A controllable temperature detection device for SLM printer molding chamber

Abstract

The invention discloses a controllable temperature detection device for a molding bin of an SLM printer, comprising a printer body, wherein a molding cavity is arranged in the printer body, a printing base is arranged at the bottom of the molding cavity, a temperature detection component is arranged on the side wall of the molding cavity, and the temperature detection component is used to detect the temperature in the molding cavity; an alarm device is arranged on one side of the printer body, the alarm device cooperates with the temperature detection component, a square through groove is arranged on the side wall of the molding cavity, and the temperature detection component is located in the square through groove; by arranging the alarm device, a high temperature signal is transmitted to the alarm device, and the alarm device sends out an alarm to remind a staff member to perform a rapid cooling process to avoid a fire caused by persistent high temperature; at the same time, by using the alarm device, it is avoided that the staff member fails to observe the high temperature situation in time due to negligence or failure to observe the printer body in real time for some reason, thereby improving the safety of the device and reducing accidents.

Description

Technical Field

[0001] The invention relates to the technical field of temperature detection of an SLM printer body, and in particular to a controllable temperature detection device for a molding bin of an SLM printer. Background Art

[0002] The SLM metal printer is a scientific instrument used in the basic disciplines of engineering and technological science, mechanical engineering, and engineering and technical fields related to product applications. It mainly relies on laser selective melting of metal technology. Laser selective melting of metal technology uses a high-energy density laser beam to scan under the control of a computer program. The pre-laid metal powder layer is selectively melted and metallurgically combined with the matrix, and then the powder is continuously laid layer by layer and scanned to finally complete the manufacture of three-dimensional metal parts.

[0003] SLM metal printers generate a lot of heat during printing. When a lot of heat cannot be discharged, workers are required to stop the printer to dissipate heat. However, when the staff does not notice the high temperature of the printer, the high temperature will cause damage to the electronic parts inside the printer body, and even cause fire and explosion. Therefore, a device is needed that can detect the temperature of the printer and remind the staff when the printer is at a high temperature. Summary of the invention

[0004] The purpose of the present invention is to provide a controllable temperature detection device for a molding chamber of a SLM printer in view of the deficiencies in the prior art, so as to solve the problems raised in the background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A controllable temperature detection device for a molding chamber of an SLM printer comprises a printer body, a molding cavity is arranged in the printer body, a through hole is arranged on one side of the printer body, a circular ring is fixedly connected in the through hole, the inner wall of the circular ring is fixedly connected to a support plate, one side of the support plate is rotatably connected to a fan, the main shaft of the fan passes through the support plate and is fixedly connected to a first pulley, one side of the printer body is fixedly connected to a horizontal plate, a vertical plate is fixed on the lower surface of the horizontal plate, a servo motor is fixed on one side of the vertical plate, the main shaft of the servo motor is fixedly connected to a second pulley, a belt is connected between the first pulley and the second pulley, the belt passes through the circular ring, and a printing base is arranged at the bottom of the molding cavity A temperature detection component is provided on the side wall of the molding cavity, and the temperature detection component is used to detect the temperature in the molding cavity. An alarm device is provided on one side of the printer body, and the alarm device cooperates with the temperature detection component. A square through groove is provided on the side wall of the molding cavity, and the temperature detection component is located in the square through groove. The temperature detection component includes a support plate, and the support plate is located in the square through groove and fixed on the bottom surface of the square through groove. The side wall of the square through groove is rotatably connected to a rotating plate, and the rotating plate is fixedly connected to a circular cylinder at one end of the molding cavity, and the upper end of the circular cylinder is fixedly connected to a breathable cover plate, and the inner wall of the circular cylinder is fixedly connected to an elastic bag, and an environmentally sensitive hydrogel is contained in the elastic bag.

[0007] As a preferred solution of the present invention, the alarm device includes a square plate, which is located above the square through groove and fixedly connected to the printer body, the upper surface of the rotating plate at one end outside the printer body is fixedly connected to the traction rope, and the traction rope passes through the square plate upward, a slide groove is provided on one side of the printer body, a slider is slidably connected in the slide groove, a first spring is fixedly connected between the slider and the slide groove, one side of the slider is fixedly connected to the rack, one side of the rack is fixedly connected to the connecting plate, the traction rope is fixedly connected to the connecting plate, one side of the printer body is fixedly connected to the first gear and the second gear, the radius of the first gear is greater than the radius of the second gear, the first gear is meshed with the rack, the first gear is meshed with the second gear, one side of the second gear is fixedly connected to the winding wheel, one side of the vertical plate is fixedly connected to the alarm, and a control line is connected between the alarm and the winding wheel.

[0008] As a preferred solution of the present invention, the upper surface of the printer body is fixedly connected to a water tank, a control device is provided on one side of the water tank, condensate is stored in the water tank, one side of the water tank is connected to a delivery pipe, one side of the circular ring is fixedly connected to a spiral condenser, the delivery pipe is connected to the condenser, and the delivery pipe passes through the printer body and the circular ring.

[0009] As a preferred solution of the present invention, the control device includes a control valve, which is installed on one side of the water tank. The control valve is used to control the condensate to enter the delivery pipe. The horizontal plate is slidably connected to a sliding rod, and a second spring is fixedly connected between the sliding rod and the horizontal plate. One side of the sliding rod is fixedly connected to a toggle rod, and the toggle rod cooperates with the control valve. One side of the lower end of the sliding rod is fixed to a toggle block, and one side of the second pulley is fixedly connected to a round rod, and the outer circle of the round rod is a one-way rotating rod.

[0010] As a preferred solution of the present invention, a torsion spring is provided at the connection between the one-way rotating rod and the round rod, a first arc surface is provided on one side of the one-way rotating rod, and a second arc surface is provided on one side of the toggle block.

[0011] Compared with the prior art, the present invention provides a controllable temperature detection device for a SLM printer molding chamber, which has the following beneficial effects:

[0012] 1. A controllable temperature detection device for a molding chamber of an SLM printer is provided with an alarm device. When the temperature detection component detects that the temperature inside the molding chamber is high, a high temperature signal is transmitted to the alarm device. The high temperature signal is transmitted to the alarm device, and the alarm device sounds an alarm to remind the staff to quickly cool down the temperature to avoid fire caused by persistent high temperature. At the same time, the alarm device can prevent the staff from being negligent or not observing the printer body in real time for some reason, resulting in the failure to observe the high temperature in time, thereby improving the safety of the device and reducing accidents.

[0013] 2. A controllable temperature detection device for a molding chamber of an SLM printer is provided. By setting a hydrogel and an elastic bag, when the temperature in the molding chamber is normal, the rotating plate and the supporting plate are kept in a horizontal and parallel state. When the temperature inside the molding chamber is too high, when the hydrogel detects that the temperature is getting high, a high-temperature shrinkage phenomenon will occur, and the elastic bag will shrink and lose the support of the elastic bag. A torsion spring is provided at the connection between the rotating plate and the printer body, so that the end of the rotating plate close to the elastic bag is close to the supporting plate, and the rotating plate is tilted. The hydrogel is very sensitive to slight changes in the surrounding environment and reacts very quickly to temperature changes inside the molding chamber.

[0014] 3. This controllable temperature detection device for the molding chamber of an SLM printer is provided with a first gear and a second gear. When the rotating plate is tilted, the other end of the rotating plate pulls the rack downward through the traction rope and the connecting plate, and the rack drives the first gear to rotate, and the first gear drives the second gear to rotate. The radius of the first gear is larger than that of the second gear, and the rotation amplitude of the second gear is larger. The first gear and the second gear can amplify the slight rotation of the rotating plate. Even if the rotating plate is only slightly tilted, the amplification by the first gear and the second gear can also make the second gear produce a larger rotation. The phenomenon is obvious and omissions are avoided.

[0015] 4. A controllable temperature detection device for a molding chamber of an SLM printer is provided with a condenser. A servo motor drives a one-way rotating rod to rotate, and the sliding rod is moved to move the sliding rod downward. At the same time, the sliding rod moves the control valve downward through the toggle rod to open the control valve. The condensate enters the spiral condenser through the delivery pipe, so that the temperature around the condenser is reduced. The wind generated by the fan is cooled when passing through the condenser, and the cold wind enters the molding cavity, and the molding cavity is quickly cooled down to avoid continuous high temperature damaging the printer body. At the same time, manpower is released. Even if the staff is not there, the device can immediately quickly cool the molding cavity. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a three-dimensional structural schematic diagram of the device;

[0017] Figure 2 It is a schematic structural diagram of the side view of the device;

[0018] Figure 3 is a cross-sectional schematic diagram of the device;

[0019] Figure 4 for Figure 3 The enlarged structural diagram at A in the middle;

[0020] Figure 5 It is a structural schematic diagram of the alarm device;

[0021] Figure 6 It is a structural schematic diagram of the condenser;

[0022] Figure 7 for Figure 6 The enlarged structural diagram at B in the middle;

[0023] Figure 8 It is a structural diagram of the control device.

[0024] In the figure: 1, printer body; 11, molding cavity; 12, printing base; 2, temperature detection component; 21, support plate; 22, rotating plate; 23, circular cylinder; 24, cover plate; 25, elastic bag; 26, hydrogel; 3, circular ring; 31, support plate; 32, fan; 33, first pulley; 34, horizontal plate; 35, vertical plate; 36, servo motor; 37, second pulley; 4, alarm device; 41, square plate; 42, traction rope; 43, slide Block; 44, first spring; 45, rack; 46, connecting plate; 47, first gear; 48, second gear; 401, winding wheel; 402, alarm; 403, control line; 5, water tank; 51, delivery pipe; 52, condenser; 6, control device; 61, control valve; 62, sliding rod; 63, second spring; 64, toggle rod; 65, toggle block; 66, round rod; 67, one-way rotating rod; 68, first arc surface; 69, second arc surface. DETAILED DESCRIPTION

[0025] 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.

[0026] See also Figure 1-8 In this implementation scheme:

[0027] A controllable temperature detection device for a molding bin of an SLM printer comprises a printer body 1, wherein a molding cavity 11 is arranged in the printer body 1, a printing base 12 is arranged at the bottom of the molding cavity 11, a temperature detection component 2 is arranged on the side wall of the molding cavity 11, and the temperature detection component 2 is used to detect the temperature in the molding cavity 11, an alarm device 4 is arranged on one side of the printer body 1, and the alarm device 4 cooperates with the temperature detection component 2, a square through groove is arranged on the side wall of the molding cavity 11, and the temperature detection component 2 is located in the square through groove, a through hole is arranged on one side of the printer body 1, a circular ring 3 is fixedly connected in the through hole, a support plate 31 is fixedly connected to the inner wall of the circular ring 3, a fan 32 is rotatably connected to one side of the support plate 31, a main shaft of the fan 32 passes through the support plate 31 and is fixedly connected to a first pulley 33, a horizontal plate 34 is fixedly connected to one side of the printer body 1, a vertical plate 35 is fixed to the lower surface of the horizontal plate 34, a servo motor 36 is fixed to one side of the vertical plate 35, a main shaft of the servo motor 36 is fixedly connected to a second pulley 37, a belt is connected between the first pulley 33 and the second pulley 37, and the belt passes through the circular ring 3.

[0028] When the printer body 1 is printing, a large amount of heat and smoke will be generated. At this time, the servo motor 36 is started, and the fan 32 is driven to rotate forward through the first pulley 33 and the second pulley 37 to extract the smoke and heat in the molding cavity 11, thereby playing a role in heat dissipation. At the same time, the temperature detection component 2 detects the temperature inside the molding cavity 11. When a large metal model is printed inside the printer body 1, a large amount of heat is continuously generated due to the long printing time. The heat dissipation effect of the fan 32 on the molding cavity 11 is fixed. When the heat generated inside the molding cavity 11 is greater than the heat extracted by the fan 32, the temperature inside the molding cavity 11 will be too high. At this time, when the temperature detection component 2 detects that the temperature inside the molding cavity 11 is high, it will transmit a high temperature signal to the alarm device 4. The alarm device 4 sounds an alarm to remind the staff to quickly cool down the temperature to avoid fire caused by persistent high temperature. At the same time, the alarm device can avoid the staff from being negligent or not observing the printer body in real time for some reason, resulting in the failure to observe the high temperature in time, thereby improving the safety of the device and reducing accidents.

[0029] The temperature detection assembly 2 includes a support plate 21, which is located in the square through groove and fixed on the bottom surface of the square through groove. The side wall of the square through groove is rotatably connected to a rotating plate 22. The rotating plate 22 is located at one end of the molding cavity 11 and is fixedly connected to a circular cylinder 23. The upper end of the circular cylinder 23 is fixedly connected to a breathable cover plate 24. The inner wall of the circular cylinder 23 is fixedly connected to an elastic bag 25. The elastic bag 25 contains an environmentally sensitive hydrogel 26. The alarm device 4 includes a square plate 41. The square plate 41 is located above the square through groove and is fixedly connected to the printer body 1. The upper surface of the rotating plate 22 at one end outside the printer body 1 is fixedly connected to a traction rope 42. The traction rope 42 passes through the square plate 41 upward. One end of the printer body 1 A slide groove is provided on the side, in which a slider 43 is slidably connected, a first spring 44 is fixedly connected between the slider 43 and the slide groove, one side of the slider 43 is fixedly connected to a rack 45, one side of the rack 45 is fixedly connected to a connecting plate 46, the traction rope 42 is fixedly connected to the connecting plate 46, one side of the printer body 1 is fixedly connected to a first gear 47 and a second gear 48, the radius of the first gear 47 is greater than the radius of the second gear 48, the first gear 47 is meshed with the rack 45, the first gear 47 is meshed with the second gear 48, one side of the second gear 48 is fixedly connected to a winding wheel 401, one side of the vertical plate 35 is fixedly connected to an alarm 402, and a control line 403 is connected between the alarm 402 and the winding wheel 401.

[0030] When the temperature in the molding cavity 11 is normal, the rotating plate 22 remains horizontal, and the lower end of the circular cylinder 23 is against the support plate 21, and the rotating plate 22 and the support plate 21 remain horizontal and parallel. When the temperature inside the molding cavity 11 is too high, when the hydrogel 26 detects that the temperature is high, it will shrink at high temperature. Initially, the elastic bag 25 is in a bulging state and presses against the support plate 21 to keep the rotating plate 22 horizontal. When the hydrogel 26 shrinks at high temperature, the elastic bag 25 shrinks and loses the support of the elastic bag 25. A torsion spring is provided at the connection between the rotating plate 22 and the printer body 1, so that the end of the rotating plate 22 close to the elastic bag 25 is close to the support plate 21, and the rotating plate 22 tilts. The hydrogel 26 is very sensitive to slight changes in the surrounding environment and reacts very quickly to temperature changes inside the molding cavity 11.

[0031] When the rotating plate 22 is tilted, the other end of the rotating plate 22 pulls the rack 45 downward through the traction rope 42 and the connecting plate 46, and the rack 45 drives the first gear 47 to rotate, and the first gear 47 drives the second gear 48 to rotate. The radius of the first gear 47 is larger than that of the second gear 48, and the rotation amplitude of the second gear 48 is larger. The first gear 47 and the second gear 48 can amplify the small rotation movement of the rotating plate 22. Even if the rotating plate 22 is only slightly tilted, the amplification by the first gear 47 and the second gear 48 can also make the second gear 48 produce a larger rotation. The phenomenon is obvious, which makes the device more accurate in detecting the internal temperature of the molding cavity 11. The rotation of the second gear 48 drives the winding wheel 401 to reel in the control line 403, and the control line 403 pulls the alarm 402, so that the alarm 402 makes a sound to warn the staff.

[0032] The upper surface of the printer body 1 is fixedly connected to a water tank 5, and a control device 6 is provided on one side of the water tank 5. Condensate is stored in the water tank 5, and one side of the water tank 5 is connected to a delivery pipe 51. A spiral condenser pipe 52 is fixedly connected to one side of the circular ring 3. The delivery pipe 51 is connected to the condenser pipe 52, and the delivery pipe 51 passes through the printer body 1 and the circular ring 3. The control device 6 includes a control valve 61, which is installed on one side of the water tank 5. The control valve 61 is used to control the condensate to enter the delivery pipe 51. The sliding rod 62 is slidably connected to the horizontal plate 34. A second spring 63 is fixedly connected between the sliding rod 62 and the cross plate 34, a toggle rod 64 is fixedly connected to one side of the sliding rod 62, the toggle rod 64 cooperates with the control valve 61, a toggle block 65 is fixed to one side of the lower end of the sliding rod 62, a round rod 66 is fixedly connected to one side of the second pulley 37, the outer circle of the round rod 66 is rotated by a one-way rotating rod 67, a torsion spring is provided at the connection between the one-way rotating rod 67 and the round rod 66, a first arc surface 68 is provided on one side of the one-way rotating rod 67, and a second arc surface 69 is provided on one side of the toggle block 65.

[0033] When the temperature in the molding cavity 11 is normal, the servo motor 36 rotates forward, and the fan 32 extracts the heat. At this time, the first arc surface 68 on the rotating one-way rotating rod 67 contacts the second arc surface 69 on one side of the toggle block 65, causing the one-way rotating rod 67 to deflect and avoid the toggle block. When the alarm 402 sounds to warn the staff, the servo motor 36 reverses, causing the fan 32 to change from exhausting air to blowing air to blow away the heat. At the same time, the reversed servo motor 36 drives the one-way rotating rod 67 to rotate, toggling the sliding rod 62, so that the sliding The rod 62 moves downward, and at the same time, the sliding rod 62 pushes the control valve 61 downward through the toggle rod 64, so that the control valve 61 is opened, and the condensate enters the spiral condenser 52 through the delivery pipe 51, so that the temperature around the condenser 52 is reduced, and the wind generated by the fan 32 is cooled when passing through the condenser 52, and the cold wind enters the molding cavity 11, and the molding cavity 11 is quickly cooled to avoid continuous high temperature damaging the printer body 1, and at the same time, manpower is released. Even if the staff is not there, the device can immediately perform a rapid cooling process on the molding cavity 11.

[0034] The working principle and use process of the present invention are as follows: when the temperature in the molding cavity 11 is normal, the servo motor 36 is started, and the fan 32 is driven to rotate forward through the first pulley 33 and the second pulley 37 to extract the smoke and heat in the molding cavity 11. At this time, the elastic bag 25 is in an inflated state and is pressed against the support plate 21, so that the rotating plate 22 remains horizontal. When the temperature in the molding cavity 11 rises, the hydrogel 26 detects that the temperature has increased and will produce high-temperature shrinkage. The elastic bag 25 shrinks and loses the support of the elastic bag 25, so that the end of the rotating plate 22 close to the elastic bag 25 approaches the support plate 21, and the rotating plate 22 tilts. The rack 45 drives the first gear 47 to rotate, and the first gear 47 drives the second gear 48 to rotate. The second gear 48 rotates to drive the winding wheel. 401 reels in control line 403, and control line 403 pulls alarm 402, causing alarm 402 to emit a sound to warn the staff. When alarm 402 emits a sound to warn the staff, servo motor 36 reverses, causing fan 32 to change from exhausting air to blowing air, and blows away the heat. At the same time, the reversed servo motor 36 drives the one-way rotating rod 67 to rotate, and moves the sliding rod 62, causing the sliding rod 62 to move downward. At the same time, the sliding rod 62 moves the control valve 61 downward through the toggle rod 64, so that the control valve 61 is opened, and the condensate enters the spiral condenser 52 through the delivery pipe 51, so that the temperature around the condenser 52 is reduced, and the wind generated by the fan 32 is cooled when passing through the condenser 52, and the cold wind enters the molding cavity 11, and the molding cavity 11 is quickly cooled.

[0035] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A controllable temperature detection device for a SLM printer molding chamber, characterized in that: The invention comprises a printer body (1), wherein a molding cavity (11) is provided in the printer body (1), a through hole is provided on one side of the printer body (1), a circular ring (3) is fixedly connected in the through hole, the inner wall of the circular ring (3) is fixedly connected to a support plate (31), one side of the support plate (31) is rotatably connected to a fan (32), the main shaft of the fan (32) passes through the support plate (31) and is fixedly connected to a first pulley (33), one side of the printer body (1) is fixedly connected to a horizontal plate (34), a vertical plate (35) is fixed on the lower surface of the horizontal plate (34), a servo motor (36) is fixed on one side of the vertical plate (35), the main shaft of the servo motor (36) is fixedly connected to a second pulley (37), a belt is connected between the first pulley (33) and the second pulley (37), the belt passes through the circular ring (3), a printing base (12) is provided at the bottom of the molding cavity (11), the molding cavity A temperature detection component (2) is provided on the side wall of the molding cavity (11), and the temperature detection component (2) is used to detect the temperature in the molding cavity (11). An alarm device (4) is provided on one side of the printer body (1), and the alarm device (4) cooperates with the temperature detection component (2). A square through groove is provided on the side wall of the molding cavity (11), and the temperature detection component (2) is located in the square through groove. The temperature detection component (2) comprises a support plate (21), and the support plate (21) is located in the square through groove and fixed on the bottom surface of the square through groove. The side wall of the square through groove is rotatably connected to a rotating plate (22). The rotating plate (22) is located at one end of the molding cavity (11) and is fixedly connected to a circular cylinder (23). The upper end of the circular cylinder (23) is fixedly connected to a breathable cover plate (24). The inner wall of the circular cylinder (23) is fixedly connected to an elastic bag (25), and the elastic bag (25) contains an environmentally sensitive hydrogel (26).

2. A controllable temperature detection device for a SLM printer molding chamber according to claim 1, characterized in that: The alarm device (4) comprises a square plate (41), the square plate (41) is located above the square through slot and is fixedly connected to the printer body (1), the upper surface of the rotating plate (22) at one end outside the printer body (1) is fixedly connected to a traction rope (42), the traction rope (42) passes through the square plate (41) upward, a slide groove is provided on one side of the printer body (1), a slider (43) is slidably connected in the slide groove, a first spring (44) is fixedly connected between the slider (43) and the slide groove, one side of the slider (43) is fixedly connected to a rack (45), one side of the rack (45) is fixedly connected to the connecting plate (4 6), the traction rope (42) is fixedly connected to the connecting plate (46), one side of the printer body (1) is fixedly connected to a first gear (47) and a second gear (48), the radius of the first gear (47) is greater than the radius of the second gear (48), the first gear (47) is meshed with a rack (45), the first gear (47) is meshed with the second gear (48), one side of the second gear (48) is fixedly connected to a winding wheel (401), one side of the vertical plate (35) is fixedly connected to an alarm (402), and a control line (403) is connected between the alarm (402) and the winding wheel (401).

3. A controllable temperature detection device for a SLM printer molding chamber according to claim 1, characterized in that: The upper surface of the printer body (1) is fixedly connected to a water tank (5), one side of the water tank (5) is provided with a control device (6), the water tank (5) stores condensate, one side of the water tank (5) is connected to a delivery pipe (51), one side of the circular ring (3) is fixedly connected to a spiral condenser pipe (52), the delivery pipe (51) is connected to the condenser pipe (52), and the delivery pipe (51) passes through the printer body (1) and the circular ring (3).

4. A controllable temperature detection device for a SLM printer molding chamber according to claim 1, characterized in that: The control device (6) comprises a control valve (61), which is installed on one side of the water tank (5) and is used to control the condensate to enter the delivery pipe (51). The transverse plate (34) is slidably connected to a sliding rod (62), a second spring (63) is fixedly connected between the sliding rod (62) and the transverse plate (34), one side of the sliding rod (62) is fixedly connected to a toggle rod (64), the toggle rod (64) cooperates with the control valve (61), one side of the lower end of the sliding rod (62) is fixedly connected to a toggle block (65), one side of the second pulley (37) is fixedly connected to a round rod (66), and the outer circle of the round rod (66) rotates a one-way rotating rod (67).

5. A controllable temperature detection device for a molding chamber of a SLM printer according to claim 4, characterized in that: A torsion spring is provided at the connection between the one-way rotating rod (67) and the round rod (66); a first arc surface (68) is provided on one side of the one-way rotating rod (67); and a second arc surface (69) is provided on one side of the shifting block (65).

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