. Input the three-dimensional solid model (22) of the toroidal worm gear hob into the UG software, based on the 4-axis linkage universal CNC milling machine of the X axis, Y axis, Z axis and C axis, the axis of the torus worm gear hob (23) and C Axes overlap, the relative position change of milling cutter (24) with respect to the three-dimensional solid model (22) of toroidal worm gear hob has three linear movement axes of X axis, Y axis and Z axis, and the three-dimensional solid model of toroidal worm gear hob ( 22) Follow the rotation of the C axis. Given the rake surface (15), left margin surface (17), right margin surface (18) and top margin surface (20) finishing allowance L of the given cutter tooth, take L=0.5mm, compile CNC milling program, rough machining of the toroidal worm gear hob on the 4-axis linkage general-purpose CNC milling machine, and then heat-treat the torus-surface worm gear hob, according to the machining allowance being zero, compile the NC program, and then run it on the 4-axis linkage general-purpose CNC milling machine The rake surface (15), the left margin surface (17), the right margin surface (18) and the top margin surface (20) of each tooth of the toroidal worm gear hob are finished, and the worm gear hob is obtained. Finished knife.

Claims (1)

1. The CAD/CAM method of the toroidal worm wheel hob based on the general CNC milling machine is characterized in that it includes the CAD/CAM method based on the torus worm wheel hob, and utilizes the helical surface forming principle of the torus worm wheel hob to calculate the uniform distribution on the left side of the hob. The three-dimensional coordinate data of the side helicoid point family (1) and the right helicoid point family (2), according to the given number of rows of teeth, rake face and land width, calculate the left edge The three-dimensional coordinate data of the point family with the end line (3) and the point family (4) of the right margin end line, according to the calculation method of the lead angle of the helical surface of the hob and the method of turning the rear face of the hob with the tip of the turning tool and Relief angle, calculate the three-dimensional coordinate data of the left relief surface point family (5) and the right relief surface point family (6) uniformly distributed on each cutter tooth, and calculate the left helical surface point family of the hob (1) and the three-dimensional coordinate data of the right helicoid point family (2), the three-dimensional coordinate data of the left margin end line point family (3) and the right margin end line point family (4) of each cutter tooth, The three-dimensional coordinate data of the left relief surface point family (5) and the side relief surface point family (6) of the cutter tooth are imported into the three-dimensional modeling software, and the left helical surface (7) and the right helical surface of the hob are respectively fitted. the helical surface (8), the left margin end line (9) and the right margin end line (10) of the cutter tooth, the left relief angle surface (11) and the right relief angle surface (12) of the cutter tooth, According to relevant parameters of the hob, the tooth top torus (13) and dedendum torus (14), the rake face (15) and the flank (16) of the cutter tooth are established, and the rake face (15) ) and left relief surface (11) to the left helical surface (7) to obtain the left margin surface (17) of the cutter tooth, through the rake surface (15) and right relief surface (12 ) to the right helical surface (8) to obtain the right margin surface (18) of the cutter tooth, and translate the rake surface (15) to the direction of the flank surface (16) by a distance of the land width and the tooth The top annular surface (13) intersects to obtain the top margin termination line (19) of the tooth, and the part of the addendum annular surface (13) between the rake face (15) and the top margin termination line (19) is For the top margin surface (20) of the cutter tooth, place the tooth top annular surface (13) on the top margin termination line (19), the left helicoid (7), the right helicoid (8) and the flank ( 16) The part between them turns around the top margin end line (19) to the tooth root annulus (14) through a relief angle, that is, the top relief surface (21) of the cutter tooth is obtained. In this way, the rake surface ( 15), left margin surface (17), left relief angle surface (11), top margin surface (20), top relief angle surface (21), right margin surface (18), right relief angle Face (12) and flank (16) have surrounded the three-dimensional solid model of a cutter tooth, similarly, can obtain the three-dimensional solid model of other cutter teeth, thereby obtain the three-dimensional solid model (22) of hob; Worm gear hob CAM, input the three-dimensional solid model (22) of the toroidal worm gear hob into the CAM software, based on the K-axis linkage general-purpose CNC milling machine, where K is a positive integer, and the value range of K is 4, 5 and 6. Given The rake face (15) of the cutter tooth, the left edge The finishing allowance L of the land surface (17), the right land surface (18) and the top land surface (20), where L is given within the range of 0.05mm-1.00mm, is programmed for CNC milling, and the K-axis linkage Rough machining of the worm gear hob on the general CNC milling machine, and then heat treatment of the worm gear hob on the general NC milling machine. The rake surface (15), the left side land surface (17), the right side land surface (18) and the top land surface (20) of the cutter tooth are finished, and the finished product of the worm gear hob is obtained.