Angle reading device of rotary rack

Abstract

The utility model discloses a rotating frame angle reading device, which comprises a main angle acquisition mechanism and a verification angle acquisition mechanism, the main angle acquisition mechanism comprises a transmission frame and an angle acquisition sensor, the transmission frame is used for controlling the inclination angle of the angle acquisition sensor and accurately reading the angle of an accelerator rotating frame, and the verification angle acquisition mechanism is used for verifying the angle of the accelerator rotating frame. The verification angle acquisition mechanism comprises a horizontal adjusting frame and an inclination angle measurement sensor. The horizontal adjusting frame is used for the inclination angle measurement sensor to accurately read the angle of the accelerator rotating rack. The main angle acquisition mechanism and the verification angle acquisition mechanism provided by the utility model are two sets of completely independent systems, and the angle reading of the inclination angle measurement sensor does not depend on a mechanical transmission device. The problem that two groups of angles of the rack have undetectable errors due to the same transmission mechanism of the main angle acquisition mechanism and the verification angle acquisition mechanism is avoided, and the treatment effect of a patient is not affected and the life of the patient is not endangered.

Description

Technical Field

[0001] The utility model relates to the technical field of angle detection of medical electronic linear accelerators, in particular to a rotating gantry angle reading device. Background Art

[0002] In a medical electronic linear accelerator, the accuracy of the gantry angle directly affects the penetrability of the radiation beam in the patient's body and the distribution of the radiation dose, thereby affecting the irradiation coverage of the treatment target area. Correctly selecting the accelerator gantry angle can ensure that the radiation dose is accurately irradiated to the target area, improve the treatment effect, and the accurate setting of the gantry angle can also reduce the radiation dose to healthy tissues and organs, thereby protecting the surrounding normal tissues and reducing the risk of side effects and complications caused by the treatment. In summary, the accuracy of the gantry angle has an important impact on both the treatment effect and the patient's safety;

[0003] To prevent incorrect angle reading, in the prior art, two sets of angle reading devices, such as potentiometers, encoders, etc., are arranged on the same transmission mechanism under the rotating gantry to read the gantry angle. One of the two sets of angle values is used as the main angle, and the other set is used as the verification angle to ensure the accuracy of the gantry angle. Because it is the same set of transmission mechanism, due to faults or other factors, if the transmission mechanism is slightly loosened or a gap is generated, small errors will occur in both sets of angles, and at the same time, the operator cannot detect this error through the appearance of the gantry, which will ultimately affect the patient's treatment effect and seriously endanger the patient's life. Summary of the Utility Model

[0004] Based on this, in view of the above technical problems, it is necessary to provide a rotating gantry angle reading device. The main angle acquisition mechanism and the verification angle acquisition mechanism of this device are two completely independent systems, and the angle reading of the inclination measurement sensor does not depend on the mechanical transmission device.

[0005] To solve the above technical problems, the utility model adopts the following technical solutions:

[0006] A rotating gantry angle reading device, the reading device is installed on the accelerator rotating gantry and the accelerator base. The reading device includes: a main angle acquisition mechanism and a verification angle acquisition mechanism. The main angle acquisition mechanism includes a transmission gantry and an angle acquisition sensor. The transmission gantry is used for the inclination control of the angle acquisition sensor and accurately reads the angle of the accelerator rotating gantry. The verification angle acquisition mechanism includes a horizontal adjustment frame and an inclination measurement sensor. The horizontal adjustment frame is used for the inclination measurement sensor to accurately read the angle of the accelerator rotating gantry.

[0007] Furthermore, the main angle acquisition mechanism is installed on the accelerator base, and the verification angle acquisition mechanism is installed on the accelerator rotating gantry.

[0008] Further, the transmission frame includes a mounting frame, a mounting plate, a driving gear, a driven gear, a connecting component and a hydraulic cylinder. The mounting frame is in a Z-shaped structure and is fixedly connected to the accelerator base through a first screw. The mounting plate is hinged to the mounting frame. The driving gear is fixedly installed on the outer surface of the accelerator rotating frame. The driven gear and the angle acquisition sensor are both rotatably installed on the back of the mounting plate. The hydraulic cylinder is hinged to the mounting frame, and the output end of the hydraulic cylinder is hinged to the mounting plate. The driven gear transmits the rotation of the accelerator rotating frame to the angle acquisition sensor through the connecting component and reads the angle.

[0009] Further, the connecting component includes a driving pulley and a driven pulley. The driving pulley is rotatably connected to the mounting plate through a driving shaft and is fixedly connected to the driven gear. The driven pulley is rotatably connected to the mounting plate through a driven shaft and enables the angle acquisition sensor to detect the rotation angle. The driven pulley is in transmission connection with the driving pulley through a synchronous belt.

[0010] Further, the horizontal adjustment frame is fixedly connected to the accelerator rotating frame through a second screw, and the inclination measurement sensor is fixed on the horizontal adjustment frame.

[0011] Further, the horizontal adjustment frame is used to ensure that the mounting surface of the inclination measurement sensor is tangent to the circumferential movement of the accelerator rotating frame.

[0012] Further, the horizontal adjustment frame is in a C-shaped structure, and a weight-reducing hole is provided on the horizontal adjustment frame.

[0013] Further, the angle acquisition sensor is one of a potentiometer or an encoder.

[0014] Further, it further includes a frame inclination controller, and both the angle acquisition sensor and the inclination measurement sensor are communicatively connected to the frame inclination controller of the accelerator.

[0015] Further, a long hole is provided on the right side of the mounting plate. An activity block is slidably connected inside the long hole. The driven shaft passes through the activity block and is rotatably connected to the activity block through a bearing. A regulating knob is threadedly connected to the right side of the mounting plate. The left end of the regulating knob is rotatably connected to the right side of the activity block through a bearing, and a limit nut is threadedly connected to the outer surface of the right side of the regulating knob.

[0016] Compared with the prior art, the present utility model has the following beneficial effects:

[0017] The rotating frame angle reading device provided by the utility model transmits the rotation angle of the accelerator rotating frame to the angle acquisition sensor through the transmission frame, so as to read the angle. At the same time, since the inclination measurement sensor is installed on the horizontal adjustment frame, and the installation surface of the inclination measurement sensor is tangent to the circular motion of the accelerator rotating frame, the inclination measurement sensor can obtain the angle of the accelerator rotating frame in real time, and then the accelerator rotating frame angle read by the main angle acquisition mechanism is compared with the accelerator rotating frame angle read by the verification angle acquisition mechanism. When the deviation of the two values ​​exceeds the set threshold value, the accelerator generates a chain reaction, the treatment is suspended, and the operator is prompted to check the angle problem of the accelerator rotating frame. The treatment can be continued only after the angle problem is solved, thereby avoiding the problem that the patient treatment effect fails to achieve the expected effect due to the inaccurate angle of the accelerator.

[0018] The utility model provides a rotating frame angle reading device, in which the main angle acquisition mechanism and the verification angle acquisition mechanism are two completely independent systems, and the angle reading of the inclination measurement sensor does not rely on a mechanical transmission device, thereby avoiding the problem of imperceptible errors in the two sets of frame angles due to the same set of transmission mechanisms for the main angle acquisition mechanism and the verification angle acquisition mechanism, and does not affect the treatment effect of patients or endanger the lives of patients. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A left-side stereoscopic schematic diagram of a rotating frame angle reading device provided by the utility model;

[0020] Figure 2 A three-dimensional schematic diagram of the main angle acquisition mechanism of the rotating frame angle reading device provided by the utility model;

[0021] Figure 3 A right-side stereoscopic schematic diagram of a rotating frame angle reading device provided by the utility model;

[0022] Figure 4 A three-dimensional schematic diagram of a verification angle acquisition mechanism of a rotating frame angle reading device provided by the utility model;

[0023] Figure 5 This is a front view structural diagram of the rotating frame angle reading device provided by the utility model;

[0024] Figure 6 The utility model provides a rotating frame angle reading device Figure 5 The enlarged schematic diagram of point A in the middle;

[0025] Figure 7 The utility model provides a schematic cross-sectional view of a driven pulley adjustment structure of a rotating frame angle reading device.

[0026] The markings in the figure are as follows:

[0027] 1. Accelerator rotating gantry; 2. Accelerator base; 3. Main angle acquisition mechanism; 4. Drive gantry; 5. Angle acquisition sensor; 6. Verification angle acquisition mechanism; 7. Horizontal adjustment frame; 8. Inclination measurement sensor; 401. Mounting frame; 402. Mounting plate; 403. Driving gear; 404. Driven gear; 405. Hydraulic cylinder; 406. Driving pulley; 407. Driven pulley; 408. Timing belt; 409. Long hole; 410. Movable block; 411. Adjusting knob; 412. Limit nut; 701. Weight reduction hole. Specific embodiments

[0028] In order to enable those skilled in the art to better understand the solution of the present utility model, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present utility model.

[0029] As described in the background art, two sets of angle reading devices are provided on the same transmission mechanism under the rotating gantry of the existing linear accelerator. Because it is the same set of transmission mechanism, due to faults or other factors, if the transmission mechanism is slightly loosened or a gap is generated, small errors will occur in both sets of angles. At the same time, the operator cannot detect this error through the appearance of the gantry, which will ultimately affect the treatment effect of the patient and seriously endanger the patient's life.

[0030] To solve this technical problem, the present utility model provides a rotating gantry angle reading device. The main angle acquisition mechanism and the verification angle acquisition mechanism are two completely independent systems, and the angle reading of the inclination measurement sensor does not depend on the mechanical transmission device.

[0031] Specifically, please refer to Figures 1-7 , the rotating gantry angle reading device, the reading device is installed on the accelerator rotating gantry 1 and the accelerator base 2, and the reading device includes:

[0032] The main angle acquisition mechanism 3, the main angle acquisition mechanism 3 includes a drive gantry 4 and an angle acquisition sensor 5. The drive gantry 4 is used for the inclination control of the angle acquisition sensor 5 and accurately reads the angle of the accelerator rotating gantry 1;

[0033] Verify the angle acquisition mechanism 6, which includes a horizontal adjustment frame 7 and an inclination measurement sensor 8. The horizontal adjustment frame 7 is used for the inclination measurement sensor 8 to accurately read the angle of the accelerator rotating frame 1. The angles read by the angle acquisition sensor 5 and the inclination measurement sensor 8 are used for comparison.

[0034] The rotating frame angle reading device provided by the utility model transmits the rotation angle of the accelerator rotating frame 1 to the angle acquisition sensor 5 through the transmission frame 4, so as to read the angle. At the same time, since the inclination measurement sensor 8 is installed on the horizontal adjustment frame 7, the inclination measurement sensor 8 can obtain the angle of the accelerator rotating frame 1 in real time. Then, the angle of the accelerator rotating frame 1 read by the main angle acquisition mechanism 3 is compared with the angle of the accelerator rotating frame 1 read by the verification angle acquisition mechanism 6. When the deviation of the two values ​​exceeds the set threshold, the accelerator generates a chain reaction, the treatment is suspended, and the operator is prompted to check the angle problem of the accelerator rotating frame 1. The treatment can be continued only after the angle problem is solved, thereby avoiding the problem that the treatment effect of the patient does not reach the expected effect due to the inaccurate angle of the accelerator.

[0035] In order to enable those skilled in the art to better understand the solution of the utility model, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the accompanying drawings.

[0036] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features and technical solutions in the embodiments may be combined with each other.

[0037] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0038] Example 1

[0039] Please refer to Figures 1-3 , a rotating frame angle reading device, the reading device is installed on the accelerator rotating frame 1 and the accelerator base 2, and the reading device includes:

[0040] The main angle acquisition mechanism 3 includes a transmission frame 4 and an angle acquisition sensor 5. The transmission frame 4 is used for controlling the inclination of the angle acquisition sensor 5 and accurately reading the angle of the accelerator rotating frame 1.

[0041] Verify the angle acquisition mechanism 6, which includes a horizontal adjustment frame 7 and an inclination measurement sensor 8. The horizontal adjustment frame 7 is used for the inclination measurement sensor 8 to accurately read the angle of the accelerator rotating frame 1. The angles read by the angle acquisition sensor 5 and the inclination measurement sensor 8 are used for comparison.

[0042] Please refer toFigures 1-7 The rotation angle of the accelerator rotating frame 1 is transmitted to the angle acquisition sensor 5 through the transmission frame 4, so as to read the angle. At the same time, the inclination measurement sensor 8 is installed on the horizontal adjustment frame 7. At this time, the inclination measurement sensor 8 will be able to obtain the angle of the accelerator rotating frame 1 in real time, and then the angle of the accelerator rotating frame 1 read by the main angle acquisition mechanism 3 is compared with the angle of the accelerator rotating frame 1 read by the verification angle acquisition mechanism 6. When the deviation of the two values ​​exceeds the set threshold, the accelerator generates a chain, the treatment is terminated, and the operator is prompted to check the angle problem of the accelerator rotating frame 1. The treatment can only be continued after the angle problem is solved, thereby avoiding the problem that the patient's treatment effect does not achieve the expected effect due to inaccurate accelerator angle.

[0043] Example 2

[0044] The rotating frame angle reading device provided in Example 1 is further optimized, specifically, as follows Figure 1 , Figure 2 , Figure 5 and Figure 6 As shown, the main angle acquisition mechanism 3 is installed on the accelerator base 2, the verification angle acquisition mechanism 6 is installed on the accelerator rotating frame 1, the transmission frame 4 includes a mounting frame 401, a mounting plate 402, a driving gear 403, a driven gear 404, a connecting assembly and a hydraulic cylinder 405, the mounting frame 401 is a Z-shaped structure and is fixedly connected to the accelerator base 2 by a first screw, the mounting plate 402 is hinged on the mounting frame 401, the driving gear 403 is fixedly installed on the outer surface of the accelerator rotating frame 1, the driven gear 404 and the angle acquisition sensor 5 are both rotatably installed on the back of the mounting plate 402, and the hydraulic cylinder 4 05 is hinged on the mounting frame 401, the output end of the hydraulic cylinder 405 is hinged to the mounting plate 402, the driven gear 404 transmits the rotation of the accelerator rotating frame 1 to the angle acquisition sensor 5 through the connecting component and reads the angle, the connecting component includes a driving pulley 406 and a driven pulley 407, the driving pulley 406 is rotatably connected to the mounting plate 402 through a driving shaft and is fixedly connected to the driven gear 404, the driven pulley 407 is rotatably connected to the mounting plate 402 through a driven shaft and enables the angle acquisition sensor 5 to detect the rotation angle, and the driven pulley 407 is transmission-connected to the driving pulley 406 through a synchronous belt 408.

[0045] Through the above structural design, when in use, a driving gear 403 is provided on the accelerator rotating frame 1. When the accelerator rotating frame 1 rotates, the rotation angle of the accelerator rotating frame 1 is transmitted to the angle acquisition sensor 5 through cooperation with the driven gear 404, the driving pulley 406, the driven pulley 407 and the synchronous belt 408, thereby reading the angle.

[0046] Example 3

[0047] The rotational gantry angle reading device provided in Embodiment 1 or 2 is further optimized. For example, Figure 3 and Figure 4 As shown, the horizontal adjustment frame 7 is fixedly connected to the accelerator rotational gantry 1 through the second screw. The inclination measurement sensor 8 is fixed on the horizontal adjustment frame 7. The horizontal adjustment frame 7 is used to ensure that the mounting surface of the inclination measurement sensor 8 is tangent to the circular motion of the accelerator rotational gantry 1. The horizontal adjustment frame 7 is of a C-shaped structure, and a weight-reducing hole 701 is provided on the horizontal adjustment frame 7.

[0048] With such a setting, since the inclination measurement sensor 8 is installed on the horizontal adjustment frame 7 and the mounting surface of the inclination measurement sensor 8 is tangent to the circular motion of the accelerator rotational gantry 1, when the accelerator rotational gantry 1 rotates, the inclination measurement sensor 8 can obtain the angle of the accelerator rotational gantry 1 in real time.

[0049] Embodiment 4

[0050] On the basis of the rotational gantry angle reading device provided in the above embodiments, the angle acquisition sensor 5 is one of a potentiometer or an encoder. A gantry inclination controller is further included. The angle acquisition sensor 5 and the inclination measurement sensor 8 are both communicatively connected to the gantry inclination controller of the accelerator;

[0051] With such a structural design, the angle of the accelerator rotational gantry 1 read by the main angle acquisition mechanism 3 and the angle of the accelerator rotational gantry 1 read by the verification angle acquisition mechanism 6 are transmitted to the gantry inclination controller. The chip inside the gantry inclination controller compares the angles. When the deviation between the two values exceeds the set threshold, the accelerator generates a chain reaction and terminates the treatment, which is very convenient to control.

[0052] Embodiment 5

[0053] On the basis of the rotational gantry angle reading device provided in the above embodiments, for example, Figure 6 and Figure 7 As shown, a long hole 409 is provided on the right side of the mounting plate 402. A movable block 410 is slidably connected inside the long hole 409. The driven shaft passes through the movable block 410 and is rotatably connected to the movable block 410 through a bearing. The right side of the mounting plate 402 is threadedly connected with an adjusting knob 411. The left end of the adjusting knob 411 is rotatably connected to the right side of the movable block 410 through a bearing. A limit nut 412 is threadedly connected to the outer surface of the right side of the adjusting knob 411.

[0054] With such a structural design, after long-term use, the limit nut 412 is loosened, and then the adjusting knob 411 is turned to rotate. Since the left end of the adjusting knob 411 is rotatably connected to the right side of the movable block 410 through the bearing, and the adjusting knob 411 is threadedly connected to the mounting plate 402, the adjusting knob 411 can drive the movable block 410, the driven shaft and the driven pulley 407 away from the driving pulley 406 during the rotation process, thereby adjusting the tightness of the synchronous belt 408, better transmitting the rotation of the accelerator rotating frame 1 to the angle acquisition sensor 5 and reading the angle, reducing the reading error.

[0055] The use process of the rotating frame angle reading device provided by the utility model is as follows:

[0056] The reading device is mainly composed of a main angle acquisition mechanism 3 and a verification angle acquisition mechanism 6, and the main angle acquisition mechanism 3 includes a transmission frame 4 and an angle acquisition sensor 5, and the verification angle acquisition mechanism 6 includes a horizontal adjustment frame 7 and an inclination measurement sensor 8. When in use, a driving gear 403 is provided on the accelerator rotating frame 1. When the accelerator rotating frame 1 rotates, the angle of rotation of the accelerator rotating frame 1 is transmitted to the angle acquisition sensor 5 through cooperation with the driven gear 404, the driving pulley 406, the driven pulley 407 and the synchronous belt 408, thereby reading the angle. At the same time, the inclination measurement sensor 8 is installed on the horizontal adjustment frame 7. , and the mounting surface of the inclination measuring sensor 8 is tangent to the circular motion of the accelerator rotating frame 1. At this time, the inclination measuring sensor 8 will be able to obtain the angle of the accelerator rotating frame 1 in real time, and then the angle of the accelerator rotating frame 1 read by the main angle acquisition mechanism 3 is compared with the angle of the accelerator rotating frame 1 read by the verification angle acquisition mechanism 6. When the deviation of the two values ​​exceeds the set threshold, the accelerator will be interlocked, the treatment will be terminated, and the operator will be prompted to check the angle problem of the accelerator rotating frame 1. The treatment can only be continued after the angle problem is solved, thereby avoiding the problem that the patient's treatment effect does not achieve the expected effect due to inaccurate accelerator angle.

[0057] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] Obviously, the embodiments described above are only a part of the embodiments of the present utility model, rather than all embodiments. The preferred embodiments of the present utility model are shown in the drawings, but they do not limit the patent scope of the present utility model. The present utility model can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosed content of the present utility model more thorough and comprehensive. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing specific embodiments, or perform equivalent replacements for some of the technical features. Any equivalent structure made by using the content of the specification and drawings of the present utility model, directly or indirectly applied in other related technical fields, is equally within the scope of the patent protection of the present utility model.

Claims

1. A rotating frame angle reading device, the reading device is installed on an accelerator rotating frame (1) and an accelerator base (2), characterized in that: The reading device comprises: A main angle acquisition mechanism (3), the main angle acquisition mechanism (3) comprising a transmission frame (4) and an angle acquisition sensor (5), the transmission frame (4) being used for controlling the inclination of the angle acquisition sensor (5) and accurately reading the angle of the accelerator rotating frame (1); A verification angle acquisition mechanism (6) is provided, wherein the verification angle acquisition mechanism (6) comprises a horizontal adjustment frame (7) and an inclination angle measurement sensor (8), wherein the horizontal adjustment frame (7) is used for the inclination angle measurement sensor (8) to accurately read the angle of the accelerator rotating frame (1).

2. The rotating frame angle reading device according to claim 1, characterized in that: The main angle acquisition mechanism (3) is installed on the accelerator base (2), and the verification angle acquisition mechanism (6) is installed on the accelerator rotating frame (1).

3. The rotating frame angle reading device according to claim 2, characterized in that: The transmission frame (4) comprises a mounting frame (401), a mounting plate (402), a driving gear (403), a driven gear (404), a connecting assembly and a hydraulic cylinder (405); the mounting frame (401) is a Z-shaped structure and is fixedly connected to the accelerator base (2) by a first screw; the mounting plate (402) is hinged on the mounting frame (401); the driving gear (403) is fixedly mounted on the outer surface of the accelerator rotating frame (1); the driven gear (404) and the angle acquisition sensor (5) are both rotatably mounted on the back of the mounting plate (402); the hydraulic cylinder (405) is hinged on the mounting frame (401); the output end of the hydraulic cylinder (405) is hinged to the mounting plate (402); and the driven gear (404) transmits the rotation of the accelerator rotating frame (1) to the angle acquisition sensor (5) through the connecting assembly and reads the angle.

4. The rotating frame angle reading device according to claim 3, characterized in that: The connection assembly comprises a driving pulley (406) and a driven pulley (407); the driving pulley (406) is rotationally connected to the mounting plate (402) via a driving shaft and is fixedly connected to the driven gear (404); the driven pulley (407) is rotationally connected to the mounting plate (402) via a driven shaft and enables an angle acquisition sensor (5) to detect a rotation angle; and the driven pulley (407) is transmission-connected to the driving pulley (406) via a synchronous belt (408).

5. The rotating frame angle reading device according to claim 1, characterized in that: The horizontal adjustment frame (7) is fixedly connected to the accelerator rotating frame (1) via a second screw, and the inclination angle measuring sensor (8) is fixed on the horizontal adjustment frame (7).

6. The rotating frame angle reading device according to claim 5, characterized in that: The horizontal adjustment frame (7) is used to ensure that the mounting surface of the inclination angle measurement sensor (8) is tangent to the circular motion of the accelerator rotating frame (1).

7. The rotating frame angle reading device according to claim 6, characterized in that: The horizontal adjustment frame (7) is a "X"-shaped structure, and a weight-reducing hole (701) is provided on the horizontal adjustment frame (7).

8. The rotating frame angle reading device according to claim 7, characterized in that: The angle acquisition sensor (5) is a potentiometer or an encoder.

9. The rotating frame angle reading device according to claim 8, characterized in that: It also includes a frame inclination controller, and the angle acquisition sensor (5) and the inclination measurement sensor (8) are both communicatively connected to the frame inclination controller of the accelerator.

10. The rotating frame angle reading device according to claim 4, characterized in that: A long hole (409) is provided on the right side of the mounting plate (402), and a movable block (410) is slidably connected inside the long hole (409). The driven shaft passes through the movable block (410) and is rotatably connected to the movable block (410) via a bearing. An adjusting knob (411) is threadedly connected to the right side of the mounting plate (402), and the left end of the adjusting knob (411) is rotatably connected to the right side of the movable block (410) via a bearing. The right outer surface of the adjusting knob (411) is threadedly connected to a limiting nut (412).

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