Sewing device and method of adjustment

Abstract

The present application belongs to the technical field of sewing machines, and discloses a sewing device and a regulating method. The sewing device comprises a base, a needle plate, a head assembly, a regulating assembly and a locking assembly. The needle plate is arranged on the base. The head assembly comprises a casing, a frame and a needle. The casing is arranged on the base, the frame is arranged in the casing, and the needle is arranged on the frame. The regulating assembly comprises a regulating drive. The regulating drive is arranged on the casing, and the output end of the regulating drive is connected to the frame. The regulating drive can drive the frame to lift or lower, so as to adjust the distance between the needle and the needle plate. The locking assembly comprises a locking drive. The locking drive is arranged on the casing, and the output end of the locking drive is provided with a limiting piece. The locking drive can drive the limiting piece to abut against the frame or drive the limiting piece to move away from the frame. The regulating method adjusts the driving of the regulating drive and the locking drive, improves the accuracy and efficiency of the relative position adjustment of the needle and the needle plate, and reduces the failure rate.

Description

Technical Field

[0001] This invention relates to the field of sewing machine technology, and more particularly to a sewing device and adjustment method. Background Technology

[0002] The column-type roller-type integrated feeding sewing machine (hereinafter referred to as roller sewing machine) is mainly suitable for industries such as shoemaking, bag making, and car seat cushion making. During the sewing process, different materials are often involved. For example, when sewing thick and thin materials, the relative positions of the needle and needle plate on the roller sewing machine need to be adjusted to adapt to the sewing of different materials and achieve satisfactory sewing results.

[0003] Currently, the needles and needle plates on roller sewing machines require professional manual adjustment by maintenance personnel. First, the maintenance personnel need to turn the handwheel to a specific position, then remove the machine head cover, loosen the needle bar fixing screw with a wrench, check and adjust the relative position of the needle plate and the needle, and tighten the fixing screw after visually estimating that the required distance has been reached. Finally, the cover is installed. The above adjustment relies on operating experience, and it is difficult to guarantee the consistency and accuracy of the needle bar position after each adjustment. Sometimes, multiple adjustments are required, which results in low accuracy and efficiency in adjusting the relative position of the needle and needle plate. Incorrect adjustment can also easily lead to sewing failures such as needle breakage and skipped stitches. Summary of the Invention

[0004] The purpose of this invention is to provide a sewing device and adjustment method. By adjusting the driving and locking driving components, the relative position adjustment of the needle and needle plate can be improved without relying on operating experience, thereby reducing the failure rate.

[0005] To achieve this objective, the present invention adopts the following technical solution: One aspect provides a sewing device, which includes: Base; A needle plate, which is mounted on a base; A head assembly, comprising a housing, a frame, and a needle, wherein the housing is disposed on the base, the frame is disposed within the housing, and the needle is disposed on the frame and extends through the housing; An adjustment assembly includes an adjustment drive, which is disposed on the housing. The output end of the adjustment drive is connected to the frame. The adjustment drive can drive the frame to rise and fall to adjust the distance between the needle and the needle plate. A locking assembly includes a locking drive, which is disposed on the housing. A limiting member is provided at the output end of the locking drive. The locking drive can drive the limiting member to abut against the frame and fix it to the housing; or drive the limiting member away from the frame.

[0006] In some embodiments, one of the housing and the frame is provided with a slide rail, and the other is provided with a slider, the slider being slidably attached to the slide rail.

[0007] In some embodiments, the adjustment assembly further includes a lead screw and a nut assembly. The lead screw is connected to the output end of the adjustment drive, and the adjustment drive can drive the lead screw to rotate. The frame is provided with a fixing hole, and the nut assembly is fixed in the fixing hole and screwed onto the lead screw.

[0008] In some embodiments, the adjusting assembly further includes a first locking block, a second locking block, and a locking rod. The wall of the fixing hole is provided with a notch. Both the first locking block and the second locking block are provided with abutting surfaces. The two abutting surfaces abut against the nut assembly through the notch. The first locking block is fixed on the frame. The locking rod is connected to the second locking block. The locking rod can drive the second locking block to move closer to or away from the first locking block, so as to drive the two abutting surfaces to clamp the nut assembly or drive the two abutting surfaces to move away from each other.

[0009] In some embodiments, the frame is provided with an elongated hole extending along the height direction, the elongated hole penetrating the frame, the housing is provided with a fixing screw hole, the limiting member includes a top abutment and a screw portion, the top abutment and the fixing screw hole are located on opposite sides of the frame, the top abutment is connected to the screw portion, the screw portion passes through the elongated hole and is screwed into the fixing screw hole, and the output end of the locking drive member is connected to the top abutment to drive the top abutment to rotate.

[0010] In some embodiments, multiple limiting members are provided, the locking assembly further includes a connecting rod, the multiple abutments are all connected to the connecting rod, and the output end of the locking drive is connected to the connecting rod.

[0011] In some embodiments, an anti-slip pad is provided on the side of the top of the abutment facing the frame.

[0012] In some embodiments, two limiting members are provided, and the two limiting members are respectively provided on the upper and lower sides of the frame. The locking drive member can drive the two limiting members to move closer to or further away from each other.

[0013] In some embodiments, the sewing device further includes a controller disposed on the housing, the controller controlling the adjustment drive and the locking drive connected thereto; a position sensor and / or pressure sensor are disposed on the limiting member, and an alarm is disposed on the housing, the alarm being signal-connected to the position sensor and / or pressure sensor via the controller.

[0014] On the other hand, an adjustment method is also provided, applied to the above-mentioned sewing device, wherein the controller has multiple height settings pre-stored, and the adjustment method includes the following steps: The controller acquires a gear height command and controls the adjustment drive to raise or lower the frame to the gear height corresponding to the gear height command according to the gear height command; After the frame is raised or lowered to the specified height, the controller controls the locking drive to drive the limiting member to fix the frame to the housing. The controller acquires the position information of the position sensor and determines whether the limiting component has reached a preset position. If it reaches the preset position, it determines that the locking is in place; if it does not reach the preset position, it determines that the locking is not in place, and the alarm sounds an alarm signal. And / or, the controller acquires the pressure value of the pressure sensor and determines whether the pressure value reaches a preset value within a preset time. If it reaches the preset value, it determines that the locking is in place; if it does not reach the preset value, it determines that the locking is not in place, and the alarm sounds an alarm signal.

[0015] The beneficial effects of this invention are: The machine frame is raised and lowered by adjusting the drive component, which in turn raises and lowers the needle, thus adjusting the distance between the needle and the needle plate. After adjustment, the frame can be fixed to the machine housing by locking the drive component and the limiting component, thereby fixing the position of the needle. Thus, the position adjustment of the needle and the needle plate can be achieved directly by adjusting the drive component and locking the drive component, without the need for the operator to disassemble the machine, eliminating the need to rely on operating experience, improving the accuracy and efficiency of the relative position adjustment of the needle and the needle plate, and reducing the failure rate. Attached Figure Description

[0016] Figure 1 This is a side view of the sewing device described in an embodiment of the present invention; Figure 2 This is a schematic diagram showing the positional relationship between the frame and the adjustment assembly according to an embodiment of the present invention; Figure 3 This is a schematic diagram showing the positional relationship between the frame and the locking assembly according to an embodiment of the present invention; Figure 4 This is an exploded view of the frame, adjustment assembly, and locking assembly described in an embodiment of the present invention; Figure 5 This is a cross-sectional view of the frame and adjustment assembly described in an embodiment of the present invention; Figure 6 This is a cross-sectional view of the frame and locking assembly described in an embodiment of the present invention; Figure 7 This is a schematic diagram of the rack described in an embodiment of the present invention; Figure 8This is a schematic diagram of the nut assembly described in an embodiment of the present invention being locked by the first locking block and the second locking block; Figure 9 This is a schematic diagram showing the contact surface of the first locking block and the second locking block according to an embodiment of the present invention.

[0017] In the picture: 1. Base; 2. Needle plate; 3. Head assembly; 31. Housing; 32. Frame; 321. Fixing hole; 322. Notch; 323. Locking hole; 324. Elongated hole; 33. Needle; 34. Slide rail; 35. Slider; 36. Needle bar; 4. Adjustment assembly; 41. Adjustment drive component; 42. Lead screw; 43. Nut pair; 44. First locking block; 45. Second locking block; 46. Locking rod; 47. Abutment surface; 5. Locking assembly; 51. Locking drive; 52. Limiting component; 521. Abutment; 522. Screw section; 523. Connecting piece; 53. Connecting rod; 54. Crank; 6. Controller; 7. Sewing drive components. Detailed Implementation

[0018] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar components or components having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0019] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium; or the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0020] In the description of this invention, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0021] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0022] like Figures 1 to 9 As shown, the present invention provides a sewing device, which includes a base 1, a needle plate 2, a sewing head assembly 3, an adjustment assembly 4, and a locking assembly 5. The needle plate 2 is disposed on the base 1. The sewing head assembly 3 includes a housing 31, a frame 32, and a needle 33. The housing 31 is disposed on the base 1, the frame 32 is disposed inside the housing 31, and the needle 33 is disposed on the frame 32 and extends out of the housing 31. The adjustment assembly 4 includes an adjustment drive 41, which is disposed on the housing 31. The output end of the adjustment drive 41 is connected to the frame 32, and the adjustment drive 41 can drive the frame 32 to rise and fall to adjust the distance between the needle 33 and the needle plate 2. The locking assembly 5 includes a locking drive 51, which is disposed on the housing 31. The output end of the locking drive 51 is provided with a limiting member 52, which can drive the limiting member 52 to abut against the frame 32, fixing it to the housing 31; or drive the limiting member 52 away from the frame 32.

[0023] By adjusting the drive component 41 to drive the frame 32 to rise and fall, the needle 33 will rise and fall, thus adjusting the distance between the needle 33 and the needle plate 2. After the adjustment is in place, the frame 32 can be fixed to the housing 31 by the locking drive component 51 driving the limiting component 52, so as to fix the position of the needle 33. Thus, the position adjustment of the needle 33 and the needle plate 2 can be directly achieved by adjusting the drive component 41 and the locking drive component 51, without the need for the operator to disassemble the machine, and without relying on operating experience, thereby improving the accuracy and efficiency of the relative position adjustment of the needle 33 and the needle plate 2 and reducing the failure rate.

[0024] like Figure 2As shown, it should also be noted that the frame 32 is also equipped with a sewing drive 7. The output end of the sewing drive 7 is equipped with a needle bar 36, and the needle 33 is fixed to the needle bar 36. The sewing drive 7 is used to drive the needle 33 to move and realize sewing. That is to say, adjusting the relative position between the needle 33 and the needle plate 2 and the sewing operation do not interfere with each other. Of course, it is understood that the sewing device also includes other commonly used components in the prior art, which will not be described in detail here.

[0025] To maintain stability during movement, such as Figure 2 and Figure 4 As shown, in some embodiments, one of the housing 31 and the frame 32 is provided with a slide rail 34, and the other is provided with a slider 35. The slider 35 can slide on the slide rail 34 to ensure movement stability. In the current embodiment, in order to save space, the slide rail 34 is provided on the housing 31, and two slide rails 34 are provided, with the two slide rails 34 spaced apart. The slider 35 is fixed on the frame 32 and slides in cooperation with the slide rail 34.

[0026] like Figures 3 to 5 As shown, in some embodiments, the adjustment drive 41 may be, but is not limited to, a cylinder, an electric push rod, etc. In the current embodiment, the adjustment drive 41 uses a servo motor. To make the adjustment more precise, the adjustment assembly 4 includes a lead screw 42 and a nut assembly 43. The lead screw 42 is connected to the output end of the adjustment drive 41, allowing the adjustment drive 41 to drive the lead screw 42 to rotate. A fixing hole 321 is provided on the frame 32, and the nut assembly 43 is fixed in the fixing hole 321 and screwed onto the lead screw 42. When the adjustment drive 41 drives the lead screw 42 to rotate, the nut assembly 43 can drive the frame 32 to rise and fall along the lead screw 42, thereby raising and lowering the needle 33. Using the lead screw 42 allows for more precise adjustment and also provides a certain locking function, improving locking stability.

[0027] To facilitate the replacement of nut assembly 43 and improve future maintenance, such as Figures 7 to 9As shown, in some embodiments, the adjusting assembly 4 further includes a first locking block 44, a second locking block 45, and a locking rod 46. A notch 322 is provided on the wall of the fixing hole 321, and a locking hole 323 is also provided on the frame 32. The locking hole 323 and the fixing hole 321 have different opening directions. The locking hole 323 communicates with the fixing hole 321 through the notch 322. The first locking block 44 is embedded and fixed in the locking hole 323, and the second locking block 45 is also embedded in the locking hole 323. Both the first locking block 44 and the second locking block 45... The assembly includes abutment surfaces 47, which are, for example, planar. Two abutment surfaces 47 abut against the nut assembly 43 through notches 322. A locking rod 46 is connected to a second locking block 45. The locking rod 46 can drive the second locking block 45 closer to the first locking block 44, thereby bringing the two abutment surfaces 47 closer together to abut against the nut assembly 43 and fixing the nut assembly 43 relative to the frame 32. Alternatively, the locking rod 46 can drive the second locking block 45 away from the first locking block 44, thereby moving the two abutment surfaces 47 away from each other to release the nut assembly 43. For example, both the first locking block 44 and the second locking block 45 have through holes. The bottom of the locking hole 323 is provided with a first thread. The locking rod 46 is a bolt. The bolt shank passes through the first locking block 44 and the second locking block 45 and is screwed into the locking hole 323. Thus, when the bolt is tightened, the bolt nut will push against the second locking block 45 and approach the first locking block 44. Loosening the bolt will release the nut pair 43.

[0028] like Figure 2 , Figure 4 and Figure 7 As shown, in some embodiments, the frame 32 is provided with an elongated hole 324 extending along the height direction, the elongated hole 324 penetrating the frame 32, and the housing 31 is provided with a fixing screw hole. The limiting member 52 includes a top abutment 521 and a screw portion 522. The top abutment 521 and the fixing screw hole are located on opposite sides of the frame 32. The screw portion 522 is connected to the top abutment 521 and is screwed into the fixing screw hole through the elongated hole 324. The output end of the locking drive member 51 is connected to the top abutment 521 so that the top abutment 521 can be driven to rotate through the locking drive member 51. When the top abutment 521 rotates, it can drive the screw portion 522 to rotate, causing it to screw into the fixing screw hole, thereby causing the top abutment 521 to abut against the frame 32 on the housing 31, increasing the friction between the two to fix the frame 32. When the top 521 is rotated in the opposite direction, it moves away from the frame 32, allowing the frame 32 to rise and fall through the elongated hole 324 without interfering with the screw section 522. For example, the locking drive 51 may, but is not limited to, be a servo motor.

[0029] like Figure 4 and Figure 5As shown, in some embodiments, multiple limiting members 52 and elongated holes 324 are provided one-to-one to increase the contact area and further enhance the stability of the lock. To save on the number of locking drive members 51 and to enable multiple limiting members 52 to move synchronously, the locking assembly 5 also includes a connecting rod 53. Each limiting member 52 has a connecting piece 523 on its abutment 521. The connecting piece 523 is connected to the connecting rod 53 by screws, and the output end of the locking drive member 51 is connected to the connecting rod 53 by a crank 54, thereby enabling the locking drive member 51 to drive multiple abutment 521 to rotate in the same direction through the connecting rod 53.

[0030] To further enhance the stability of the lock, an anti-slip pad can be provided on the side of the top 521 facing the frame 32, thereby increasing the friction between the anti-slip pad and the frame 32 and improving the locking stability.

[0031] In some embodiments, a position sensor is provided on the limiting member 52, and an alarm is provided on the housing 31. The alarm is signal-connected to the position sensor. The position sensor determines whether the device is fully engaged. If the device is not fully engaged, the alarm will sound to remind the operator to perform timely maintenance. For example, the position sensor can be specifically located on the engagement point 521. It is understood that a pressure sensor can also be provided on the limiting member 52 to determine whether the device is fully engaged based on the engagement pressure value.

[0032] In some alternative embodiments, two limiting members 52 are provided, one on the upper side and one on the lower side of the frame 32, respectively. The locking drive member 51 can drive the two limiting members 52 to move closer together, thereby clamping the frame 32 between the two limiting members 52 to lock it in place; or the locking drive member 51 can drive the two limiting members 52 to move away from each other, thereby allowing the frame 32 to have room to move. Exemplarily, the limiting member 52 can be a clamping plate, and the locking drive member 51 can be a double-headed cylinder or a double-headed linear motor. To further improve clamping stability, the limiting member 52 can be, but is not limited to, sliding on the housing 31.

[0033] In some embodiments, the sewing device further includes a controller 6, which is mounted on the housing 31. The controller 6 controls the adjustment drive 41 and the locking drive 51, thereby automating the adjustment. It is understood that the controller 6 has multiple pre-stored height commands to meet different control requirements. It is also understood that the controller 6 may have a control panel for operator use, such as a capacitive touchscreen or physical buttons. It should be noted that the pre-stored specific height settings are not specifically limited and can be customized according to different sewing device sizes and usage types.

[0034] This application also provides an adjustment method applied to the above-mentioned sewing device, the adjustment method comprising the following steps: The controller 6 obtains the gear height command and controls the adjustment drive component 41 according to the gear height command, so that it drives the frame 32 to rise and fall to the gear height corresponding to the gear height command; After the frame 32 is raised or lowered to the gear position, the controller 6 controls the locking drive 51 to drive the limiting component 52 to fix the frame 32 on the housing 31.

[0035] In some embodiments, the controller 6 is connected to an alarm, which is mounted on the housing 31. A position sensor is mounted on the limiting member 52, and the position sensor is also connected to the controller 6. The position sensor can transmit the real-time position information of the limiting member 52 to the controller 6, and can be displayed on, but is not limited to, a capacitive touchscreen. In addition, the position sensor and the alarm are also connected via signals from the controller 6. After the locking drive 51 drives the limiting member 52 to perform a locking operation, the controller 6 obtains the feedback position information from the position sensor and determines whether the limiting member 52 has reached a preset position within a preset time. The preset time can be 5s, 10s, or 15s, etc. If it reaches the preset position, it is determined that the locking is in place; if it does not reach the preset position, it is determined that the locking is not in place. The capacitive touchscreen can display the current position, and the alarm can also emit an alarm signal. This step enables monitoring of the locking and avoids the phenomenon that the locking cannot be achieved due to component aging or mechanical failure.

[0036] Of course, in some alternative embodiments, a pressure sensor is provided on the limiting member 52. The pressure sensor is also connected to the controller 6. After the control locking drive member 51 drives the limiting member 52 to perform the locking operation, the controller 6 obtains the feedback pressure information from the pressure sensor and determines whether the pressure value reaches the preset value within a preset time. Thus, it determines whether the limiting member 52 reaches the preset position within the preset time. If the pressure reaches the preset value, it is determined that the locking is in place. If it does not reach the preset value, it is determined that the locking is not in place, and the alarm can issue an alarm signal.

[0037] In some embodiments, the gear height mentioned above includes the initial gear height, and it is understood that the initial gear height can be customized. When the sewing device is turned on, the controller 6 determines whether the needle 33 is at the initial gear height. If it is, there is no action; if not, the controller controls the adjustment drive 41 to drive the frame 32 to rise and fall, so that the needle 33 moves to the initial gear height.

[0038] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A sewing device, characterized in that, include: Base (1); Needle plate (2), said needle plate (2) is disposed on base (1); The head assembly (3) includes a housing (31), a frame (32) and a needle (33). The housing (31) is disposed on the base (1), the frame (32) is disposed inside the housing (31), and the needle (33) is disposed on the frame (32) and extends out of the housing (31). The adjustment component (4) includes an adjustment drive (41), which is disposed on the housing (31). The output end of the adjustment drive (41) is connected to the frame (32). The adjustment drive (41) can drive the frame (32) to rise and fall to adjust the distance between the needle (33) and the needle plate (2). The locking component (5) includes a locking drive (51), which is disposed on the housing (31). A limiting member (52) is disposed at the output end of the locking drive (51). The locking drive (51) can drive the limiting member (52) to abut against the frame (32) and fix it on the housing (31); or drive the limiting member (52) away from the frame (32).

2. The sewing device according to claim 1, characterized in that, One of the housing (31) and the frame (32) is provided with a slide rail (34), and the other is provided with a slider (35), the slider (35) sliding on the slide rail (34).

3. The sewing device according to claim 1, characterized in that, The adjustment assembly (4) also includes a lead screw (42) and a nut pair (43). The lead screw (42) is connected to the output end of the adjustment drive (41), and the adjustment drive (41) can drive the lead screw (42) to rotate. The frame (32) is provided with a fixing hole (321), and the nut pair (43) is fixed in the fixing hole (321) and screwed onto the lead screw (42).

4. The sewing device according to claim 3, characterized in that, The adjustment assembly (4) further includes a first locking block (44), a second locking block (45), and a locking rod (46). The wall of the fixing hole (321) is provided with a notch (322). Both the first locking block (44) and the second locking block (45) are provided with abutting surfaces (47). The two abutting surfaces (47) abut against the nut pair (43) through the notch (322). The first locking block (44) is fixed on the frame (32). The locking rod (46) is connected to the second locking block (45). The locking rod (46) can drive the second locking block (45) to move closer to or away from the first locking block (44) so ​​that the two abutting surfaces (47) can clamp the nut pair (43) or drive the two abutting surfaces (47) to move away from each other.

5. The sewing device according to claim 1, characterized in that, The frame (32) is provided with an elongated hole (324) extending along the height direction, the elongated hole (324) penetrates the frame (32), the housing (31) is provided with a fixing screw hole, the limiting member (52) includes a top abutment (521) and a screw part (522), the top abutment (521) and the fixing screw hole are located on opposite sides of the frame (32), the top abutment (521) is connected to the screw part (522), the screw part (522) passes through the elongated hole (324) and is screwed into the fixing screw hole, the output end of the locking drive member (51) is connected to the top abutment (521) so as to drive the top abutment (521) to rotate.

6. The sewing device according to claim 5, characterized in that, Multiple limiting members (52) are provided, and the locking assembly (5) also includes a connecting rod (53). Multiple abutments (521) are connected to the connecting rod (53), and the output end of the locking drive member (51) is connected to the connecting rod (53).

7. The sewing device according to claim 5, characterized in that, An anti-slip pad is provided on the side of the top (521) facing the frame (32).

8. The sewing device according to claim 1, characterized in that, Two limiting members (52) are provided, and the two limiting members (52) are respectively provided on the upper and lower sides of the frame (32). The locking drive member (51) can drive the two limiting members (52) to move closer or further away from each other.

9. The sewing device according to any one of claims 1-8, characterized in that, The sewing device also includes a controller (6), which is disposed on the housing (31). The controller (6) controls the adjustment drive (41) and the locking drive (51). A position sensor and / or a pressure sensor are disposed on the limiting member (52). An alarm is disposed on the housing (31). The alarm is connected to the position sensor and / or the pressure sensor via the controller (6).

10. An adjustment method, applied to the sewing device as described in claim 9, characterized in that, The controller (6) has multiple gear height commands pre-stored, and the adjustment method includes the following steps: The controller (6) acquires the gear height instruction and controls the adjustment drive (41) to drive the frame (32) to rise or fall to the gear height corresponding to the gear height instruction according to the gear height instruction; After the frame (32) is raised or lowered to the gear height, the controller (6) controls the locking drive (51) to drive the limiting member (52) to fix the frame (32) on the housing (31); The controller (6) acquires the position information of the position sensor and determines whether the limiting member (52) reaches the preset position within a preset time. If it reaches the preset position, it is determined that the locking is in place. If it does not reach the preset position, the locking is not in place, and the alarm sounds an alarm signal. And / or, the controller (6) acquires the pressure value of the pressure sensor and determines whether the pressure value reaches the preset value within a preset time. If it reaches the preset value, it is determined that the locking is in place. If it does not reach the preset value, the locking is not in place, and the alarm sounds an alarm signal.

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