73results about How to "Low elongation" patented technology

Alloy elements are reasonably matched, N and nitrides are added to form elements such as tungsten W, vanadium V, niobium Nb, cobalt Co, rare earth RE and the like for microalloying smelting, a forged and rolled material finished product is subjected to proper heat treatment, and the stainless steel subjected to heat treatment has good heat treatment performance through metallographic observation. According to the stainless steel, nanoscale carbides are separated out in a solid solution state, and fine particles mainly containing nitrides are dispersed and separated out in crystals in a thermodynamic state, so that the material is strengthened and does not diffuse to a crystal boundary, and the room-temperature mechanical property and the high-temperature mechanical property of the material are greatly improved; and when the stainless steel material produced by the method is used for manufacturing related products, the thickness of the stainless steel material can be reduced, and the overall input of the stainless steel material is greatly reduced, so that the large-scale application of noble metal strategic resource nickel is saved, and the aims of saving resources, energy and investment are fulfilled.

The invention belongs to the technical field of automobile manufacturing, and particularly relates to a rivet welding connection process method. A rivet welding connection process method comprises the steps that a plate is obtained, and mounting holes are formed in the plate; providing a first riveting die, and installing a rivet on the first riveting die; the first riveting die pushes the rivet in the first direction, so that a riveting leg of the rivet is inserted into and extends out of the mounting hole; the first riveting die presses the riveting head of the rivet, so that the riveting shoulder of the rivet presses the plate; a second riveting die is provided, the second riveting die moves towards the plate in the second direction, and the end, away from the riveting head, of a riveting leg of the rivet is compressed so that a lock catch protruding out of the peripheral face of the riveting leg can be formed at the end; wherein the first direction is opposite to the second direction. According to the method, the problem that multi-layer plates made of heterogeneous materials such as ultrahigh-strength steel and aluminum are difficult to connect is solved, connection between ultrahigh-strength steel and multi-layer aluminum plates and steel plates or between ultrahigh-strength steel and carbon fibers and other heterogeneous materials can be achieved, and collinear production of a steel-aluminum multi-material hybrid vehicle body on a traditional steel vehicle body is achieved.

The invention relates to the technical field of load-bearing detection cables, and provides a high-strength load-bearing detection cable capable of preventing water and gas from flowing, which is characterized in that a plurality of wire cores are twisted to form a cable core; the carbon fiber filling material is filled in a gap between the adjacent wire cores, and the carbon fiber filling material and the cable core form a cylindrical inner core structure; the carbon fiber weaving layer is formed by weaving carbon fiber yarns and sleeves the periphery of the cylindrical inner core structure; the inner armor layer is of an annular steel ring structure and is arranged on the periphery of the carbon fiber woven layer in a sleeving mode, and a plurality of inner-layer steel wires are sequentially in lap joint in the annular shape to form the annular steel ring structure. The outer armor layer is arranged on the periphery of the inner armor layer in a sleeving manner, and the outer armor layer comprises a plurality of twisted outer-layer steel wires; and a gap between the peripheries of the outer armor layer and the inner armor layer is filled with the blocking layer. According to the technical scheme, the problems of low sealing performance, tensile performance, high temperature resistance and magnetic field interference resistance of the load-bearing detection cable are solved.

The invention provides a positive pole piece, a battery, an energy storage device and electric equipment, the positive pole piece comprises a positive current collector, the surface, deviating from a winding center, of the positive current collector is provided with a first positive material layer, and the surface, facing the winding center, of the positive current collector is provided with a second positive material layer; the average non-sphericity degree of particles of the positive electrode material with the particle size larger than or equal to 1 micron is k1, Dv50 is D1, k1 is larger than or equal to 10% and smaller than or equal to 19%, and D1 is larger than or equal to 0.8 micron and smaller than or equal to 1.2 microns; in the second positive electrode material layer, the average non-sphericity degree of positive electrode material particles with the particle size larger than or equal to 1 [mu] m is k2, Dv50 is D2, k2 is larger than or equal to 21% and smaller than or equal to 35%, and D2 is larger than or equal to 1.2 [mu] m and smaller than or equal to 1.7 [mu] m.

The invention discloses a film plate and an optimization method thereof and a film container, the film plate comprises a plate body, the plate body is provided with a first corrugated structure, a second corrugated structure and at least one intersecting curved surface, the first corrugated structure is arranged in a convex manner, the second corrugated structure is arranged in a concave manner, and the first corrugated structure and the second corrugated structure are arranged in an intersecting manner through the intersecting curved surface; wherein a design curved surface is defined, the design curved surface is of a curved surface structure formed in the mode that the first convex curve translates along the first concave curve and the vertex of the first convex curve slides on the first concave curve, the first corrugated structure and the second corrugated structure can penetrate through the design curved surface, and an intersecting curved surface is defined by intersecting lines. The corrugated structure and the intersecting curved surface are matched together to improve the displacement compensation capacity of the film plate, and the liquid tightness and the air tightness of the film container can be improved; the plate body is low in ductility, small in forming thinning amount and small in residual stress; the design and manufacturing cost and difficulty are reduced, and the forming precision is easy to control; and the performance optimization of the thin film plate can be realized.

The invention discloses a preparation method of a lightweight high-strength plastic Mg-Li-Zn-Gd alloy bar, which comprises the following steps: (1) in an argon atmosphere, selecting alloy raw materials according to the mass percentage, heating and melting to prepare an alloy melt; (2) carrying out casting molding on the alloy melt to obtain an alloy ingot; (3) preheating the alloy ingot, and performing extrusion forming to obtain an extruded bar of the magnesium-lithium alloy; and (5) carrying out rotary forging deformation treatment on the extruded bar at room temperature. Gadolinium (Gd) with a grain refinement effect and zinc (Zn) with a solid solution strengthening effect are added into a magnesium-lithium alloy system to serve as main alloying elements, meanwhile, nano precipitated phases such as Mg3Zn3Gd2 and MgZn2 in the alloy and segregation of the Zn element near the precipitated phases are regulated and controlled through the extrusion-rotary forging process, and therefore the strength and plasticity of the alloy are improved; the yield strength of the light high-strength plastic magnesium-lithium alloy bar reaches 276 MPa, and the tensile strength of the light high-strength plastic magnesium-lithium alloy bar is 303 MPa; the ductility is 24%; and the density is 1.565 g / cm < 3 >.

A golf club head alloy is provided to solve the problem that the existing alloy cannot be used to make a striking face plate. The golf club head alloy includes 11-13% by weight of molybdenum, 5-7% of zirconium, 0.5-2.5% of iron and 3-4% of aluminum, and the golf club head alloy further includes a balanced amount of titanium and inevitable impurities. Through the above-mentioned composition, the hard and brittle phase of the golf club head alloy can be reduced, so that the striking face plate made of the golf club head alloy can pass the golf ball impact test, and whether the striking face plate is heat treated is determined according to the needs of the user, so that the striking face plate can have high rebound performance or high strength characteristics. The present application also relates to a method for manufacturing a golf club head from the golf alloy.

The invention provides a positive pole piece, a battery, an energy storage device and electric equipment, the positive pole piece comprises a positive pole current collector, at least one surface of the positive pole current collector is provided with a first positive pole material layer and a second positive pole material layer, the second positive pole material layer is located on one surface, deviating from the positive pole current collector, of the first positive pole material layer, and the second positive pole material layer is located in the first positive pole material layer. The average non-sphericity degree of particles of the positive electrode material with the particle size greater than or equal to 1 mu m is k1; in the second positive electrode material layer, the average non-sphericity degree of positive electrode material particles with the particle size larger than or equal to 1 micron is k2; k1-k2 is greater than or equal to 25% and less than or equal to 35%, and the first positive electrode material layer comprises a titanium element and a vanadium element.

The invention discloses adjustable tungsten filament processing and stretching equipment, and relates to the technical field of stretching. Supporting plates are arranged at the corners of the bottom of the device body, two vertical plates are arranged on the right side of the top of the device body and symmetrically distributed with the device body as the center, motors are arranged on the outer walls of the vertical plates, transmission rods are rotationally installed on the inner walls of the vertical plates, and one ends of the transmission rods penetrate through and are fixedly installed on the front faces of the output ends of the motors. A plurality of take-up assemblies are fixedly installed on the outer wall of the transmission rod at equal intervals. The distance between the tungsten filament and the take-up assembly can be freely adjusted when the tungsten filament is stretched, namely, the relative stretching position is effectively changed according to needs, meanwhile, the tungsten filament on the outer wall of the pay-off assembly is stretched and preheated through the U-shaped heating assembly, internal stress of the tungsten filament is effectively reduced, and the elongation and tensile strength of the tungsten filament are prevented from being reduced; the breakage probability of the tungsten filament in the stretching process is increased; and the overall quality of the tungsten filament is reduced.

The invention provides a preparation method of a high-strength and high-plasticity AZ31 magnesium alloy sheet with a gradient nanostructure to solve the problem that an existing magnesium alloy sheet is insufficient in strength and plasticity. Commercial as-cast AZ31 magnesium alloy is used as a raw material, a magnesium alloy plate is obtained through rolling, extrusion and other deformation processes firstly, then the plate is further treated through an ultrasonic surface deep rolling technology, and the AZ31 magnesium alloy sheet with the gradient nano structure is prepared, and the strength and plasticity of the AZ31 magnesium alloy sheet are greatly improved compared with as-cast alloy; the comprehensive mechanical property of the magnesium alloy plate is superior to that of a commercial AZ31 magnesium alloy plate, and a high-performance and low-cost lightweight material is provided for intelligent equipment, 3C products and the like.

The utility model discloses an automobile tire fastening belt which comprises a macromolecule outer colloid belt and a steel wire rope inner net curtain, and the macromolecule outer colloid belt is wrapped outside the steel wire rope inner net curtain through mould pressing or injection molding. Due to the adoption of the steel-plastic composite structure, compared with an original woven polyester belt, the steel-plastic composite belt has the advantages of being high in strength, low in ductility, high in friction force with a tire joint surface and capable of preventing looseness under the condition of the same function. And moreover, the wear-resistant, scratch-resistant and anti-shearing characteristics are realized, and the service life can be greatly prolonged.

The utility model discloses a gear side cover grease dispensing assembly device, and relates to the technical field of gear grease dispensing assembly. The gear side cover point grease assembling device comprises a fixing column, a synchronous belt sliding table assembly, a sliding seat and a multifunctional mechanism, the top of the fixing column is connected with a connecting plate, the synchronous belt sliding table assembly is installed on the connecting plate, the sliding seat slides on the synchronous belt sliding table assembly, and the multifunctional mechanism is installed on the sliding seat. According to the gear side cover grease dispensing assembly device, grease dispensing can be conveniently conducted on a side cover on the rotary disc through lifting movement of the grease dispensing assembly on the multifunctional mechanism, meanwhile, the assembly assembly can ascend and descend to clamp a gear, and then the gear can be clamped through movement of the synchronous belt sliding table assembly; the assembling assembly clamping the gear can move and assemble the gear into an inner cavity of the side cover, the two steps of grease dispensing and gear assembling can be synchronously carried out at a time, the elongation of an assembling process production line is reduced, and the assembling efficiency of the gear and the side cover is improved.

The invention discloses a high-strength and high-toughness cast aluminum alloy as well as a preparation method and application thereof, and the cast aluminum alloy comprises the following components in percentage by mass: 4%-11% of Si, 0.2%-0.8% of Mg, 0.3%-1.8% of Cu, 0.10%-0.14% of Ti, 0-1.0% of Zn, 0.10%-0.30% of Fe, 0.015%-0.030% of Sr and the balance of Al and inevitable impurities. Zn + Cu is less than or equal to 2%, and Cu / Mg is greater than or equal to 2; the preparation method comprises the following steps: carrying out heat treatment on an aluminum alloy ingot; the heat treatment comprises three stages of solid solutions, and the temperatures of the three stages are respectively 490-500 DEG C, 530-540 DEG C and 545-555 DEG C. The aluminum alloy is high in tensile strength and yield strength and high in ductility, the solid solution time is remarkably shortened during preparation, and the production cost is remarkably reduced.

The present invention discloses a component bidirectional gradient energetic charge liner charging structure, the energetic charge liner charging structure includes a component bidirectional gradient charge liner, the energy density and ductility of the component bidirectional gradient charge liner bidirectionally gradient along the generatrix direction and the wall thickness direction, along the direction from the liner top to the liner mouth and from the outer surface to the inner surface, the energy density of the material constituting the charge liner gradually increases and the ductility gradually decreases; the material properties close to the liner top and the outer surface are biased towards the inert charge liner; the material properties away from the liner top and the outer surface are biased towards the energetic charge liner, and the explosive mainly forms an energetic pestle after detonation, which breaks into a large amount of fragment clouds and releases chemical energy after the jet penetrates the target plate. The above energetic charge liner charging structure combines the advantages of the energetic charge liner and the traditional inert charge liner, and can effectively improve the damage aftereffect of the armor-piercing warhead on the basis of retaining the high penetration depth performance.

A display device in which a pad electrode of a circuit board and a pad electrode of a display panel are aligned is provided. The display device includes: a display panel; and a circuit board connected to the display panel, in which the circuit board includes a plurality of sub-bonding portions separated from each other by a plurality of slits, and a length of each of the plurality of sub-bonding portions is set based on an elongation of the circuit board. In the display device, alignment of a pad electrode of a circuit board and a pad electrode of a display panel is improved.

The utility model discloses a high-speed carding card clothing applied to a spinning after-finishing process, and belongs to the technical field of carding machines. Comprising a base body and a plurality of needle bodies evenly distributed on the base body, 230-290 needle bodies are arranged on the base body per square inch, an X direction and a Y direction which are perpendicular to each other are arranged on the plane where the base body is located, 2-4 needle bodies form a group, the needle bodies in the X direction and the Y direction are arranged in a matrix shape, and the needle bodies in the X direction and the Y direction are arranged in parallel. And the arrangement direction of the needle bodies in each group is inclined to the X direction and the Y direction. According to the carding machine, the problem that in the prior art, long wool and fluff are prone to falling when being carded by a carding machine is solved.

The utility model provides a paper composite yarn with unequal twist. The paper composite yarn comprises a paper yarn, the first modified polyester supercool multifilament and the second modified polyester supercool multifilament are sequentially wrapped on the outer surface of the paper yarn from inside to outside, the twisting direction and the wrapping twisting direction of the first modified polyester supercool multifilament are both opposite to the twisting direction of the paper yarn, the twisting direction and the wrapping twisting direction of the second modified polyester supercool multifilament are both the same as the twisting direction of the paper yarn, and the first modified polyester supercool multifilament and the second modified polyester supercool multifilament are arranged on the outer surface of the paper yarn. The twist of the paper yarn, the twist of the first modified polyester supercool multifilament and the twist of the second modified polyester supercool multifilament are sequentially reduced, and the coating twist of the first modified polyester supercool multifilament and the coating twist of the second modified polyester supercool multifilament are sequentially reduced.

The invention discloses a carbon fiber material printing template and a manufacturing method thereof. The carbon fiber material printing template comprises an outer frame and an inner net, wherein the outer frame is composed of ceramics, and the inner net is composed of a carbon fiber composite material, wherein the ceramics contain a polyimide-PDVB nanocomposite material, and the carbon fiber composite material is formed by laser cutting a carbon fiber plate containing a polyimide-PDVB nanocomposite material.

The invention belongs to the technical field of road paving materials, and particularly relates to a preparation method of a cementing material for cold-mixed colored permeable asphalt, and the preparation method comprises the following steps: 1) under a stirring condition, firstly adding epoxy resin and allyl glycidyl ether into a mixing kettle, stirring and mixing, slowly adding a plasticizer, and stirring and mixing; (2) sequentially adding heavy calcium carbonate, talcum powder and pigment, and stirring until the materials are uniformly dispersed without particles and bubbles, so as to obtain the component A; (3) uniformly mixing the component A and the component B under a stirring condition according to the weight ratio in the claim 1 to obtain a cementing material; and the component B is an alicyclic amine curing agent. The cementing material prepared by the method disclosed by the invention has the advantage of high water permeability, and also has excellent durability and rutting resistance.

This utility model provides a ligation release liner mechanism and a ligation device, relating to the field of medical device technology. The ligation release liner mechanism includes: a flexible cable and a flexible line connecting the flexible cable; the flexible cable is used to drive and connect to the actuator of the ligation device, and the flexible line is used to wind around a reel; the elongation rate of the flexible cable under a unit tensile force is less than that of the flexible line under a unit tensile force. Utilizing the flexibility of the flexible line, it is smoothly wound around the circumference of the reel, and the tensile force is transmitted through the flexible cable with a lower elongation rate, thereby reducing the overall elongation rate of the ligation release liner mechanism. This is particularly suitable for the tensile force transmission when the ligation device releases multiple ligation loops continuously, avoiding the problem of ligation loop release failure due to the release line being stretched and elongated.

The invention relates to the technical field of shiatsu adhesives for automobile manufacturing, in particular to a shiatsu adhesive stable in storage and free of wire drawing and a preparation method of the shiatsu adhesive. The invention relates to a finger-pressing adhesive with storage stability and no wire drawing, which is prepared from the following raw material components in parts by weight: 13 to 18 parts of powdered nitrile rubber, 13 to 17 parts of plasticizer, 23 to 27 parts of HPVC resin, 5 to 10 parts of thickening agent, 32 to 40 parts of filler, 5 to 10 parts of tackifier, 0.6 to 1 part of curing agent and 0.3 to 0.5 part of adhesion promoter, and the sum of the parts by weight of all the components is 100. The shiatsu glue with stable storage and no wiredrawing has the characteristics of no hand sticking, no wiredrawing and no hair slip, has small needle penetration change within three-month storage period, has good construction performance and mechanical property, and solves the technical problems that the existing shiatsu glue is easy to stick to hands, wiredrawing and hair slip are caused during use, the storage period is short, and the existing shiatsu glue is hard after being placed for a long time and is not easy to construct.

This polypropylene film is characterized in that the maximum value Dmax and the minimum value Dmin of tanδ in the main alignment direction within a range of -10°C to 50°C satisfy the relationship of formula 1, and that the tensile elongation in a main alignment orthogonal direction at 90°C is 70% or more. 0.00≤Dmax−Dmin / Dmax≤0.30 Provided is a polypropylene film capable of maintaining quality even after being subjected to a processing step at a high temperature.

This utility model discloses an abrasive belt structure, comprising a substrate and an abrasive layer disposed on the substrate. The substrate is a metal wire mesh substrate, which includes a plurality of warp metal wires and a plurality of weft metal wires. The weft metal wires are arranged sequentially at intervals along the warp direction, and the warp metal wires are arranged sequentially along the weft direction and interwoven with each other. The diameter of the weft metal wires is larger than the diameter of the warp metal wires. In this utility model, the substrate is a metal wire mesh substrate, formed by the interweaving of warp and weft metal wires. The diameter of the weft metal wires is larger than the diameter of the warp metal wires, and the warp density is greater than the weft density, allowing for a densely woven metal mesh with high tensile strength and low elongation, meeting the requirements for long-term, high-volume grinding applications.

The invention belongs to the field of optical fiber communication, and discloses an easy-to-open skylight optical cable suitable for fiber-to-the-home and application and a preparation method thereof.The easy-to-open skylight optical cable comprises a cable core and an outer sheath wrapping the cable core, the outer sheath comprises a first phase and a second phase which are distributed in the axial direction, the first phase serves as an outer sheath main body part, and a reinforcing piece is arranged in the outer sheath main body part; the first phase is used as an outer sheath, the second phase is used as a reserved skylight part, the reserved skylight part is used for being integrally pulled out and stripped from the outer sheath in the skylight opening operation of the optical cable, the reserved skylight part integrally extends into and penetrates through the outer sheath in the radial direction, and the elastic modulus and the elongation at break of materials of a main body part of the reserved skylight part and the outer sheath have a certain difference degree. When in use, the reserved skylight part is picked out to serve as a tearing end according to the elasticity modulus of the material, and the end of the reserved skylight part is torn manually. The invention also provides a preparation method of the composition. The optical cable manufactured by the method has low requirements on operation techniques of constructors, is simple and labor-saving, can be manufactured by using existing equipment, and has relatively simple requirements on the equipment and the process.

The invention belongs to the technical field of microbial engineering, discloses a bifidobacterium animalis subsp. Lactis composition for improving vision health and application thereof, and finds that the bifidobacterium animalis subsp. Lactis i797 has an outstanding effect on improving the vision health. The invention provides the animal bifidobacterium subsp. Lactis composition for improving the vision health, which contains the animal bifidobacterium subsp. Lactis i797, and can reduce the eyeball diopter of a myopia guinea pig model, remarkably improve the diopter of a low-myopia guinea pig model and relieve asthenopia, so that the aim of improving the vision health is fulfilled; the composition of the bifidobacterium animalis subsp. Lactis i797, the xanthophyll and the vitamin A in a specific proportion can remarkably improve vision health. The bifidobacterium animalis subsp. Lactis composition is suitable for preparing the bifidobacterium animalis subsp. Lactis composition for improving the vision health, and is used for preparing dairy products for improving the vision health or probiotics for improving the vision health.

The present invention discloses an assembled asphalt pavement prefabricated block and a manufacturing method thereof. The prefabricated block is provided with a reinforcement layer, an asphalt lower layer, an interlocking layer, an anti-skid asphalt upper layer and a super-hydrophobic coating in sequence from bottom to top, and two adjacent layers of the structure are bonded by spraying a tack coat oil; a connection portion is provided on the prefabricated block, and a plurality of prefabricated blocks are longitudinally connected through the connection portion; the present invention can realize factory production by prefabricating the asphalt surface layer, improve construction accuracy and engineering quality, reduce construction pollution, simplify construction procedures, and improve labor efficiency; and each prefabricated block is numbered for rapid positioning and maintenance and replacement; at the same time, a sensor device can also be buried in advance during prefabrication to provide support for intelligent monitoring of road quality.

The invention discloses a mesh-sandwiched pool material with good dimensional stability and a preparation method thereof, and belongs to the technical field of mesh-sandwiched materials, and the preparation method comprises the following steps: carrying out dipping treatment on mesh cloth by adopting paste, then drying, and carrying out hot-pressing lamination on the mesh cloth, a preheated surface membrane and a preheated bottom membrane. The mesh cloth is treated by adopting a method of firstly dipping and then pressing, so that the yarn fixing effect can be enhanced, the elongation of the material is reduced, the dimensional stability of the product is ensured, and the obtained mesh-sandwiched pool material has good waterproof performance and pressure-bearing performance.

The invention discloses a reinforced polypropylene material which comprises the following components in parts by weight: 80 parts of co-polypropylene resin; 1 to 5 parts of maleic anhydride grafted polypropylene; 5 to 30 parts of glass fiber; 0.5 to 1 part of carbon black; wherein the crystallinity of the co-polypropylene resin is 36 to 56 percent; the grafting rate of maleic anhydride in the maleic anhydride grafted polypropylene is 0.5-1.5 wt%. According to the invention, the crystallization behavior and molecular chain morphology of co-polypropylene resin after thermal storage are predicted, and the crystallinity of a resin matrix, the grafting rate of maleic anhydride grafted polypropylene and the particle size of carbon black powder are screened; the glass fiber reinforced polypropylene material with high tensile strength retention rate and elongation at break retention rate can be obtained.

The application discloses a kind of warp cross-weft and bundling's grid woven fabric and its warp knitting method and modified rapier loom, and the warp fiber bundle, weft fiber bundle and binding fiber bundle of woven fabric are woven in the same surface layer fabric;Connecting fiber bundle is between upper layer organization fabric and lower layer organization fabric, and it is the thickness direction of woven fabric, and connecting fiber bundle is cross-weft warp knitting.In a weaving unit, connecting fiber bundle is between two warp fiber bundles, and binding fiber bundle is outside the warp fiber bundle;Two warp fiber bundles and a weft fiber bundle are woven to clamp the weft fiber bundle in warp direction and sink in two weft fiber bundles, and it is bound by binding fiber bundle;Binding fiber bundle is only sunk in weft fiber bundle after cross binding.Woven fabric obtained by the method of the application has stable fabric structure in warp tensile test, and does not come off and does not slip.

The invention discloses a high-precision telescopic inserting and taking structure for a horizontal machining center machine tool workbench. A middle fork main body plate is located on the upper surface of a lower fork main body plate, an upper fork main body plate is located on the upper surface of the middle fork main body plate, and a connecting assembly is used for connecting the middle fork main body plate and the upper fork main body plate; the upper fork main body plate also axially moves on the upper surface of the middle fork main body plate, the movement direction of the middle fork main body plate is consistent with that of the upper fork main body plate, and the driving assembly is arranged on the lower surface of the lower fork main body plate, at least partially penetrates through the lower fork main body plate, is connected with the middle fork main body plate and is configured to drive the middle fork main body plate to move. Two-stage reciprocating motion of the pallet fork is achieved through one chain, the space size is greatly reduced, the stretching part of one chain is only one fifth of the total length, the elongation rate after long-time operation is greatly reduced, long-time stability can be kept, and the chain is matched with the long chain rack and multiple teeth, so that the service life of the pallet fork is greatly prolonged. And errors caused by low precision of the chain are reduced.