CN217878100U - Hollow shell-shaped PDMS flexible pressure sensing device with embedded planar inductance coil - Google Patents

Abstract

The utility model discloses an embedded planar inductance coil's flexible pressure sensing device of vacant shell form PDMS, include: the anti-radiation flexible substrate comprises a flexible substrate, a hollow shell-shaped porous PDMS supporting body and an installation frame, wherein the hollow shell-shaped porous PDMS supporting body is fixed at the upper part of the flexible substrate in a limiting mode, a PI film matched with the flexible substrate is adhered to the top of the hollow shell-shaped porous PDMS supporting body, and anti-radiation cloth wraps the flexible substrate and the outer side of the PI film. The utility model discloses a quick automatic re-setting of supporter, the operation of continuous detection pressure, when pressure acts on the top of porous PDMS supporter gradually, whole cavernosum can be compressed gradually, makes the relative distance between its inside coil reduce gradually, and the inductance value of whole circuit rises thereupon, when external pressure withdraws gradually, whole empty shell form porous PDMS supporter resumes to initial shape gradually under the elastic action, the utility model discloses can reach the ideal height, improve gentle elasticity, have fine interference killing feature, it is more accurate practical at the in-process that detects.

Description

Hollow shell-shaped PDMS flexible pressure sensing device with embedded planar inductance coil

Technical Field

The utility model relates to a pressure sensing technical field specifically is an embedded planar inductance coils's flexible pressure sensing device of vacant shell form PDMS.

Background

As a core part of a flexible electronic device, the flexible sensor has the advantages of strong elasticity, high softness, easy adhesion to the surface of a machine and the like, and has wide application prospect and huge application potential in the aspects of ship pressure detectors, human health monitoring bracelets, artificial intelligent equipment, biomedical equipment, microfluidic equipment, energy acquisition equipment, flexible electronic skin and the like.

At present, the main problems faced by flexible sensors are high manufacturing cost, complex manufacturing process, small working range, low sensitivity, poor anti-interference capability, etc., and in order to overcome the above disadvantages, many new flexible pressure sensors are continuously proposed and improved. Currently, the flexible pressure sensor has been developed and broadly classified into four major categories, i.e., piezoresistive type, piezoelectric type, capacitive type, and triboelectric type, according to the detection principle. The capacitive flexible pressure sensor is mainly researched, and the capacitive flexible pressure sensor detects and indicates the change of the external pressure by using the change of the capacitance of the capacitive flexible pressure sensor as a basic principle. The method has the advantages of excellent sensitivity, and especially has good advantage for detecting the tiny pressure signals. This type of sensor is very susceptible to external environmental disturbances, and to vibrations themselves, which greatly reduces the possibility of putting capacitive sensors into practical use,

in order to solve the problem, the utility model provides a flexible pressure sensor of inductance type, this sensor uses the inductance change between two miniature planar inductance coils to realize the detection to pressure variation as the key point, has extremely strong interference killing feature, and manufacturing process is very simple, and manufacturing cost is comparatively cheap, has profound meaning to flexible pressure sensor's development and research.

SUMMERY OF THE UTILITY MODEL

The purpose of the utility model is to solve the shortcoming that exists among the prior art, if: the existing capacitive flexible pressure sensor is poor in anti-interference capability, the elastic element is required to be timely reset, the data when the pressure sensor is detected next time is more accurate, the pressure sensor is installed outside for a long time, the surface of the pressure sensor can be corroded, the surface of the pressure sensor is oxidized, the surface of the pressure sensor is prone to cracking when the pressure sensor is detected, the use of the pressure sensor is influenced, the service life is prolonged, a wire is arranged outside the pressure sensor, when the pressure sensor is installed and used, the wire is pulled, the situation that the wire is broken and falls off easily occurs, the pressure sensor is inconvenient in the use process, and the practicability is reduced.

In order to achieve the above object, the utility model provides a following technical scheme:

a hollow shell-shaped PDMS (polydimethylsiloxane) flexible pressure sensing device with embedded planar inductance coils comprises a flexible bottom lining, a hollow shell-shaped porous PDMS supporting body and a mounting frame, wherein the hollow shell-shaped porous PDMS supporting body is fixed at the upper part of the flexible bottom lining in a limiting manner, a PI (polyimide) film matched with the flexible bottom lining is pasted on the top of the hollow shell-shaped porous PDMS supporting body, radiation-proof cloth wraps the outer sides of the flexible bottom lining and the PI film, a first inductance coil and a second inductance coil are fixedly mounted on the inner wall of the hollow shell-shaped porous PDMS supporting body respectively, a first lead and a second lead extending out of the hollow shell-shaped porous PDMS supporting body are electrically connected to the outer sides of the first inductance coil and the second inductance coil respectively, and the mounting frame is fixedly mounted on the outer side of the flexible bottom lining;

the utility model discloses a lead screw fixed mounting of fixing frame, including mounting bracket, first grip block, second grip block, lead screw spiral installation, the outside fixedly connected with dead lever of mounting bracket, and the top of dead lever and the all movable mounting in bottom have first grip block and second grip block, one side fixed mounting of first grip block and second grip block has the fixed block, the inboard of fixed block has the extrusion piece through lead screw spiral installation, the outside fixed mounting of fixed block have with lead screw complex mount.

Preferably, the flexible bottom lining and the hollow shell-like porous PDMS support are fixed in a limited manner through an installation groove, and the flexible bottom lining is flush with the top of the hollow shell-like porous PDMS support.

Preferably, the PI film is yellow and transparent and is made of a PI film insulating material.

Preferably, the radiation-proof cloth is made of silver fiber fabric, and the surface of the radiation-proof cloth is covered with the protective layer.

Preferably, the radiation-proof cloth is made of silver fiber fabric, and the surface of the radiation-proof cloth is covered with the protective layer.

Preferably, the outer side of the protective layer is wrapped with a wear-resistant layer, and the wear-resistant layer is made of polyethylene plastics.

Preferably, the hollow porous PDMS support and the flexible bottom lining are slidably mounted through a sliding block, and sliding grooves matched with the sliding block are formed in the inner wall of the flexible bottom lining.

Preferably, the hollow-shell-shaped porous PDMS supporting body, the first inductance coil and the second inductance coil are fixedly adhered through an adhesive tape, and the first inductance coil and the second inductance coil are installed in parallel and oppositely.

Preferably, the top and the bottom of the fixed rod are welded with mounting seats, and the mounting seats, the first clamping blocks and the second clamping blocks are movably mounted through movable shafts.

Preferably, the first clamping block and the second clamping block are fixed through a fixing knob, and a butt joint rod matched with the fixing knob is fixedly installed on the inner side of the second clamping block.

Preferably, a protective pad is adhered to the inner side of the extrusion block, and a rotating disc is welded to the outer side of the screw rod.

Compared with the prior art, the beneficial effects of the utility model are that:

the utility model discloses be applied to in the detection, the interference killing feature is strong, this kind of inductance detection scheme has very strong resistance to electromagnetic interference equally, its output signal can not fluctuate by a wide margin because of electromagnetic signal's around existence, counter-looking capacitive sensor, its output signal has produced continuous fluctuation by a wide margin when external electromagnetic interference exists equally, consequently, capacitive sensor does not have the resistance to external interference, and electromagnetic interference and organism interference are the most common interference of a kind in the life, if put into commercial use with the sensor, this kind of interference is inevitable, consequently, this shortcoming greatly reduced of capacitive sensor its probability of coming into practical life and using, this just more shows the research value and the meaning of the inductance type pressure sensor who has stronger interference killing feature.

The utility model discloses a carry out quick automatic re-setting operation, through being provided with the porous PDMS supporter of empty shell form, the PI film, second inductance coil and the first inductance coil between mutually support, when the sensor does not receive the ambient pressure effect, whole sponge presents upright state under the support of the porous wall of whole empty shell form porous PDMS supporter flexibility all around, when pressure acts on the top of porous PDMS supporter gradually, outside flexible bending expansion can take place gradually around the flexible porous wall, whole empty shell form porous PDMS supporter can be compressed gradually, lead to the plane inductance coil that its top layer is fixed to be close to its bottom gradually, make the distance between first inductance coil and the second inductance coil reduce, the inductance value of whole circuit constantly rises, when the ambient pressure withdraws gradually, whole empty shell form porous PDMS supporter resumes to initial shape under the elastic action gradually, make the relative distance between its inside coil reduce gradually, the inductance value of whole circuit descends thereupon, it is more convenient to make the in-process of carrying out the detection, the practicality has been increased.

The utility model discloses a be provided with the cloth of protecting against radiation, mutually supporting between inoxidizing coating and the wearing layer, utilize silver-colored fibre surface fabric, can be effectual, be in the same place metal fiber and the blending of cloth fibre with silver-colored fibre surface fabric, form the metal mesh, what can be convenient plays the radiation protection effect, utilize polyethylene plastics to make simultaneously and can make and conveniently wear-resisting, make and detect that extruded in-process surface can be convenient carry out abrasive treatment, make the in-process that uses more high-efficient, increased life.

The utility model discloses a be provided with first grip block, the fixed block, mutually support between second grip block and the extrusion piece, it is rotatory to be able to drive the lead screw in step through rotatory rolling disc, make the lead screw can remove to the inboard of fixed block along the mount, messenger's extrusion piece that can be convenient is close to each other, it is fixed to carry out the centre gripping with first wire and second wire, can protect between first wire and the second wire through the protection pad, the effectual too big condition that causes the damage to first wire and second wire that prevents the centre gripping dynamics, it is too big to prevent that the external dynamics of dragging, make to produce the cracked condition that drops between the wire, the practicality has been increased the convenience.

Drawings

Fig. 1 is a schematic view of the appearance three-dimensional structure of the present invention;

FIG. 2 is a schematic view of a partial structure of the hollow porous PDMS support of the present invention;

FIG. 3 is a schematic view of the front internal structure of the hollow porous PDMS support of the present invention;

fig. 4 is a schematic view of a partial structure of the fixing sleeve of the present invention;

FIG. 5 is a schematic view of a partial structure of the fixing rod of the present invention;

fig. 6 is a schematic view of the local structure of the extrusion block of the present invention.

In the figure: 1-a flexible bottom lining; 101-PI film; 102-a sliding groove; 103-radiation protection cloth; 104-an overcoat layer; 105-a wear resistant layer; 106-mounting grooves; 2-an empty shell-like porous PDMS support; 201-a sticky tape; 202-a slider; 203-a first inductor winding; 204-a second inductor winding; 205-a first wire; 206-a second wire; 3-mounting a frame; 301-a fixation bar; 302-a mount; 303-a movable shaft; 4-a first clamping block; 401-a second clamping block; 402-a docking bar; 403-fixing the knob; 404-fixed block; 405-an extrusion block; 406-a protective pad; 407-screw mandrel; 408-a fixed mount; 409-rotating disk.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "front end", "rear end", "both ends", "one end", "the other end" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the device or element to which the reference is made must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "disposed," "connected," and the like are to be construed broadly, and for example, "connected" may be either fixedly connected or detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present invention can be understood as a specific case by those skilled in the art.

Example one

Referring to fig. 1-6, the present invention provides a flexible pressure sensing device of hollow shell PDMS with an embedded planar inductive coil, including a flexible substrate 1, a hollow shell porous PDMS support 2 and an installation frame 3, the top of the flexible substrate 1 is fixed with the hollow shell porous PDMS support 2 in a limited manner through an installation groove 106, a PI film 101 cooperating with the flexible substrate 1 is installed on the top of the hollow shell porous PDMS support 2 in a butt joint manner, the hollow shell porous PDMS support 2, a first inductive coil 203 and a second inductive coil 204 are both adhered and fixed by an adhesive tape 201, the first inductive coil 203 and the second inductive coil 204 can be conveniently installed inside the hollow shell porous PDMS support 2 by using the adhesive tape 201, the PI film 101 can be conveniently deformed and then extruded on the top of the hollow shell porous PDMS support 2 by using the adhesive tape 201, the PI film 101 has good insulation property, and is helpful to realize isolation of external air interference, so that the sensitivity of the PI film 101 can be conveniently used in the process of using the hollow shell PDMS, the two parallel flexible substrate PDMS support can be conveniently installed in the hollow shell PDMS, and the hollow shell PDMS support, the whole flexible substrate support can be conveniently and the hollow shell PDMS, the two parallel sensor can be conveniently installed in the hollow shell porous PDMS support 106, and the process of the hollow shell porous PDMS, the parallel sensor, the structure, the PI film can be conveniently and the improved sensitivity of the thin film can be further, the practicability is improved, the outer sides of the flexible bottom lining 1 and the PI film 101 are wrapped with the radiation-proof cloth 103, the radiation-proof cloth 103 is made of silver fiber fabric, the surface of the radiation-proof cloth 103 is provided with the protective layer 104, the outer side of the protective layer 104 is sleeved with the wear-resistant layer 105, the wear-resistant layer 105 is made of polyethylene plastic, the radiation-proof cloth 103 is made of silver fiber fabric, the silver fiber fabric can be effectively formed by blending metal fiber and cloth fiber to form a metal net, the radiation-proof effect can be conveniently achieved, meanwhile, the polyethylene plastic is made to be convenient and wear-resistant, the surface can be conveniently subjected to wear-resistant treatment in the process of detecting and extruding, the use process is more convenient, the service life is prolonged, the hollow shell-shaped porous PDMS supporting body 2, the flexible bottom lining 1 and the PI film 101 are slidably mounted through the sliding block 202, the PI film 101 and the inner wall of the flexible bottom lining 1 are provided with a sliding groove 102 matched with the sliding block 202, the sliding block 202 slides along the inner part of the sliding groove 102 to enable the first inductance coil 203 and the second inductance coil 204 to be in a parallel state conveniently in the deformation process, the measurement process is more accurate, the practicability is improved, the pressure measurement precision is improved, the inner wall of the hollow porous PDMS supporting body 2 is provided with the first inductance coil 203 and the second inductance coil 204 in an adhesive manner through an adhesive tape 201, the first inductance coil 203 and the second inductance coil 204 are arranged in parallel and oppositely, the first inductance coil 203 and the second inductance coil 204 can be conveniently adhered to the inner wall of the hollow porous PDMS supporting body 2 through the adhesive tape 201, the first inductance coil 203 and the second inductance coil 204 are not easy to fall off, and the stability is improved, the outer sides of the first inductance coil 203 and the second inductance coil 204 are electrically connected with a first lead 205 and a second lead 206 which extend out of the hollow shell-shaped porous PDMS supporting body 2, the mutual approach between the first inductance coil 203 and the second inductance coil 204 enables the inductance to change, pressure is detected through changed data, and practicability is improved.

Example two

Referring to fig. 1-6, the present invention provides an empty-shell PDMS flexible pressure sensing device with embedded planar inductive coil, compared to the first embodiment, the present embodiment further includes: the flexible bottom liner 1 and the outer side of the PI film 101 are fixedly provided with a mounting frame 3, the outer side of the mounting frame 3 is fixedly connected with a fixed rod 301, the fixed rod 301 can be conveniently mounted through the mounting frame 3, the top of the fixed rod 301 is welded with a mounting seat 302, the mounting seat 302 is movably mounted between the first clamping block 4 and the second clamping block 401 through a movable shaft 303, so that the fixing process of the first lead 205 and the second lead 206 is more convenient and the convenience is improved, meanwhile, the mounting seat 302 can be used for connecting the first clamping block 4 and the second clamping block 401, the movable shaft 303 can be used for conveniently overturning the first clamping block 4 and the second clamping block 401, so that the clamping and fixing processes are more convenient and the practicability is improved, the first clamping block 4 and the second clamping block 401 are fixed through a fixed knob 403, and the butt joint rod 402 matched with the fixed knob is fixedly arranged on the inner side of the second clamping block 401, the movable shaft 303 is utilized to conveniently turn over the first clamping block 4 and the second clamping block 401, the fixing knob 403 and the butt joint rod 402 are used for limiting and fixing, so that the process of clamping the first lead 205 and the second lead 206 is more convenient and faster, the first lead 205 and the second lead 206 can be conveniently fixed by being pulled, the situation that the external pulling force is too large and the leads fall off and break is generated between the leads is prevented, the practicability is increased, one side of the first clamping block 4 and one side of the second clamping block 401 are fixedly provided with a fixed block 404, the outer side of the fixed block 404 is fixedly provided with a fixed frame 408 matched with the lead screw 407, the outer side of the lead screw 407 is welded with a rotating disc 409, the lead screw 407 can be synchronously driven to rotate by rotating the rotating disc 409, so that the lead screw 407 can move towards the inner side of the fixed block 404 along the fixed frame 408, the messenger that can be convenient extrudees the piece 405 and is close to each other, it is fixed to carry out the centre gripping with first wire 205 and second wire 206, the messenger is more stable at the in-process that carries out the centre gripping, convenient operation is swift, the practicality has been increased, the inboard of fixed block 404 has extrudees the piece 405 through lead screw 407 spiral mounting, the inboard of extrusion piece 405 is pasted and is had protection pad 406, through the centre gripping that carries out that extrusion piece 405 can be convenient, can protect between first wire 205 and second wire 206 through protection pad 406 simultaneously, the effectual too big condition that causes the damage to first wire 205 and second wire 206 of centre gripping dynamics that prevents, better protection, the convenience has been increased.

The working principle is as follows: when detection is carried out, when pressure is applied to the outer side of the protective layer 104, the PI film 101 can be conveniently deformed and then the top of the hollow shell-shaped porous PDMS supporting body 2 is extruded, when the hollow shell-shaped porous PDMS supporting body 2 is extruded, the sliding block 202 slides along the inside of the sliding groove 102 to enable the first inductance coil 203 and the second inductance coil 204 to be in a parallel state in the deformation process, the measurement process is more accurate, the practicability is improved, the pressure measurement precision is improved, functional elements in the inductive sensor can be conveniently enabled to enable the two parallel-opposite miniature planar inductance coils to be infinitely close to each other, the flexibility and the elastic force of the whole flexible PDMS sponge can be favorably improved, the sensitivity of the sensor is improved, the inductance can be changed due to the mutual close of the first inductance coil 203 and the second inductance coil 204, the pressure can be detected through changed data, the cloth 103 is made of the silver fiber fabric, the wear-resistant fiber and the wear-resistant fabric can be effectively formed by blending metal fibers, the metal fiber fabric, the anti-radiation fabric can be conveniently formed in the extrusion process, the anti-radiation detection process, the anti-radiation polyethylene mesh can be conveniently used in the anti-radiation process, and the anti-radiation detection process, the anti-radiation detection process can be conveniently carried out;

can drive lead screw 407 through rotatory rolling disc 409 in step rotatory, make lead screw 407 can remove to the inboard of fixed block 404 along mount 408, can be convenient make extrusion piece 405 be close to each other, it is fixed to carry out the centre gripping with first wire 205 and second wire 206, make the in-process of carrying out the centre gripping more stable, can be convenient carry out the centre gripping through extrusion piece 405, utilize protection pad 406 to protect between first wire 205 and the second wire 206 through protection pad 406 simultaneously, the effectual too big circumstances that causes the damage of first wire 205 and second wire 206 of prevention clamping dynamics, prevent that the external dynamics of dragging is too big, make to produce the fracture circumstances that drops between the wire, the practicality has increased 303 the convenience, utilize that the loose axle can be convenient overturn between first grip block 4 and the second grip block 401, carry out spacing fixed through fixing knob 403 and butt joint pole 402, it is more convenient in the installation to first grip block 4 and second grip block 401, make the in-process of carrying out the installation more convenient, the practicality has been increased.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (10)

1. The utility model provides a flexible pressure sensing device of empty shell form PDMS of embedded plane inductance coils, includes flexible end liner (1), empty shell form porous PDMS supporter (2) and mounting bracket (3), its characterized in that: a hollow-shell-shaped porous PDMS support (2) is fixed to the upper portion of the flexible substrate (1) in a limiting mode, a PI film (101) matched with the flexible substrate (1) is adhered to the top of the hollow-shell-shaped porous PDMS support (2), radiation-proof cloth (103) wraps the outer sides of the flexible substrate (1) and the PI film (101), a first inductance coil (203) and a second inductance coil (204) are fixedly mounted on the inner wall of the hollow-shell-shaped porous PDMS support (2) respectively, a first lead (205) and a second lead (206) extending out of the hollow-shell-shaped porous PDMS support (2) are electrically connected to the outer sides of the first inductance coil (203) and the second inductance coil (204) respectively, and a mounting frame (3) is fixedly mounted on the outer side of the flexible substrate (1);

the outside fixedly connected with dead lever (301) of mounting bracket (3), and the top of dead lever (301) and the all movable mounting in bottom have first grip block (4) and second grip block (401), one side fixed mounting of first grip block (4) and second grip block (401) has fixed block (404), there is extrusion piece (405) inboard of fixed block (404) through lead screw (407) spiral mounting, the outside fixed mounting of fixed block (404) have with lead screw (407) complex mount (408).

2. The hollow PDMS flexible pressure sensor according to claim 1, wherein: the flexible bottom lining (1) and the hollow shell-shaped porous PDMS supporting body (2) are fixed in a limiting mode through the mounting groove (106), and the flexible bottom lining (1) is flush with the top of the hollow shell-shaped porous PDMS supporting body (2).

3. The hollow PDMS flexible pressure sensing device with an embedded planar inductor according to claim 1, wherein: the PI film (101) is yellow and transparent, and is made of an insulating material of the PI film (101).

4. The hollow PDMS flexible pressure sensor according to claim 1, wherein: the radiation-proof cloth (103) is made of silver fiber fabric, and the surface of the radiation-proof cloth (103) is covered with the protective layer (104).

5. The hollow PDMS flexible pressure sensor according to claim 4, wherein: the outer side of the protective layer (104) is wrapped with a wear-resistant layer (105), and the wear-resistant layer (105) is made of polyethylene plastics.

6. The hollow PDMS flexible pressure sensing device with an embedded planar inductor according to claim 1, wherein: the hollow porous PDMS support body (2) and the flexible bottom lining (1) are installed in a sliding mode through a sliding block (202), and sliding grooves (102) matched with the sliding block (202) are formed in the inner wall of the flexible bottom lining (1).

7. The hollow PDMS flexible pressure sensing device with an embedded planar inductor according to claim 1, wherein: the hollow porous PDMS support body (2), the first inductance coil (203) and the second inductance coil (204) are fixedly adhered through an adhesive tape (201), and the first inductance coil (203) and the second inductance coil (204) are installed in parallel and oppositely.

8. The hollow PDMS flexible pressure sensor according to claim 1, wherein: the top and the bottom of the fixed rod (301) are welded with mounting seats (302), and the mounting seats (302), the first clamping blocks (4) and the second clamping blocks (401) are movably mounted through movable shafts (303).

9. The hollow PDMS flexible pressure sensor according to claim 1, wherein: the first clamping block (4) and the second clamping block (401) are fixed through a fixing knob (403), and a butt joint rod (402) matched with the fixing knob (403) is fixedly installed on the inner side of the second clamping block (401).

10. The hollow PDMS flexible pressure sensing device with an embedded planar inductor according to claim 1, wherein: a protective pad (406) is adhered to the inner side of the extrusion block (405), and a rotating disc (409) is welded to the outer side of the screw rod (407).

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