High-torque thread servo motor automatic tightening equipment with large transmission ratio RV reducer

Abstract

An automatic tightening device for high-torque threaded servo motors with a large transmission ratio RV reducer includes an encoder module, a permanent magnet servo synchronous motor module, a large transmission ratio RV reducer module, a torque sensor module, and a tightening output shaft module. The encoder module collects the rotation angle and speed signals of the permanent magnet servo synchronous motor module and transmits them to the control system. The permanent magnet servo synchronous motor module provides power to the large transmission ratio RV reducer module. The torque sensor module performs real-time torque monitoring and feeds back to the control system. The tightening output shaft module transmits the power from the permanent magnet servo synchronous motor module, after being reduced in speed and increased in torque by the large transmission ratio RV reducer module, to the threaded connector to be tightened. This invention makes the output shaft of the AC permanent magnet synchronous motor into a gear shaft and uses a novel reducer combining involute planetary transmission and cycloidal wheel low-tooth-difference transmission, which meets the comprehensive requirements of high efficiency, small size, large transmission ratio, strong load-bearing capacity, and stable operation of servo tightening equipment.

Description

Technical Field

[0001] This invention belongs to the field of precision reduction transmission technology for automatic thread tightening equipment, and specifically relates to an automatic thread tightening device with a high torque servo motor and a large transmission ratio RV reducer. Background Technology

[0002] With the development of industrialization and the advent of the era of intelligent manufacturing, robots have been widely used in industrial production lines and outdoor assembly production. From the assembly of key components in aviation, aerospace, shipbuilding, and automobiles, to the production lines of household appliances such as refrigerators, air conditioners, and washing machines, to the assembly of electronic components and automotive parts, as well as the fastening of large iron frames, bridges, and oil and gas pipelines, there is a great demand for constant torque thread tightening equipment with high precision, wide torque range, high reliability, and good servo performance.

[0003] Thread tightening equipment is gradually evolving from manual, pneumatic, or electric tools to high-precision, high-reliability, and low-noise servo tightening equipment. Electric thread servo tightening equipment has become the mainstream method and is widely used. Fully automatic electric thread servo tightening equipment typically consists of an AC permanent magnet servo synchronous motor, a precision reducer, an automatic torque monitoring device, and its automatic control system hardware and software. The precision reducer is mainly responsible for matching the speed and transmitting torque between the AC permanent magnet servo synchronous motor power source and the tightening head actuator, thus playing the role of speed reduction and torque increase.

[0004] Currently, electric thread servo tightening equipment commonly adopts involute tooth profile multi-stage NGW planetary gear reduction (such as application number CN202221937373.8, name: a high torque reducer for a bolt tightening machine; application number CN202321742643.4, name: multi-protection tightening mechanism). Specifically, the output shaft of the permanent magnet synchronous motor is connected to the sun gear of the reduction mechanism through a coupling, and the internal gear ring of the reduction mechanism is fixed to the housing. When the motor output shaft drives the sun gear to rotate through the coupling, it drives the planet gears to rotate around the central axis of the reduction mechanism. The rotational motion of the planet carrier drives the entire planet carrier to rotate, and then transmits the power to the output shaft of the tightening machine through the planet carrier, achieving the purpose of speed reduction and torque increase.

[0005] The involute tooth profile NGW type multi-stage planetary reduction mechanism used in the above-mentioned thread tightening equipment has the following shortcomings: 1) The transmission ratio of the high torque thread tightening device is as high as 30 to 100. If the NGW type gear planetary transmission is used for the thread tightening device, due to the limitation of radial size, the single-stage transmission ratio is usually 2 to 4, which leads to the need to use 3 to 5 transmission stages of NGW planetary transmission, resulting in too large axial size, too large weight, high cost, and inconvenience of use; 2) Since the high torque thread tightening device uses 3 to 5 transmission stages of NGW type gear planetary transmission, if the efficiency of a single-stage planetary transmission is 90%, the transmission efficiency of 3 to 5 stages is only 60% to 73%, so the efficiency of multi-stage planetary transmission is low; 3) Since the NGW type involute tooth profile gears used in the planetary transmission have relative sliding at the meshing point, the transmission noise is large and the wear is serious.

[0006] In summary, the existing NGW-type planetary reduction scheme for electric thread servo tightening equipment can no longer meet the comprehensive requirements of high efficiency, small size, large transmission ratio, strong load-bearing capacity, and stable operation of servo tightening equipment. Summary of the Invention

[0007] To overcome the shortcomings of the prior art, the present invention aims to provide an automatic tightening device for a high-torque thread servo motor with a large transmission ratio RV reducer. The device uses a gear shaft structure for the output shaft of the AC permanent magnet synchronous motor and a novel reducer combining involute planetary transmission and cycloidal wheel low tooth difference transmission. This satisfies the comprehensive requirements of high efficiency, small size, large transmission ratio, strong load-bearing capacity, and stable operation of the servo tightening device.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] An automatic tightening device for high-torque threaded servo motors with a large transmission ratio RV reducer includes an encoder module I, a permanent magnet servo synchronous motor module II, a large transmission ratio RV reducer module III, a torque sensor module IV, and a tightening output shaft module V. The encoder module I collects the rotation angle and speed signals of the permanent magnet servo synchronous motor module II and transmits them to the control system of the tightening device. The permanent magnet servo synchronous motor module II provides power to the large transmission ratio RV reducer module III. The torque sensor module IV collects the output torque of the entire tightening device, enabling real-time monitoring of the torque during operation and feeding it back to the control system. The tightening output shaft module V transmits the power from the permanent magnet servo synchronous motor module II (after speed reduction and torque amplification via the large transmission ratio RV reducer module III) to the threaded connector to be tightened, completing the power output of the entire tightening device.

[0010] The permanent magnet servo synchronous motor module II includes a permanent magnet motor housing 1, a permanent magnet motor stator 2, and a permanent magnet motor rotor 3. The permanent magnet motor housing 1 and the permanent magnet motor stator 2 are connected by an interference fit. The permanent magnet motor shaft 5, which is connected to the permanent magnet motor rotor 3, is supported by a permanent magnet motor shaft bearing 6, and the axial displacement of the permanent magnet motor shaft 5 is restricted by a motor front sleeve 4.

[0011] The large transmission ratio RV reducer module Ⅲ includes a planetary carrier fixed end 9 connected to the reduction mechanism housing 7. The end face of the planetary carrier fixed end 9 has a plurality of circumferentially distributed first mounting holes, each of which is interference-fitted with one end of the planetary carrier connecting shaft 22. The other end of the planetary carrier connecting shaft 22 is interference-fitted with a plurality of circumferentially distributed second mounting holes on the end face of the planetary carrier auxiliary end 17.

[0012] The permanent magnet motor shaft 5 has involute gear teeth machined at its front end, and the permanent magnet motor shaft 5 meshes with the planetary gears 23. The planetary gears 23 are circumferentially distributed, and the inner holes of the planetary gears 23 are connected to the rear end of the crankshaft 19 by a key. The fixed end 9 of the planetary carrier and the auxiliary end 17 of the planetary carrier have multiple circumferentially distributed bearing holes on their end faces, which are interference-fitted with the outer ring of the crankshaft-planetary carrier bearing 21 in the bearing holes. The inner ring of the crankshaft-planetary carrier bearing 21 in the bearing holes is interference-fitted with the crankshaft 19. A crankshaft-planetary carrier bearing retaining ring 25 is provided on the outer side of the crankshaft-planetary carrier bearing 21.

[0013] The crankshaft 19 is connected to the cycloidal wheel 18 via the crankshaft-cycloidal wheel bearing 20. The cycloidal wheel 18 is fixed by the planetary carrier fixed end 9. The entire mechanism uses two cycloidal wheels 18, which are symmetrically distributed with a radial offset of 180 degrees. The cycloidal wheels 18 have circumferentially distributed through holes to ensure that the cycloidal wheels 18 will not interfere with the planetary carrier connecting shaft 22 when oscillating.

[0014] The outer side of the cycloidal wheel 18 and the pin gear 11 are engaged by a pin tooth pin to form a cycloidal tooth profile. When the cycloidal wheel 18 swings, each swing will cause a relative rotation of one tooth between the cycloidal wheel 18 and the pin gear 11.

[0015] The outer circumference of the needle gear 11 is interference-fitted with the needle roller bearing 10 on the outside of the needle gear. The outer ring of the needle roller bearing 10 on the outside of the needle gear is interference-fitted with the inside of the housing 7 of the reduction mechanism. The front end face of the needle gear 11 is connected to the tightening output shaft 15 of the tightening output shaft module V through the output shaft fixing screw 12, which ensures that when the needle gear 11 rotates, it drives the tightening output shaft 15 to rotate and output power to the next stage.

[0016] The tightening output shaft module V includes a tightening output shaft 15, an output shaft deep groove ball bearing 16, and a bearing end cover 13. The tightening output shaft 15 is connected to the reduction mechanism housing 7 through the output shaft deep groove ball bearing 16, and the bearing end cover 13 provided on the outside of the output shaft deep groove ball bearing 16 is connected to the reduction mechanism housing 7.

[0017] The reduction mechanism housing 7 is directly connected to the permanent magnet motor housing 1, thus achieving structural integration of the motor and the reducer.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1) This invention adopts a cycloidal tooth profile planetary transmission mechanism with small tooth difference. The single-stage transmission ratio can reach 6 to 119, which is much greater than that of NGW involute planetary transmission. When used in high-torque thread tightening equipment, it has a compact structure, small size, light weight, and strong load-bearing capacity. Compared with the same power involute tooth profile multi-stage NGW planetary transmission, the volume can be reduced by 1 / 2 to 2 / 3, and the weight can be reduced by about 1 / 3 to 1 / 2.

[0020] 2) In this invention, the cycloidal wheel and the crankshaft, the cycloidal wheel and the needle tooth, and the needle tooth and the needle gear all have rolling friction, which avoids the sliding friction between the teeth of the involute tooth profile. Therefore, its transmission efficiency is high, and the single-stage transmission efficiency reaches 90% to 95%.

[0021] 3) This invention adopts cycloidal tooth profile meshing transmission, which avoids the relative sliding of involute gears at the meshing point compared with NGW involute planetary transmission; at the same time, because there are many meshing teeth and a large overlap during operation, the transmission noise of this invention is low and wear is minimal. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall invention.

[0023] Figure 2 This is a structural diagram of the large transmission ratio RV reducer module of the present invention.

[0024] Figure 3 This is a partial enlarged view of the crankshaft portion of the high-ratio RV reducer of the present invention.

[0025] In the diagram: Ⅰ. Encoder module; Ⅱ. Permanent magnet servo synchronous motor module; Ⅲ. High-ratio RV reducer module; Ⅳ. Torque sensor module; Ⅴ. Tightening output shaft module; 1. Permanent magnet motor housing; 2. Permanent magnet motor stator; 3. Permanent magnet motor rotor; 4. Motor front sleeve; 5. Permanent magnet motor shaft; 6. Permanent magnet motor shaft bearing; 7. Reducer housing; 8. Planetary carrier locating pin; 9. Planetary carrier fixed end; 10. Needle roller bearing on the outer side of the pin gear. 11. Needle gear; 12. Output shaft fixing screw; 13. Bearing end cover; 14. Bearing end cover fixing screw; 15. Tighten output shaft; 16. Output shaft deep groove ball bearing; 17. Planetary carrier auxiliary end; 18. Cycloidal wheel; 19. Crankshaft; 20. Crankshaft-cycloidal wheel bearing; 21. Crankshaft-planetary carrier bearing; 22. Planetary carrier connecting shaft; 23. Planetary gear; 24. Crankshaft-planetary carrier bearing gasket; 25. Crankshaft-planetary carrier bearing retaining ring. Detailed Implementation

[0026] The present invention will now be described in detail with reference to the embodiments and accompanying drawings.

[0027] Reference Figure 1 An automatic tightening device for high-torque threaded servo motors with a large transmission ratio RV reducer is disclosed, comprising an encoder module I, a permanent magnet servo synchronous motor module II, a large transmission ratio RV reducer module III, a torque sensor module IV, and a tightening output shaft module V. The encoder module I collects signals such as the rotation angle and speed of the permanent magnet servo synchronous motor module II and transmits them to the control system of the tightening device. The permanent magnet servo synchronous motor module II serves as the power source for the entire tightening device, providing power to the large transmission ratio RV reducer module III. The torque sensor module IV collects the output torque of the entire tightening device, enabling real-time monitoring of the torque during operation and providing feedback to the control system. The tightening output shaft module V, as the next stage after the permanent magnet servo synchronous motor module II, is the torque output section of the entire tightening device. It transmits the power from the permanent magnet servo synchronous motor module II, after being reduced in speed and increased in torque by the large transmission ratio RV reducer module III, to the threaded connector to be tightened, thus completing the power output of the entire tightening device.

[0028] Reference Figure 2 The permanent magnet servo synchronous motor module II includes a permanent magnet motor housing 1, a permanent magnet motor stator 2, a permanent magnet motor rotor 3, a motor front sleeve 4, a permanent magnet motor shaft 5, and a permanent magnet motor shaft bearing 6. The permanent magnet motor housing 1 and the permanent magnet motor stator 2 are connected by an interference fit. The permanent magnet motor shaft 5, which is connected to the permanent magnet motor rotor 3, is supported by the permanent magnet motor shaft bearing 6, and the axial displacement of the permanent magnet motor shaft 5 is restricted by the motor front sleeve 4. When the mechanism is running, the permanent magnet motor stator 2 and the permanent magnet motor rotor 3 undergo armature reaction, causing the permanent magnet motor rotor 3 to rotate, which in turn drives the permanent magnet motor shaft 5 to rotate and output power to the next stage.

[0029] Reference Figure 2 The large transmission ratio RV reducer module III includes a planetary carrier fixed end 9 connected to the reduction mechanism housing 7 via a planetary carrier positioning pin 8, ensuring the relative position of the planetary carrier fixed end 9; the end face of the planetary carrier fixed end 9 has three circumferentially distributed first mounting holes, each first mounting hole having an interference fit with one end of the planetary carrier connecting shaft 22; the other end of the planetary carrier connecting shaft 22 and the end face of the planetary carrier auxiliary end 17 have three circumferentially distributed second mounting holes having an interference fit; the three sets of parts, planetary carrier fixed end 9, planetary carrier auxiliary end 17, and planetary carrier connecting shaft 22, form a fixed whole through two interference fits, and the relative position between the entire planetary carrier mechanism and the reduction mechanism housing 7 is ensured by the planetary carrier positioning pin 8.

[0030] Reference Figure 2 and Figure 3 The permanent magnet motor shaft 5 has involute gear teeth machined at its front end, and the permanent magnet motor shaft 5 meshes with planetary gears 23. The planetary gears 23 are circumferentially distributed, and the inner holes of the planetary gears 23 are connected to the right end of the crankshaft 19 by a key. The fixed end 9 of the planetary carrier and the auxiliary end 17 of the planetary carrier have three circumferentially distributed bearing holes, which are interference-fitted with the outer ring of the crankshaft-planetary carrier bearing 21 in the bearing holes. The inner ring of the crankshaft-planetary carrier bearing 21 in the bearing holes is interference-fitted with the crankshaft 19, ensuring that the crankshaft 19 and the planetary carrier mechanism can rotate relative to each other. A crankshaft-planetary carrier bearing retainer ring 25 is provided on the outer side of the crankshaft-planetary carrier bearing 21, which restricts the axial movement of the crankshaft-planetary carrier bearing 21.

[0031] Reference Figure 2 and Figure 3 The crankshaft 19 is connected to the cycloidal wheel 18 via the crankshaft-cycloidal wheel bearing 20, and the cycloidal wheel 18 is fixed by the planetary carrier fixed end 9. The cycloidal wheel 18 has circumferentially distributed bearing holes for installing the crankshaft-cycloidal wheel bearing 20, ensuring that the cycloidal wheel 18 and the crankshaft 19 can rotate relative to each other. The entire mechanism uses two cycloidal wheels 18, which are symmetrically distributed with a radial offset of 180 degrees, balancing the unbalanced radial force of the cycloidal wheel 18 when it oscillates. The cycloidal wheel 18 has circumferentially distributed through holes to ensure that the cycloidal wheel 18 will not interfere with the planetary carrier connecting shaft 22 when it oscillates.

[0032] Reference Figure 2 The outer side of the cycloidal wheel 18 and the pin gear 11 are engaged by a pin tooth pin. When the cycloidal wheel 18 swings, each swing will cause a relative rotation of one tooth between the cycloidal wheel 18 and the pin gear 11 due to the engagement of the cycloidal tooth profile, thus achieving the purpose of deceleration, torque increase and power transmission.

[0033] Reference Figure 2The outer circumference of the pin gear 11 is interference-fitted with the needle roller bearing 10 of the pin gear externally, and the outer ring of the needle roller bearing 10 is interference-fitted with the inside of the reduction mechanism housing 7. The needle roller bearing 10 of the pin gear externally ensures that the pin gear 11 and the reduction mechanism housing 7 can rotate relative to each other. The left end face of the pin gear 11 is connected to the tightening output shaft 15 of the tightening output shaft module V through the output shaft fixing screw 12, which ensures that when the pin gear 11 rotates, it drives the tightening output shaft 15 to rotate and output power to the next stage.

[0034] Reference Figure 2 The tightening output shaft module V includes a tightening output shaft 15, an output shaft deep groove ball bearing 16, a bearing end cap 13, and a bearing end cap fixing screw 14. The tightening output shaft 15 is connected to the reduction mechanism housing 7 through the output shaft deep groove ball bearing 16. The bearing end cap 13, which is provided on the outside of the output shaft deep groove ball bearing 16, is threadedly connected to the reduction mechanism housing 7 through the bearing end cap fixing screw 14, thus restricting the axial displacement of the output shaft deep groove ball bearing 16. The output shaft deep groove ball bearing 16 supports the tightening output shaft 15 while ensuring that the tightening output shaft 15 and the reduction mechanism housing 7 can rotate relative to each other.

[0035] Reference Figure 2 The reduction mechanism housing 7 and the permanent magnet motor housing 1 are directly fixed together by bolts, which realizes the structural integration of the motor and the reducer, reduces the weight of the entire tightening equipment, and shortens the radial dimension of the equipment.

[0036] The working principle of this invention is as follows: An AC permanent magnet servo synchronous motor is used as the power source, equipped with a large transmission ratio RV reducer with a reduction ratio exceeding 30, and outputs high torque and features an automatic thread tightening device with automatic torque monitoring. During operation, the permanent magnet motor shaft 5 undergoes speed reduction transmission through gear meshing, driving the planetary gears 23 to rotate. The planetary gears 23 drive the crankshaft 19, ensuring synchronous rotation between the crankshaft 19 and the planetary gears 23. Simultaneously, the rotation of the crankshaft 19 further drives the cycloidal wheel 18 to oscillate, and the cycloidal wheel 18 engages with the pin gear 11 via a pin pin. Since the cycloidal wheel 18 is fixed via the planetary carrier fixed end 9, the pin gear 11 rotates according to the principle of relative motion. After completing two stages of speed reduction, the cycloidal wheel 18 drives the tightening output shaft 15, which is fixed to the pin gear 11, to output power to the next stage.

[0037] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions to the technical solutions of the present invention are all within the scope of protection of the present invention.

Claims

1. An automatic tightening device for a high-torque thread servo motor with a large transmission ratio RV reducer, characterized in that: The system includes an encoder module (Ⅰ), a permanent magnet servo synchronous motor module (Ⅱ), a high-ratio RV reducer module (Ⅲ), a torque sensor module (Ⅳ), and a tightening output shaft module (Ⅴ). The encoder module (Ⅰ) collects the rotation angle and speed signals of the permanent magnet servo synchronous motor module (Ⅱ) and transmits them to the control system of the tightening equipment. The permanent magnet servo synchronous motor module (Ⅱ) provides power to the high-ratio RV reducer module (Ⅲ). The torque sensor module (Ⅳ) collects the output torque of the entire tightening equipment, completes the real-time monitoring of the torque during the operation of the tightening equipment, and feeds it back to the control system of the tightening equipment. The tightening output shaft module (Ⅴ) transmits the power of the permanent magnet servo synchronous motor module (Ⅱ) after speed reduction and torque increase through the high-ratio RV reducer module (Ⅲ) to the threaded connector to be tightened, completing the power output of the entire tightening equipment. The permanent magnet servo synchronous motor module (II) includes a permanent magnet motor housing (1), a permanent magnet motor stator (2), and a permanent magnet motor rotor (3). The permanent magnet motor housing (1) and the permanent magnet motor stator (2) are connected by an interference fit. The permanent magnet motor shaft (5) connected to the permanent magnet motor rotor (3) is supported by a permanent magnet motor shaft bearing (6) and the axial displacement of the permanent magnet motor shaft (5) is restricted by a motor front sleeve (4). The large transmission ratio RV reducer module (Ⅲ) includes a planetary carrier fixed end (9) connected to the reducer housing (7). The end face of the planetary carrier fixed end (9) has a plurality of circumferentially distributed first mounting holes. Each first mounting hole is interference-fitted with one end of the planetary carrier connecting shaft (22). The other end of the planetary carrier connecting shaft (22) and the end face of the planetary carrier auxiliary end (17) have a plurality of circumferentially distributed second mounting holes interference-fitted. The permanent magnet motor shaft (5) is machined with involute gear teeth at its front end, and the permanent magnet motor shaft (5) meshes with the planetary gear (23). The planetary gear (23) is circumferentially distributed, and the inner hole of the planetary gear (23) is connected to the rear end of the crankshaft (19) by a key. The fixed end (9) of the planetary carrier and the auxiliary end (17) of the planetary carrier have multiple circumferentially distributed bearing holes, which are interference-fitted with the outer ring of the crankshaft-planetary carrier bearing (21) in the bearing hole. The inner ring of the crankshaft-planetary carrier bearing (21) in the bearing hole is interference-fitted with the crankshaft (19). A crankshaft-planetary carrier bearing retaining ring (25) is provided on the outer side of the crankshaft-planetary carrier bearing (21). The crankshaft (19) is connected to the cycloidal wheel (18) via the crankshaft-cycloidal wheel bearing (20), and the cycloidal wheel (18) is fixed via the planetary carrier fixed end (9). The entire mechanism uses two cycloidal wheels (18), which are symmetrically distributed with a radial offset of 180 degrees. The cycloidal wheel (18) has circumferentially distributed through holes to ensure that the cycloidal wheel (18) will not interfere with the planetary carrier connecting shaft (22) when it swings. The outer side of the cycloidal wheel (18) and the pin gear (11) are engaged by a pin tooth pin. When the cycloidal wheel (18) swings, each swing will cause a relative rotation of one tooth between the cycloidal wheel (18) and the pin gear (11).

2. The high-torque thread servo motor automatic tightening device according to claim 1, characterized in that: The outer circumference of the needle gear (11) is press-fitted with the needle roller bearing (10) of the needle gear. The outer ring of the needle roller bearing (10) of the needle gear is press-fitted with the inner ring of the housing (7) of the reduction mechanism. The front end face of the needle gear (11) is connected to the tightening output shaft (15) of the tightening output shaft module V through the output shaft fixing screw (12), which ensures that when the needle gear (11) rotates, it drives the tightening output shaft (15) to rotate and output power to the next level.

3. The high-torque thread servo motor automatic tightening device according to claim 2, characterized in that: The tightening output shaft module (V) includes a tightening output shaft (15), an output shaft deep groove ball bearing (16), and a bearing end cover (13). The tightening output shaft (15) is connected to the reduction mechanism housing (7) through the output shaft deep groove ball bearing (16). The bearing end cover (13) provided on the outside of the output shaft deep groove ball bearing (16) is connected to the reduction mechanism housing (7).

4. The high-torque thread servo motor automatic tightening device according to claim 1, characterized in that: The deceleration mechanism housing (7) is directly connected to the permanent magnet motor housing (1), thus achieving structural integration of the motor and the reducer.

Images