89results about How to "Reduce the amount of processing" patented technology

The invention discloses a ring rolling process method of a titanium alloy seamless barrel for four-meter unmanned deep diving, and belongs to the technical field of hot rolling forming of large barrel parts. The method comprises the following steps that a titanium alloy cast ingot is smelted, and the chemical components of the titanium alloy cast ingot and the actual temperature of a phase transformation point T beta are detected; the titanium alloy cast ingot is cogged, and then the cogged cast ingot is subjected to reversing upsetting and rounding according to the actual temperature of the phase transformation point T beta to be manufactured into a bar billet; punching is conducted on the bar blank, and a ring blank is manufactured; a core rod is inserted into the ring blank, and the ring blank is drawn to the length of a finished cylinder piece; chambering the ring blank on a mandrel supporter; rolling the ring blank into a 4000 mm cylinder piece; the 4000 mm cylinder part is subjected to heat treatment bulging; performing bulging treatment on the cylinder part; surface and wall thickness machining is conducted on the cylinder part; and carrying out finished product detection on the cylinder piece. The problems that an existing four-meter titanium alloy barrel part cannot be integrally formed, the structure and performance are not uniform, the material utilization rate is low, the production cost is high, the use safety is low, and the service life is short can be solved.

The invention discloses a mobile phone middle frame manufacturing process, and belongs to the technical field of portable intelligent equipment middle frame structure manufacturing processes, the mobile phone middle frame manufacturing process comprises the following steps: firstly preparing a middle plate die casting, then respectively preparing a plurality of frame pieces, and then connecting the middle plate die casting with at least two frame pieces by using a laser welding process; the middle plate-frame part is machined, so that the preset positions of the middle plate die casting and the frame part are machined to prepare injection molding groove positions; thirdly, in-mold injection molding is carried out on the machined middle plate-frame piece, finally, after in-mold injection molding is carried out on the workpiece, mechanical finish machining is carried out, and surface treatment is carried out to obtain a finished product. According to the manufacturing process of the mobile phone middle frame, the technical problems that in the prior art, products are low in end, the process is limited, the machining cost is high, and the quality is unstable are solved.

This invention belongs to the field of aerospace structural component manufacturing technology, specifically relating to an arc-shaped cap and its integrated bending forming method and application. The integrated bending forming method includes the following steps: S1, blanking to obtain a cap plate blank or cap frame blank; S2, milling to machine the external dimensions and hole positions before bending, obtaining a flat, non-arc semi-finished product; S3, bending, placing the flat semi-finished product between the punch and die of a bending die, and applying pressure to press it into an arc-shaped part with a predetermined curvature; S4, stress-relieving treatment of the bent arc-shaped part to eliminate its internal residual stress; S5, shaping, bending and shaping again to stabilize its curvature shape, obtaining the final arc-shaped cap product. This invention effectively solves the problem of springback during sheet metal bending by introducing a combination of bending die design, graded pressure control, and stress-relieving and shaping processes, ensuring the accuracy of the final product's curvature and external dimensions.

The invention provides a preparation method capable of preparing a special-shaped diamond-copper-tungsten composite material, which comprises the following steps: mixing metal tungsten powder and an organic binder, granulating, and injecting into a special-shaped mold to obtain a shell green body; degumming and sintering the shell green body to obtain a first tungsten skeleton shell with a porous structure; filling the first tungsten skeleton shell with a porous structure with the diamond powder coated with the metal tungsten to obtain a second tungsten skeleton shell; and the second tungsten framework shell is placed in a mold, metal copper is placed on the surface of the second tungsten framework shell for vacuum infiltration, and the diamond-copper-tungsten composite material is obtained. According to the preparation method, various special-shaped parts can be directly prepared while the dimensional precision of the product is guaranteed, the finished product can be obtained only by performing fine treatment on the surface, the machining amount is reduced, and the effects of reducing cost and improving efficiency are achieved.

The present invention discloses a fine blanking process method for a compressor intermediate plate blank, which is characterized in that it includes the following processes: material preparation → stamping → turning the outer circle → drilling small holes → double-sided grinding → cleaning → full inspection and packaging; wherein, the fine blanking process includes the use of a special composite mold, and the special composite mold includes an upper mold component and a lower mold component that are relatively arranged up and down; both the upper mold component and the lower mold component adopt a relatively scientific and reasonable structure to realize the synchronous processing of key holes and the shape. Its advantages are: it saves two processes of heating and correction, and the drilling process reduces the processing amount of 7 holes, greatly reduces and simplifies the processing process, reduces production costs, improves efficiency, and improves product quality; the key holes are processed synchronously with the shape, and no secondary positioning is required, there is no accumulated error, the shape and position dimensions are more stable, and the product yield is greatly improved; the consumption of materials and energy is greatly reduced, energy saving and environmental protection; it also solves the problem that the φ7 and φ9 holes have small margins and are difficult to form.

The present invention provides a shock-absorbing tenon test bench and test method, which relate to the field of bridge construction technology, in order to solve the problems of low efficiency and complicated operation of the shock-absorbing tenon test device. The shock-absorbing tenon test bench comprises an upper clamping assembly and an L-shaped claw movably connected to the test bench frame, the upper clamping assembly is connected to the actuator of the test bench, and the upper clamping assembly is used to clamp the ball head of the shock-absorbing tenon; the upper clamping assembly comprises a movable chuck and a fixed chuck cooperating with the movable chuck, the movable chuck is movably connected to the fixed chuck, the fixed chuck is connected to the actuator, and the movable chuck and the fixed chuck both have a trapezoidal groove for accommodating the ball head; the claw is used to clamp the side and upper surface of the flange of the shock-absorbing tenon. The shock-absorbing tenon test bench provided by the present invention is used for reciprocating performance testing of shock-absorbing tenons.

The utility model discloses a pressure-resistant coil framework structure of a displacement sensor, which comprises a pressure-resistant pipe, a first sealing head and a second sealing head, and the first sealing head and the second sealing head are respectively arranged on the outer sides of the two end parts of the pressure-resistant pipe. The two ends of the pressure-resistant pipe coaxially penetrate into the first sealing head and the second sealing head respectively; outer threads are arranged on the outer sides of the two ends of the pressure-resistant pipe, the two ends of the pressure-resistant pipe are in threaded connection with the first sealing head and the second sealing head through the two sets of outer threads, and two sets of annular mounting grooves are coaxially formed in the outer side of the second sealing head. The utility model has the beneficial effects that the functions of the pressure-resistant pipe and the framework are integrated, the pressure-resistant pipe and the framework are not independently arranged for splicing, and the pressure-resistant pipe is of a through hole structure and is processed by using a pipe material, so that the processing amount of parts is reduced, and the processing difficulty and the processing cost are reduced; and a sealing ring is arranged in the mounting groove to serve as a sealing structure, an original welding sealing structure is replaced, and the mounting difficulty is reduced.

The present invention provides a switch structure for a tramway, which is mainly composed of a manganese steel base and a straight base rail and a curved tip rail fixed inside the manganese steel base, wherein the manganese steel base includes a first connecting section located at the head, a second connecting section located at the tail, and a base section located between the first connecting section and the second connecting section. The base is integrally cast using high manganese steel, which has a short process production cycle, a small processing amount, and a great advantage in production cost. Since the base is integrally cast, after assembling the straight base rail and the curved tip rail, the overall structural stability is very good and the assembly accuracy is also higher. The straight base rail and the curved tip rail can be made of alloy steel plates, and their hardness is usually above 380HBW, which can well meet the user's requirements for wear resistance and reduce the workload of maintenance and repair.

The invention relates to the technical field of torsional spring angle detection measuring tools, in particular to a universal angle detection measuring tool and method for a central arm torsional spring, and the device comprises an outer main body, a sliding block assembly, a sliding ruler, an inner main body assembly, a centering assembly and the like. Measurement, use and operation are convenient, the measurement result is accurate, and the torsion spring structure universality and applicability are good; the measuring function of replacing the existing special angle sample block can be met, and the function of actually measuring any angle value is achieved; the processing and manufacturing number of the torsion spring angle gauge blocks is reduced, the use cost of the measuring tool is reduced, and the period of manufacturing a special measuring tool is also reduced; and the technical requirements of short production cycle, low cost and high quality at present are met.

The joint self-calibration lower limb rehabilitation exoskeleton device comprises a hip joint, a thigh component, a knee joint, a shank component, an ankle joint and a sole bearing plate, a limb extension part is telescopically arranged at the end, opposite to the knee joint, of the thigh component, and the thigh component is connected with the knee joint through the limb extension part; a magnetic locking module is fixed on the side wall of the thigh component, a groove is formed in one side of the limb extension part, and an iron patch is fixed on the groove through a bolt. According to the lower limb rehabilitation exoskeleton device with the joint self-calibration function, through the combined arrangement of the magnetic locking module and the iron patch, the effect of locking the limb extension part can be effectively achieved, and therefore compared with the mode in the prior art, the problem that in a disclosed patent, manual locking and pre-length adjustment can only be achieved, and the operation is inconvenient is solved. And the problem that the length cannot be adjusted in the movement process is solved.

The utility model discloses a ball valve limiting mechanism of an RD pressure test valve, which comprises a ball cage, a ball valve arranged in an inner hole of the ball cage, a spherical pit arranged on the surface of the ball valve, a compression screw arranged on the side wall of the ball cage, a spring arranged in an inner hole of the compression screw, one end of the spring connected with the compression screw, and the other end of the spring connected with a steel ball. The steel ball is used for being matched with the spherical pit to limit the ball valve. The steel ball is arranged on the ball cage, and the spherical pit is formed in the ball valve, so that the ball valve can be locked at the opening position after being opened, and the inner hole of the ball body is kept concentric with the inner hole of the tool body, and the problem that the inner hole of the ball body is not concentric with the inner hole of the tool body after the ball valve of the RD pressure test valve is opened in the prior art is solved. The inner hole of the ball valve and the sealing surface of the ball seat are eroded, and the service life of the ball valve is further influenced.

The present invention provides a protective device and method for argon arc welding of gas turbine inserts, including a welding protective tool, wherein the welding protective tool includes a base, a cover plate, an adjusting screw and a bottom pad, wherein the upper end of the base is an arc surface structure, the lower end of the base is connected to the cover plate, and an argon gas channel is provided on the base; one end of the adjusting screw is connected to the lower end of the cover plate; the free end of the adjusting screw is connected to the bottom pad; the present invention utilizes a protective device to ensure an accurate welding position, prevent internal welding defects and welding cracks, and improve labor production efficiency and processing quality.

The present invention relates to a method for manufacturing a crossbeam of a digital printing machine. The method is to manufacture the crossbeam by combining a polymer composite material with a steel beam blank. First, the steel beam blank and a mold are prepared, and then the steel beam blank is placed in the mold. Finally, the composite material is poured into the mold to form a guide rail mounting surface of the crossbeam. The present invention makes the accuracy of the guide rail mounting surface on the crossbeam have good controllability by pouring a polymer composite material layer, greatly reduces the processing amount, and thus greatly reduces the deformation generated during the processing, so that the crossbeam has the advantages of high precision and good stability, and the entire manufacturing process is simple, fast and efficient.

The application discloses a kind of laser cutting equipment and method for metal processing, including base, the outside of the base is provided with wheel rotation mechanism, the wheel rotation mechanism includes rotating roller, the shaft end of the rotating roller is connected with support plate, the outer surface of the support plate is fixedly connected with the outer surface of base, the outer camber surface of the rotating roller is opened with clamping groove at equal angle, the outer surface of the rotating roller is fixedly connected with telescopic link on both sides, the output end of telescopic link on both sides is fixedly connected with connecting plate, the body of the connecting plate is rotatably connected with two rotating rods, one end of one rotating rod is fixedly connected with circular platform, relate to cutting equipment technical field, solve the problem that actual processing efficiency is reduced, power consumption is increased when existing laser cutting equipment is used, since only single metal pipe can be carried during cutting process, metal pipe cannot be accurately blanked due to not being provided with guiding and buffering measures, and metal pipe cannot be avoided to be damaged by collision.

The present invention relates to a positioning tool for welding an auger shaft, comprising a support frame, a tool support platform fixed on the support frame, a fixed end positioning mechanism for positioning the shaft head at one end of the auger shaft installed at one end above the tool support platform, and a sliding end positioning mechanism for positioning the shaft head at the other end of the auger shaft installed at the other end; an array of positioning clamping mechanisms is arranged between the fixed end positioning machine and the sliding end positioning mechanism along the setting direction of the auger shaft; two groups of pop-up rotating support seats for lifting the auger shaft to the upper working position are arranged at intervals between the array of positioning clamping mechanisms. The positioning tool has accurate and reliable positioning, reduces the amount of post-welding processing, is suitable for welding various types of auger shafts, reduces work intensity, and improves work efficiency.

[Problem] To provide: a novel tetrahydroisoquinoline (THIQ) alkaloid compound having a macrocyclic structure; an intermediate of the compound; and a method for producing the compound. [Solution] Provided is a compound represented by formula (I), or a pharmaceutically acceptable salt thereof. The present invention also provides: a method for synthesizing this compound; and an intermediate compound useful in this synthesis.

The utility model discloses a fiber bragg grating displacement sensor with an anti-tamper self-destruction casting shell, which comprises an anti-tamper self-destruction shell, a displacement measurement conduction unit, a measurement unit and a self-destruction device, and is characterized in that the displacement measurement conduction unit and the measurement unit are both mounted on the anti-tamper self-destruction shell; the measuring unit comprises a modularized temperature compensation substrate, a modularized displacement elastic sheet, a fiber inlet pressing plate and a fiber inlet pressing plate fixing bolt; the modularized temperature compensation substrate and the substrate of the modularized displacement elastic sheet are both made of inorganic elastic materials and are packaged in a solid state. The utility model aims to reduce the processing amount, reduce the batch production cost, improve the processing efficiency, improve the safety and confidentiality of monitoring work, and prevent human factors from influencing the authenticity of monitoring data; the measuring center position and the vertical direction of a measured object point are kept unchanged all the time, installation is more flexible and convenient, the guide block uses a screw to further limit radial run-out of the sliding column, and the measuring precision is further improved.

The invention discloses a preparation method of a zirconium ball valve core, which is characterized by comprising the following steps: S1, smelting to obtain a zirconium ingot with the specification of phi 600mm; s2, saw cutting is conducted, and the materials are divided into four equal parts; s3, cogging forging is conducted, and a rough circle of phi 350 mm is manufactured; s4, sawing again; s5, blank manufacturing and forging are carried out, and a blank with the height being 330 mm is obtained; s6, punching is conducted, and an annular blank is obtained; and S7, a finished product is rolled into the blank, an 80KN broaching machine is used for broaching, an inner hole and the outer diameter are continuously rolled to the forging size, then heat treatment is conducted, finish machining is completed after heat treatment, and the valve element is obtained. The preparation method of the valve element is suitable for batch production, the product structure uniformity is stable, the quality is good, the overall strength is high, abrasion is not prone to occurring, raw materials are saved, the regular spherical surface is directly rolled, the machining amount is small, the machining time cost is greatly reduced, and the cost is greatly reduced.

The invention discloses a pipeline anti-deviation motorized different-direction disc cutting machine which comprises a mounting base, a cutting mechanism and a clamping plate, the cutting mechanism and the clamping plate are arranged at the top end of the mounting base, a hinge table is mounted at the top end of the mounting base, an arc-shaped frame is arranged on one side of the hinge table, one end of the hinge table is movably clamped on the arc-shaped frame, and the cutting mechanism is rotationally arranged at the top end of the hinge table. A pair of rib plates is arranged on the mounting base, the clamping plate is movably clamped between the rib plates, a chip groove is formed in the bottom of the mounting base and located between the rib plates, and a buffer frame and a protective frame are arranged at the top end of the clamping plate. Compared with the prior art, a steel pipe can be rapidly positioned and clamped through the movable inserting rod and the positioning sliding block on one side, the adjusting shaft at one end is adjusted to move according to the size and the inner diameter of the steel pipe, the limiting shaft and the steel pipe are concentrically arranged, and the limiting shaft can abut against one end of the steel pipe in the subsequent clamping process; and the influence caused by vibration deviation is reduced, and the stability of cutting machining is guaranteed.

The application discloses a laser additive manufacturing method for obtaining a titanium alloy dual-phase structure and a titanium alloy, and relates to the field of laser additive manufacturing of metal materials. The method comprises the following steps: S1, loading titanium alloy powder into a powder feeder; S2, fixing a substrate on a forming table in a closed argon warehouse; S3, after the water and oxygen content in the argon warehouse is less than 50 ppm, starting laser additive manufacturing, and melting and depositing the titanium alloy powder synchronously fed on the substrate; S4, after continuously depositing 3-4 layers, reducing the powder feeding rate to 20%-30% of the original powder feeding rate, keeping other laser additive manufacturing parameters unchanged, and continuously depositing a layer; and S5, repeating the steps S3 and S4 until the size requirement of the titanium alloy component is reached. Through the above method, the remelting depth is accurately controlled, the heat cycle effect is realized, the spheroidization regulation of the micron-thin sheet of the deposited layer sample is realized, and thus the titanium alloy component with the dual-phase structure is directly prepared.

The present disclosure provides a piezoelectric ceramic driving array and a surface shape adjustment method. The piezoelectric ceramic driving array comprises a bottom electrode layer, a piezoelectric ceramic array and an insulating layer which are sequentially stacked, the bottom electrode layer comprises arrayed bottom electrodes; the piezoelectric ceramic array comprises at least one layer of piezoelectric ceramic array units, and the plurality of layers of piezoelectric ceramic array units are stacked, each layer of piezoelectric ceramic array units comprises a positive electrode layer and a negative electrode layer which are stacked; the positive electrode layer comprises a first piezoelectric ceramic sheet and a positive electrode array formed on the surface of the first piezoelectric ceramic sheet, and the negative electrode layer comprises a second piezoelectric ceramic sheet and a negative electrode array formed on the surface of the second piezoelectric ceramic sheet; each positive electrode on the same positive electrode layer is independent of each other, and the positive electrodes at the same position on different positive electrode layers are connected to the bottom electrode at the corresponding position after being adjacent; each negative electrode on the same negative electrode layer is connected to at least one adjacent negative electrode, and the negative electrodes at the same position on the edges of different negative electrode layers are connected to an external circuit after being adjacent.

An encoding method of generating a first bitstream to be merged with a second bitstream. The encoding method includes: determining a first adaptive loop filter (ALF) setting that is a setting of an ALF for a first subpicture to be encoded into the first bitstream (S1061); encoding first ALF setting information indicating the first ALF setting into the first bitstream (S1062); and encoding the first subpicture into the first bitstream according to the first ALF setting (S1063), in which, in the determining of the first ALF setting, an ALF setting that does not refer to an adaption parameter set (APS) index referred to in the second bitstream is determined as the first ALF setting.

The utility model discloses a low-cost split type valve seat for a knife gate valve, which comprises a valve main body, the valve main body is composed of a side valve body I and a side valve body II, a gate plate groove is arranged in the side valve body I, valve seat grooves are communicated with the two sides of the gate plate groove in the side valve body I, and the valve seat grooves are communicated with the gate plate groove in the side valve body II. U-shaped ring grooves are formed in the left side, the right side and the lower end of the gate plate groove in a communicating mode, the upper ends of the two sides of each U-shaped ring groove are communicated with the corresponding valve seat grooves respectively, valve seat blocks are clamped in the valve seat grooves, through grooves matched with the valve seat blocks are formed in the positions, corresponding to the U-shaped ring grooves, of the valve seat blocks in a communicating mode, and U-shaped sealing rings are clamped in the U-shaped ring grooves. The upper ends of the two sides of the U-shaped sealing ring are clamped in the through grooves correspondingly, and the end, away from the first side valve body, of the valve seat block and the end, away from the second side valve body, of the U-shaped sealing ring abut against the second side valve body. The valve body is small in machining amount and low in cost, and the flashboard is easy to open.

The invention is applicable to the technical field of special-shaped composite materials, and provides a high-strength arc-shaped composite material plate which comprises a glass fiber layer and a resin layer, wherein the glass fiber layer is formed by sequentially laying three kinds of glass fiber cloth with different specifications; the resin layer is prepared from the following raw materials in parts by weight: 100 parts of resin, 81.95 to 82.05 parts of a curing agent and 0.245 to 0.0.25 part of an accelerant. The invention further provides a forming process of the high-strength arc-shaped composite material plate. According to the invention, a vacuum resin pouring molding process is adopted, and the resin infiltrates the glass fabric in a vacuum state, so that the contents of air and other volatile matters are greatly reduced, and the composite material plate has excellent performance; the mold adopts the female mold, so that the problem of wrinkles after vacuumizing of the glass fabric is greatly reduced, shrinkage and deformation of a formed product are fully considered, during specific implementation, the reversible deformation size is calculated according to actual conditions, the mold is designed according to the size, the processing amount is reduced, and the mechanical strength of the composite material plate is improved.

The present application relates to the technical field of part processing, and discloses a forging forming method and tool for large thin-wall drum-shaped parts, comprising the following steps: step 1, designing a forging drawing according to the size of the part; step 2, designing a tire mold tool according to the forging drawing; the tire mold tool comprises a hollow forming tire mold, an upper pad mold and a punching tool; step 3, determining the process parameters of staged heating and the forging process parameters of each step; step 4, performing forging forming processing according to the steps, and obtaining a forging part. The present application can achieve high product processing quality, help to improve processing efficiency and reduce processing cost.

The invention discloses a production method of a main sliding cylinder die forging of an undercarriage system for an airplane, and relates to the technical field of forging. According to the specific technical scheme, the method comprises the steps of forging-changing heating, forging-changing forging, blank making heating, blank making forging, rough pressure heating, rough pressure forging, primary trimming, primary corrosive washing damage repairing, pre-forging heating, pre-forging forging, secondary trimming, secondary corrosive washing damage repairing, final forging heating, final forging forging, third corrosive washing damage repairing, annealing, machining, solution treatment and aging treatment. The method comprises the steps of forging-changing heating, forging-changing forging, blank making heating, blank making forging, rough pressure heating, rough pressure forging, primary trimming, primary corrosive washing damage repairing, pre-forging heating, pre-forging forging, secondary trimming, secondary corrosive washing damage repairing, final forging heating, final forging forging, third corrosive washing damage repairing, annealing, machining, solution treatment and aging treatment. According to the production process for the main sliding cylinder die forging of the undercarriage system for the airplane, the main sliding cylinder die forging which is good in comprehensive performance, small in machining amount and stable in quality can be produced, the main sliding cylinder die forging can replace an imported die forging, and the use requirement of a commercial airplane is met.

The utility model discloses a belt pulley forging device which is characterized by comprising a machine frame, a supporting table is arranged in the middle of the machine frame, a notch is formed in the middle of the supporting table, a supporting block is arranged in the notch, rotating shafts are connected to the left end and the right end of the supporting block, and rotating seats are arranged at the positions, located on the left side and the right side of the supporting block, in the machine frame. The rotating shafts are rotationally arranged in the rotating seats, a turnover motor is arranged in the rack, a motor shaft of the turnover motor is in driving connection with one rotating shaft, and limiting holes are formed in the left side and the right side of the supporting block correspondingly. According to the die-casting die, a die-cast product can be turned over and discharged, and the situation that the product falls off and scalds workers is avoided.

The application discloses a titanium alloy special-shaped material production process for a mobile phone physical SIM card holder, and comprises the following steps: continuously hot-rolling titanium alloy wire rods to deform to corresponding sizes; performing acid pickling at least once before the last hot-rolling to remove the surface oxides of the wire rods; performing annealing treatment at least once after the last hot-rolling; performing cold-rolling and shape correction after the annealing to make the cross-sectional size of the product meet the final product size; performing annealing treatment at least once after the cold-rolling; performing acid pickling at least once after the cold-rolling and annealing treatment to remove the surface oxides of the wire rods; cutting after online straightening to form the final special-shaped material for the SIM card holder; and the multiple rolling and heat treatment mode solves the problem of difficult machining and forming of the titanium alloy, the shape of the wire rod is shaped through cold-rolling, the titanium alloy wire rod is shaped, and the mobile phone SIM card holder special-shaped material is formed through rolling.

The invention provides a forging tool of a skirt edge cylinder for a pressure container and an integral forming method of the skirt edge cylinder. The forging tool comprises a bottom gasket, an inner die, a lower outer die and an upper outer die. By means of the forging tool and the integral forming method, integral forming of the skirt edge cylinder can be achieved, the size precision of the skirt edge position of the cylinder is high, the machining amount is small, the material utilization rate is increased, the skirt edge position is integrally formed, the metal streamline is matched with the appearance structure, the fatigue life of the structure can be effectively prolonged, and the anti-pressure capacity of the structure can be effectively improved.

The invention belongs to the technical field of mill auxiliary equipment, and particularly discloses a small light-weight long cantilever type mill lining plate replacing manipulator which comprises a front arm and a large arm, the large arm comprises an inner arm and an outer arm which are movably arranged in a sleeved mode, the inner arm and the outer arm each comprise a body of a rectangular steel structure, and the rear end of the body of the outer arm is movably connected with a base. The outer arm body can move front and back relative to the base, a lining plate trolley is movably connected to the top of the outer arm body and can move front and back relative to the outer arm body, the rear end of the inner arm body is slidably connected with the outer arm body, and the front end of the inner arm body is rotatably connected with the rear end of the front arm through a rotation assembly. The inner arm body can drive the front arm to stretch and retract back and forth in the axial direction of the outer arm body, the front arm can rotate by 360 degrees on the horizontal plane relative to the inner arm body, the weight is light, the structure is compact, the machining amount is small, the device can penetrate through a mill opening with the diameter being 860 mm, and the device is suitable for a small-caliber mill.