22667results about How to "Low cost" patented technology

The invention discloses a vehicle idling start and stop control system and method. The control system judges whether a vehicle has idling start and stop conditions by monitoring the water temperatureof an engine, the capacity of a storage battery, a safety belt and other information, judges whether the vehicle has conditions of stopping the engine by monitoring the rotating speed of the engine, the speed of the vehicle, the brake air pressure and other conditions, and judges whether the vehicle has conditions of starting the engine by monitoring the gear of a gearbox, the speed of the vehicle, a hand brake and other information. When the relevant conditions are met, start and stop work signals are sent to the engine though a CAN bus. In order to guarantee the reliability of frequent startand stop of the engine, the system strengthens flywheel gear rings of a starter and the engine. In order to ensure that the battery does not lose power, a storage battery capacity sensor is added tothe system on the basis of increasing the capacity of the storage battery, and the idling start and stop are allowed when the state of charge (SOC) of the storage battery satisfies a safe starting threshold. The idling start and stop control system has advantages of low cost and high reliability, and is especially suitable for commercial vehicles.

The invention belongs to the field of biochar adsorbing materials, and relates to a method for preparing modified biochar with aquatic plant waste and hematite. The method includes the following steps: (1) naturally drying aquatic plants prior to crushing to obtain aquatic plant powder; (2) crushing the hematite to obtain hematite powder; (3) weighing the hematite powder prior to putting the hematite powder into deionized water, and performing ultrasonic treatment to obtain suspension; (4) weighing the aquatic plant powder, soaking the aquatic plant powder in the suspension, and stirring and drying to obtain fully mixed aquatic plant and hematite mixture; (5) weighing the fully mixed aquatic plant and hematite mixture, putting the mixture in a batch-type atmosphere furnace, and feeding nitrogen into the furnace; performing temperature programming to the target temperature, and maintaining final-temperature pyrolysis; after the pyrolysis process is finished, obtaining the target product, namely the modified biochar. The modified biochar has strong adsorbability in nitrate and phosphate, high in stability and reusable.

The invention relates to the technical field of drying equipment, in particular to clothing cloth drying equipment. The clothing cloth drying equipment comprises a box body, a discharging shaft for discharging cloths, a drying module, an ironing module, an air-drying module, a rolling shaft for rolling the cloths and a controller. The top of the left side of the box body is provided with a storinghole for storing the cloths, a damping piece mounted at the bottom of the box body is arranged under the storing hole, and the discharging shaft is vertically mounted on the damping piece. The dryingmodule is used for drying the cloths, the ironing module is used for ironing the cloths, and the air-drying module is used for air-drying the ironed cloths. The rolling shaft is located on the rightside of the air-drying module, a material taking hole for taking out the cloths is formed in the top of the box body over the rolling shaft, the rolling shaft is driven through a rolling motor, and the rolling motor is electrically connected with the controller. The clothing cloth drying equipment is mainly suitable for being used in a clothing manufacturing shop and has the characteristics that the size is small, the weight is small, the price is low, and energy consumption is little.

A broadband omni-directional bicone antenna. The antenna can comprise conductive surfaces of conical voids provided within a solid dielectric structure. The outside surface of the solid structure can support a radio frequency (RF) lens geometry operable for beam forming. The beam forming can modify the elevation pattern of the electromagnetic radiation from the bicone antenna. The solid dielectric structure may be machined or molded from a single piece of material. The conical voids provided within the solid structure can be metallized to provide conductive bicone radiators. The outer surface beam shaping lenses can be zoned or continuous and can provide elevation patterns with increased gain, cosecant squared falloff, or various other patterns. The beam shaping lens may be formed from any low-loss dielectric. Alternatively, the lens may be formed from a less dense material such as dielectric foam that can support radial conductive beam forming vanes.

Disclosed is a wheel cylinder and a drum brake having the same, in which the number of position as well as other elements accompanied with the piston may be reduced, resulting in reduced manufacturing cost.

The invention discloses a pole climbing robot for a wind power tower pole, which is characterized in that the robot mainly comprises a robot body, 4-8 pole climbing mechanisms, a snake-shaped swing arm and a movable studio, wherein the snake-shaped swing arm and the movable studio are mounted on one side of the robot body; the robot body is an annular body formed by combining two semicircular cambered bodies or three equal cambered bodies; the diameter of an internal ring of the circular body is matched with the diameter of the wind power tower pole; the pole climbing mechanisms mainly comprise upper foot wheels, lower foot wheels, connecting arms, driving gears, thrust screw rods, nut gears and supporting seats; the upper foot wheels are connected with the lower foot wheels by the connecting arms through wheel shafts; the connecting arms are connected with the thrust screw rods by connecting pin shafts on the connecting arms, and form movable hinges; the 4-8 pole climbing mechanisms are distributed in the circular robot body uniformly; the snake-shaped swing arm consists of three swing arm parts, namely a large arm, a middle arm and a small arm; and the movable studio comprises two paralleled linear guide rails, a walk driving device and an operation room.

The invention belongs to the technical field of power station boiler waste heat recycling energy-saving equipment and relates to a plate-and-shell type coal economizer. The plate-and-shell type coal economizer comprises a corrugated plate heat exchange core body (1), a heat exchanger shell (2), a first and a second water inlet / outlet water tank (3, 3') and a first and a second exhaust gas inlet / outlet pipeline (4, 4'), wherein the corrugated plate heat exchange core body (1) is mounted in the heat exchanger shell (2), the first and second water inlet / outlet water tanks (3, 3') are respectively arranged at the upper and lower ends of the front side of the corrugated plate heat exchange core body (1), and the first and second exhaust gas inlet / outlet pipelines (4, 4') are respectively arranged at the upper and lower sides of the corrugated plate heat exchange core body (1). The plate-and-shell type coal economizer solves the problem that the length of a water passage needs to be increased to solve the problem of unapparent water heating due to the great difference between an exhaust gas density and a water density, and meanwhile, a corrugated passage at the exhaust gas side enables the exhaust gas flow turbulivity to be increased and the heat transfer efficiency to be improved; the blockage due to ash accumulation happens rarely, even if the ash is accumulated, the cleaning is easy to finish.

The invention discloses a high-strength silver-free copper-based brazing filler metal which is composed of P, Sn, Ni and Cu. The high-strength silver-free copper-based brazing filler metal is low in cost, safe, environmentally friendly and good in welding effect; through the adding of Sn and Ni, the melting point of brazing filler metal alloy is reduced, and the tensile strength and wettability of the brazing filler metal alloy are enhanced.

The invention relates to a low-noise water purifier. The water purifier includes a shell, an integrated waterway plate and booster pumps. The integrated waterway plate is fixed to the shell and is connected to water outlets of the booster pumps through pressure stabilizing tanks. The pressure stabilizing tanks are disposed between the booster pumps and the integrated waterway plate. The integrated waterway plate is connected to a plurality of evenly arranged connection tubes and is connected to filter core base assemblies through the connection tubes in a one-one correspondence manner. Beneficial effects of the water purifier are that 1) water knocking abnormal sound of the water purifier is reduced, thus improving user experience, 2) the structure is simple, water leakage is prevented and the production efficiency is high, and 3) replacement of a consumable of the product is simpler and more convenient.

The invention belongs to the technical field of artificial intelligence and information retrieval, and provides a multi-modal retrieval method and system based on a lightweight knowledge graph and an index table, and the method comprises the steps: obtaining multi-modal source data, and extracting a structured semantic tag set; constructing a lightweight knowledge graph and a metadata index table; analyzing a natural language query input by a user to obtain a semantic query vector and a keyword set, executing semantic retrieval in the knowledge graph to obtain a text candidate result, and executing keyword matching in the metadata index table to obtain a non-text candidate result; for each non-text meta record, fusing the cross-modal similarity between the non-text meta record and the text candidate result, performing index matching on an original score and a graph semantic evidence score, calculating a comprehensive correlation score, and performing reordering; and generating a natural language answer containing a non-text record link according to a reordering result. The method is suitable for efficient cross-modal knowledge retrieval in a high-security and low-resource scene.

The invention provides a tunnel hard rock non-blasting excavation method. The tunnel hard rock non-blasting excavation method can realize efficient excavation of complete or relatively complete hard rock without adopting large excavation equipment such as a heading machine and the like , and is characterized by comprising the following steps of 1, drilling contour holes along a tunnel face contour line so as to determine a tunnel excavation range, and determining each drilling and grooving position according to the excavation range, then, forming and drilling a plurality of cavity expanding holes in the position close to the positions; 2, drilling a plurality of rows of guide holes between the contour holes and the cavity expanding holes; 3, drilling groove forming holes which are meshed and overlapped with each other at the determined drilling and grooving positions, and finally forming a groove cavity; 4, enabling the cavity expanding holes near the groove cavity to be subjected to impact crushing, and therefore expanding excavation is conducted on the groove cavity; 5, according to a certain excavation sequence, starting from the guide holes close to the expanded and excavated groove cavity, adopting a hydraulic breaking hammer for conducting impact breaking on the guide holes, so that excavation of the rock mass of a main body part is completed; and 6, conducting impact crushing on the contour holes.

A natural gas filling device reliable in sealing is disclosed. The device is characterized in that the device comprises a liquid filling gun, a liquid receiving component matched with the liquid filling gun and used for filling a gas cylinder with liquid, and a gas returning component communicated with the gas outlet of the gas cylinder; the liquid filling gun is provided with a first outer shell, a first rotating fastener disposed in the first outer shell and connected to the first outer shell and the inner wall of which is provided with a symmetrical spiral groove, a first valve body between the first rotating fastener and the first shell, and a first valve core disposed in the first valve body and containing a liquid inlet and a liquid outlet; and the liquid receiving component is provided with a first shell, wherein the head of the first shell extends into the first rotating fastener and is in sealing match with the tail part of the first valve body, and the periphery of the first shell is provided with a first pivot pin engaged with the spiral groove in the first rotating fastener. The device is convenient in maintenance, replacement and operation of quick-wear parts and convenient to use. The device can be used for other low-temperature liquid media besides LNG and is simple in structure, low in cost, convenient in operation and reliable in sealing.

The inventive technique process of grainy calcium material for preventing and treating peanut blight primarily includes: adopting the shell powder and weathered coal as raw materials, machining into peanut blight prevention material through agglomeration granulation. The invention has innovative and reasonable design, which not only has simple process, easy implementing, but also has low cost of raw materials, product application convenience, remarkable peanut blight prevention effect, and capability of promoting high-efficient production pf peanut. In particular, the invention applies coastal oyster shell wastes for machining calcium materials for preventing and treating peanut blight, which not only reduces environmental pollution, but also promotes recycling of resources, has very significant economic, social and ecological benefits and greater promotional value.

The invention discloses a light aging test instrument, which includes a test cavity, a bottom baseplate, the top cover board which is fixed on the bottom and the top of the test cavity respectively. A lamp socket which fitted with a lamp is right on the centre of the base plate, the photo permeable holes are set at the same height on the side wall of the test cavity. A visual light narrow wave band filter sheet is in the photo permeable hole, and the sample trough is fitted on the photo permeable hole. The test instrument has a compact structure, easy to disassemble and assemble, inflexible for employ, with low cost of the production.

The invention relates to an anorthite material and a preparation method thereof. The adopted technical proposal comprises the following steps of: according to (ZL200510019664.3) patent technology, namely a method for preparing titanium and a titanium alloy by utilizing titanium-containing furnace slag, taking molten tailings which is extracted with the titanium alloy as a raw material, adding 20 to 50 weight percent of silica, 0 to 60 weight percent of clay and 0 to 40 percent aedelforsite, and cooling a melt to obtain the anorthite material after the mixture is completely molten and a bath composition is uniform; or taking cold tailings extracted with the titanium alloy as the raw material, adding 20 to 50 weight percent of the silica, 0 to 60 weight percent of the clay and 0 to 40 percent the aedelforsite, carrying out mix grinding on the raw material and the admixture until the particle size is less than 0.1 mm, performing blank compression, and calcining the mixture at a temperature of between 1,200 and 1,400 DEG C to obtain the anorthite material. The method takes the tailings extracted with the titanium as the raw material, saves precious bauxite resources, has low cost, ensures that industrial residue is utilized with high added value, is environment-friendly and has simple process.

The invention belongs to the technical field of knowledge graph construction, and particularly relates to a multi-source heterogeneous data fusion and knowledge graph automatic construction system, which comprises a semantic extraction module for extracting minimum semantic fragments from multi-source data and performing cross-source alignment to generate a symbolized semantic framework; the data purification module converts multi-source data into symbolic predicates according to the framework, filters low-evidence data and outputs a purification set; the ternary generation module inputs the initial triad candidate set into a minimum rule grammar, and extracts entities, relationships and attributes to generate an initial triad candidate set; the disambiguation calibration module generates entity two-hop topological fingerprints based on the candidate set, completes disambiguation alignment and corrects conflicts, and outputs unambiguous structured knowledge; the mapping fusion module fuses the mapping information with the minimum connected ontology, and constructs and verifies an initial mapping knowledge domain; and the incremental updating module processes newly added data, performs incremental merging and maintains consistency, and forms a complete knowledge graph. According to the method, through full-link automatic construction, efficient fusion and high-quality atlas are realized.

A flow direction control device of heating stream and cooling stream is prepared as connecting said device separately to the first heat exchange unit, the second heat exchange unit, air conditioner and compressor for controlling heated working fluid from the first heat exchange unit to be sent to air conditioner for being used as the first heat media or to be sent to the second heat exchanger for being condensed there then to send it to air conditioner for being used as the second cooling media in order to make air conditioner output hot and cold alternatively, enabling to set heating course on the first heat exchange unit for providing the third heat media out.

The invention relates to a bactericidal composition containing fluxapyroxad and thiediazole copper. The bacterial composition is compounded from fluxapyroxad and thiediazole copper in a binary mode, wherein a mass ratio of fluxapyroxad to thiediazole copper is (1-50) to (50-1); a mass fraction of fluxapyroxad and thiediazole in the preparation is 1%-80%, and the rest of the preparation is auxiliary components which are allowed to use and are acceptable in a pesticide. A dosage form of the bactericidal composition is missible oil, a suspending agent, wettable powder, a water dispersible granule, emulsion in water, microemulsion, a granule and a micro-capsule. The bactericidal composition is mainly used for controlling plant gray mold, peronospora and phytophthora germs.

The invention provides stamping equipment for automobile engine oil pan production, and belongs to the technical field of oil pan stamping equipment. Which comprises a stamping equipment body and is characterized in that a lower die and an upper die are installed on the stamping equipment body, a first supporting frame is installed on one side of the stamping equipment body, and a second supporting frame is installed on the other side of the stamping equipment body; an automobile oil pan material plate is placed on the top of the first supporting frame. By arranging the auxiliary feeding mechanism and the auxiliary discharging mechanism, the auxiliary feeding mechanism can be utilized, workers do not need to make direct contact with an automobile oil pan material plate, the automobile oil pan material plate can be rapidly and stably transferred to the position between the lower die and the upper die, and accurate alignment can be achieved after transferring, and the automobile oil pan material plate can be reliably placed on the top of the lower die; and compared with a traditional manual handheld plate feeding mode, the feeding device is safer and more reliable.

The utility model discloses rotary shuttling transportation mold connecting equipment which comprises a rotating device and a mold, the rotating device is arranged on an injection molding machine, at least one mold lifting and positioning device is arranged on the rotating device, and the mold is arranged on the mold lifting and positioning device and matched with the injection molding machine. According to the rotary shuttling transportation mold connecting equipment, the rotating device is arranged on one side of the injection molding machine, the two molds are installed on the rotating device, the injection molding machine and a worker are located on the corresponding mold sides respectively, and the two molds change positions back and forth on the positions of the injection molding machine and the worker under reciprocating transportation of the rotating device; therefore, when the mold at one end is in corner connection, the mold at the other end is in strip installation, the problem of long waiting time of workers or frequent walking of the workers is avoided, the production efficiency is improved, and the cost of an injection molding machine and the mold can be saved within the same production efficiency of the conventional production mode.

The invention discloses a coated titanium anode and an embedding preparation method thereof, and belongs to the technical field of coated titanium anodes, metal salt powder, an organic additive and inert filler are fully mixed to form embedding agent powder, the mass fraction of metal salt is 45-59%, the mass fraction of the organic additive is 1-5%, and the mass fraction of the inert filler is 40-50%; the sintering treatment is as follows: the pretreated titanium substrate is completely immersed in the embedding agent powder, the sintering temperature is 400-600 DEG C, the sintering time is 1-3 hours, and the heating rate is 5-10 DEG C / min. According to the method, low-temperature sintering is realized by precisely regulating and controlling the components and the proportion of the embedding medium and combining process parameters such as low-temperature sintering, and the damage to a titanium substrate is avoided; and meanwhile, the coating binding force of the titanium anode is improved, the service life of the titanium anode is prolonged, and technical innovation and industrial value are achieved.

The invention belongs to the cross technical field of remote sensing data processing and soil environment monitoring, and discloses a multi-source remote sensing collaborative soil quality index inversion and comprehensive evaluation system and method, and the method comprises the following steps: obtaining different types of remote sensing data in a target area, and constructing a multi-source data set; the acquired multi-source remote sensing data are preprocessed, data noise and system errors are eliminated, and data consistency is ensured; performing multi-source remote sensing data fusion by adopting a spectrum-polarization-texture collaborative fusion strategy in combination with a multi-scale decomposition and weighted fusion model; based on the fusion data, constructing a machine learning inversion model, and inverting soil quality key indexes; and carrying out comprehensive evaluation on the soil quality by adopting an analytic hierarchy process-matter element extension model to realize grading of the soil quality. By adopting the multi-source remote sensing collaborative soil quality index inversion and comprehensive evaluation system and method disclosed by the invention, rapid, accurate, large-area and dynamic monitoring and comprehensive evaluation of soil quality are realized.

The invention discloses a preparation method of a high-yield camellia oleifera shell pulp. The preparation method of the high-yield camellia oleifera shell pulp specifically comprises the steps of mechanical grinding, pre-impregnation, mechanical disc grinding treatment, washing, defibering and screening. The preparation method prepares the high-yield camellia oleifera shell pulp through a chemical and mechanical method; the prepared high-yield camellia oleifera shell pulp has the advantages of being high in yield, good in pulping performance and drainability and the like and can be applied tothe fields of paper-based packaging, molding and decorating materials and the like, thereby to some extent easing the stress brought about by shortage in papermaking fiber resources. Besides, a largenumber of waste camellia oleifera shells are applied to the fields of pulping and papermaking to achieve efficient and high-value application of agricultural waste.

The invention discloses a cisatracurium besilate content testing method which comprises the following steps: respectively weighing a test substance and a reference substance in a measuring flask, adding hydrochloric acid for dissolving and metering a volume to a scale, shaking up to prepare a corresponding solution, finally, measuring the solution according to an ultraviolet-visible spectrophotometry, measuring absorbance at a place of a maximum adsorption wavelength of 280nm, and calculating the content of cisatracurium besilate according to an anhydrous substance. According to the cisatracurium besilate content testing method, the solution is simply and conveniently prepared, no organic solvent is used, and the pollution to the environment and the harm to a human body are small. The cisatracurium besilate content testing method is higher in testing speed, and the time of testing each batch of products in average only needs 30 min. A place of a maximum adsorption wavelength of 280 nm is selected, so that the testing accuracy is ensured. The cost of a reagent used in a process of checking each batch of samples does not exceed 20 yuan; the testing cost of each batch of samples by adopting a high-performance liquid chromatography method is not less than 200 yuan, so that the cost of enterprises is greatly lowered.

The invention discloses a multipath channel parameter reconstruction and beam coverage prediction method, and relates to the technical field of wireless communication. Aiming at the problems of low data utilization efficiency, limited environment modeling precision, strong coupling of measured data and antenna beam configuration and the like in the prior art, the method comprises the steps of configuring antenna beams and orientation parameters, collecting reference signal receiving strength, performing deterministic channel modeling simulation, establishing a mapping model, performing sparse recovery, constructing a channel propagation model, evaluating a channel map and the like. In combination with a coherence perception weighting network (CARE-Net) algorithm and ray tracing (RT) physical prior guidance, accurate reconstruction from a low-dimensional reference signal receiving strength (RSRP) measurement value to a high-dimensional multipath parameter is realized. The method has the advantages that the reconstructed multi-path parameters are decoupled from the antenna configuration, the method has the cross-beam / cross-configuration generalization prediction capability, the channel coverage performance under different antenna configurations can be accurately predicted, a reliable basis is provided for wireless network optimization, and the method is low in cost, high in precision and strong in generalization.

The invention discloses an SNP (Single Nucleotide Polymorphism) molecular marker related to sheep fecundity and application of the SNP molecular marker. The SNP molecular marker comprises an SNP1 (Single Nucleotide Polymorphism) and / or an SNP2; the SNP1 is located at a base at the 115747587 site of a chromosome 6 of a sheep reference genome AR-UIRamV2.0 version, and the polymorphism of the SNP1 is T / G; the SNP2 is located at a basic group at the 41419566th site of a chromosome 22 of a sheep reference genome AR-UIRamV2.0 version, and the polymorphism of the SNP2 is A / G. According to the scheme, the SNP molecular marker related to sheep fecundity is provided, sheep with the high fecundity character can be efficiently and accurately identified and screened out, and the marker is high in typing quality, single in copy and high in polymorphism and can be used for sheep fecundity molecular marker assisted breeding.

The invention relates to an ultrasonic fluid metering precision improving method and related equipment, and the method comprises the steps: exciting a first ultrasonic transducer through an excitation wave sequence, enabling a second ultrasonic transducer to work, obtaining a received digital signal corresponding to the excitation wave sequence, and calculating the signal-to-noise ratio of the received digital signal; wherein the excitation wave sequence is a combination of a main wave and a self-damping wave, and the signal-to-noise ratio is a ratio of a peak-to-peak value of a receiving signal area to a peak-to-peak value of a noise area; judging whether the signal-to-noise ratio is greater than a signal-to-noise ratio threshold value or not, if not, adjusting the occupation time of the high and low levels of the self-damping waves, and executing the excitation work again according to the adjusted excitation wave sequence until the actual signal-to-noise ratio is greater than the signal-to-noise ratio threshold value; and determining the corresponding excitation wave sequence when the actual signal-to-noise ratio is greater than the signal-to-noise ratio threshold as a target excitation wave sequence, and exciting the ultrasonic transducer to work according to the target excitation wave sequence so as to execute metering operation. According to the method, the measurement precision is remarkably improved while the hardware cost is not increased.

The invention provides an air source heat pump system. The air source heat pump system comprises a compressor, a fin heat exchanger, a shell tube heat exchanger and a gas-liquid separator, wherein the shell tube heat exchanger comprises a gas tube, a liquid tube, a heat exchange tube and a liquid separating device, the air source heat pump system further comprises a four-way valve, the four-way valve is correspondingly communication with the compressor, the gas-liquid separator, the fin heat exchanger and the gas pipe, the fin heat exchanger is in communication with the liquid separating device through a orifice plate and a first one-way valve; the fin heat exchanger is in communication with the liquid tube through an expansion valve and a second one-way valve; the first one-way valve is used for the one-way conduction of the fin heat exchanger to the liquid separating device; the second one-way valve is used for the one-way conduction of the liquid pipe to the fin heat exchanger. By the adoption of the system, a liquid storage device of the liquid refrigerant does not need to be added in the system, so that the cost is saved; a large amount of liquid refrigerant cannot flow back to the compressor after defrosting is finished; during the refrigeration mode, the refrigerant running shell pass does not need to be subjected to suction superheat, so that the air suction pressure and the operation efficiency of the refrigeration mode are improved; and the overall use valve of the system is less, and the reliability is high.

The invention discloses an Mg + Nb co-doped TiO2 giant dielectric ceramic material and a preparation method thereof, and relates to the technical field of giant dielectric materials. The (Mg + Nb) co-doped TiO2 ceramic is successfully prepared by adopting a traditional solid phase method, the performance of the TiO2-based giant dielectric ceramic is regulated and controlled through a new doping strategy, the raw material is single, the preparation process is simple, the cost is low, the repeatability is good, the yield is high, the obtained ceramic material has giant dielectric performance, and the preparation method is suitable for industrial production. The (Mg + Nb) co-doped TiO2 novel giant dielectric ceramic can meet the requirements of a dielectric material with high dielectric constant, low dielectric loss and good temperature and frequency stability, and compared with other widely applied giant dielectric materials, the titanium dioxide-based giant dielectric ceramic has the characteristics of simplicity in preparation and excellent dielectric property.

The invention relates to a two-chamber low-pressure casting holding furnace and a low-pressure casting method. The two-chamber low-pressure casting holding furnace comprises a heat preservation chamber, a low-pressure casting chamber, a communicating cavity, a liquid rising pipe, a first air inlet pipe and a liquid opening, wherein the heat preservation chamber comprises a precipitation cavity and a confluence cavity; and the communicating cavity comprises a liquid inlet section, a transition section and a liquid outlet section. Compared with the prior art, the heat preservation chamber of the holding furnace is directly communicated with the low-pressure casting chamber, an intermediate valve is omitted, and the pressure bearing capacity of the holding furnace is greatly improved; and large pressure can be generated by arranging a second air inlet pipe and enabling the second air inlet pipe to be matched with the first air inlet pipe, so that the overall working performance of the holding furnace is improved in a spanning manner, the holding furnace can be used for producing thin structural parts, such as automobile chassis parts, A columns and B columns, with larger projection areas, and the practicability of the holding furnace is greatly improved.