Rectifying tower for pharmaceutical and chemical intermediates

Abstract

The utility model relates to the technical field of pharmaceutical chemicals, and discloses a pharmaceutical chemical intermediate rectifying tower which comprises a rectifying tower body, and a base is arranged at the bottom of the rectifying tower body and slidably arranged on a supporting seat. A first positioning and fixing assembly and a second positioning and fixing assembly are arranged between the base and the supporting seat; the first positioning and fixing assembly and the second positioning and fixing assembly are both in sliding insertion fit with the base and in sliding insertion fit with the supporting base, and the first positioning and fixing assembly and the second positioning and fixing assembly are in transmission fit and used for pushing the second positioning and fixing assembly to be inserted into the base and the supporting base in a sliding mode. A power assembly is installed in the supporting base, is in transmission connection with the first positioning and fixing assembly and is used for pushing the first positioning and fixing assembly to be slidably inserted into the base and the supporting base. According to the utility model, the first positioning and fixing assembly and the second positioning and fixing assembly are linked through the power assembly, so that the base can be positioned and fixed, and the up-down, left-right and front-back movement of the rectifying tower body is limited.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of medical chemical technology, especially relates to the rectifying column for medical chemical intermediates. BACKGROUND

[0002] The rectifying column is a tower type vapor-liquid contact device for rectification. By utilizing the different volatility of each component in the mixture, i.e. the different vapor pressure of each component at the same temperature, the light components (low-boiling substances) in the liquid phase are transferred to the gas phase, and the heavy components (high-boiling substances) in the gas phase are transferred to the liquid phase, so as to achieve the purpose of separation. At present, in the chemical industry such as the synthesis of pharmaceutical and pesticide intermediates, the preparation process of the intermediate tetrahydrophthalimide needs to be rectified, and the rectification process is carried out in the rectifying column.

[0003] The rectifying column for high-purity medical chemical intermediates disclosed in the patent with the publication number CN213313420U comprises a rectifying column body, two support plates are symmetrically fixedly connected to the side walls on the lower side of the rectifying column body, a same bottom plate is fixedly connected to the lower ends of the two support plates, an L-shaped mounting seat is arranged below the bottom plate, rollers are fixedly connected to the four corners of the lower surface of the bottom plate, an installation plate is fixedly connected to the side wall on the left side of the L-shaped mounting seat, a plurality of through holes are formed in the side wall on the upper side of the installation plate, bolts are movably sleeved in the through holes, a rotating hole is formed in the vertical side wall on the left side of the L-shaped mounting seat, and a threaded rod is inserted into the rotating hole.

[0004] The rectifying column for high-purity medical chemical intermediates disclosed in the patent with the publication number CN218529835U comprises a support base and a rectifying column body, a vertical plate is vertically installed at the edge of the top surface of the support base, a strip-shaped hole is formed through the surface of the vertical plate, an installation cavity is installed in the support base, a double-shaft motor is installed in the installation cavity, screw rods are installed at the two ends of the output end of the double-shaft motor, threaded sleeves are threadedly connected to the outer surfaces of the screw rods, connecting rods are arranged on the surfaces of the threaded sleeves, limit plates are installed at the top ends of the connecting rods, the limit plates are slidably inserted into the strip-shaped hole, a base is arranged at the bottom end of the rectifying column body, limit grooves are formed in the surfaces of the two sides of the base, and the limit plates are in interference fit with the limit grooves.

[0005] Based on the above technical features, the problem is that in the prior art, the bottom of the rectifying column is fixedly assembled with a base for supporting the rectifying column. Once the base is positioned and fixed, the rectifying column is positioned and fixed. The positioning and fixing of the base include the positioning and fixing of the side parts and the bottom. However, the two positioning and fixing processes are driven by two independent and unrelated driving systems, which increases the number of driving systems, complicates the structure, and makes the operation process cumbersome and the use cost high.

[0006] Therefore, it is necessary to solve the above problems by using a rectifying column for pharmaceutical and chemical intermediates. SUMMARY

[0007] The utility model discloses a rectifying column for pharmaceutical and chemical intermediates to solve the problems in the above background art.

[0008] To achieve the above object, the utility model provides the following technical scheme: a rectifying column for pharmaceutical and chemical intermediates, including rectifying column body, the bottom fixed connection base of rectifying column body is below setting support seat, the base is slidably arranged on the support seat, first positioning and fixing assembly and second positioning and fixing assembly are arranged between the base and the support seat, first positioning and fixing assembly and second positioning and fixing assembly are both slidably inserted with the base and the support seat, first positioning and fixing assembly and second positioning and fixing assembly drive cooperation are used for sliding insertion to the base and the support seat of second positioning and fixing assembly, the inside fixed mounting power assembly of support seat, power assembly is transmission connection with first positioning and fixing assembly, is used for sliding insertion to the base and the support seat of first positioning and fixing assembly of pushing.

[0009] Preferably, the power assembly includes a motor, the motor is fixedly arranged in the support seat, a first gear is fixedly sleeved on the output shaft of the motor, the first gear is engaged with a second gear, the second gear is fixedly sleeved with a bidirectional screw rod, the bidirectional screw rod is rotatably connected with the support seat and transmission connected with the first positioning and fixing assembly.

[0010] Preferably, the first positioning and fixing assembly includes a limiting block, a fixed plate is fixedly connected on the support seat, the limiting block is limitingly and slidably connected with the fixed plate, the limiting block is slidably inserted with the base and transmission connected with the second positioning and fixing assembly, a connecting block is fixedly arranged on the limiting block, a connecting rod is fixedly arranged on the connecting block, and the connecting rod is threadedly connected with the bidirectional screw rod.

[0011] Preferably, the second positioning and fixing assembly includes a first sliding block, the first sliding block is slidably arranged in the base, the first sliding block is abutted and slidably connected with the limiting block in the support seat, a first sliding rod is fixedly arranged at the bottom of the first sliding block, the first sliding rod is slidably arranged in the base and slidably inserted with the support seat, a first spring is sleeved on the first sliding rod, and the first spring is fixedly connected with the base and the first sliding block.

[0012] Preferably, the power assembly includes an electric push rod, the electric push rod is fixedly arranged in the support seat, and the output end of the electric push rod is transmission connected with the first positioning and fixing assembly.

[0013] Preferably, the first positioning and fixing assembly comprises a second sliding rod coaxially fixed at the output end of the electric push rod; the second sliding rod is slidably inserted into the base; a transmission assembly is slidably arranged in the base and in transmission cooperation with the second sliding rod and the second positioning and fixing assembly.

[0014] Preferably, the transmission assembly comprises a third sliding block slidably arranged in the base; the third sliding block is in transmission cooperation with the second sliding rod and the second positioning and fixing assembly.

[0015] Preferably, the second positioning and fixing assembly comprises a second sliding block slidably arranged in the base; the second sliding block is in sliding cooperation with the third sliding block; a limiting rod is fixedly connected to the second sliding block; a fixed plate is fixedly connected to the support base; the limiting rod is slidably inserted into the base and in sliding cooperation with the fixed plate; a second spring is sleeved on the limiting rod and fixedly connected to the base and the second sliding block.

[0016] The technical effects and advantages of the present application are as follows: the first positioning and fixing assembly is driven by a power assembly, and the first positioning and fixing assembly is linked with the second positioning and fixing assembly, so that the side and bottom of the base are fixed, and the rectifying tower body is limited from moving up and down, left and right, and forward and backward; the power source is only one, the structure is simple, the operation process is simple, and the use cost is low. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 It is a three-dimensional structure schematic view of the embodiment one of the present application;

[0018] Figure 2 It is an internal structure schematic view of the support base of the embodiment one of the present application;

[0019] Figure 3 It is an internal structure schematic view of the base of the embodiment one of the present application;

[0020] Figure 4 It is a three-dimensional structure schematic view of the embodiment two of the present application;

[0021] Figure 5 It is a half-partial sectional view schematic view of the embodiment two of the present application.

[0022] In the figure: 1, rectifying tower body; 2, base; 3, support seat; 4, connecting rod; 5, fixed plate; 6, two-way screw rod; 7, connecting block; 8, first limiting hole; 9, limiting block; 10, groove; 11, motor; 12, first gear; 13, second gear; 14, first limiting groove; 15, first sliding block; 16, first sliding rod; 17, first spring; 18, first sliding groove; 19, second limiting hole; 20, limiting rod; 21, second sliding block; 22, second sliding groove; 23, second sliding rod; 24, electric push rod; 25, third sliding block; 26, third sliding groove; 27, second spring. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the utility model will be clearly and completely described below with reference to the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the utility model.

[0024] Embodiment one:

[0025] The utility model provides a rectifying tower for medical and chemical industry intermediate as Figures 1 to 3 As shown in the figure, the utility model discloses a rectifying tower for medical and chemical industry intermediate, including rectifying tower body 1, the bottom fixed connection of rectifying tower body 1 is used for the support base 2, the same position of four corners of base 2 bottom is all bolted universal wheel, four universal wheels are used for supporting base 2 again, and the rectifying tower body 1 is conveniently moved.

[0026] The support seat 3 is fixedly installed on the ground, the support seat 3 is an isosceles trapezoidal support table, the front and rear end faces are inclined surfaces with small slopes, the rectifying tower body 1 is conveniently supported on the base 2 and the support seat 3 without large inclination and falling. The left and right end faces of the support seat 3 are vertical faces in isosceles trapezoidal shape. Two sliding grooves are cut out on the top of the support seat 3 and matched with the universal wheels. The two sliding grooves are parallel to each other and are both opened from front to back along the top contour of the support seat 3. The two sliding grooves are used for rolling guidance of the universal wheels and form primary positioning of the base 2 fixedly connected to the bottom of the rectifying tower body 1.

[0027] The inside of the support seat 3 is equipped with a power assembly. The power assembly includes a motor 11, which is bolted in the support seat 3. A groove 10 is excavated in the inside of the support seat 3, and the motor 11 is located in the groove 10. A first gear 12 is fixedly sleeved on the output shaft of the motor 11, the first gear 12 is engaged with a second gear 13, and the second gear 13 is fixedly sleeved with a two-way screw rod 6. The two-way screw rod 6 is arranged horizontally left and right, and the two-way screw rod 6 penetrates through the support seat 3 and is rotationally connected with the support seat 3. The two-way screw rod 6 is transmissionally connected with a first positioning and fixing assembly, and is used for driving the first positioning and fixing assembly to position and fix the base 2.

[0028] The left and right end faces of the support base 3 are each welded and fixed with a fixed plate 5, and the two fixed plates 5 are vertical plates and are symmetrically distributed on the left and right sides of the support base 3. The first positioning and fixing assembly is in limiting sliding cooperation with the two fixed plates 5, so as to ensure that the first positioning and fixing assembly is not out of position. The first positioning and fixing assembly is used for positioning and fixing the side of the base 2. The first positioning and fixing assembly comprises two limiting blocks 9, which are symmetrically distributed on the left and right sides of the support base 3 and are each arranged horizontally left and right. The two limiting blocks 9 correspond one-to-one to the two fixed plates 5, and each limiting block 9 slides through the corresponding fixed plate 5.

[0029] The proximal ends of the two limiting blocks 9 are each welded and fixed with a wedge-shaped block, which is located below the limiting block 9 and the inclined surface of which is located at the bottom of the wedge-shaped block. The left and right side ends of the base 2 are each cut to form a first limiting groove 14, and the two first limiting grooves 14 correspond one-to-one to the two limiting blocks 9. The wedge-shaped block on each limiting block 9 is matched with and inserted into the corresponding first limiting groove 14, and the two limiting blocks 9 are in abutting fixed cooperation with the base 2, so as to position and fix the base 2. The distal ends of the two limiting blocks 9 are each welded and fixed with a connecting block 7, the bottom of each connecting block 7 is welded and fixed with a connecting rod 4, the bottom of each connecting rod 4 is in threaded connection with the two-way screw rod 6, and the two limiting blocks 9 are ensured to move closer to or away from each other.

[0030] The connecting block 7 and the wedge-shaped block located on the same limiting block 9 are separately arranged on the two sides of the fixed plate 5 in sliding cooperation with the limiting block 9. The left and right side ends of the base 2 are each cut to form a first sliding groove 18, and the two first sliding grooves 18 correspond one-to-one to the two first limiting grooves 14. Each first sliding groove 18 is in communication with the corresponding first limiting groove 14 and is located directly below the first limiting groove 14. The second positioning and fixing assembly is fitted in the two first sliding grooves 18, the second positioning and fixing assembly is in transmission cooperation with the two limiting blocks 9, and the two limiting blocks 9 are used to drive the second positioning and fixing assembly to position and fix.

[0031] The second positioning and fixing assembly comprises two first sliding blocks 15, which are symmetrically distributed on the left and right sides of the base 2, correspond one-to-one to the two first sliding grooves 18, and are each slidingly arranged in the corresponding first sliding groove 18. Each first sliding block 15 is a wedge-shaped block in the shape of a right-angled triangle, and the inclined surface of each first sliding block 15 faces upward. When the inclined surface of the first sliding block 15 is in contact with the bottom inclined surface of the wedge-shaped block on the limiting block 9, the first sliding block 15 is in sliding abutment with the limiting block 9, so as to push the first sliding block 15 to move downward along the first sliding groove 18.

[0032] Each first slider 15 has a first sliding rod 16 welded to its bottom. Each first sliding rod 16 slides vertically downward through the base 2 and slidably engages with the support 3 for positioning and fixing the base 2. Two first limiting holes 8 are drilled at the bottom of the support 3, corresponding one-to-one with the two first sliding rods 16. Each first sliding rod 16 engages with its corresponding first limiting hole 8. A first spring 17 is fitted onto each first sliding rod 16. The bottom and top ends of each first spring 17 are fixedly connected to the base 2 and the first slider 15, respectively, for resetting the first slider 15. When the first slider 15 is not in contact with the limiting block 9, the top of the first slider 15 abuts against the inner top wall of the first limiting groove 14, and the first spring 17 is always in a compressed state.

[0033] Working principle of Example 1:

[0034] Before use, each first spring 17 is in a compressed state, and the top of each first slider 15 abuts against the top inner wall of the corresponding first limiting groove 14. Each connecting block 7 is away from the corresponding fixing plate 5.

[0035] In use, push the base 2 so that it is directly above the support 3, thereby moving the distillation column body 1 to the appropriate position. Then, start the motor 11. The motor 11 drives the first gear 12 to rotate, the first gear 12 drives the second gear 13 to rotate, the second gear 13 drives the double-acting screw 6 to rotate, the double-acting screw 6 drives the two connecting rods 4 to move closer to each other, and the two connecting rods 4 drive the two connecting blocks 7 to move closer to each other. The two connecting blocks 7 drive the two limiting blocks 9 to move closer to each other, at which point the two limiting blocks 9 move towards the base 2.

[0036] As the two limiting blocks 9 continue to move, they slide into their respective first limiting grooves 14. Simultaneously, the inclined surfaces of the wedge-shaped blocks at the bottom of the two limiting blocks 9 slide against the inclined surfaces of their respective first sliders 15, causing the two first sliders 15 to move downwards along their respective first sliding grooves 18. This, in turn, drives the two first sliding rods 16 downwards, while the two first springs 17 continue to be compressed. This continues until the two first sliding rods 16 slide into the two first limiting holes 8 on the support base 3, achieving side and bottom positioning and fixing of the base 2, thereby positioning and fixing the distillation column body 1 for distillation operations.

[0037] Example 2

[0038] like Figures 4 to 5The illustrated pharmaceutical chemical intermediates rectifying column, this embodiment is different from embodiment one in that the power assembly includes an electric push rod 24, the output end of the electric push rod 24 is vertically upward and is drivingly connected to the first positioning and fixing assembly. The first positioning and fixing assembly includes a second sliding rod 23, the second sliding rod 23 is coaxially fixed with the output end of the electric push rod 24, the second sliding rod 23 vertically slides out of the support base 3 and is slidingly inserted into the base 2.

[0039] The transmission assembly and the second positioning and fixing assembly are slidingly installed inside the base 2. The first positioning and fixing assembly is drivingly matched with the second positioning and fixing assembly through the transmission assembly. The transmission assembly includes a third sliding block 25, the third sliding block 25 is drivingly matched with the second positioning and fixing assembly as well as the second sliding rod 23. The third sliding block 25 is composed of a horizontally placed ladder-shaped wedge and a vertical rod, the vertical rod is fixedly welded at the middle position of the bottom of the third sliding block 25. The ladder-shaped wedge is slidingly arranged in a third sliding groove 26 excavated inside the base 2, the ladder-shaped wedge is limitingly and slidingly matched with the base 2 through the third sliding groove 26. The left and right end faces of the ladder-shaped wedge are both inclined faces, the two inclined faces are drivingly matched with the second positioning and fixing assembly, the vertical rod downwardly slides through the base 2, the vertical rod is both abuttingly contacted with and drivingly matched with the second sliding rod 23.

[0040] When the second sliding rod 23 slides out of the support base 3 along with the output end of the electric push rod 24, the second sliding rod 23 will be coaxially contacted with the bottom of the third sliding block 25 and slidingly inserted into the base 2, along with the continuous movement of the second sliding rod 23, the third sliding block 25 will be pushed to slide upward along the third sliding groove 26. In this process, the positioning and fixing of the bottom of the base 2 and the transmission of the transmission assembly are both completed.

[0041] The second positioning and fixing assembly includes two second sliding blocks 21 which are both horizontally arranged leftward and rightward, the two second sliding blocks 21 are symmetrically distributed at the left and right sides of the third sliding block 25. The opposite proximal end faces of the two second sliding blocks 21 are both inclined faces, the inclined faces of the two second sliding blocks 21 correspond to the two inclined faces of the third sliding block 25 one by one, the two corresponding inclined faces are slidingly abutted. When the third sliding block 25 moves upward, the two second sliding blocks 21 will be pushed to slide away from each other through the inclined faces.

[0042] The distal end of each of the two second sliding blocks 21 is fixedly welded with a left-right horizontally arranged limiting rod 20, the two limiting rods 20 correspond to the two fixed plates 5 one by one, the two limiting rods 20 slide relative to each other and pass through the base 2, and each limiting rod 20 is slidingly inserted into the corresponding fixed plate 5. Second limiting holes 19 are drilled in the two fixed plates 5, the two second limiting holes 19 correspond to the two limiting rods 20 coaxially, each limiting rod 20 is slidingly inserted into the corresponding second limiting hole 19, and the left and right sides of the base 2 are positioned and fixed. Each limiting rod 20 is sleeved with a second spring 27, and the two ends of each second spring 27 are fixedly connected with the corresponding second sliding block 21 and the base 2 respectively. The two second sliding blocks 21 are reset.

[0043] The inside of the base 2 is provided with two second sliding grooves 22, and the two second sliding grooves 22 are symmetrically distributed on the left and right sides of the third sliding groove 26 and communicate with the third sliding groove 26. The two second sliding grooves 22 correspond to the two second sliding blocks 21 one by one, each second sliding block 21 is slidingly arranged in the corresponding second sliding groove 22, and each second sliding block 21 is limitingly and slidingly matched with the base 2 through the second sliding groove 22.

[0044] The working principle of the second embodiment is as follows:

[0045] Before use, all the second springs 27 are in a compressed state, and the two second sliding blocks 21 abut against the third sliding block 25.

[0046] In use, the base 2 is pushed so that the base 2 is located directly above the support seat 3, and then the rectifying tower body 1 is moved to a proper position.

[0047] Then, the electric push rod 24 is started, the output end of the electric push rod 24 drives the second sliding rod 23 to slide out of the support seat 3, and as the second sliding rod 23 continues to move, the second sliding rod 23 will abut against the bottom of the third sliding block 25 and then push the third sliding block 25 to move upward, and at the same time, the second sliding rod 23 is slidingly inserted into the base 2 to complete the positioning and fixing of the bottom of the base 2.

[0048] When the third sliding block 25 moves upward, the two second sliding blocks 21 are pushed to slide away from each other, and then the two second limiting rods 20 slide out of the base 2 and move towards the corresponding fixed plates 5, until the two second limiting rods 20 are slidingly inserted into the second limiting holes 19 in the corresponding fixed plates 5, so that the side of the base 2 is positioned and fixed, and finally the rectifying tower body 1 is completely fixed.

[0049] Finally, it should be noted that: the above only for the preferred embodiments of the present application, and is not intended to limit the present application, although the foregoing embodiments of the present application has been described in detail, for the skilled in the art, it still can be modified, or for part of the technical features of the equivalent replacement, the spirit and principles of the present application, made any modification, equivalent replacement, improvement, etc., should be included within the scope of the present application.

Claims

1. A rectifying column for pharmaceutical chemical intermediates, comprising a rectifying column body (1), the bottom of the rectifying column body (1) is fixedly connected with a base (2), characterized in that: The lower part of the base (2) is provided with a support seat (3), the base (2) is slidingly arranged on the support seat (3); the first positioning and fixing assembly and the second positioning and fixing assembly are arranged between the base (2) and the support seat (3); the first positioning and fixing assembly and the second positioning and fixing assembly are both slidingly inserted with the base (2) and the support seat (3); the first positioning and fixing assembly and the second positioning and fixing assembly are drivingly connected, used for slidingly inserting the second positioning and fixing assembly into the base (2) and the support seat (3); the power assembly is fixedly installed in the inside of the support seat (3), the power assembly is drivingly connected with the first positioning and fixing assembly, used for slidingly inserting the first positioning and fixing assembly into the base (2) and the support seat (3).

2. The rectification column for pharmaceutical chemical intermediates according to claim 1, characterized in that: The power assembly comprises a motor (11), the motor (11) is fixedly arranged in the support seat (3); a first gear (12) is fixedly sleeved on the output shaft of the motor (11), the first gear (12) is in meshing engagement with a second gear (13), the second gear (13) is fixedly sleeved with a bidirectional screw rod (6), the bidirectional screw rod (6) is both rotatably connected with the support seat (3) and drivingly connected with the first positioning and fixing assembly.

3. The rectification column for pharmaceutical chemical intermediates according to claim 2, characterized in that: The first positioning and fixing assembly comprises a limiting block (9), the support seat (3) is fixedly connected with a fixed plate (5), the limiting block (9) is in limiting sliding engagement with the fixed plate (5); the limiting block (9) is both slidingly inserted with the base (2) and drivingly connected with the second positioning and fixing assembly; the limiting block (9) is fixedly provided with a connecting block (7), the connecting block (7) is fixedly provided with a connecting rod (4), the connecting rod (4) is threadedly connected with the bidirectional screw rod (6).

4. The rectification column for pharmaceutical chemical intermediates according to claim 3, characterized in that: The second positioning and fixing assembly comprises a first sliding block (15), the first sliding block (15) is slidingly arranged in the base (2); the first sliding block (15) is in abutting contact and sliding engagement with the limiting block (9) in the support seat (3); the bottom of the first sliding block (15) is fixedly provided with a first sliding rod (16), the first sliding rod (16) is slidingly arranged out of the base (2) and is in sliding insertion with the support seat (3); a first spring (17) is sleeved on the first sliding rod (16), the first spring (17) is fixedly connected with the base (2) and the first sliding block (15) respectively.

5. The rectification column for pharmaceutical, chemical and intermediate use according to claim 1, characterized in that: The power assembly comprises an electric push rod (24), the electric push rod (24) is fixedly arranged in the support seat (3); the output end of the electric push rod (24) is drivingly connected with the first positioning and fixing assembly.

6. The rectification column for pharmaceutical, chemical and intermediate use according to claim 1, characterized in that: The first positioning and fixing assembly comprises a second sliding rod (23), the second sliding rod (23) is coaxially fixed on the output end of the electric push rod (24); the second sliding rod (23) is slidingly arranged out of the support seat (3) and is in sliding insertion with the base (2); a transmission assembly is slidingly arranged in the base (2), the transmission assembly is both drivingly connected with the second sliding rod (23) and drivingly connected with the second positioning and fixing assembly.

7. The rectification column for pharmaceutical chemical intermediates according to claim 6, characterized in that: The transmission assembly comprises a third sliding block (25) slidingly arranged in the base (2); the third sliding block (25) is in abutment and transmission cooperation with the second sliding rod (23); the third sliding block (25) is in transmission cooperation with the second positioning and fixing assembly.

8. The rectification column for pharmaceutical chemical intermediates according to claim 7, characterized in that: The second positioning and fixing assembly comprises a second sliding block (21) slidingly arranged in the base (2); the second sliding block (21) is in sliding abutment with the third sliding block (25); a limiting rod (20) is fixedly connected to the second sliding block (21); a fixed plate (5) is fixedly connected to the support base (3); the limiting rod (20) slidingly penetrates through the base (2) and is in sliding plug-in cooperation with the fixed plate (5); a second spring (27) is sleeved on the limiting rod (20), and the second spring (27) is fixedly connected with the base (2) and the second sliding block (21) respectively.

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