An electric stationery

Abstract

The utility model relates to an electric stationery, which comprises a shell, a first accommodating cavity arranged in the shell, a power mechanism arranged in the first accommodating cavity, the power mechanism comprising a battery assembly, a bottom cover rotatably connected to the bottom of the shell and capable of opening or covering the bottom of the first accommodating cavity, and an intermediate conductive part fixed on the bottom cover, wherein the battery assembly is turned on when the intermediate conductive part is aligned with the battery assembly by rotating the bottom cover in the circumferential direction of the shell, and the battery assembly is turned off when the intermediate conductive part is dislocated from the battery assembly by rotating the bottom cover in the opposite direction of the shell. The electric stationery can turn on and off the battery assembly, has a simplified structure and is convenient to operate.

Description

Technical Field

[0001] This utility model relates to the field of stationery technology, specifically to an electric stationery. Background Technology

[0002] Existing electric stationery, such as electric pencil sharpeners, typically use a motor and a battery pack to power the motor. The operation of these devices is generally achieved by controlling the motor's start and stop, with less emphasis on controlling the battery pack's on / off state. For example, Chinese utility model patent CN212373046U discloses an electric pencil sharpener where the control switch is located below the output gear of the transmission assembly. When a pencil is inserted into the feeding mechanism, the pencil presses down on the cutting mechanism's blade holder, which in turn presses down on the output gear, triggering the control switch. This activates the motor, which then drives the cutting mechanism to automatically sharpen the pencil.

[0003] However, existing electric stationery has the following technical problems: it only controls the start and stop of the motor, but does not control the on / off state of the battery pack. Therefore, there is an urgent need to design an electric stationery that can switch the battery pack on and off, has a simplified structure, and is easy to operate. Summary of the Invention

[0004] The technical problem to be solved by this utility model is to provide an electric stationery with a switchable battery assembly, a simplified structure, and convenient operation.

[0005] The technical solution of this utility model is: an electric stationery, including a shell, a first receiving cavity provided inside the shell, a power mechanism provided inside the first receiving cavity, the power mechanism including a battery assembly, and further comprising... A bottom cover, which is rotatably connected to the bottom of the outer casing, and can open or close the bottom of the first accommodating cavity; An intermediate conductive component is fixedly mounted on the bottom cover; When the bottom cover is rotated circumferentially along the outer casing to align the intermediate conductive element with the battery assembly, the battery assembly is powered on; when the bottom cover is rotated in the opposite direction along the outer casing to misalign the intermediate conductive element with the battery assembly, the battery assembly is powered off.

[0006] With the above structure, this utility model has the following advantages: The bottom cover of this electric stationery is also the battery cover, and combining the two into one simplifies the structure. Then, an on / off structure is integrated on the bottom cover to realize the on / off of the battery assembly. This on / off structure only requires a middle conductive component, which further simplifies the structure. During operation, the battery assembly can be turned on or off simply by rotating the bottom cover, and the operation is also very simple.

[0007] Preferably, the battery assembly includes at least two batteries. When the intermediate conductive member is aligned with the battery assembly, its two ends are respectively connected to the positive and negative terminals of two of the batteries. The number of intermediate conductive members matches the number of batteries, allowing all batteries to be connected in series. This arrangement allows the battery assembly to be switched on and off simply by changing the number of intermediate conductive members, without the need for additional structures when the number of batteries increases.

[0008] Preferably, the intermediate conductive member has a first protrusion at one end and a first elastic member at the other end. When the intermediate conductive member is aligned with the battery assembly, the positive terminal of one of the batteries abuts against the first protrusion of the intermediate conductive member, and the negative terminal of the other battery abuts against the first elastic member of the intermediate conductive member. This arrangement utilizes the first protrusion to reliably connect one end of the intermediate conductive member to the positive terminal of the battery, and the first elastic member to reliably connect the other end of the intermediate conductive member to the negative terminal of the battery.

[0009] Preferably, a bracket is also fixed inside the first accommodating cavity, the battery is vertically mounted on the bracket, and the intermediate conductive component is mounted on the bottom surface of the bottom cover. This arrangement is reasonable and allows for a compact overall structure.

[0010] Preferably, a first rotary fastening structure is provided between the bottom cover and the bottom of the bracket. When the bottom cover is rotated circumferentially along the bracket, the bottom cover is fixed to the bracket through the first rotary fastening structure, and the intermediate conductive element is aligned with the battery assembly, thus enabling the battery assembly to conduct electricity. When the bottom cover is rotated in the opposite direction along the bracket, the bottom cover can be separated from the bracket, and the intermediate conductive element is misaligned with the battery assembly, thus de-energizing the battery assembly. This first rotary fastening structure not only facilitates the fixing and separation of the bottom cover and the bracket, but also facilitates the switching on and off of the battery assembly.

[0011] Preferably, the bottom of the bracket is provided with a first annular seat, and the bottom cover is provided with a second annular seat that fits into the first annular seat. The first rotary fastening structure includes a first locking block disposed on one of the first annular seat and the second annular seat, and a first sliding groove disposed on the other. One end of the first sliding groove has a first opening and the other end is closed. A latching structure is provided between the first sliding groove and the first locking block near the closed end. When the first locking block is inserted into the first sliding groove through the first opening and slides circumferentially along the first sliding groove until it is limited within the first sliding groove by the latching structure, the intermediate conductive element aligns with the battery assembly, thereby enabling the battery assembly to conduct electricity. This arrangement ensures that the battery assembly is only aligned and connected with the intermediate conductive element when the bottom cover and the bracket are fully fastened in place, thus making the power supply of the battery assembly more stable and reliable.

[0012] Preferably, the latching structure includes a positioning groove on the first latching block and a positioning protrusion within the first sliding groove. This latching structure is simple and easy to position and separate.

[0013] Preferably, two first sliding grooves are provided and spaced apart circumferentially along the outer side wall of the first annular seat, and the number and position of the first locking blocks match the first sliding grooves. This arrangement makes the bottom cover and the bracket fit more securely.

[0014] Preferably, a second rotatable fastening structure is provided between the bottom cover and the bottom of the outer casing. When the bottom cover is rotated circumferentially along the outer casing, the bottom cover is fixed to the outer casing via the second rotatable fastening structure and to the bracket via the first rotatable fastening structure. When the bottom cover is rotated in the opposite direction along the outer casing, the bottom cover can be separated from the outer casing and the bracket. This arrangement allows for more even force distribution on the bottom cover and further strengthens the fastening between the bottom cover and the bracket, thereby ensuring reliable power supply to the battery assembly.

[0015] Preferably, the bottom cover is provided with a third annular seat that fits into the bottom of the outer shell. The second rotary fastening structure includes a second locking block disposed on one of the bottom of the outer shell and the third annular seat, and a second sliding groove disposed on the other. One end of the second sliding groove has a second opening and the other end is closed. When the second locking block is inserted into the second sliding groove through the second opening and slides circumferentially along the second sliding groove to the closed end, the first locking block of the first rotary fastening structure is precisely limited within the first sliding groove by the locking structure. This second rotary fastening structure is simple and can cooperate with the first rotary fastening structure to achieve synchronous positioning of the bottom cover, the bracket, and the outer shell. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the electric stationery cover of this utility model when the bottom cover is closed; Figure 2 A schematic diagram of the structure of the electric stationery of this utility model when the bottom cover is opened; Figure 3 This is a cross-sectional view of the electric stationery of this utility model; Figure 4 This is an exploded view of the electric stationery of this utility model; Figure 5 This is a schematic diagram of the structure of the electric stationery of this utility model after the outer shell is hidden; Figure 6 This mainly shows a schematic diagram of the bottom structure of the outer shell and the bracket of this utility model; Figure 7 This is a schematic diagram of the structure of the bottom cover of this utility model; Figure 8The main illustration shows the structural diagram of the bottom cover fitting onto the bracket and the outer shell; Figure 9 The main display shows a schematic diagram of the structure after the bottom cover is separated from the bracket and the outer shell; In the diagram: 1-Outer shell, 2-First accommodating cavity, 3-Second accommodating cavity, 4-Pen feeding mechanism, 5-Cutting mechanism, 6-Power mechanism, 7-Motor, 8-Battery assembly, 9-Battery, 10-Bracket, 11-Bottom cover, 12-Intermediate conductive element, 13-First protrusion, 14-First elastic element, 15-Positive electrode of the battery, 16-Negative electrode of the battery, 17-Positive conductive element, 18-Negative conductive element, 19-Second protrusion, 20-Second elastic element, 21-Vertical slide, 22-First annular seat, 23-Second annular seat, 24-First locking block, 25-First sliding groove, 26-First opening, 27-Positioning groove, 28-Positioning protrusion, 29-Horizontal slide, 30-Second locking block, 31-Second sliding groove, 32-Second opening, 33-Upper shell, 34-Lower shell, 35-Top cover, 36-Transmission assembly, 37-Third annular seat. Detailed Implementation

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments. Example

[0018] like Figure 1-9 As shown, an electric stationery device includes a housing 1, a first receiving cavity 2 inside the housing 1, a power mechanism 6 inside the first receiving cavity 2, and a battery assembly 8. The bottom cover 11 is rotatably connected to the bottom of the outer casing 1 and can open or close the bottom of the first receiving cavity 2; The intermediate conductive element 12 is fixed on the bottom cover 11; When the bottom cover 11 is rotated circumferentially along the outer casing 1 so that the intermediate conductive element 12 is aligned with the battery assembly 8, the battery assembly 8 is powered on; when the bottom cover 11 is rotated in the opposite direction along the outer casing 1 so that the intermediate conductive element 12 is misaligned with the battery assembly 8, the battery assembly 8 is powered off.

[0019] In this embodiment, the bottom cover 11 of the electric stationery is also the battery cover, and combining the two into one simplifies the structure. Then, an on / off structure is integrated on the bottom cover 11 to realize the on / off of the battery assembly 8. This on / off structure only requires the middle conductive part 12, which further simplifies the structure. During operation, the battery assembly 8 can be turned on / off simply by rotating the bottom cover 11, and the operation is also very simple.

[0020] The battery assembly 8 includes at least two batteries 9. When the intermediate conductive member 12 is aligned with the battery assembly 8, its two ends are connected to the positive terminal 15 and negative terminal 16 of two of the batteries 9, respectively. The number of intermediate conductive members 12 matches the number of batteries 9, allowing all batteries 9 to be connected in series. This arrangement allows the battery assembly 8 to be switched on or off simply by changing the number of intermediate conductive members 12, without the need for additional structures when the number of batteries 9 increases.

[0021] One end of the intermediate conductive member 12 is provided with a first protrusion 13 and the other end is provided with a first elastic member 14. When the intermediate conductive member 12 is aligned with the battery assembly 8, the positive terminal 15 of one battery 9 abuts against the first protrusion 13 of the intermediate conductive member 12, and the negative terminal 16 of the other battery 9 abuts against the first elastic member 14 of the intermediate conductive member 12. This arrangement allows one end of the intermediate conductive member 12 to be reliably connected to the positive terminal 15 of the battery 9 using the first protrusion 13, and the first elastic member 14 allows the other end of the intermediate conductive member 12 to be reliably connected to the negative terminal 16 of the battery 9.

[0022] A bracket 10 is also fixed inside the first accommodating cavity 2. The battery 9 is vertically mounted on the bracket 10, and the intermediate conductive component 12 is mounted on the bottom surface of the bottom cover 11. This arrangement is reasonable and makes the overall structure compact.

[0023] A first rotary fastening structure is provided between the bottom cover 11 and the bottom of the bracket 10. When the bottom cover 11 is rotated circumferentially along the bracket 10, the bottom cover 11 is fixed to the bracket 10 through the first rotary fastening structure, and the intermediate conductive element 12 is aligned with the battery assembly 8, thus enabling the battery assembly 8 to conduct electricity. When the bottom cover 11 is rotated in the opposite direction along the bracket 10, the bottom cover 11 can be separated from the bracket 10, and the intermediate conductive element 12 is misaligned with the battery assembly 8, thus de-energizing the battery assembly 8. The first rotary fastening structure not only facilitates the fixing and separation of the bottom cover 11 and the bracket 10, but also facilitates the switching on and off of the battery assembly 8.

[0024] The bottom of the bracket 10 is provided with a first annular seat 22, and the bottom cover 11 is provided with a second annular seat 23 that fits into the first annular seat 22. The first rotating fastening structure includes a first locking block 24 provided on one of the first annular seat 22 and the second annular seat 23, and a first sliding groove 25 provided on the other. One end of the first sliding groove 25 is provided with a first opening 26 and the other end is closed. A buckle structure is provided between the first sliding groove 25 and the first locking block 24 near the closed end. When the first locking block 24 is inserted into the first sliding groove 25 through the first opening 26 and slides circumferentially along the first sliding groove 25 until it is limited within the first sliding groove 25 by the buckle structure, the intermediate conductive member 12 is aligned with the battery assembly 8, thus making the battery assembly 8 conductive. This arrangement ensures that the battery assembly 8 is aligned and connected with the intermediate conductive member 12 only when the bottom cover 11 and the bracket 10 are fully fastened in place, thereby making the power supply of the battery assembly 8 more stable and reliable.

[0025] The snap-fit ​​structure includes a positioning groove 27 on the first snap-fit ​​block 24 and a positioning protrusion 28 in the first slide groove 25. This snap-fit ​​structure is simple and easy to position and separate.

[0026] Two first sliding grooves 25 are provided and spaced circumferentially along the outer side wall of the first annular seat 22. The number and position of the first locking blocks 24 match the first sliding grooves 25. In this embodiment, two first locking blocks 24 are provided and located on top of the second annular seat 23. This arrangement makes the engagement between the bottom cover 11 and the bracket 10 more secure.

[0027] A second rotating fastening structure is also provided between the bottom cover 11 and the bottom of the outer casing 1. When the bottom cover 11 is rotated circumferentially along the outer casing 1, the bottom cover 11 is fixed to the outer casing 1 by the second rotating fastening structure and to the bracket 10 by the first rotating fastening structure. When the bottom cover 11 is rotated in the opposite direction along the outer casing 1, the bottom cover 11 can be separated from the outer casing 1 and the bracket 10. This arrangement allows the bottom cover 11 to be subjected to more even force, and further makes the fastening between the bottom cover 11 and the bracket 10 more secure, thereby ensuring reliable power supply to the battery assembly 8.

[0028] The bottom cover 11 is provided with a third annular seat 37 that fits into the bottom of the outer shell 1. The second rotary fastening structure includes a second locking block 30 disposed on one of the bottom of the outer shell 1 and the third annular seat 37, and a second sliding groove 31 disposed on the other. One end of the second sliding groove 31 is provided with a second opening 32 and the other end is closed. When the second locking block 30 is inserted into the second sliding groove 31 through the second opening 32 and slides circumferentially along the second sliding groove 31 to the closed end, the first locking block 24 of the first rotary fastening structure is just limited in the first sliding groove 25 by the locking structure. In this embodiment, the third annular seat 37 is coaxially disposed outside the second annular seat 23, the second locking block 30 is disposed on the inner side wall of the third annular seat 37, and the second sliding groove 31 is disposed on the outer side wall of the bottom of the outer shell 1. One second locking block 30 is provided, and the second locking block 30 and the two first locking blocks 24 are not on the same straight line. Thus, the principle of three points determining a plane can be used to make the bottom cover 11 more securely fixed to the outer shell 1 and the bracket 10. The second rotary fastening structure is simple and can cooperate with the first rotary fastening structure to achieve synchronous positioning of the bottom cover 11, the bracket 10, and the outer shell 1.

[0029] The bracket 10 is also fixed with a positive conductive element 17 and a negative conductive element 18. The positive conductive element 17 and the negative conductive element 18 are electrically connected to the positive terminal 15 and the negative terminal 16 of the batteries 9 at both ends of the battery assembly 8, respectively. The positive conductive element 17 and the negative conductive element 18 are also electrically connected to the power input terminal of the motor 7. This arrangement uses the positive conductive element 17 and the negative conductive element 18 to lead out the voltage of the battery assembly 8, thereby facilitating electrical connection with the power input terminal of the motor 7.

[0030] The positive conductive element 17 has a second protrusion 19 that abuts against the positive electrode 15 of the battery 9, and the negative conductive element 18 has a second elastic element 20 that abuts against the negative electrode 16 of the battery 9. This arrangement allows the positive conductive element 17 to be reliably connected to the positive electrode 15 of the battery 9 by means of the second protrusion 19, and allows the negative conductive element 18 to be reliably connected to the negative electrode 16 of the battery 9 by means of the second elastic element 20.

[0031] In this embodiment, two batteries 9 are provided and one intermediate conductive member 12 is provided; the positive conductive member 17 and the negative conductive member 18 are both installed on the top of the bracket 10. The second protrusion 19 of the positive conductive member 17 abuts against the positive electrode 15 of the first battery 9, the first elastic member 14 of the intermediate conductive member 12 abuts against the negative electrode 16 of the first battery 9, the second elastic member 20 of the negative conductive member 18 abuts against the negative electrode 16 of the second battery 9, and the first protrusion 13 of the intermediate conductive member 12 abuts against the positive electrode 15 of the second battery 9.

[0032] In this embodiment, the second annular seat 23 of the bottom cover 11 is sleeved on the outside of the first annular seat 22 of the bracket 10, and the third annular seat 37 of the bottom cover 11 is sleeved on the bottom of the outer shell 1; the first slide groove 25 includes a vertical slide 21 and a transverse slide 29 connected to one side of the upper end of the vertical slide 21; the lower end of the vertical slide 21 is provided with a first opening 26, and the end of the transverse slide 29 away from the vertical slide 21 is closed and a positioning protrusion 28 is provided near that end; the positive electrode conductive element 17 and the negative electrode conductive element 18 are both installed on the top of the bracket 10 through a plug-in structure; the fixing structure between the bracket 10 and the outer shell 1 can adopt the existing technology, or the bracket 10 and the outer shell 1 can be integrally formed.

[0033] In this embodiment, the electric stationery is an electric pencil sharpener. The power mechanism 6 also includes a motor 7 electrically connected to the battery assembly 8, and the motor 7 is also mounted on the bracket 10. The first accommodating cavity 2 is located in the lower part of the outer shell 1, and the upper part of the outer shell 1 is provided with a second accommodating cavity 3. The second accommodating cavity 3 is provided with a pencil feeding mechanism 4 and a cutting mechanism 5. The outer shell 1 includes an upper shell 33 and a lower shell 34. The upper shell 33 is open at both the top and bottom, and the lower shell 34 is closed at the top and open at the bottom. The bottom cover 11 is located at the bottom of the lower shell 34, and the top cover 35 is provided at the top of the upper shell 33. The body 34 and the bottom cover 11 enclose each other to form a first accommodating cavity 2, and the top cover 35, the upper shell 33 and the top of the lower shell 34 enclose each other to form a second accommodating cavity 3. The top cover 35 is detachably connected to the top of the upper shell 33 through a third rotating fastening structure. The third rotating fastening structure is the same as the first rotating fastening structure, and will not be described in detail here. The cutting mechanism 5 is located below the pen feeding mechanism 4. The power mechanism 6 also includes a transmission component 36. The motor 7 is connected to the cutting mechanism 5 through the transmission component 36. The pen feeding mechanism 4, the cutting mechanism 5 and the transmission component 36 can be made using existing technologies.

[0034] The working principle of the electric pencil sharpener in this embodiment is as follows: During normal use, the bottom cover 11 is fixed and covers the bottom of the first accommodating cavity 2 by the first rotating fastening structure, and is also fixed to the outer shell 1 by the second rotating fastening structure. At this time, the positive terminal 15 of one battery 9 abuts against the first protrusion 13 of the intermediate conductive member 12, and the negative terminal 16 of the other battery 9 abuts against the first elastic member 14 of the intermediate conductive member 12. The two batteries 9 are connected in series, and the battery assembly 8 is conductive. The positive conductive member 17 and the negative conductive member 18 output voltage to the power terminal of the motor 7, thereby providing power to the motor 7. When the pencil feeding mechanism 4 inserts the pencil, the motor 7 will drive the cutting mechanism 5 to work and cut the pencil. When it is necessary to turn the battery assembly 8 on or off, simply rotate the bottom cover 11 circumferentially to make the intermediate conductive member 12 and the battery assembly 8 misaligned.

Claims

1. An electric stationery, comprising a housing (1), wherein a first receiving cavity (2) is provided within the housing (1), and a power mechanism (6) is provided within the first receiving cavity (2), wherein the power mechanism (6) includes a battery assembly (8), characterized in that: Also includes The bottom cover (11) is rotatably connected to the bottom of the outer shell (1) and can open or close the bottom of the first receiving cavity (2); An intermediate conductive element (12) is fixed on the bottom cover (11); When the bottom cover (11) is rotated circumferentially along the outer shell (1) so that the intermediate conductive element (12) is aligned with the battery assembly (8), the battery assembly (8) is turned on; when the bottom cover (11) is rotated in the opposite direction along the outer shell (1) so that the intermediate conductive element (12) is misaligned with the battery assembly (8), the battery assembly (8) is de-energized.

2. The electric stationery according to claim 1, characterized in that: The battery assembly (8) includes at least two batteries (9). When the intermediate conductive element (12) is aligned with the battery assembly (8), the two ends of the intermediate conductive element (12) are respectively connected to the positive electrode (15) and negative electrode (16) of two of the batteries (9). The number of intermediate conductive elements (12) matches the number of batteries (9) for connecting all the batteries (9) together in series.

3. An electric stationery device according to claim 2, characterized in that: One end of the intermediate conductive member (12) is provided with a first protrusion (13) and the other end is provided with a first elastic member (14). When the intermediate conductive member (12) is aligned with the battery assembly (8), the positive electrode (15) of one of the batteries (9) abuts against the first protrusion (13) of the intermediate conductive member (12), and the negative electrode (16) of the other battery (9) abuts against the first elastic member (14) of the intermediate conductive member (12).

4. An electric stationery device according to claim 2, characterized in that: The first accommodating cavity (2) is also fixedly provided with a bracket (10), the battery (9) is vertically installed on the bracket (10), and the intermediate conductive element (12) is installed on the bottom surface of the bottom cover (11).

5. An electric stationery device according to claim 4, characterized in that: A first rotating fastening structure is provided between the bottom cover (11) and the bottom of the bracket (10). When the bottom cover (11) is rotated circumferentially along the bracket (10), the bottom cover (11) is fixed to the bracket (10) through the first rotating fastening structure and the intermediate conductive element (12) is aligned with the battery assembly (8) to make the battery assembly (8) conductive. When the bottom cover (11) is rotated in the opposite direction along the bracket (10), the bottom cover (11) can be separated from the bracket (10) and the intermediate conductive element (12) is misaligned with the battery assembly (8) to make the battery assembly (8) de-energized.

6. An electric stationery device according to claim 5, characterized in that: The bottom of the bracket (10) is provided with a first annular seat (22), and the bottom cover (11) is provided with a second annular seat (23) that is fitted with the first annular seat (22). The first rotating fastening structure includes a first locking block (24) provided on one of the first annular seat (22) and the second annular seat (23) and a first sliding groove (25) provided on the other. One end of the first sliding groove (25) is provided with a first opening (26) and the other end is closed. A buckle structure is provided between the first sliding groove (25) and the first locking block (24) near the closed end. When the first locking block (24) is inserted into the first sliding groove (25) through the first opening (26) and slides circumferentially along the first sliding groove (25) until it is limited in the first sliding groove (25) by the buckle structure, the intermediate conductive member (12) is aligned with the battery assembly (8) to make the battery assembly (8) conductive.

7. An electric stationery device according to claim 6, characterized in that: The buckle structure includes a positioning groove (27) provided on the first buckle block (24) and a positioning protrusion (28) provided in the first slide groove (25).

8. An electric stationery device according to claim 6, characterized in that: The number of the first slide groove (25) is set to two and is spaced apart along the outer side wall of the first annular seat (22). The number and position of the first locking block (24) match the first slide groove (25).

9. An electric stationery device according to claim 6, characterized in that: A second rotating fastening structure is provided between the bottom cover (11) and the bottom of the outer shell (1). When the bottom cover (11) is rotated circumferentially along the outer shell (1), the bottom cover (11) is fixed to the outer shell (1) through the second rotating fastening structure and fixed to the bracket (10) through the first rotating fastening structure. When the bottom cover (11) is rotated in the opposite direction along the outer shell (1), the bottom cover (11) can be separated from the outer shell (1) and the bracket (10).

10. An electric stationery device according to claim 9, characterized in that: The bottom cover (11) is provided with a third annular seat (37) that fits into the bottom of the outer shell (1). The second rotating fastening structure includes a second locking block (30) provided on one of the bottom of the outer shell (1) and the third annular seat (37) and a second sliding groove (31) provided on the other. One end of the second sliding groove (31) is provided with a second opening (32) and the other end is closed. When the second locking block (30) is inserted into the second sliding groove (31) through the second opening (32) and slides circumferentially along the second sliding groove (31) to the closed end, the first locking block (24) of the first rotating fastening structure is just limited in the first sliding groove (25) by the buckle structure.

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