CN115040763A

CN115040763A - Laboratory is with portable decompression suction filter micropump

Info

Publication number: CN115040763A
Application number: CN202210635231.4A
Authority: CN
Inventors: 王佳佳; 张国庆; 钟海星; 赵建帅; 方宗平; 顾婷婷; 王世全
Original assignee: Air Force Medical University of PLA
Current assignee: Air Force Medical University of PLA
Priority date: 2022-06-07
Filing date: 2022-06-07
Publication date: 2022-09-13
Anticipated expiration: 2042-06-07
Also published as: CN115040763B

Abstract

The invention discloses a portable pressure reduction suction filtration device micropump for a laboratory, which comprises a mounting seat, wherein a collecting box is fixed at the upper end of the mounting seat, a miniature pressure reduction pump is fixed at the upper end of the mounting seat, a connecting pipe is fixed at the port part of the miniature pressure reduction pump, the end part of the connecting pipe penetrates into the collecting box, a fixing column is fixed at the bottom of the mounting seat, an absorption pipe is inserted at the bottom of the fixing column in a penetrating manner, a plurality of feeding pipes are inserted in the inner wall of the absorption pipe in a penetrating manner, the feeding pipes are obliquely arranged, and a fixing block is fixed at the upper end of the mounting seat. Has the advantages that: utilize collecting box under the negative pressure state, can make the bloodstain and the cerebrospinal fluid of dura mater department flow in inside the collecting box along the absorption tube to can guarantee the clean clear visibility in epidural field of vision district, can make things convenient for the injection of capillary electrode intraductal viral vector to use, can avoid the cotton ball to absorb the condition that causes the wound to block up, thereby can make things convenient for experimenter's use.

Description

Laboratory is with portable decompression suction filter micropump

Technical Field

The invention relates to the technical field of experimental auxiliary equipment, in particular to a portable pressure reduction suction filtration device micropump for a laboratory.

Background

Neuroscience is a leading-edge subject of rapid development in recent years, from 'understanding a brain', 'protecting the brain' to 'simulating the brain', people are trying to understand the working principle of a nervous system, in the understanding research, people need to utilize various tools, a virus vector is one of the very important and key tools, in order to realize accurate regulation and control of a deep brain region nucleus, the operation of a nucleus neuron by injecting a virus through a stereotaxic instrument local nucleus is a common experimental technology, and the accurate transmission of the virus into a target nucleus is a prerequisite for realizing accurate regulation and control of the target nucleus neuron;

in actual operation, after coordinates are set for a target brain area, a skull drill is used for windowing, a dura mater is exposed in a visible range, after the skull is polished by the skull drill, the dura mater is broken by a syringe and leakage of cerebrospinal fluid is often accompanied, if a target nucleus is close to a sagittal suture rich in capillaries, bleeding also accompanies, the leaked cerebrospinal fluid and blood seriously affect the needle inserting operation of the visual field area, a common method is that blood stains and cerebrospinal fluid are sucked away by a medical cotton ball, but the medical cotton ball wool is easy to adhere to a wound, so that the wound is easy to block when a needle is inserted into a virus injection electrode.

Disclosure of Invention

The invention aims to solve the problem that wool is easy to adhere to a wound to cause the blockage of the wound when blood stains and cerebrospinal fluid are treated by cotton balls in the prior art, and provides a portable vacuum filtration device micropump for a laboratory.

In order to achieve the purpose, the invention adopts the following technical scheme: a portable pressure reduction suction filtration device micropump for a laboratory comprises a mounting seat, wherein a collecting box is fixed at the upper end of the mounting seat, a miniature pressure reduction pump is fixed at the upper end of the mounting seat, a connecting pipe is fixed at the port of the miniature pressure reduction pump, the end part of the connecting pipe penetrates into the collecting box, a fixing column is fixed at the bottom of the mounting seat, an absorption pipe is inserted at the bottom of the fixing column in a penetrating manner, a plurality of inlet pipes are inserted in the inner wall of the absorption pipe in a penetrating manner, the inlet pipes are obliquely arranged, a fixing block is fixed at the upper end of the mounting seat and is a U-shaped block, a first sealing sliding plate and a second sealing sliding plate are connected to the inner wall of the fixing block in a sealing and sliding manner, the bottom of the first sealing sliding plate is fixedly connected with the inner bottom of the fixing block through a supporting spring, and a first vertical rod is fixed at the bottom of the first sealing sliding plate, and a second vertical rod is fixed at the bottom of the second sealing sliding plate, virus injection equipment is arranged at the bottom of the first vertical rod, and hard membrane breaking equipment is arranged at the bottom of the second vertical rod.

In the portable decompression suction filtration device micropump for laboratories, the upper end of the absorption tube penetrates through the mounting seat and extends to the inside of the collection box, a buffer solution is filled between the first sealing sliding plate and the second sealing sliding plate, the first sealing sliding plate and the second sealing sliding plate are respectively located at two ends of the fixed block, and the bottoms of the first vertical rod and the second vertical rod respectively penetrate through the inner walls of two ends of the fixed block.

In foretell portable decompression suction filtration device micropump is used in laboratory, the dura mater is broken equipment and is a plurality of including being fixed in a plurality of dead levers of mount pad bottom, and is a plurality of the common sliding connection of circumference lateral wall of dead lever has the horizontal plate, the bottom of the vertical pole of second runs through the mount pad and is fixed with the upper end of horizontal plate, the bottom of horizontal plate is fixed with the syringe needle.

In foretell portable decompression suction filtration device micropump is used in laboratory, the bottom of horizontal plate is provided with a plurality of screens devices, and is a plurality of the screens device equidistance sets up, the screens device is including the fixed plate that is fixed in the horizontal plate bottom, the lateral wall of fixed plate runs through sliding connection and has the gag lever post, the fixed plate corresponds with the dead lever.

In foretell portable decompression suction filtration device micropump is used in laboratory, the lateral wall of gag lever post is fixed with vertical baffle, vertical baffle offsets with the horizontal plate bottom, vertical baffle lateral wall passes through reset spring fixed connection with the fixed plate lateral wall, the lateral wall of dead lever runs through and has seted up a plurality of spacing grooves, the circumference lateral wall and the spacing inslot wall of dead lever correspond and offset.

In foretell portable decompression suction filter device micropump is used in laboratory, virus injection equipment is including being fixed in the circular slab of first vertical pole bottom, the bottom of first vertical pole runs through to the below of mount pad, the bottom of circular slab is provided with spacing clamping device.

In foretell portable decompression suction filtration device micropump is used in laboratory, limit clamping device is including being fixed in the baffle of circular slab bottom, the both ends lateral wall of baffle all is connected with the regulation pole, two through the bearing rotation the one end that the regulation pole is adjacent passes through connecting rod fixed connection, two the other end of adjusting the pole all is fixed with the carousel, it is the threaded rod, two to adjust the pitch of pole the same and the screw thread is revolved to opposite.

In foretell portable decompression suction filter device micropump is used in laboratory, the equal screw rotation of the circumference lateral wall of two regulation poles is connected with the movable block, and two the upper end of movable block all offsets with the bottom of circular slab, the movable block is L type piece, two the lateral wall of movable block all is fixed with the chucking piece, two the lateral wall that the chucking piece is adjacent all is fixed with the protective layer.

In foretell portable decompression suction filter device micropump is used in laboratory, the chucking piece is the arc piece, the protective layer adopts rubber materials to make, two the lateral wall of protective layer offsets jointly there is capillary electrode pipe, the circumference lateral wall of capillary electrode pipe is fixed with two lantern rings, two the lantern ring offsets with the upper end and the bottom of two chucking pieces respectively.

Compared with the prior art, the invention has the advantages that:

1. in the invention, the collecting box in a negative pressure state is utilized, so that blood traces and cerebrospinal fluid at the dura mater can flow into the collecting box along the absorption tube, thereby ensuring that a epidural visual field area is clean and visible, facilitating the injection and use of virus vectors in the capillary electrode tube, avoiding the condition of wound blockage caused by cotton ball absorption and facilitating the use of experimenters;

2. according to the invention, the distance between the two clamping blocks can be rapidly adjusted by arranging the limiting and clamping device, so that capillary electrode tubes with different sizes can be clamped and used, the side walls of the clamping blocks are provided with the protective layers, the safety of the capillary electrode tubes in the clamping process can be ensured, and the capillary electrode tubes are better in injection stability and higher in experimental accuracy by combining the lantern rings on the capillary electrode tubes;

3. according to the invention, the clamping device is arranged, so that the horizontal plate can slide up and down along the fixed rod, the parking height of the needle head can be controlled, and the corresponding adjustment of the height of the virus injection equipment can be realized under the action of the fixed block and the internal buffer solution, so that the needle head, the absorption tube and the capillary electrode tube can be conveniently used in sequence, the interference in the use process can be avoided, and the experiment use of a small experimental body can be conveniently realized;

4. according to the invention, the needle head for puncturing the dura mater, the capillary electrode tube for injecting the virus vector and the equipment for absorbing the blood stain and the cerebrospinal fluid at the dura mater are all arranged on the mounting seat, so that the occupied space of the experimental equipment is small, various experimental equipment does not need to be manually prepared in advance, and meanwhile, the auxiliary equipment in a laboratory can be conveniently and conveniently carried.

Drawings

FIG. 1 is a schematic structural view of a micropump of a portable pressure reduction suction filtration device for a laboratory, which is provided by the invention;

FIG. 2 is a main sectional view of a clamping device in a micropump of the portable pressure-reducing suction filtration device for a laboratory, which is provided by the invention;

FIG. 3 is an enlarged view of portion A of FIG. 1;

FIG. 4 is a bottom view of a limiting and clamping device part in a micropump of the portable pressure-reducing suction filtration device for a laboratory, which is provided by the invention;

FIG. 5 is a top view of a portable vacuum filtration device micropump for a laboratory.

In the figure: 1 mount pad, 2 collecting boxes, 3 miniature decompression pumps, 4 connecting pipes, 5 fixed columns, 6 absorbent tubes, 7 inlet pipes, 8 fixed blocks, 9 first sealed slide, 10 second sealed slide, 11 buffer solutions, 12 first vertical poles, 13 second vertical poles, 14 supporting springs, 15 horizontal plates, 16 fixed poles, 17 fixed plates, 18 gag lever posts, 19 vertical baffles, 20 reset springs, 21 spacing grooves, 22 pinheads, 23 circular plates, 24 clapboards, 25 adjusting rods, 26 turntables, 27 connecting rods, 28 moving blocks, 29 chucking blocks, 30 protective layers, 31 capillary electrode tubes, 32 lantern rings.

Detailed Description

The following examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

Referring to fig. 1-5, a portable pressure-reducing suction filtration device micropump for a laboratory comprises a mounting base 1, a collecting box 2 is fixed at the upper end of the mounting base 1, a miniature pressure-reducing pump 3 is fixed at the upper end of the mounting base 1, a connecting pipe 4 is fixed at the port of the miniature pressure-reducing pump 3, the end of the connecting pipe 4 penetrates into the collecting box 2, a fixing column 5 is fixed at the bottom of the mounting base 1, an absorption pipe 6 is inserted at the bottom of the fixing column 5, a plurality of feed pipes 7 are inserted in the inner wall of the absorption pipe 6, the plurality of feed pipes 7 are obliquely arranged, a fixing block 8 is fixed at the upper end of the mounting base 1, the fixing block 8 is a U-shaped block, a first sealing slide plate 9 and a second sealing slide plate 10 are connected to the inner wall of the fixing block 8 in a sealing and sliding manner, the bottom of the first sealing slide plate 9 is fixedly connected with the inner bottom of the fixing block 8 through a supporting spring 14, a first vertical rod 12 is fixed at the bottom of the first sealing slide plate 9, a second vertical rod 13 is fixed at the bottom of the second sealing sliding plate 10, virus injection equipment is arranged at the bottom of the first vertical rod 12, and hard membrane breaking equipment is arranged at the bottom of the second vertical rod 13; the upper end of absorption tube 6 runs through mount pad 1 and along inside 2 collecting boxes, it has buffer solution 11 to fill between first sealed slide 9 and the sealed slide 10 of second, first sealed slide 9 and the sealed slide 10 of second are located the both ends of fixed block 8 respectively, the bottom of first vertical pole 12 and the vertical pole 13 of second runs through the both ends inner wall of fixed block 8 respectively, utilize fixed block 8 and buffer solution 11, can move up the in-process realization first vertical pole 12 of moving down at the vertical pole 13 of second, thereby can make things convenient for the dura mater to break equipment, use in proper order of extraction equipment and virus injection equipment, can avoid the interference that causes in the narrow and small space, make things convenient for experimenter's operation and use.

The dura mater pricking device comprises a plurality of fixing rods 16 fixed at the bottom of the mounting seat 1, the circumferential side walls of the fixing rods 16 are jointly connected with a horizontal plate 15 in a sliding manner, the bottom of the second vertical rod 13 penetrates through the mounting seat 1 and is fixed with the upper end of the horizontal plate 15, and a needle 22 is fixed at the bottom of the horizontal plate 15; the bottom of the horizontal plate 15 is provided with a plurality of clamping devices which are arranged at equal intervals, each clamping device comprises a fixing plate 17 fixed at the bottom of the horizontal plate 15, the side wall of each fixing plate 17 is connected with a limiting rod 18 in a penetrating and sliding manner, and each fixing plate 17 corresponds to each fixing rod 16; the lateral wall of gag lever post 18 is fixed with vertical baffle 19, and vertical baffle 19 offsets with horizontal plate 15 bottom, and vertical baffle 19 lateral wall passes through reset spring 20 fixed connection with fixed plate 17 lateral wall, and the lateral wall of dead lever 16 runs through and has seted up a plurality of spacing grooves 21, and the circumference lateral wall of dead lever 16 corresponds with spacing groove 21 inner wall and offsets.

The virus injection equipment comprises a circular plate 23 fixed at the bottom of a first vertical rod 12, the bottom of the first vertical rod 12 penetrates below the mounting base 1, and a limiting and clamping device is arranged at the bottom of the circular plate 23; the limiting and clamping device comprises a partition plate 24 fixed at the bottom of the circular plate 23, the side walls of the two ends of the partition plate 24 are rotatably connected with adjusting rods 25 through bearings, the adjacent ends of the two adjusting rods 25 are fixedly connected through connecting rods 27, the other ends of the two adjusting rods 25 are respectively fixed with a rotating disc 26, the adjusting rods 25 are threaded rods, the screw pitches of the two adjusting rods 25 are the same, and the thread turning directions are opposite; the circumferential side walls of the two adjusting rods 25 are both in threaded rotation connection with moving blocks 28, the upper ends of the two moving blocks 28 are both abutted against the bottom of the circular plate 23, the moving blocks 28 are L-shaped blocks, clamping blocks 29 are fixed on the side walls of the two moving blocks 28, and protective layers 30 are fixed on the adjacent side walls of the two clamping blocks 29; the chucking block 29 is the arc piece, and protective layer 30 adopts rubber materials to make, and the lateral wall of two protective layers 30 supports in the same phase has capillary electrode pipe 31 altogether, and capillary electrode pipe 31's circumference lateral wall is fixed with two lantern rings 32, and two lantern rings 32 offset with the upper end and the bottom of two chucking blocks 29 respectively, utilize adjustable distance's chucking block 29, can realize the tight use of clamp to not unidimensional capillary electrode pipe 31 to can effectively increase the suitability of device.

In the invention, in the injection process of the virus vector in the neuroscience research, firstly, the marking of a target brain area needs to be realized on an experimental body, then a skull drill is used for windowing at the marked position to expose a dura mater in a visible range, at the moment, the mounting seat 1 is moved to be right above the dura mater by moving the mounting seat 1, then the mounting seat 1 is slowly moved to enable a needle head 22 to gradually approach the dura mater, the dura mater at the marked position is punctured by the needle head 22, the dura mater at the marked position can be punctured conveniently by the needle head 22 because the heights of the capillary electrode tube 31, the absorption tube 6 and the needle head 22 are sequentially reduced without causing interference on the needle head 22, the limiting rod 18 on the side wall of the vertical baffle plate 19 is separated from the limiting groove 21 at the bottommost part on the fixed rod 16 by pulling the vertical baffle plate 19, the stretching of the reset spring 20 can be realized, at the moment, the clamping device at the bottom of the horizontal plate 15 reaches the limiting groove 21 at the middle position by upwards pushing the horizontal plate 15, under the action of the reset spring 20 in a stretching state, the reset of the vertical baffle 19 can be realized, so that the limiting rod 18 can enter the limiting groove 21 again, and the stable limiting of the horizontal plate 15 is realized;

in the upward sliding process of the horizontal plate 15, the second sealing sliding plate 10 can be driven to slide upward, so that the buffer solution 11 in the fixed block 8 can push the first sealing sliding plate 9, the first sealing sliding plate 9 and the first vertical rod 12 can slide downward, the downward movement of the virus injection device can be realized, meanwhile, in the downward movement process of the first sealing sliding plate 9, the compression of the supporting spring 14 can be realized, the downward movement of the circular plate 23 is caused by the upward movement of the horizontal plate 15, so that the needle 22 and the capillary electrode tube 31 are both positioned above the feeding tube 7, and the absorption of the absorption tube 6 cannot be influenced;

meanwhile, by starting the miniature pressure reducing pump 3, air negative pressure can be generated inside the collecting box 2, the negative pressure can enable bloodstains and cerebrospinal fluid at the dura mater to flow into the collecting box 2 along the absorption tube 6, so that the epidural visual field area at the mark can be clearly seen, the aperture of the absorption tube 6 is small, the absorption capacity of the absorption tube 6 can be stronger, the feeding tubes 7 which are obliquely arranged are arranged on the side wall of the absorption tube 6, the bloodstains and the cerebrospinal fluid at the dura mater can be absorbed more quickly, the wound can be cleaned and used quickly, the accurate positioning insertion of the subsequent capillary electrode tube 31 can be facilitated, and the injection of virus carriers is more accurate;

after the bloodstains and the cerebrospinal fluid at the wound are cleaned, the limiting of the clamping device on the horizontal plate 15 is released again, the horizontal plate 15 is pushed to the position of the limiting groove 21 at the top, meanwhile, the virus injection equipment can move downwards again under the action of the fixing block 8, the capillary electrode tube 31 can be positioned at the bottommost part, the capillary electrode tube 31 is inserted into the opening of the dura mater by moving the mounting seat 1, and then the virus carrier is injected to the designated position through the capillary electrode tube 31, so that the accurate regulation and control of the target nuclear group neurons can be realized;

when the adjusting rod 25 at one end is rotated, under the action of the connecting rod 27, two threaded rods with opposite screw thread turning directions and same screw thread pitch can be simultaneously rotated, so that the two moving blocks 28 and the clamping blocks 29 can be mutually close to or separated from each other, and the distance between the two clamping blocks 29 can be quickly adjusted, so that capillary electrode tubes 31 with different sizes can be clamped, the virus carriers of the capillary electrode tubes 31 with different specifications can be conveniently injected and used, the applicability of the virus carriers can be effectively increased, the side walls of the clamping blocks 29 are provided with the protective layers 30 made of rubber materials, the safe clamping of the capillary electrode tubes 31 can be ensured, the damage to the capillary electrode tubes 31 can be avoided, and the service life of the capillary electrode tubes 31 is longer;

through the syringe needle 22 of stabbing the dura mater, the capillary electrode pipe 31 of viral vector injection and the dura mater department bloodstain, the absorption equipment of cerebrospinal fluid install to mount pad 1 on for the occupation space of experimental facilities is less, can make things convenient for lightly carrying of laboratory auxiliary assembly, and utilizes fixed block 8, can realize the adjustment of syringe needle 22 and capillary electrode pipe 31 action height, can avoid the interference that causes in the narrow and small space, thereby can make things convenient for laboratory technician's use.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. The utility model provides a laboratory is with portable decompression suction filtration device micropump, includes mount pad (1), its characterized in that, the upper end of mount pad (1) is fixed with collecting box (2), the upper end of mount pad (1) is fixed with miniature decompression pump (3), the port department of miniature decompression pump (3) is fixed with connecting pipe (4), the tip of connecting pipe (4) runs through to inside collecting box (2), the bottom of mount pad (1) is fixed with fixed column (5), the bottom of fixed column (5) runs through and inserts and is equipped with absorption tube (6), the inner wall of absorption tube (6) runs through and inserts and is equipped with a plurality of inlet pipes (7), a plurality of inlet pipes (7) slope and set up, the upper end of mount pad (1) is fixed with fixed block (8), fixed block (8) are U type piece, the inner wall sealing sliding connection of fixed block (8) has first sealed slide (9) and second sealed slide (10), the bottom of first sealed slide (9) and the interior bottom of fixed block (8) pass through supporting spring (14) fixed connection, the bottom of first sealed slide (9) is fixed with first vertical pole (12), the bottom of the sealed slide of second (10) is fixed with second vertical pole (13), the bottom of first vertical pole (12) is provided with virus injection equipment, the bottom of second vertical pole (13) is provided with the dura mater and breaks equipment.

2. The portable decompression suction filtration device micropump for the laboratory according to claim 1, wherein the upper end of the absorption tube (6) penetrates through the mounting seat (1) and along the inside of the collection box (2), a buffer solution (11) is filled between the first sealing sliding plate (9) and the second sealing sliding plate (10), the first sealing sliding plate (9) and the second sealing sliding plate (10) are respectively located at two ends of the fixed block (8), and the bottoms of the first vertical rod (12) and the second vertical rod (13) respectively penetrate through the inner walls of two ends of the fixed block (8).

3. The portable decompression suction filtration device micropump for the laboratory according to claim 1, wherein the dura mater pricking device comprises a plurality of fixing rods (16) fixed at the bottom of the mounting seat (1), the circumferential side walls of the plurality of fixing rods (16) are jointly and slidably connected with a horizontal plate (15), the bottom of the second vertical rod (13) penetrates through the mounting seat (1) and is fixed with the upper end of the horizontal plate (15), and a needle (22) is fixed at the bottom of the horizontal plate (15).

4. The portable decompression suction filtration device micropump for the laboratory according to claim 3, wherein a plurality of clamping devices are arranged at the bottom of the horizontal plate (15) at equal intervals, the clamping devices comprise a fixed plate (17) fixed at the bottom of the horizontal plate (15), a limiting rod (18) is connected to a side wall of the fixed plate (17) in a penetrating and sliding manner, and the fixed plate (17) corresponds to the fixed rod (16).

5. The portable decompression suction filtration device micropump for the laboratory according to claim 4, wherein a vertical baffle (19) is fixed on a side wall of the limiting rod (18), the vertical baffle (19) abuts against the bottom of the horizontal plate (15), the side wall of the vertical baffle (19) is fixedly connected with the side wall of the fixing plate (17) through a return spring (20), a plurality of limiting grooves (21) are formed in the side wall of the fixing rod (16) in a penetrating manner, and a circumferential side wall of the fixing rod (16) abuts against the inner wall of each limiting groove (21) correspondingly.

6. The portable vacuum filtration device micropump for laboratories according to claim 2, wherein the virus injection device comprises a circular plate (23) fixed at the bottom of the first vertical rod (12), the bottom of the first vertical rod (12) penetrates below the mounting seat (1), and a limiting and clamping device is arranged at the bottom of the circular plate (23).

7. The laboratory is with portable decompression suction filter device micropump of claim 6, characterized in that, limiting clamping device is including being fixed in baffle (24) of circular slab (23) bottom, the both ends lateral wall of baffle (24) all is connected with through the bearing rotation and adjusts pole (25), two the adjacent one end of adjusting pole (25) is through connecting rod (27) fixed connection, two the other end of adjusting pole (25) all is fixed with carousel (26), adjust pole (25) and be the threaded rod, two the pitch of adjusting pole (25) is the same and the screw thread is revolved to opposite direction.

8. The portable pressure-reducing suction filtration device micropump for the laboratory according to claim 7, wherein the circumferential side walls of the two adjusting rods (25) are both in threaded rotation connection with a moving block (28), the upper ends of the two moving blocks (28) are both abutted against the bottom of the circular plate (23), the moving block (28) is an L-shaped block, the side walls of the two moving blocks (28) are both fixed with clamping blocks (29), and the adjacent side walls of the two clamping blocks (29) are both fixed with a protective layer (30).

9. The portable decompression suction filtration device micropump for the laboratory according to claim 8, wherein the clamping blocks (29) are arc-shaped blocks, the protective layers (30) are made of rubber materials, the side walls of the two protective layers (30) are abutted to the capillary electrode tube (31) in common, two lantern rings (32) are fixed to the circumferential side wall of the capillary electrode tube (31), and the two lantern rings (32) are abutted to the upper end and the bottom of the two clamping blocks (29) respectively.