442 results about "Static friction" patented technology

The invention relates to the field of transmission towers, and discloses a tension type transmission tower buffer connecting device which comprises a supporting frame, a plurality of isolation assemblies are symmetrically arranged on the upper surface of the supporting frame, sliding seats are slidably connected into the isolation assemblies, and connecting rods are fixedly connected to the outer surfaces of the sliding seats. A belleville spring set is arranged between the outer surface of the sliding base and the inner wall of the isolation assembly, the belleville spring set is arranged on the outer surface of the connecting rod in a sleeving mode, and a telescopic rod and a first spring are fixedly connected between the outer surface of the sliding base and the inner wall of the isolation assembly. A primary buffer layer is formed by the belleville spring set and the first spring, axial impact force can be absorbed without sliding of the sliding seat during daily wind vibration and wire slight galloping, meanwhile, vibration can be restrained through the huge static friction torque of the fan-shaped friction face and the friction ball in the omnidirectional damping assembly, the circuit is kept stable, and slight load impact is effectively dealt with.

The invention discloses a device and a method for measuring dragging torque of an electronic mechanical brake caliper assembly, and belongs to the technical field of automobile brake system testing. The device comprises a first supporting seat, a driving rotating shaft, a brake disc and a driven rotating shaft assembly with a torque sensor, and precise positioning of a caliper support is achieved through cooperation of a rotating clamp and a guide pin. During testing, the calipers clamp the brake disc firstly to output clamping force and then release pressure, the motor drives the brake disc to rotate by a circle to eliminate inertia moment, and then the torque sensor dynamically collects dragging torque. A modularized brake disc fixing seat is adopted to adapt to products of different specifications, a coupler compensates for shafting offset, a fixing block locking mechanism guarantees non-measurement state safety, and inertia errors are eliminated in combination with a dynamic and static friction separation measurement method. According to the scheme, the problems of positioning deviation, mechanical interference and friction interference in a traditional test are solved, and the measurement precision and efficiency of the dragging torque of the brake calipers are remarkably improved.

The utility model relates to a clamp for accurate grinding of a right-angle measuring tool workpiece. The clamp comprises a base, a pressing plate and a top plate. The base is L-shaped, a plurality of vacuum chucks are embedded in the bottom surface of the positioning groove at intervals, and the bottom of each vacuum chuck is connected to a vacuum generator; two limiting tables are arranged on the base, supporting blocks are fixed to the tops of the two limiting tables respectively, the two ends of the top plate are fixed to the two supporting blocks respectively, guide rods arranged in the vertical direction are fixed between the two supporting blocks and the top plate respectively, the pressing plate is located between the base and the top plate, and the two ends of the pressing plate are slidably connected to the two guide rods in a sleeving mode respectively; and the top plate is connected with a pressing driver. The base is matched with the pressing plate, the right-angle measuring tool to be machined is pressed and positioned under the combined action of the L-shaped upper clamping face and the L-shaped lower clamping face, and clamping is reliable; a vertical pressure is provided through a vacuum negative pressure adsorption force mode, so that the horizontal plane static friction force of the right-angle measuring tool to be machined is improved, and a workpiece is stably clamped on the clamp.

The invention discloses an automatic measuring device and measuring method for dynamic and static friction torques of medium and large-sized bearings, and belongs to the technical field of bearing detection.The device comprises a bearing assembly, a moving plate is arranged on the bearing assembly, a rotating motor is connected to the bottom of the bearing assembly, and a driving shaft system is arranged on an output shaft of the rotating motor; the top end of the driving shaft system is provided with an inner ring fixing mandrel, the upper surface of the moving plate is connected with a torque sensor through an upper fixing frame, the bottom end of the torque sensor is provided with a measuring shaft system, the bottom end of the measuring shaft system is sleeved with a center adjusting assembly through two guide columns, the bottom of the center adjusting assembly is provided with an outer ring loading tool, and the outer ring loading tool is provided with an inner ring. Under the cooperation of the structure, not only can the dynamic friction torque be measured, but also the multi-point static friction torque can be automatically measured, more comprehensive bearing friction characteristic data are provided, and optimization of bearing design and model selection is facilitated.

The invention relates to the technical field of clamping tools, in particular to a clamping device for a cylindrical thin-wall precision component, which comprises a supporting unit, a bracket, a positioning unit, a positioning mechanism arranged in the bracket, a clamping unit and a clamping mechanism arranged on the positioning mechanism, the inflating mechanism is arranged on the clamping mechanism and is used for preventing the part from being clamped and deformed; balance of deformation prevention and stable clamping is achieved through flexible contact and self-adaptive air pressure adjustment, an elastic cushion and an air inflation bag cushion are arranged in the clamping mechanism, a self-adaptive adjusting structure is formed by matching with an air inflation mechanism, it is guaranteed that the static friction force is enough to prevent parts from sliding, and the clamping effect is good. According to the clamping device, the clamping force is reduced, sinking, ovality out-of-tolerance or inner wall plastic deformation caused by too large clamping force are avoided, the problems of deformation and the like of components in the machining and clamping process can be effectively avoided, the product rejection rate is further reduced, and the actual machining efficiency is further improved.

The application relates to the technical field of chip packaging, and discloses a power device packaging structure, which comprises an upper pressing plate assembly, a chip layer and a heat sink assembly, the chip layer is arranged between the upper pressing plate assembly and the heat sink assembly, the upper pressing plate assembly comprises a first connecting part, the heat sink assembly comprises a second connecting part, the first connecting part comprises a plurality of first insulating microwires, and the second connecting part comprises a plurality of second insulating microwires; the first insulating microwires and the second insulating microwires are connected through static friction, the static friction connection between the first insulating microwires and the second insulating microwires is not affected by temperature, and therefore the reliability of the power device packaging structure is improved.

A bicycle wheel assembly structure includes an annular rim, a hub, nipples, and spokes. The annular rim includes multiple rim penetration sections, each of which includes a rim-side limiting part on a circumference. The hub is arranged at the center of the annular rim. The hub includes multiple hub penetration sections. The rim-side limiting part and the nipple limiting part, and also the hub-side limiting part and the spoke limiting part, are all made in a hexagonal pyramid form with apex truncated to form a planar surface and including bevel facets so as to provide an anti-sliding effect resulting from geometric constraint and high static friction at both the annular rim-side and the hub-side. The angle of the hexagonal pyramid of the nipple limiting part is 60°, 90°, or 120°, and an optimum arrangement can be made based on the material elongation of the spokes and the desired tension.

The invention discloses a forging die for suspension clamp preparation, and relates to the technical field of suspension clamp forging dies, the forging die comprises an upper die, a lower die and a guide pillar guide limiting structure arranged between the upper die and the lower die; the upper die comprises an upper die base and a male die fixed below the upper die base. The lower mold comprises a lower mold base, a female mold and an ejection mechanism, the female mold is fixed on the lower mold base, a mold cavity of the female mold is matched with the male mold core, and the ejection mechanism is an automatic demolding mechanism with an energy storage impact function and comprises a lifting assembly, an ejection rod, a positioning assembly, a transmission assembly and an unlocking assembly. The problem that in the prior art, when a suspension clamp is forged, constant ejection force cannot overcome increased demolding resistance caused by product cooling shrinkage, static friction and vacuum adsorption jointly is solved. The energy storage impact type ejection mechanism has the advantages that instant mechanical impact can be automatically applied to damage vacuum adsorption and static friction force when a product is stuck in a mold, demolding is facilitated, and the like.

The invention provides a return difference measuring method and device of a gear transmission mechanism in a motor driving system. According to the return difference measurement method, the return difference measurement value is indirectly determined by identifying the critical point that the gear transmission mechanism starts to respond to the driving signal, the critical point marks that the gear transmission mechanism completes the change from the idle stroke state to the effective transmission state, and the return difference measurement value is calculated based on the position data before the critical point. The return difference measurement value is a comprehensive index which contains the comprehensive influence of the gear backlash, the elastic deformation of the transmission shaft and the static friction force and reflects the overall transmission performance of the system, so that the return difference measurement value which reflects the overall transmission performance of the system and is real and comprehensive is obtained through measurement according to the technical scheme of the invention. According to the method, the transmission lag characteristic of the system under the actual working condition can be represented more accurately, and a more reliable data basis is provided for subsequent high-precision motion control.

The utility model relates to the technical field of centrifugal pumps, and discloses a vertical centrifugal pump medium-pressure mechanical seal which comprises a mechanical seal seat, a first limiting sleeve is installed at the upper end of the mechanical seal seat, a spring is installed between the mechanical seal seat and the first limiting sleeve, and a dynamic friction pair is movably connected into the upper end of the first limiting sleeve in a sleeved mode. And an O-shaped sealing ring is mounted between the first limiting sleeve and the dynamic friction pair. According to the medium-pressure mechanical seal of the vertical centrifugal pump, when the spring pushes the first limiting sleeve to move upwards, the first limiting sleeve and the dynamic friction pair can be controlled to be attached to keep tightness, meanwhile, the O-shaped sealing ring is controlled to be installed outside the output shaft, and the mechanical seal base, the first limiting sleeve and the dynamic friction pair synchronously rotate along with rotation of the output shaft; the sealing performance can be kept under the action of the O-shaped sealing ring, meanwhile, the static friction pair is installed on the limiting device, and the sealing sleeve seals the end of the output shaft, so that convenience is kept during installation, and the overall sealing performance of the pump body is improved.

A combined carpet is provided. The combined carpet includes an upper carpet body and a lower carpet body. The upper carpet body includes a first layer and a first attaching layer under the first layer; the lower carpet body is configured to be paved between the upper carpet and an object surface, and includes a second attaching layer and a second layer under the second attaching layer. An edge area of the first attaching layer extends beyond the second attaching layer to contact the object surface and does not overlap with the second attaching layer, a main area of the first attaching layer and the second attaching layer body realize a relative rest through a static friction force, to prevent relative movement when the upper and lower carpet bodies are connected, thereby forming a detachable combination between the upper carpet body and the lower carpet body.

The utility model relates to the field of semiconductors, and discloses a wafer bearing device and wafer detection equipment, and the wafer bearing device comprises a bearing seat, and a bearing area is provided with a limiting table; the supporting bracket comprises a friction contact surface protruding out of the bearing seat in the height direction of the bearing seat, and the friction contact surface is used for fixing the wafer through static friction force. In order to solve the problem that wafers made of some semiconductor materials cannot be adsorbed through static electricity, a supporting bracket is installed in a bearing area of a bearing seat, and the friction contact surface of the supporting bracket makes static friction contact with the wafers, so that the wafers are stabilized on the bearing seat through friction force, the requirement for bearing the wafers made of different semiconductor materials is met, the stability of the wafers is improved, and the service life of the wafers is prolonged. The wafer sliding probability is reduced, and the application range of the wafer bearing device is expanded; the wafer placed on the friction contact surface is limited through the limiting table, limiting protection after wafer sliding is achieved, and the safety of the wafer bearing device is improved.

The invention discloses a super-precision spring performance monitoring method and system, and relates to the technical field of precision manufacturing, and the method comprises the steps: determining the static friction state of a contact surface between a super-precision spring and a supporting clamp after a compression force is applied to the super-precision spring; if the static friction state is that the contact surface of the clamp is lubricated abnormally, interface friction dissipation and spring body energy dissipation are calculated after axial circulation loading is executed on the super-precision spring; after the axial cyclic loading is paused and the compression force is applied again, a static friction coefficient is obtained; according to the interface friction dissipation, the spring body energy dissipation and the static friction coefficient, performance detection is conducted, and a performance detection result is obtained. According to the invention, the performance monitoring of the super-precision spring is realized, and the accuracy is improved.

The utility model relates to the technical field of workshop assembly lines, and discloses an assembly line tray positioning mechanism which comprises a conveying belt, a tray is arranged on one side of the upper portion of the conveying belt, a supporting plate is arranged on the other side of the lower portion of the conveying belt, an electric push rod is fixedly connected to the lower surface of the supporting plate, and a plurality of plugs are fixedly connected to the upper surface of the supporting plate. A friction reduction unit is arranged in the tray, an auxiliary unit is arranged on the lower surface of the tray, and a stability augmentation unit is arranged on one side of the tray. According to the assembly line tray positioning mechanism, through cooperation of the conveying belt, the tray, the supporting plate, the electric push rod, the plug and the friction reduction unit, threaded transmission is conducted on a threaded cylinder, the flitch plate is limited through a vertical rod, the flitch plate can move upwards, a gap is generated between an anti-skid pad and the conveying belt, and at the moment, static friction force cannot be generated between the running conveying belt and the tray; abrasion to the conveying belt can be greatly reduced, and the purposes of reducing cost and increasing efficiency can be achieved for enterprises.

The invention provides a multi-degree-of-freedom robot clamping jaw structure and a control method thereof, and relates to the technical field of self-adaptive clamping jaws, and the multi-degree-of-freedom robot clamping jaw structure comprises a multi-degree-of-freedom mechanical arm, a double-shaft-hole plate, a first rotating shaft, a second rotating shaft, a cam part, a wobble wheel part and a driving unit. The invention creatively provides a pre-positioning and rolling clamping two-stage clamping mode, firstly, self-adaptive pre-tightening is carried out through independent rotation of the wobble wheel piece, and a gap is eliminated; then continuous rolling extrusion force is applied to the side wall of the workpiece through synchronous and same-direction rotation of the cam piece and the wobble wheel piece; by means of the dynamic linear contact extrusion mode, anti-rotation torque far larger than static friction force can be generated, and therefore on the premise of not depending on the large static friction force, axial movement and circumferential rotation of the workpiece in the carrying process are effectively restrained, and stable clamping in essence is achieved.

The invention discloses an automatic hooking and unhooking method and system for a gantry crane, and relates to the technical field of gantry cranes. The automatic hooking and unhooking method of the gantry crane comprises the steps of coarse positioning, multi-mode sensing, dynamic prediction and path planning, self-adaptive hooking and unhooking and closed loop confirmation. According to the automatic hooking and unhooking method for the gantry crane, through combination of multi-mode sensing and the digital twinborn prediction model, high-precision positioning and path planning in a dynamic environment are achieved, and accurate butt joint of the lifting hook and the corner fitting is achieved. Dynamically predicting a real-time simulation motion track based on a digital twin model, and planning an optimal path to counteract swinging; self-adaptive operation allows fine adjustment of the tail end of the lifting hook to adapt to tiny deviation; static friction and mechanical clamping stagnation can be broken through the micro-motion track action during unhooking, hook residues are prevented, closed-loop confirmation passes multi-sensor cross validation, and it is ensured that operation succeeds.

The invention relates to the field of fungus frame racking, in particular to a stable fungus frame racking machine, the bottom of a fungus frame is usually supported on a movable bearing roller, although a fixing device is arranged on the upper portion of the fungus frame, in the lifting motion, due to the mobility of the bearing roller, the fungus frame can still generate micro displacement or shaking, the fungus frame is separated from a fixing point, and therefore the fungus frame can not be separated from the fixing point. And safety risks in professional conveying of the fungus frames are further caused. When the mushroom frame is horizontally positioned and locked with the locking mechanism, the supporting of the bottom of the mushroom frame and the supporting rollers is converted into static friction from rolling friction, so that the risk of displacement and shaking of the mushroom frame caused by accidental rotation of the supporting rollers in the lifting process is eliminated, and the stability and the safety in the carrying process are improved.

This invention discloses a wide-range power adjustment device for a power vehicle, comprising a frame, a foot crank, a flywheel shaft, a flywheel, a static friction plate, an annular airbag, an airbag baffle, a return spring, a cantilever beam force sensor, a Hall sensor, and a controller. The flywheel shaft with the foot crank is rotatably connected to the frame, and the flywheel is fixedly connected to the flywheel shaft. The static friction plate, the annular airbag, and the airbag baffle are respectively clearance-fitted to the flywheel shaft. The annular airbag is fixedly connected between the static friction plate and the airbag baffle. Each return spring is connected between the static friction plate and the airbag baffle. The fixed cantilever beam force sensor is connected to the top of the static friction plate via a top steel wire rope. The speed measuring probe of the Hall sensor faces the flywheel. The inflation mechanism, the deflation mechanism, the cantilever beam force sensor, and the Hall sensor are all connected to the controller. This invention adopts a friction-damped power adjustment method, without a transmission structure, achieving zero power output and increasing the maximum power range.

This invention discloses a wind turbine yaw bushing device that is easy to disassemble, belonging to the field of wind turbine technology. It includes a yaw bushing body, which is installed in a mounting hole on a base. A pushing assembly is movably disposed within the bottom side wall of the yaw bushing body. A driving sleeve is rotatably disposed within the disassembly hole. A limiting ring is disposed above the driving sleeve, and a limiting block is rotatably disposed at the bottom of the limiting ring. When the yaw bushing body is disassembled, the driving sleeve rotates, causing it to move downwards and propelling the pushing assembly out from the bottom of the yaw bushing body. This allows the yaw bushing body to move upwards within the mounting hole. Simultaneously, lubricating liquid quickly seeps into the space between the yaw bushing body and the mounting hole through a groove, rapidly forming a lubricating film. This effectively reduces the force required to overcome the initial static friction, thus enabling rapid disassembly of the yaw bushing body.

The application relates to the technical field of bridge construction equipment, in particular to a steel box girder bridge plate hoisting structure and a hoisting method. The steel box girder bridge plate hoisting structure comprises a base, a traction wheel rotatably arranged on the base, static friction discs fixed on the two sides of the traction wheel, a support fixed on the base, dynamic friction discs slidably arranged on the support, and driving rods abutting against the two dynamic friction discs; a plurality of clamping grooves are annularly arranged on the traction wheel hub; a locking rod is rotatably arranged on the base and always has a tendency to move away from the clamping grooves under the action of an elastic element; a pull rope is arranged at the end of the locking rod and connected with the driving rod at the other end of the dynamic friction disc. The traction wheel braking is changed, in addition to the friction braking between the dynamic friction disc and the static friction disc, a rigid locking structure of the locking rod inserted into the traction wheel hub is further arranged. Compared with the traditional compression type friction braking, the combination of the friction braking and the rigid locking is equivalent to the rigid braking mode of the inserted locking, and the rigid braking mode of the inserted locking is more stable.

A shape memory alloy actuator assembly (1) comprising a first part (4), a second part (20), at least one SMA element (80) and a controller. The second part is movable relative to the first part across a first surface. The at least one SMA element is arranged, on actuation, to drive movement of the second part relative to the first part. The assembly is arranged such that the second part and the first surface are biased against each other with a normal force, thereby generating a static frictional force that constrains the movement of the second part relative to the first part when the at least one SMA element is not actuated. The controller is configured to control actuation of the at least one SMA element. Specifically, during a power-on sequence of the at least one SMA element, the controller causes an increase of a power supplied to the at least one SMA element gradually from zero to an operating power, and / or during a power-off sequence of the at least one SMA element, the controller causes a decrease of a power supplied to the at least one SMA element gradually from an operating power to zero.

The invention discloses an MEMS (Micro Electro Mechanical System) inertial sensor with high static friction resistance. The MEMS inertial sensor includes a support structure and an inertial structure. The inertial structure comprises at least one inertial mass block, an elastic structure and a stop structure. The resilient structure is mechanically coupled to the inertial mass and the support structure such that when the support structure is subjected to acceleration parallel to the first direction, the inertial mass is movable in a direction parallel to the first direction. The stop structure is fixed relative to the support structure and includes at least one primary stop element and one secondary stop element. If the acceleration exceeds a first threshold, the inertial mass abuts the primary stop element and then rotates about an axis of rotation defined by the primary stop element. If the acceleration exceeds a second threshold, rotation of the inertial mass is terminated when the inertial mass abuts the secondary stop element.

The application discloses a differential pressure mechanical sealing structure and a compressor, and relates to the technical field of mechanical sealing structures, and in particular relates to a differential pressure mechanical sealing structure and a compressor. The structure comprises a shell, an input shaft, a sealing static ring and a sealing dynamic ring, opposite sides of a mounting cavity on the shell are provided with shaft holes which are respectively connected with the inside of the shell and the outside; the input shaft passes through the mounting cavity and the shaft holes on the opposite sides of the mounting cavity and is connected with the sealing static ring; the dynamic friction surface of the end of the sealing dynamic ring is opposite to and adheres to the static friction surface of the sealing static ring, and the outer side of the sealing dynamic ring is provided with a ring of sealing pairs, so that the closed cavity of the mounting cavity is divided into an internal pressure cavity which is connected with the inside of the shell and an oil pressure cavity which is connected with an oil return channel. The sealing structure of the application divides high and low pressure areas by arranging the sealing pairs with comb-shaped sealing on the sealing dynamic ring, forms high and low pressure differences on both sides of the sealing dynamic ring, and forms a pre-tightening force difference between the sealing dynamic ring and the sealing static ring by combining the projection area corresponding to the pressure. The pre-tightening force difference does not decay with the abrasion of the mechanical sealing dynamic ring and the mechanical sealing static ring, but is only related to the current working pressure difference.

The invention discloses an intelligent material sorting device, and belongs to the technical field of material sorting, the intelligent material sorting device comprises a plurality of supports, two symmetrically arranged side plates are mounted on the supports, and a transmission mechanism is mounted between the two side plates; the angle adjusting mechanism can be linked through the scanning controller, the angle of the discharging plate is flexibly adjusted by means of the first electric push rod and the rolling wheels, the static friction force and the gliding requirement of materials with different sizes and weights are met, and the problem of blockage or too fast speed caused by a traditional fixed angle is solved; by means of a transmission belt of the auxiliary discharging mechanism, materials with too small sizes can be accurately pushed to be separated from the transmission belt, and the problem that the materials are difficult to slide off is solved; by matching with the moving and arranging function of the baffle, the material placing deviation can be corrected, and the storage difficulty is reduced; and meanwhile, the materials stably slide down to the second material receiving box along the adaptive angle, so that the collision damage risk is greatly reduced, automatic and precise sorting is integrally realized, the sorting efficiency is improved, and the material loss is reduced.

The invention relates to the field of fluid adjustment, in particular to a control valve with small maximum static friction force between a sealing part and a valve element part, the valve element part can rotate around the axis corresponding to the valve element part, the sealing part is provided with a concave part, and the wall parts corresponding to the two sides of the sealing part in the thickness direction abut against the valve element part and a seat body part respectively. The sunken part is located on the side, close to the valve element part, of the sealing part in the thickness direction, and at least part of the part, abutting against the valve element part, of the sealing part is located between the sunken part and the second communication part, so that the stability of the valve element part during rotation is guaranteed, meanwhile, the contact area between the sealing part and the valve element part is reduced, and under the same friction coefficient and pressure, the sealing performance is improved. And the maximum static friction force between the sealing part and the valve core part is reduced.

The invention discloses an assembly positioning system and method suitable for medium and large castings, and belongs to the technical field of precision mechanical assembly.The assembly positioning system comprises a platform, stand columns are arranged on the two sides of the platform, the stand columns are fixedly connected with a cross beam, a traveling crane is arranged on the cross beam, a first-stage weight reduction system is installed on the traveling crane, and a first casting is fixedly installed on the platform; a second casting is placed on the first casting, and a second-stage resistance reduction system and a third-stage fine adjustment system are arranged on the second casting. According to the assembly positioning system and method suitable for the medium and large castings, the positioning-fitting contradiction of heavy-load precision assembly is solved through cooperation of a weight reduction-resistance reduction-fine adjustment three-stage coupling mechanism, and the gravity influence of the second casting is weakened through the air cylinder set controlled by the pressure valve; physical coupling between the contact faces of the second casting and the first casting is reserved, static friction balance is broken through vibration of the vibration exciter, the propelling load of the micro-motion ejector rod is reduced, and high-precision displacement control is conducted through the micro-motion ejector rod to achieve precise positioning.

The invention relates to the technical field of combined machining, in particular to a special-shaped ring rolling process method for tooth blank die forging forming, which comprises the following steps: circularly adjusting the rotating speed of a main roller and the feeding speed of a core roller of a ring rolling device in real time according to the actual rotating angle of an annular blank, and correcting the eccentric degree of the annular blank; reflecting the matching condition of the radial strain rate and the axial strain rate according to the change of the convex part of the annular blank, adjusting a correction parameter for correcting the eccentricity degree of the annular blank, and adjusting the holding roller compression rate of the rolling ring device to make up the change of the length of the convex part; estimating the required torque of the main roller and the maximum static friction, and judging whether the eccentricity of the corrected annular blank can cause the required torque of the main roller to exceed the limit or not; when the required torque of the main roller exceeds the limit, the adjusting amplitude of the rotating speed of the main roller and the feeding speed of the core roller is reduced, and the judgment standard for judging whether the eccentricity degree of the annular blank can be corrected or not is called back. The forming uniformity of the non-standard annular special-shaped tooth blank is improved by combining die forging with ring rolling.

The application relates to a paper box production equipment field, in particular to a paperboard automatic feeding device, which comprises a feeding mechanism, the bottom of the falling paperboard is pushed by a pushing piece, the falling paperboard is pushed over to the feeding mechanism, the degree of automation is improved, and the production efficiency is improved; due to the friction force between the adjacent paperboards, part of the paperboards is suspended in the air when falling in the vertical direction static friction with the front and rear paperboards; when the pushing piece pushes over the front paperboard, the part of the paperboard loses the friction force and falls to the upper side of the supporting strip and keeps the vertical state; in the retracting process of the turning-over mechanism, the rear side of the pushing piece abuts against the front side of the frontmost paperboard, then the pushing piece is turned over downward along the hinge joint of the inclined block and the U-shaped block in the continuous retracting process, then passes through the lower side of the part of the paperboard, and the pushing piece is turned over upward and reset by the pulling force of the tension spring after passing through the part of the paperboard, so that the paperboard is prevented from being pressed and bent, and the production reliability is improved.

A gripper which has a friction estimation module configured to estimate static and / or dynamic friction forces acting on gripping jaws is provided. The static friction force is calculated on the basis of constraining reactions whereto the gripping jaws are subjected, the constraining reactions being calculated at least as a function of an actuation force exerted on the gripping jaws, a coefficient of friction of gripper materials and / or lubricant used being known. The dynamic friction force is calculated on the basis of speed of the gripping jaws, width of sliding surfaces and distance between the sliding surfaces of the gripping jaws, the viscosity of the lubricant used being known.