Lead screw direct-coupled closed loop system for hybrid stepper motors

Abstract

The invention discloses a screw direct-connected closed-loop system for a hybrid stepper motor, comprising a base, a stepper motor, an actuator and a control system, an actuator screw and a detection device; the actuator screw passes through the actuator, the base and the stepper motor; the actuator screw also includes a screw thread portion, a screw nut sleeve, a screw pair and a screw tail shaft connected in sequence from left to right; the screw thread is located on the surface of the actuator screw; the screw nut sleeve is hollow inside and has threads, and is sleeved on the screw thread portion; the screw pair is located at one end of the actuator screw, has a smooth surface and a cross-sectional diameter smaller than the screw thread portion; the part of the screw tail shaft connected to the screw pair has a section of thread, and the part close to the end of the actuator screw is a smooth surface; the detection device is installed on the screw tail shaft. The component has the characteristics of simple structure, easy installation, high cost performance, low failure rate, high performance, accurate feedback, etc.

Description

Technical Field

[0001] The invention relates to a motor system, in particular to a screw direct-connected closed-loop system for a hybrid stepping motor, and belongs to the technical field of mechatronics. Background Art

[0002] The stepper motor is one of the key components in mechatronics products and is a digital actuator with good performance. It can convert electrical pulse signals into corresponding angular displacements. One of the main advantages of stepper motors is that they are close to open-loop control. Under open-loop control, the stepper motor is controlled by a pulse sequence with a specified time interval, and no feedback sensor and corresponding electronic circuit are required in the control system. However, the open-loop control of the stepper motor cannot avoid the shortcomings of the stepper motor itself, namely resonance, oscillation, loss of step and difficulty in achieving high speed. On the other hand, it is difficult for the open-loop controlled stepper motor system to have a higher accuracy than the graded one, and its positioning accuracy is relatively low.

[0003] The protruding part of the traditional lead screw is directly glued to the bearing sleeve in the motor rotor assembly. Therefore, it is easy for the lead screw to become loosely bonded and fall off when the motor is running. At this time, the code disk and code reader assembly at the rear end can only detect that the motor is still idling, and it is difficult to find that the front end lead screw has stopped running, so the operating position of the actuator cannot be accurately monitored, which is a great obstacle to the discovery and elimination of machine faults. Summary of the invention

[0004] In order to solve the problems raised in the above-mentioned background technology, overcome the existing stepper motor resonance, oscillation, loss of step and difficulty in achieving high-speed operation, as well as the problem that the glue-bonded screw is easy to fall off and affect the operation, the present invention provides a screw direct-connected closed-loop system for a hybrid stepper motor, including a base, a stepper motor, an actuator and a control system, and also includes an actuator screw and a detection device; the actuator screw passes through the actuator, the base and the stepper motor; the actuator screw also includes a screw thread portion, a screw nut sleeve, a screw pair and a screw tail connected in sequence from left to right; the screw thread is located in the actuator The surface of the actuator screw; the screw nut sleeve is hollow inside and has threads, and is sleeved on the threaded part of the screw; the screw pair is located at one end of the actuator screw, has a smooth surface and a cross-sectional diameter smaller than the threaded part of the screw; the part of the screw tail shaft connected to the screw pair has a section of thread, and the part close to the end of the actuator screw is a smooth surface; the detection device is installed on the screw tail shaft, and also includes a code disk, a mounting bracket and a code reader; the code disk is a disc with a through hole at the center, which fits the cross-section of the screw tail shaft; the mounting bracket fixes the stepping motor and the code reader; the code reader is aligned with the code disk.

[0005] Preferably, it also includes a rear end locking nut, which is installed on the thread of the tail shaft of the screw and is located between the stepping motor and the detection device.

[0006] Preferably, the base further comprises a safety grating sensor, and the safety grating sensor is located at the upper part of the connection between the actuator lead screw and the base.

[0007] Compared with the prior art, the present invention has the following beneficial effects:

[0008] 1. Closed-loop control of stepper motors, using position feedback and (or) speed feedback to determine the phase transition that is suitable for the rotor position, can greatly improve the performance of stepper motors. In a closed-loop controlled stepper motor system, the operating speed range can be expanded when tracking and feedback are performed with a given accuracy, and the tracking and positioning accuracy can be improved at a given speed, and the limit speed index and limit accuracy index can be obtained.

[0009] 2. By changing the split-type lead screw to an integrated type, the tail shaft is extended from the lead screw, so that the closed-loop system can directly detect and feedback the rotation of the lead screw. The code disk does not go through any adapters, so it can truly and effectively feedback the working conditions of the actuator. Since the number of structural parts is reduced, the installation is simpler and more effective, and the feedback failure caused by the failure of the connector is eliminated.

[0010] 3. The present invention arranges a light curtain formed by a safety grating sensor just above the lead screw and the actuator, so as to sense whether an object falls from above the exposed lead screw, thereby providing timely feedback to the control system to stop the machine operation, thereby preventing objects from being drawn into the lead screw and causing it to become stuck, fall off, be damaged, or break, etc., thereby extending the service life of the lead screw and ensuring the personal safety of the operator. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is the overall structure diagram of the system of the present invention.

[0012] Figure 2 This is an exploded view of the lead screw portion of the actuator of the present invention.

[0013] Figure 3 This is a partial exploded view of a traditional split screw.

[0014] Figure 4 This is a structural diagram of the closed-loop system of the present invention.

[0015] As shown in the figure: 1. Base, 2. Stepper motor, 3. Actuator, 4. Actuator screw, 5. Detection device, 6. Screw threaded part, 7. Screw nut sleeve, 8. Screw pair, 9. Screw tail shaft, 10. Code disk, 11. Mounting bracket, 12. Code reader, 13. Rear end locking nut, 14. Safety grating sensor. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] A screw direct-connected closed-loop system for a hybrid stepping motor comprises a base 1, a stepping motor 2, an actuator 3 and a control system, and also comprises an actuator screw 4 and a detection device 5.

[0018] like Figure 3 As shown in the partial exploded diagram of the traditional split screw, the traditional screw only has the screw threaded portion 6, the screw nut sleeve 7, and the screw pair 8. Therefore, when the screw is inserted into the bearing sleeve 15 inside the stepper motor 2, the screw and the bearing sleeve 15 can only be glued together. During operation, the screw part and the bearing sleeve 15 part are very easy to fall off. However, since the bearing sleeve 15 is still rotating driven by the motor rotor, it is impossible to detect in time that the front end screw part has stopped running.

[0019] Therefore, in order to reduce the number of components used in the middle, make the structure simple, and avoid the feedback information from being unable to be transmitted in time, the present invention sets a rod-type long cylindrical actuator screw 4, which passes through the actuator 3, the base 1 and the stepper motor 2; the actuator screw 4 also includes a screw thread part 6, a screw nut sleeve 7, a screw pair 8 and a screw tail shaft 9 connected from left to right in sequence; the screw thread part 6 is located on the surface of the actuator screw 4; the screw nut sleeve 7 is hollow inside and has threads, and is sleeved on the screw thread part 6; the screw pair 8 is located at one end of the actuator screw 4, has a smooth surface and a cross-sectional diameter smaller than the screw thread part 6; the screw tail shaft 9 has a section of thread connected to the screw pair 8. In order to position the actuator screw 4 with the internal sleeve of the motor, the end portion of the actuator screw 4 is a smooth surface.

[0020] In order to avoid resonance, oscillation, loss of step and difficulty in achieving high speed during motor operation caused by an open-loop system, position feedback and speed feedback are respectively performed on the working actuator 3 and the stepper motor 2 in a timely manner to determine the phase conversion corresponding to the rotor position. The present invention installs a detection device 5 on the screw tail shaft 9, and the detection device 5 is installed on the screw tail shaft 9, and also includes a code disk 10, a mounting bracket 11 and a code reader 12; the code disk 10 is a disc with a through hole at the center, which matches the cross-section of the screw tail shaft 9. In order to enable the screw tail shaft 9 to drive the code disk 10 to rotate, the shapes of the cross-section and the through hole are irregular, and the mounting bracket 11 fixes the stepper motor 2 and the code reader 12; the code reader 12 is aligned with the code disk 10.

[0021] The closed-loop control adopted by the present invention, i.e., the detection device 5, is a basic concept of control theory: the distance moved by the actuator on the lead screw is indirectly measured through a closed-loop system, and the motor rotor as the controlled output returns to the input end of the control as a rotation angle, i.e., the control system. The control system judges whether the operation is normal through feedback data and makes appropriate treatments corresponding to different situations, and automatically gives the driving pulse sequence of the stepping motor. This driving pulse sequence changes at any time according to the load or the position of the rotor. There are many ways to implement this control method. In situations where high precision is required, it can achieve high position accuracy requirements by combining micro-step driving technology and microcomputer control technology. The present invention selects an angle digital code disk to convert the input quantity into a digital quantity output. All code channels of a single-disc encoder are on a disk. Since the angle represented by the resolution of the encoder is not a neat number, a pulse equivalent conversion circuit is required for this purpose, so that the control system display can be expressed in degrees, minutes, and seconds.

[0022] In order to fix the position of the stepper motor and the lead screw and prevent forward and backward sliding, the present invention provides a rear end locking nut 13, which is installed on the thread of the lead screw tail shaft 9 and is located between the stepper motor 2 and the detection device 5.

[0023] In order to prevent the screw from being damaged by objects falling during the operation of the motor, the present invention sets the safety grating sensor 14 at the upper part of the connection between the actuator screw 4 and the base 1. The light emitter in the safety grating sensor 14 emits infrared light to the light receiver to form a row of light curtains. When the light curtain is blocked, the light receiver detects a change in the intensity of a certain light path, and can determine that a foreign object has entered the dangerous area set by the light curtain, and immediately output a control signal, which is transmitted to the production equipment control system through a cable. The control system will control the equipment to stop running or prevent misstarting.

[0024] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A screw direct-connected closed-loop system for a hybrid stepper motor, comprising a base (1), a stepper motor (2), an actuator (3) and a control system, characterized in that: The actuator also includes an actuator lead screw (4) and a detection device (5); the actuator lead screw (4) passes through the actuator (3), the base (1) and the stepping motor (2); the actuator lead screw (4) also includes a lead screw threaded portion (6), a lead screw nut sleeve (7), a lead screw pair (8) and a lead screw tail shaft (9) which are connected in sequence from left to right; the lead screw threaded portion (6) is located on the surface of the actuator lead screw (4); the lead screw nut sleeve (7) is hollow inside and has threads, and is sleeved on the lead screw threaded portion (6); the lead screw pair (8) is located at one end of the actuator lead screw (4) and has a smooth surface. and the cross-sectional diameter is smaller than the threaded portion (6) of the screw; the portion of the screw tail shaft (9) connected to the screw pair (8) has a thread, and the portion near the end of the actuator screw (4) is a smooth surface; the detection device (5) is mounted on the screw tail shaft (9), and also includes a code disk (10), a mounting frame (11) and a code reader (12); the code disk (10) is a disc-shaped disk with a through hole at the center thereof, which matches the cross-sectional shape of the screw tail shaft (9); the mounting frame (11) fixes the stepping motor (2) and the code reader (12); the code reader (12) is aligned with the code disk (10).

2. The screw direct connection structure and closed-loop system matching assembly for a hybrid stepping motor according to claim 1, characterized in that: It also includes a rear end locking nut (13), which is mounted on the thread of the screw tail shaft (9) and is located between the stepping motor (2) and the detection device (5).

3. The screw direct connection structure and closed-loop system matching assembly for a hybrid stepping motor according to claim 1, characterized in that: The base further comprises a safety grating sensor (14), wherein the safety grating sensor (14) is located at the upper part of the connection between the actuator lead screw (4) and the base (1), and the light curtain formed by the safety grating sensor (14) is located directly above the lead screw and parallel to the base (1).

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