268 results about "Central symmetry" patented technology

The invention discloses a quartz boat holder fixing carrier capable of accurately positioning, and relates to the technical field of quartz boat holder fixing.The quartz boat holder fixing carrier comprises a square clamping plate, the square clamping plate is used for clamping and positioning the clamping portion of a quartz boat holder from the two sides in a central symmetry mode, and a sleeve type square plate is arranged on one side of the square clamping plate; according to the quartz boat support fixing carrier with the accurate positioning function, the two square clamping plates in the direction parallel to the clamping groove are arranged on one side of the clamping groove so that the clamping part of a quartz boat support can be clamped and positioned in a central symmetry mode; according to the fixing carrier for fixing the quartz boat support, the phenomenon that the quartz boat support is difficult to accurately position due to the fact that the size of a clamping groove, matched with the quartz boat support, on the fixing carrier for fixing the quartz boat support is too large is prevented, and a square sponge plate made of a flexible material is arranged on one side of a square clamping plate to be in contact with a clamping part of the quartz boat support; the situation that when the square clamping plate directly pushes, presses and clamps the clamping portion of the quartz boat support, hard pressure is difficult to control, and the clamping portion is damaged is prevented.

The invention discloses a regional prediction method for a wind power coefficient of a large reflecting surface based on a neural network. The method comprises the following steps: generating a wind power cloud picture according to resistance, lateral force and lift force of an antenna reflecting surface corresponding to a pitching angle and an azimuth angle under different working conditions; the method comprises the following steps: importing a wind power cloud picture into MATLAB: dividing an antenna reflecting surface according to the central symmetry and central stiffness distribution characteristics of the antenna reflecting surface to obtain circular ring partitions; dividing the wind power cloud picture of the near area of the antenna reflecting surface along the Z-axis direction of the YOZ plane according to the wind speed gradient to obtain Z-axis partitions; calculating a wind power coefficient of a region determined by the Z-axis partition and the circular ring partition; inputting the pitching angle and the azimuth angle under different working conditions and the wind power coefficient of each area as training data into a prediction network for training to obtain a trained prediction network; and inputting the pitching angle and the azimuth angle to be tested under different working conditions into the trained prediction network, and outputting the predicted wind power coefficient of the reflecting surface. The precision of wind power analysis is improved.

The invention discloses a metasurface based on multi-unit periodic array distribution, the metasurface is mainly formed by periodically arranging a plurality of microstructure units, each microstructure unit comprises a subunit A1, a subunit B1, a subunit A2 and a subunit B2, the subunit A1 and the subunit A2 are in a central symmetry structure, and the subunit B1 and the subunit B2 are arranged in parallel. The subunit B1 and the subunit B2 are of a central symmetry structure, the wave absorber formed by the super-structure surface comprises a plurality of wave absorbing units which are arranged periodically, each wave absorbing unit comprises a conductive reflecting layer, a dielectric interlayer, a microstructure unit layer and a dielectric top layer which are sequentially attached from bottom to top, the electromagnetic wave absorption rate can reach 90% or above on the frequency band of 8.31-41.75 GHz, and the wave absorbing efficiency can reach 90% or above. The microwave absorber has the advantages of being flexible, easy to prepare, good in wave absorbing effect and beneficial to integration, and is suitable for being used in the technical fields of electromagnetic shielding, microwave imaging and the like, and most of electromagnetic wave energy entering the inside of the microwave absorber is lost under the action of dielectric loss and ohmic loss, and the microwave absorber has the advantages of being flexible, easy to prepare, good in wave absorbing effect and beneficial to integration.

The invention relates to a plate three-point incremental forming track designing and forming method. The method comprises the following steps that S100, a two-point incremental forming track is generated according to a three-dimensional model of a target part; s200, the track is divided into two areas, the two parts of the track are achieved through two forming tools (2 and 3) respectively, and the connecting line of cutter location points of the two forming tools at the same moment always passes through the same central symmetry axis; s300, a simple support (7) is installed, the periphery of the plate (8) is clamped, a forming tool is installed, and tool setting is conducted; s400, pre-stretching is applied to the plate, and then the two execution tail ends of the machining equipment are made to run according to the tracks of the two forming tools correspondingly to machine the plate; and S500, after machining is completed, the clamping force is removed, and the formed workpiece is taken down. Three-point constraint is formed on the plate through the simple support and the two forming tools, the overall deflection and shaking of the plate during forming are remarkably reduced, and then the geometric accuracy of a final part is improved.

The invention discloses a C2 symmetric chiral metasurface and application and verification methods of phase control, and belongs to the field of micro-nano optics, the C2 symmetric chiral metasurface comprises a surface layer, a middle layer and a back plate layer which are sequentially arranged from top to bottom, the surface layer is composed of a left arc-shaped ring and a right arc-shaped ring which are arranged in a central symmetry mode, and protrusions are arranged on the opposite sides of the left arc-shaped ring and the right arc-shaped ring; the protrusions on the left arc-shaped ring and the protrusions on the right arc-shaped ring are symmetrically arranged about the circle center, and the central angle beta of the notch of the left arc-shaped ring and the central angle beta of the notch of the right arc-shaped ring are obtuse angles. By adopting the C2 symmetric chiral metasurface and the application and verification method of phase control, the spin decoupling phase control of the co-polarized circularly polarized terahertz wave can be realized only through the chiral phase by using the superatoms which have no mirror symmetry and have second-order rotation (C2) symmetry and the mirror atoms thereof.

The utility model belongs to the technical field of fastening structures, and particularly relates to a rotary fastening structure which comprises a rotary block, a key, a locking assembly and a grating, two fins with oblique openings are arranged at the bottom of the rotary block, the rotary block is of a central symmetry structure, a driven piece is arranged on the rotary block, and the locking assembly is arranged on the driven piece. A driving piece corresponding to the driven piece is arranged on the key, the locking assembly comprises a locking piece and an accessory, a hole is formed in the accessory, and a connecting piece corresponding to the rotating block is arranged on the front portion of the locking piece. According to the utility model, through the installed rotating block, the key is connected with the rotating block and then rotates to drive the fins to be embedded into the grooves or gaps at the root part of the grid, the rotating block is locked and fixed with the grid through the screwing of the locking piece after being preliminarily positioned, and meanwhile, accessories in the locking assembly are fixed on the grid; the purpose of individually storing or fixing equipment is achieved, the position of the accessory can be conveniently adjusted, and lossless installation is achieved.

The invention relates to the technical field of cable clamps, and mainly relates to an adjustable reducing clamp for communication engineering. Comprising a clamping jaw, arc-shaped grooves are formed in the two sides of the clamping jaw, notches are formed in the two sides of the clamping jaw, limiting blocks which are distributed in a central symmetry mode are arranged on one side of the clamping jaw, limiting holes which are distributed in a central symmetry mode are formed in the clamping jaw, and limiting holes are formed in the limiting blocks. The limiting holes of the limiting blocks are communicated with the adjacent limiting holes of the clamping jaws, the clamping jaws are provided with rectangular limiting grooves distributed in a central symmetry mode, limiting columns are fixedly connected into the rectangular limiting grooves of the clamping jaws, arc-shaped plates are fixedly connected into arc-shaped grooves of the clamping jaws, the clamping jaws are provided with spline blind holes, and the spline blind holes are communicated with the limiting columns. And a spline shell is in spline connection in the spline blind hole of the clamping jaw. According to the cable clamping device, the cable is clamped through relative movement of the two clamping jaws, so that the cables with different thicknesses are clamped and fixed, and the clamping force is kept.

The invention relates to a negative stiffness adjustable vibration reduction device based on permanent magnet nonlinear vibration absorption, and belongs to the technical field of vibration reduction. The negative stiffness adjustable vibration reduction device comprises a base and a bearing platform located above the base and used for bearing equipment to be subjected to vibration reduction, and the bearing platform is connected with the base through a plurality of vibration isolation springs; an elastic damper, a vibrator and a magnetic vibration absorption device are sequentially arranged between the bearing platform and the base from top to bottom in the vertical direction, the periphery of the vibrator is connected with a plurality of adjustable negative stiffness mechanisms which are arranged in a central symmetry mode, and each adjustable negative stiffness mechanism comprises a negative stiffness fine adjustment device and a horizontal elastic element. And the horizontal elastic element is positioned between the negative stiffness fine adjustment device and the vibrator. The displacement change rate during vibration impact can be greatly reduced, and multi-frequency-band vibration reduction is achieved in a small space.

The invention discloses a horizontal flushing device which comprises two saw blade control mechanisms and two saw blade driving mechanisms for driving the two saw blade control mechanisms to move respectively. The saw blade control mechanisms are arranged in a mirroring manner, the saw blade driving mechanisms are arranged in a central symmetry manner, and the two saw blade driving mechanisms are configured to synchronously translate along a horizontally arranged conveying direction or synchronously move towards or away from each other; the saw blade control mechanism comprises a saw blade, the saw blade is vertically arranged and rotates around a shaft in the horizontal direction, and the saw blade is configured to translate in the conveying direction, translate in the direction perpendicular to the conveying direction and revolve around an axis in the vertical direction with a first distance as the radius. The invention provides equipment which can move along with a plate on a conveying line and perform flush cutting on the plate pasted with an edge sealing strip at the same time.

The utility model discloses an adjustable centering mechanism for welding an outer weld joint of a pore plate stay tube, which is characterized in that three support arms of a support are arranged in a regular triangle star shape, support blocks are respectively fixed below the outer ends of the three support arms, and a support wheel is respectively fixed on each support block; the axes of the three supporting wheels are parallel to the axes of the corresponding supporting arms and are distributed in a central symmetry mode. A lead screw extending upwards is fixedly connected to the center of the support, a coupler is arranged at the upper end of the lead screw, an adjusting nut is screwed to the middle section of the lead screw, a clamping sleeve is fixed below the adjusting nut, three connecting rods are symmetrically hinged to the circumference of the clamping sleeve, and short shafts are hinged to the lower ends of the connecting rods respectively. The short shafts penetrate through the hollowed-out adjusting grooves of the corresponding supporting arms respectively, positioning bearings are fixed to the lower ends of the short shafts respectively, and the positioning bearings are distributed in a central symmetry mode with the axis of the lead screw as the center. The mechanism can provide accurate in-pipe positioning for the welding gun, and even if the inner diameter of the pull pipe has deviation, the mechanism cannot cause adverse effects on centering of the welding gun, and the welding quality is high.

The invention discloses a mixed star-shaped mechanical metamaterial unit and a metamaterial structure, and relates to the technical field of metamaterial structures, the mixed star-shaped mechanical metamaterial unit comprises a concave polygonal honeycomb structure which is of a central symmetry structure and is provided with a long edge and short edges which are bent inwards, and two ends of the long edge are respectively connected with one ends of the two short edges to form a closed structure; the two concave polygonal honeycomb structures are respectively arranged along an X axis and a Y axis and have the same symmetric center, and the long sides of the two concave polygonal honeycomb structures define a star-shaped structure by taking the symmetric center as a base point; the short edge is bent inwards to form a mounting part matched with the vibration reduction assembly in shape, and the vibration reduction assembly is arranged on the mounting part; the straight line where the two ends of the short edge are located is a base line. The outer edge of the damping assembly is located outside the base line. Each mixed star-shaped mechanical metamaterial unit is composed of two inwards-concave polygonal honeycomb structures and a vibration reduction assembly, and has the large-load bearing capacity and the vibration isolation function.

The invention discloses a holosymmetric four-mass MEMS gyroscope which comprises four sensitive mass block coupling structures which are arranged in a central symmetry manner, and four first U-shaped beams, four n-shaped beams and a cross-shaped coupling structure which are arranged in a central symmetry manner and are connected with the four sensitive mass block coupling structures, compared with the prior art, the four sensitive mass block coupling structures are designed compactly and symmetrically, so that the sensitivity can be effectively improved, and thermally induced drift can be effectively reduced. The driving mode and the working mode are separated through the specific coupling mechanism, so that frequency coupling is avoided, and environmental vibration interference is reduced. And meanwhile, the symmetry of the structure is beneficial to uniform distribution of thermal stress or mechanical stress, so that zero drift caused by temperature change is inhibited.

The utility model discloses a medium-speed diesel engine roller guide cylinder lining installation tool which comprises a guide shaft, two guide flat keys, a punching sleeve and a lower supporting seat, and the guide flat keys are fixed in key grooves of the guide shaft. A guide gap delta is reserved between the inner hole of the punching sleeve and the outer circle of the guide shaft; the lower supporting base is in an inverted-flat-bottom V shape, and the center of the top of the lower supporting base extends upwards to form a positioning block. The inner sides of the two bevel edges of the inverted flat-bottomed V-shaped lower supporting seat abut against base circles of corresponding cams of the cam shaft respectively, the guide shaft is inserted into a corresponding roller guide cylinder hole of the rack, the central symmetry plane of the key groove is parallel to the axis of the cam shaft, the positioning block is embedded into a central positioning groove in the bottom of the guide shaft, and the bottom of the guide shaft abuts against the top face of the lower supporting seat. The roller guide cylinder bushing mounting device is simple in structure, the mounting difficulty of the roller guide cylinder bushing is remarkably reduced, and the mounting quality and the mounting efficiency of the roller guide cylinder bushing are improved.

The invention relates to a die bonding swing arm device which comprises a main shaft rotating motor which is fixed on a base below, and the output end of the bottom of the main shaft rotating motor is connected with a rotating main shaft which can rotate around a vertical axis; the two independent lifting modules are symmetrically and fixedly mounted on the left side and the right side of the rotating main shaft by taking the axis of the rotating main shaft as a symmetric center; and the two swing arm assemblies are installed on the swing arm fixing bases of the two lifting modules correspondingly, and a suction cup is installed at the tail end of each swing arm assembly. According to the double-swing-arm alternating parallel operation mode, crystal taking and crystal fixing actions are almost synchronously carried out, the theoretical carrying efficiency is nearly doubled compared with that of a single swing arm, and the equipment productivity is greatly improved.

The utility model belongs to the technical field of scanners, and discloses a tracking type scanner. The tracking type scanner comprises marking modules, each marking module comprises a first marking part and a second marking part, the multiple first marking parts are sequentially and annularly arranged along the periphery of a first shaft, the first marking parts are obliquely arranged relative to the first shaft, and the second marking parts are arranged in an annular area defined by the multiple first marking parts; the center of the second marking part and the first shaft are arranged in a staggered mode, and / or a preset angle is formed between the axis of the second marking part and the first shaft, and the preset angle is not equal to 0. According to the utility model, the problems that in the prior art, due to the fact that the marking modules are distributed in a central symmetry mode, identification errors of the marking point modules are possibly caused, and errors of judgment from a certain marking point to another marking point module are possibly caused can be solved, and the identification accuracy is improved.

The invention provides a mask and an overlay error measurement method, and relates to the technical field of detection. The mask plate comprises a test pattern structure arranged in the middle area of the mask plate, the test pattern structure is used for forming an overlay mark on a wafer, and the test pattern structure comprises a first overlay pattern group, a first reference pattern group, a second overlay pattern group and a second reference pattern group which are sequentially arranged in the circumferential direction of a rotation center, the first reference pattern group and the second reference pattern group are of a central symmetry structure, and marks, mapped on the wafer, of the first overlay pattern group and the second overlay pattern group are arranged in a mutually offset mode and do not coincide with the marks, mapped on the wafer, of the first reference pattern group and the second reference pattern group. According to the invention, a plurality of different pattern groups are integrated on a single mask plate at the same time, and three overlay layer marks can be directly formed in the quadrant region corresponding to the wafer, so that more effective overlay mark image information is obtained, and the detection precision of the overlay error is improved.

The invention relates to an aircraft which is arranged in a central symmetry mode in the axial direction and comprises a first driving system and a second driving system used for driving the aircraft to move horizontally. The first driving system comprises two driving motors which are coaxially arranged and two groups of wind wings which are arranged in a conjugate manner; coaxial cavities are respectively formed in the two driving motors; the two sets of wind wings are arranged in the circumferential directions of rotors of the two driving motors correspondingly. The second driving system is arranged on the first driving system in the axial direction; the ratio of the outer diameter of the driving motor to the axial length of the driving motor is larger than or equal to 10 and smaller than or equal to 300. According to the invention, the navigation stability of the aircraft can be improved.

This invention discloses a method for fitting the geometric center of a centrally symmetric image, comprising: S1, constructing a pixel coordinate system based on the original image and obtaining the pixel coordinates of the edges of the centrally symmetric image on the original image; S2, selecting the two edge pixels with the largest distance from all edge pixels, and taking the midpoint between the two edge pixels with the largest distance as a temporary center point; S3, constructing a virtual pixel matrix in the area surrounding the temporary center point, and selecting the virtual pixel with the smallest sum of distances to all edge pixels as a new temporary center point; S4, repeating step S3 until the fitting accuracy of the temporary center point meets the design requirements. This invention directly fits the geometric center of a graphic based on the geometric characteristics of a centrally symmetric image. The calculation process is simple and direct, and it is widely applicable to the geometric center fitting of all centrally symmetric images. At the same time, the multi-step fitting and multiple iteration methods fully ensure the fitting accuracy.

The invention provides an automatic tool clamp for grinding a crankshaft through floating clamping and precise positioning, and belongs to the field of grinding clamps. The problems that an original crankshaft grinding clamp is high in precision requirement and poor in adjusting capacity are solved. Comprising a clamp body, a positioning cone, a spring jacket, a headstock center, a tailstock center, a crankshaft workpiece, a positioning screw, a positioning ejector pin, an oil cylinder and a machine tool headstock spindle, the clamp body is connected with the machine tool headstock spindle, and the oil cylinder in the clamp body is communicated with an oil way in a machine tool headstock; the oil cylinder is connected with a spring clamping sleeve in the clamp through a rotary buckle, and can push the spring clamping sleeve to carry out precession in the direction of a main shaft of a machine tool and clamp the crankshaft workpiece to be machined; the clamping end of the spring jacket is composed of four parts which are centrosymmetric, and a space is reserved for clamping action and positioning of the ejector pin; the machine tool headstock center and the machine tool tailstock center abut against the crankshaft workpiece to be machined at the two ends respectively, and the machine tool headstock center penetrates through the spring jacket along a center hole of the spring jacket; the tail end of a positioning ejector pin in the clamp is a hemispheroid, and the hemispheroid penetrates through the notch in the outer circle of the spring clamping sleeve and abuts against the tooth face of the crankshaft to be machined in the opposite direction.

The utility model relates to the technical field of veneer reeling machines, and discloses a veneer reeling machine high-precision roller positioning device which comprises a veneer reeling machine body, a base, an adjusting mechanism, a material taking mechanism and an encoder. The first guide rods are symmetrically arranged relative to the center of the first lead screw, the first sliding block is in threaded connection with the outer side of the first lead screw, and the mounting plate is fixedly mounted on the side, close to the plate rolling machine body, of the first sliding block. The first motor drives the first lead screw to rotate so as to drive the sliding block to move longitudinally, then the sliding block and the mounting plate are used in cooperation so as to drive the working roller to move longitudinally, the first lead screw is connected with the encoder through the elastic coupler, and the encoder measures the rotation of the first lead screw so as to adjust the position of the working roller. Therefore, the longitudinal displacement distance of the working roll driven by the first sliding block can be accurately calculated, and high-precision adjustment of the working roll is achieved.

The utility model discloses an open-close type annular coil for electromagnetic pulse, which comprises two semicircular annular coils which are arranged in a central symmetry manner, two ends of each annular coil are provided with ports which are connected into or out of an external power supply platform, and the connected ports of the two annular coils are not adjacent to each other. Each annular coil is arranged on the corresponding insulating ring, and the opposite faces of the two insulating rings are provided with inserting structures capable of achieving combination of the insulating rings. The whole processing is simple, the production is easy, the mechanical strength is high, the service life is long, and the switching of the opening and closing states of the coil can be quickly realized during welding, so that the problem of processing limitation of the traditional closing coil is solved.

The utility model discloses a work fixture for processing shaft body parts, which comprises a frame body movably connected with a shell. A turntable is rotationally connected in the shell; a plurality of arc-shaped grooves are formed in the turntable; the arc-shaped grooves are arranged in a central symmetry mode, and the inner sides of the arc-shaped grooves incline towards the outer sides. A connecting rod is connected in the arc-shaped groove; the lower end of the rotating disc is fixedly connected with a limiting plate matched with the arc-shaped groove. A limiting groove communicated with the arc-shaped groove is formed in the upper end of the limiting plate; a moving rod is connected to the limiting groove in a sliding manner; the lower end of the connecting rod is fixedly connected with the moving rod; the moving rod is driven by the connecting rod to move in the limiting groove; the end, located on the outer side, of the movable rod penetrates through the limiting plate and is connected with an abutting rod. The rotating disc with the arc-shaped groove is arranged in the shell, and the limiting plate is arranged at the lower end of the rotating disc, so that the connecting rod drives the connecting rod and the moving rod at the lower end to move towards the inner side and the outer side at the same time for abutting and clamping.

The utility model provides a torque loading device of a torque sensor, and relates to the field of loading calibration. The device mainly comprises a loading part, a bracket and a base. The two loading blocks are distributed on the two sides of the loading rod in a central symmetry mode, a load F is applied to one loading block, and quasi-static force loads F'which are opposite in direction and approximately equal in size can be generated on the other side of the loading rod. The loading head can simulate a working condition that a loading head of a standard loading table applies a load F to an object, and a proper loading head can be selected according to different working conditions of the loading table. The problem that the quasi-static calibration table can only be loaded in a single direction is solved, so that the quasi-static torque is obtained. The method can be applied to scenes requiring torque loading.

The utility model provides a novel combined type sliding block pull rod mechanism which comprises two sets of driving assemblies arranged in a central symmetry mode, each driving assembly comprises a sliding block base, an inclined guide column, a first sliding block and a second sliding block, and the first sliding block and the second sliding block are connected with the outer side end of a first half module and the outer side end of a second half module respectively. One end of the pull rod is fixedly connected with the sliding block seat, and the other end of the pull rod is connected with the second sliding block of the driving assembly on the other side. Through linkage arrangement of the pull rod, the second sliding block of the other driving assembly can be driven to move at the same time, linkage can be achieved by controlling the two sliding block bases to move face to face or relative to each other so as to drive the two modules to open or close, the cavities in the modules are transversely arranged, the overall structure is compact, the size is small, and the working efficiency is high.

The utility model belongs to the technical field of pipeline installation, and particularly relates to a pipeline installation regulator which comprises a base with the semicircular inner surface and opening and closing seats connected to the two ends of the base, the opening and closing seats are rotationally connected with the base through rotating pins, and a circular installation groove for fixing a pipeline is defined by the base and the inner surfaces of the two opening and closing seats. The fixed end of the opening and closing control structure is installed on the base, the power end of the opening and closing control structure is connected with the rotating pin, and the opening and closing control structure is used for controlling the opening and closing base to rotate inwards or outwards to clamp or loosen the pipeline; the two locking teeth are symmetrically arranged on the inner surface of the base, one locking tooth is arranged on the inner surface of each opening and closing seat, and the four locking teeth are distributed in a central symmetry mode; and one propelling structure is arranged corresponding to each locking tooth. After being applied to pipeline mounting operation, the device can avoid errors between pipeline preformed holes, reduces pipeline mounting difficulty, and meanwhile can be quickly adapted to mounting of pipelines with different pipe diameters.

The invention provides a Hall memristor based on an aged insulator and storage and calculation integrated computing equipment, and the method comprises the steps: firstly, through symmetry engineering design, employing a quasi-two-dimensional aged insulator which breaks the central symmetry and rotational symmetry, supporting a quantum abnormal Hall state at the same time, and generating track magnetization and the coupling of an in-plane electric field and out-of-plane magnetization; secondly, a quantum geometric mechanism is introduced into the quantum Hall state without the Fermi surface, intrinsic track magnetoelectric coupling is achieved, and the dependence of a traditional mechanism on the Fermi surface is broken through; and the domain wall is directly driven by the in-plane electric field to move to realize magnetization overturning, so that the participation of body current is avoided, and the energy consumption is remarkably reduced. And finally, the device combines the overturning of the magnetic state with the hysteresis behavior of the Hall resistor, and the inherent non-volatility and memory characteristics of the device provide a key device basis for constructing novel calculation hardware integrating storage and calculation.

The utility model belongs to the technical field of HWS static pressure molding method casting, and discloses a brake drum one-mold four-piece HWS static pressure molding casting device which comprises four brake drum models, a pouring cup, a straight pouring gate, four transverse pouring gates and eight inner pouring gates, the upper end of the straight pouring gate is communicated with the pouring cup, the four transverse pouring gates are arranged in a cross mode, and the inner pouring gates are communicated with the pouring cup. The four brake drum models are arranged in a central symmetry mode, the symmetry center is a central intersection point of four cross gates which are crossed, the central intersection point is communicated with the lower end of the straight gate, each cross gate is communicated with two inner gates, and the two ends of each inner gate are respectively communicated with one brake drum model. According to the utility model, the casting production of four brake drums in one mold is realized, the yield of more than 90% can be realized, the utilization efficiency of materials in the casting process is obviously improved, the production efficiency of brake drum castings is greatly improved, the production cost of the brake drum castings is effectively reduced, and the brake drum casting mold has obvious technical advantages and process advancement.

The utility model discloses a combined injection mold, which is characterized in that a first profiling block, a second profiling block, a first side puller and a second side puller are assembled to form a first spiral bump, a third profiling block, a fourth profiling block, a third side puller and a fourth side puller are assembled to form a second spiral bump, and the first spiral bump and the second spiral bump are matched with each other. A spiral rotating cavity of a product can be filled with the first spiral protruding block and the second spiral protruding block which are in central symmetry, after injection molding is completed, the first side puller, the second side puller, the third side puller and the fourth side puller are demoulded respectively, the structure is simple and compact, product demoulding is reliable, the speed is high, and the production efficiency is improved. The injection molding problem that the outer surface of a product is provided with a spiral groove which spirally ascends can be solved.

The utility model relates to a wheel set capable of adjusting the length of a main chord of a composite bow, which belongs to the technical field of adjustment of the main chord of the composite bow and comprises a wheel set, two groups of parallel bowstring grooves used for winding of the main chord are arranged on the wheel set, an adjusting frame fixedly connected is arranged on the wheel set, and fixing columns fixedly connected are symmetrically arranged on the center of the adjusting frame. The fixing column is close to the starting end of the bowstring groove, a main string adjusting module used for adjusting the tension degree of the main string is arranged on the fixing column, a plurality of adjusting holes used for fixing the main string adjusting module are evenly formed in the outer edge of the adjusting frame, and the two ends of the main string are connected with the main string adjusting modules on the two wheel sets arranged on the same side in a mirror image mode respectively. The rotation angle of the main chord adjusting module on the fixing column on the adjusting frame is adjusted, the tensioning degree of the two ends of the main chord is fixedly adjusted through the adjusting holes, the deviation problem of four included angles of the bead base fixed to the main chord is adjusted, it is guaranteed that the distances between the four included angles of the bead base and the main chord adjusting module are the same, and therefore accurate shooting is guaranteed.

The utility model aims to solve the problems of complex process, high cost and unstable distortion control effect in the heat treatment process of a gear shaft in the prior art, and provides a heat-resistant tool for heat treatment of a duplicate gear shaft. The two partition plates are arranged on the upper end wall and the lower end wall of the rectangular frame in a central symmetry mode respectively, and the two partition plates are fixedly connected through a connecting plate and are parallel to the long side wall of the rectangular frame. One group of fixing plates is vertically connected between one partition plate and one longer side wall of the rectangular frame, and the other group of fixing plates is vertically connected between the other partition plate and the other longer side wall of the rectangular frame; a gap is formed between the two fixing plates included in each group of fixing plates, a first arc-shaped clamping groove is formed in the upper edge of one longer side wall of the rectangular frame located between the gaps, and a second arc-shaped clamping groove corresponding to the first arc-shaped clamping groove is formed in the upper edge of the other longer side wall of the rectangular frame located between the gaps; supporting structures are arranged at the two ends of the two long side walls in the rectangular frame.