Numerical control hobbing machine for machining external gear of helical gear

Abstract

The application discloses a numerical control gear hobbing machine for helical gear outer tooth processing and relates to the field of gear hobbing machines, which comprises a bed body, a workpiece spindle unit and a cutting shaft unit, the workpiece spindle unit comprises a workpiece spindle and a center, the cutting shaft unit comprises a cutting shaft, an infeed movement shaft and a rotary adjustment table, the cutting shaft is provided with a hobbing cutter, the rotary adjustment table is used for adjusting the angle of the cutting shaft, the infeed movement shaft is used for driving the hobbing cutter to move infeed, the rotary adjustment table is fixedly provided with a baffle, and the tangential direction of the cutting point of the hobbing cutter is towards the baffle; the material of the baffle is ferromagnetic metal, and the side, away from the hobbing cutter, of the baffle is provided with a plurality of electromagnets. The application can reduce the range of chip splashing in the helical gear processing process, thereby reducing the cleaning work of the gear hobbing machine.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of gear hobbing machine, in particular to a numerical control gear hobbing machine for machining helical gear outer teeth. BACKGROUND

[0002] Gear machining methods include forming method and generating method, wherein the forming method directly mills tooth profile with a milling cutter, and the machining is discontinuous, the production efficiency and machining precision are low, and the forming method is not suitable for large-scale and high-precision gear production. The gear hobbing generating method overcomes the disadvantages of the forming method, improves the gear machining efficiency and precision, and is most widely used in gear machining.

[0003] The generating method is to process gears by using the principle that the tooth profiles of two gears are mutual envelope lines when the two gears are engaged. During machining, the cutter and the tooth blank move like a pair of mutually engaged gears, and finally the cutter cuts out the involute tooth profile of the tooth blank. The generating method commonly used for machining gears is the method of gear shaping and gear hobbing. In gear hobbing, the gear hobbing cutter is like a trapezoidal thread screw, and the axial secondary surface tooth profile is an accurate straight line tooth profile. During machining, the gear hobbing cutter and the gear to be cut rotate around their own axes, and their movement relationship is similar to the engagement of gears and racks. In addition to rotation, the hobbing cutter also moves axially along the wheel blank to cut the entire tooth width.

[0004] Gear hobbing method can be used to process spur gears and helical gears. During helical gear machining, the angle of the hobbing cutter rotating table needs to be adjusted according to the different inclinations of the gears, and the direction of the flying chips during cutting changes accordingly, which increases the range of the falling points of the chips, thereby increasing the cleaning work of the gear hobbing machine and the workload of the workers. SUMMARY

[0005] In order to reduce the range of the flying chips during helical gear machining and reduce the cleaning work of the gear hobbing machine, the present application provides a numerical control gear hobbing machine for machining helical gear outer teeth.

[0006] The numerical control gear hobbing machine for machining helical gear outer teeth provided by the present application adopts the following technical scheme:

[0007] The numerical control gear hobbing machine for machining helical gear outer teeth comprises a bed, a workpiece spindle unit and a cutting shaft unit. The workpiece spindle unit comprises a workpiece spindle and a center. The cutting shaft unit comprises a cutting shaft, an axial feed movement shaft and a rotary adjustment table. The cutting shaft is provided with a hobbing cutter. The rotary adjustment table is used to adjust the angle of the cutting shaft. The axial feed movement shaft is used to drive the hobbing cutter to move axially. The rotary adjustment table is fixedly provided with a baffle, and the tangential direction of the cutting point of the hobbing cutter is towards the baffle. The material of the baffle is ferromagnetic metal, and the side of the baffle away from the hobbing cutter is provided with a plurality of electromagnets.

[0008] By adopting the technical scheme, the cutting shaft rotates the hob to cut the workpiece on the workpiece spindle, and in this process, the cutting chips generated by cutting are splashed onto the baffle. Since the baffle is fixedly arranged on the rotary adjusting table, no matter how the angle of the rotary adjusting table is adjusted, the angle relationship between the tangential direction of the cutting point of the hob and the baffle remains unchanged, so that the baffle can always play the function of shielding the cutting chips. After the electromagnet is powered on, the baffle can be magnetized, so that the baffle can adsorb the iron cutting chips through magnetic attraction, so that the cutting chips are not easy to rebound after splashing onto the baffle. When the electromagnet is powered off, the cutting chips falling from the baffle are relatively easy to collect and clean, which is conducive to reducing the workload of cleaning the cutting chips.

[0009] Optionally, one side of the baffle close to the hob is provided with a plastic film, and the plastic film shields the surface of the baffle.

[0010] After the electromagnet magnetizes the baffle, even if the electromagnet is powered off, the baffle still has a small magnetic force, so that the small cutting chips are not easy to fall off; by adopting the above technical scheme, the plastic film separates the cutting chips from the surface of the baffle, and by moving the plastic film away from the surface of the baffle, the small cutting chips adsorbed by the baffle can also fall off from the plastic film.

[0011] Optionally, the plastic film is an electrostatic film, and the plastic film is adsorbed on the baffle through electrostatic adsorption.

[0012] By adopting the above technical scheme, the plastic film is adsorbed on the baffle through electrostatic adsorption, so that the plastic film is convenient to disassemble and assemble on the baffle.

[0013] Optionally, the baffle comprises a metal frame and a steel wire mesh, the steel wire mesh is fixed to one side of the metal frame close to the hob, the side of the steel wire mesh away from the metal frame is provided with a plastic film, the plastic film is connected with the metal frame through a clamp, and the electromagnet is located on the side of the steel wire mesh away from the plastic film.

[0014] By adopting the above technical scheme, the electromagnet magnetizes the steel wire mesh, so that the steel wire mesh can adsorb the cutting chips through magnetic attraction, and the plastic film separates the steel wire mesh from the cutting chips, so that the cutting chips are relatively easy to clean. When the cutting chips splash onto the steel wire mesh, the steel wire mesh vibrates, so that the steel wire mesh can consume the kinetic energy of the cutting chips, so that the cutting chips are not easy to rebound.

[0015] Optionally, the baffle is an arc-shaped plate, the inner concave arc surface of the arc-shaped plate faces the hob, and the curvature center line of the arc-shaped plate is perpendicular to the axis of the hob.

[0016] By adopting the above technical scheme, the cutting coolant splashed onto the baffle will drip from the baffle, and by arranging the baffle as an arc-shaped plate, the dripping range of the cutting coolant can be relatively concentrated.

[0017] Optionally, the baffle is provided with an avoiding gap for avoiding the workpiece spindle or the tailstock.

[0018] By using the above technical scheme, the avoiding gap avoids the workpiece spindle or the tailstock, so that the baffle can be as close to the workpiece as possible.

[0019] Optionally, the baffle is connected to the rotary adjusting table through a plurality of bolts, the bolts are threadedly connected to the rotary adjusting table after penetrating through the baffle, the bolts are sleeved with elastic buffers, the elastic buffers are located between the rotary adjusting table and the baffle; the baffle is provided with a plurality of permanent magnet limiters, the permanent magnet limiters are magnetically connected to the baffle, the permanent magnet limiters are located between the caps of two adjacent bolts, the permanent magnet limiters have two parallel limit surfaces, and the two limit surfaces abut against the caps of two adjacent bolts; the caps of the bolts are square or hexagonal, the distance between the two limit surfaces is greater than the minimum distance of the circumcircle of the two adjacent caps, and is less than the minimum distance of the incircle of the two caps.

[0020] By using the above technical scheme, the baffle and the rotary adjusting table are separated by the elastic buffers, so that the vibration generated by the cutting chip impacting the baffle is not easy to act on the rotary adjusting table, which is beneficial to keeping the rotary adjusting table stable. The permanent magnet limiters are arranged between the caps of two bolts and abut against the caps of the two bolts through the two limit surfaces, so that the bolts are not easy to loosen.

[0021] Optionally, the baffle is provided with a waist-shaped hole for penetrating the bolts, and the length direction of the waist-shaped hole is perpendicular to the opening direction of the avoiding gap.

[0022] By using the above technical scheme, the bolts are connected to the waist-shaped hole on the baffle, so that the installation position of the baffle can be adjusted, and the position of the avoiding gap can adapt to the change of the inclination angle between the workpiece and the hob.

[0023] Optionally, the rotary adjusting table comprises a mounting shell, a rotating seat, a servo motor and a worm and gear transmission assembly, the mounting shell is mounted to the feed movement shaft, the rotating seat and the servo motor are respectively mounted to the mounting shell, the worm and gear transmission assembly comprises a worm wheel and a worm, the worm wheel is fixedly connected to the rotating seat, the worm is provided with two, the two worms are rotationally mounted to the mounting shell and are parallel to each other, the two worms are located on the two sides of the worm wheel and are in meshing with the worm wheel, and the screw directions of the two worms are opposite; the servo motor is coaxially connected to one of the worms, and the two worms are connected through a synchronous belt assembly.

[0024] By adopting the technical scheme, the servo motor can drive two worms at the same time, and then the two worms drive the worm gear to rotate at the same time, so as to realize the purpose of adjusting the angle of the rotary seat. The worm gear is meshed with the two worms at the same time, so that the position of the worm gear is more stable, and the stability of the rotary seat is improved.

[0025] Optionally, among the two worms, one is a first worm, and the other is a second worm, wherein the first worm is close to the servo motor, one end of the first worm is provided with a rigid coupling, and the other end is provided with a flexible coupling, the rigid coupling is connected to the output shaft of the servo motor, and the flexible coupling is provided with a transmission shaft away from one end of the first worm, and the transmission shaft is connected to the second worm through the synchronous belt assembly.

[0026] By adopting the above technical scheme, in the case of driving the worm gear by two worms at the same time, the flexible coupling is arranged to compensate for the slight transmission error between the two worms, so as to improve the smoothness of the rotation of the worm gear.

[0027] In summary, the present application has at least one of the following beneficial technical effects:

[0028] During the operation of the hobbing machine, no matter how to adjust the angle of the rotary adjusting table, the angle relationship between the tangential direction of the cutting point of the hob and the baffle remains unchanged, so that the baffle can always play the function of shielding the chips. When the electromagnet is de-energized, the chips falling from the baffle are relatively easy to collect and clean, which is beneficial to reduce the workload of cleaning the chips.

[0029] The plastic film separates the chips from the surface of the baffle, and by moving the plastic film away from the surface of the baffle, the small chips adsorbed by the baffle can also fall off from the plastic film. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a schematic diagram of the overall structure of embodiment 1.

[0031] Figure 2 is a schematic diagram of the connection relationship between the worm gear and the worm of embodiment 1.

[0032] Figure 3 is a schematic diagram of the structure of the rotary adjusting table of embodiment 1.

[0033] Figure 4 is a schematic diagram of the structure of the rotary adjusting table of embodiment 1 from another perspective.

[0034] Figure 5 is a schematic diagram of the connection relationship between the worm gear and the worm of embodiment 2.

[0035] Figure 6 is a schematic diagram of the structure of the baffle of embodiment 3.

[0036] Figure 7 is a schematic view of the installed state of the baffle of Example 4.

[0037] BRIEF DESCRIPTION OF DRAWINGS

[0038] 1, bed; 2, workpiece spindle unit; 21, workpiece spindle; 22, center; 23, workpiece approach and retreat movement shaft; 3, cutting shaft unit; 31, cutting shaft; 32, feed movement shaft; 33, rotation adjustment table; 331, mounting housing; 332, rotating seat; 333, servo motor; 334, worm gear; 335, worm; 3351, first worm; 3352, second worm; 3361, rigid coupling; 3362, flexible coupling; 3363, transmission shaft; 337, synchronous belt assembly; 34, hob; 4, baffle; 41, avoidance notch; 42, waist-shaped hole; 43, plastic film; 45, bolt; 46, elastic buffer; 47, permanent magnet limiting piece; 471, limiting surface; 48, metal frame; 49, steel mesh; 5, electromagnet; 6, clip. DETAILED DESCRIPTION

[0039] The following will be described in detail in combination with the accompanying drawings Figures 1-7 The application is further described in detail. Example 1

[0040] The application discloses a helical gear outer tooth processing numerical control hobbing machine. Referring to Figure 1 , the helical gear outer tooth processing numerical control hobbing machine comprises a bed 1, a workpiece spindle unit 2 and a cutting shaft unit 3. The workpiece spindle unit 2 comprises a workpiece spindle 21, a center 22 and a workpiece approach and retreat movement shaft 23. The workpiece spindle 21 is used for mounting a workpiece and driving the workpiece to rotate. The center 22 is used for positioning the workpiece to make the workpiece rotate stably. The workpiece approach and retreat movement shaft 23 is used for driving the workpiece to approach or retreat from the cutting shaft unit 3. The movement direction of the workpiece approach and retreat movement shaft 23 is arranged along the length direction of the bed 1. The cutting shaft unit 3 comprises a cutting shaft 31, a feed movement shaft 32 and a rotation adjustment table 33. The cutting shaft 31 is provided with a hob 34. The cutting shaft 31 can make the hob 34 perform a rotary cutting action. The rotation adjustment table 33 is used for adjusting the angle of the cutting shaft 31. The feed movement shaft 32 is used for driving the hob 34 to move in the feed direction. In the embodiment, the movement direction of the feed movement shaft 32 is vertical.

[0041] Referring to Figure 1 and Figure 2The rotary adjusting table 33 comprises a mounting housing 331, a rotating seat 332, a servo motor 333 and a worm gear 334 and worm 335 transmission assembly, the mounting housing 331 is mounted on the feed movement shaft 32, the rotating seat 332 and the servo motor 333 are respectively mounted on the mounting housing 331, the worm gear 334 and worm 335 transmission assembly comprises a worm gear 334 and a worm 335, the worm gear 334 is fixedly connected with the rotating seat 332, the worm 335 is rotatably mounted on the mounting housing 331 and is engaged with the worm gear 334; the servo motor 333 is coaxially connected with the worm 335.

[0042] With reference to Figure 1 and Figure 3 , the rotating seat 332 is fixedly provided with a baffle 4, and a tangential direction of a cutting point of the hob 34 is towards the baffle 4. The baffle 4 is an arc-shaped plate, an inner concave arc surface of the arc-shaped plate is towards the hob 34, and a curvature center line of the arc-shaped plate is perpendicular to an axis of the hob 34. The baffle 4 is made of ferromagnetic metal, and a side of the baffle 4 away from the hob 34 is provided with a plurality of electromagnets 5, the electromagnets 5 are uniformly distributed, and the electromagnets 5 can be fixedly connected by adhesion or using threaded fasteners.

[0043] In the case that the electromagnets 5 are powered, the chips generated by the cutting hob 34 cutting the workpiece are splashed to the baffle 4, the baffle 4 is magnetized by the electromagnets 5, and the baffle 4 can adsorb the chips; when the electromagnets 5 are powered off, the chips on the baffle 4 fall within a smaller range and are relatively easy to clean.

[0044] In the embodiment, the moving direction of the feed movement shaft 32 is set as vertical, and the curvature center line of the baffle 4 is set as horizontal, in another embodiment, the baffle 4 can be set as inclined, or when the moving direction of the feed movement shaft 32 is set as horizontal, the curvature center line of the baffle 4 is set as vertical.

[0045] With reference to Figure 3 , a side of the baffle 4 close to the hob 34 is provided with a plastic film 43, the plastic film 43 shields the surface of the baffle 4, the plastic film 43 is an electrostatic film, and the plastic film 43 is electrostatically adsorbed on the surface of the baffle 4. In another embodiment, the plastic film 43 and the baffle 4 can also be clamped and connected by a clip 6.

[0046] With reference to Figure 3 and Figure 4The baffle 4 is connected with the rotating seat 332 through a plurality of bolts 45. The baffle 4 is provided with through holes for the bolts 45 to pass through. The bolts 45 are threadedly connected with the rotary adjusting table 33 after passing through the through holes on the baffle 4. The bolts 45 are sleeved with elastic buffer members 46. The elastic buffer members 46 are rubber pads, silica gel pads or compression springs. The elastic buffer members 46 are located between the rotary adjusting table 33 and the baffle 4. The elastic buffer members 46 separate the baffle 4 from the rotating seat 332, so that the vibration of the baffle 4 caused by the impact of the chips cannot easily act on the rotating seat 332.

[0047] With reference to Figure 4 The baffle 4 is provided with a plurality of permanent magnet limiting members 47. The permanent magnet limiting members 47 are magnetically connected with the baffle 4. The permanent magnet limiting members 47 are located between the caps of two adjacent bolts 45. The caps of the bolts 45 are hexagonal. The permanent magnet limiting members 47 have two parallel limiting surfaces 471. The two limiting surfaces 471 abut against the caps of two adjacent bolts 45 respectively. The distance between the two limiting surfaces 471 is greater than the minimum distance of the circumcircle of the two adjacent caps and is less than the minimum distance of the incircle of the two caps. The permanent magnet limiting members 47 can hinder the rotation of the bolts 45, so that the bolts 45 are not easy to loosen. In the embodiment, the material of the permanent magnet limiting members 47 is magnetic rubber, so that the permanent magnet limiting members 47 can better adapt to the arc-shaped baffle 4.

[0048] With reference to Figure 1 And Figure 3 The baffle 4 is provided with an avoiding gap 41 for avoiding the workpiece spindle 21 or the center 22. The through hole on the baffle 4 is a waist-shaped hole 42. The length direction of the waist-shaped hole 42 is perpendicular to the opening direction of the avoiding gap 41. The through hole is designed as the waist-shaped hole 42, so that the installation position of the baffle 4 can be adjusted according to the adjustment of the rotation angle of the rotating seat 332.

[0049] The working principle of the numerical control gear hobbing machine for machining the external gear of a helical gear is as follows: during the working process of the gear hobbing machine, the cutting shaft 31 rotates the hob 34 to cut the workpiece on the workpiece spindle 21. In this process, the chips generated by cutting are splashed onto the baffle 4. Since the baffle 4 is fixedly arranged on the rotary adjusting table 33, no matter how the angle of the rotary adjusting table 33 is adjusted, the angle relationship between the tangential direction of the cutting point of the hob 34 and the baffle 4 always remains unchanged, so that the baffle 4 can always play the function of shielding the chips. After the electromagnet 5 is energized, the baffle 4 can be magnetized, so that the baffle 4 can adsorb the ferrous chips through magnetic attraction, so that the chips splashed onto the baffle 4 are not easy to rebound. After the electromagnet 5 is de-energized, the chips falling from the baffle 4 are relatively easy to be collected and cleaned, which is conducive to reducing the workload of cleaning the chips.

[0050] The numerical control hobbing machine is used for machining gears. After machining each workpiece, the workpiece feeding and withdrawing shaft 23 drives the workpiece spindle 21 to move away from the hob 34 and the baffle 4, so as to clamp a new workpiece. At the same time, under the condition that the electromagnet 5 is powered off, the rotary adjusting table 33 drives the baffle 4 to rotate from the horizontal state to the vertical state, so that the chips on the baffle 4 fall off the baffle 4, to prevent the chips from accumulating too much on the baffle 4. Embodiment 2

[0051] With reference to Figure 5 The difference between this embodiment and embodiment 1 is that the rotary adjusting table 33 comprises a mounting shell 331, a rotating seat 332, a servo motor 333 and a worm wheel 334 and worm 335 transmission assembly. The mounting shell 331 is mounted on the feed moving shaft 32. The rotating seat 332 and the servo motor 333 are respectively mounted on the mounting shell 331. The worm wheel 334 and worm 335 transmission assembly comprises a worm wheel 334 and two worms 335. The worm wheel 334 is fixedly connected with the rotating seat 332. The two worms 335 are rotatably mounted on the mounting shell 331 and are parallel to each other. The two worms 335 are located on both sides of the worm wheel 334 and are in meshing engagement with the worm wheel 334. The screw directions of the two worms 335 are opposite.

[0052] Among the two worms 335, one is a first worm 3351 and the other is a second worm 3352. The first worm 3351 is close to the servo motor 333. One end of the first worm 3351 is provided with a rigid coupling 3361, and the other end of the first worm 3351 is provided with a flexible coupling 3362. The rigid coupling 3361 is connected with the output shaft of the servo motor 333. The flexible coupling 3362 is provided with a transmission shaft 3363 away from one end of the first worm 3351. The transmission shaft 3363 is connected with the second worm 3352 through the synchronous belt assembly 337.

[0053] The servo motor 333 can simultaneously drive the two worms 335, and then drive the worm wheel 334 to rotate at the same time, so as to achieve the purpose of adjusting the angle of the rotating seat 332. The worm wheel 334 is in meshing engagement with the two worms 335 at the same time, so that the position of the worm wheel 334 is more stable, which is conducive to improving the stability of the rotating seat 332. In the case of driving the worm wheel 334 by the two worms 335 at the same time, the flexible coupling 3362 is arranged to compensate for the slight transmission error between the two worms 335, so as to facilitate the smoothness of the rotation of the worm wheel 334. Embodiment 3

[0054] With reference to Figure 6The difference between the embodiment and the embodiment 1 is that the baffle 4 in the embodiment comprises a metal frame 48 and a steel mesh 49, the steel mesh 49 is fixed to the metal frame 48 close to the hob 34, the steel mesh 49 is fixed with the metal frame 48 through welding or is connected and fixed by using rivets, screws and the like fasteners, the side of the steel mesh 49 away from the metal frame 48 is provided with a plastic film 43, the plastic film 43 is connected with the metal frame 48 through the clip 6, the clip 6 can be a plastic buckle clip 6 or a long-tail clip, the plastic film 43 is connected by using the clip 6, so that the plastic film 43 is convenient to disassemble and assemble, and the user can select whether to install the plastic film 43 according to the need. The edge part of the plastic film 43 clamped by the clip 6 can be folded to the opposite side of the metal frame 48, so as to improve the stability of clamping the plastic film 43.

[0055] The electromagnet 5 is fixed to the side of the steel mesh 49 away from the plastic film 43. The electromagnet 5 magnetizes the steel mesh 49, so that the steel mesh 49 can attract the chips by magnetic attraction, the plastic film 43 separates the steel mesh 49 and the chips, so that the chips are more easily removed. When the chips are splashed to the steel mesh 49, the steel mesh 49 vibrates, so that the steel mesh 49 can consume the kinetic energy of the chips, so that the chips are not easy to rebound. Embodiment 4

[0056] Reference Figure 7 The difference between the embodiment and the embodiment 1 is that the baffle 4 in the embodiment is arranged in a state of gradually inclining upward away from the rotary adjusting table 33, so that when the chips accumulated on the baffle 4 slide due to the vibration of the machine tool, the chips tend to move away from the workpiece spindle 21, so as to reduce the situation that the chips fall on the workpiece spindle 21.

[0057] In the embodiment, the inclined state of the baffle 4 is realized by arranging the elastic buffer 46 in the form of a wedge-shaped rubber pad or a wedge-shaped silica gel pad.

[0058] The above are the preferred embodiments of the present application, which do not limit the protection scope of the present application, therefore: any equivalent changes made on the structure, shape and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A numerically controlled gear hobbing machine for machining external toothing of helical gears, characterized in that: The application relates to a machining center, which comprises a machine body (1), a workpiece spindle unit (2) and a cutting spindle unit (3), the workpiece spindle unit (2) comprises a workpiece spindle (21) and a tailstock (22), the cutting spindle unit (3) comprises a cutting spindle (31), an infeed movement spindle (32) and a rotary adjustment table (33), the cutting spindle (31) is provided with a hob (34), the rotary adjustment table (33) is used for adjusting the angle of the cutting spindle (31), the infeed movement spindle (32) is used for driving the hob (34) to move infeed, the rotary adjustment table (33) is fixedly provided with a baffle (4), and the tangential direction of the cutting point of the hob (34) is towards the baffle (4); the material of the baffle (4) is ferromagnetic metal; the baffle (4) is provided with a plurality of electromagnets (5). One side of the baffle (4) close to the hob (34) is provided with a plastic film (43), and the plastic film (43) shields the surface of the baffle (4). The plastic film (43) is an electrostatic film, and the plastic film (43) is adsorbed on the baffle (4) through electrostatic adsorption. The baffle (4) comprises a metal frame (48) and a steel wire mesh (49), the steel wire mesh (49) is fixed to one side of the metal frame (48) close to the hob (34), one side of the steel wire mesh (49) away from the metal frame (48) is provided with a plastic film (43), the plastic film (43) and the metal frame (48) are connected through a clip (6), and the electromagnet (5) is located on one side of the steel wire mesh (49) away from the plastic film (43).

2. A CNC gear hobber for the machining of the external teeth of helical gears according to claim 1, characterized in that: The baffle (4) is an arc-shaped plate, the concave arc surface of the arc-shaped plate is towards the hob (34), and the center line of the curvature of the arc-shaped plate is perpendicular to the axis of the hob (34).

3. The numerically controlled gear hobbing machine for machining the external gear teeth of helical gear according to claim 1, characterized in that: The baffle (4) is provided with an avoiding gap (41), and the avoiding gap (41) is used for avoiding the workpiece spindle (21) or the tailstock (22).

4. A CNC gear hobber for the machining of the external teeth of helical gears according to claim 3, characterized in that: The baffle (4) is connected with the rotary adjustment table (33) through a plurality of bolts (45), the bolts (45) are threadedly connected with the rotary adjustment table (33) after penetrating through the baffle (4), the bolts (45) are sleeved with elastic buffers (46), the elastic buffers (46) are located between the rotary adjustment table (33) and the baffle (4), the baffle (4) is provided with a plurality of permanent magnet limiters (47), the permanent magnet limiters (47) are magnetically connected with the baffle (4), the permanent magnet limiters (47) are located between the caps of two adjacent bolts (45), the permanent magnet limiters (47) have two parallel limit surfaces (471), the two limit surfaces (471) abut against the caps of two adjacent bolts (45) respectively, the caps of the bolts (45) are square or hexagonal, the distance between the two limit surfaces (471) is greater than the minimum distance of the circumcircle of the caps of two adjacent bolts (45) and smaller than the minimum distance of the incircle of the caps of two adjacent bolts (45).

5. A CNC gear hobber for the machining of the external teeth of helical gears according to claim 4, characterized in that: The baffle (4) is provided with a waist-shaped hole (42) for the bolt (45) to pass through, and the length direction of the waist-shaped hole (42) is perpendicular to the opening direction of the avoiding gap (41).

6. The numerically controlled gear hobber for machining the external gear teeth of bevel gears as defined in claim 1, characterized in that: The rotary adjusting table (33) comprises a mounting shell (331), a rotating seat (332), a servo motor (333) and a worm gear (334) transmission assembly, the mounting shell (331) is mounted on the feeding moving shaft (32), the rotating seat (332) and the servo motor (333) are respectively mounted on the mounting shell (331), the worm gear (334) transmission assembly comprises a worm gear (334) and a worm (335), the worm gear (334) is fixedly connected with the rotating seat (332), the worm (335) is provided with two, the two worm (335) are rotatably installed on the mounting shell (331) and are parallel to each other, the two worm (335) are respectively located on the two sides of the worm gear (334) and are engaged with the worm gear (334), the screw directions of the two worm (335) are opposite; the servo motor (333) is coaxially connected with one of the worm (335), and the two worm (335) are connected through a synchronous belt assembly (337).

7. A CNC gear hobber for the machining of the external teeth of helical gears according to claim 6, characterized in that: Among the two worm (335), one is a first worm (3351), and the other is a second worm (3352), wherein the first worm (3351) is close to the servo motor (333), one end of the first worm (3351) is provided with a rigid coupling (3361), and the other end is provided with a flexible coupling (3362), the rigid coupling (3361) is connected with the output shaft of the servo motor (333), the flexible coupling (3362) is provided with a transmission shaft (3363) away from one end of the first worm (3351), the transmission shaft (3363) is connected with the second worm (3352) through the synchronous belt assembly (337).

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