77results about How to "The lifting process is stable" patented technology

The invention relates to a middle packaging machine. The middle packaging machine comprises a material tidying mechanism, a packaging bag pushing mechanism, a bag suction mechanism, a bag conveying mechanism, a bag opening mechanism and an opening sealing mechanism and further comprises a flattening mechanism. The material tidying mechanism tidies supplied materials and then conveys the materials to the flattening mechanism, the materials are flattened by the flattening mechanism and then are conveyed to a packaging bag pushing way of the packaging bag pushing mechanism, a plurality of packaging bags are divided into single packaging bags by the bag conveying mechanism and then are conveyed to the position below a bag suction rod of the bag suction mechanism, the bag suction rod of the bag suction mechanism sucks up and opens the packaging bags, the packaging bags are opened by an opening claw of the bag opening mechanism, a packaging bag pushing block of the packaging bag pushing mechanism pushes the supplied materials to the packaging bags, the packaging bag pushing block of the packaging bag pushing mechanism drops out, then the opening claw of the bag opening mechanism drops out, and the opening sealing mechanism seals openings of the packaging bags and packages the bags. Raw materials are tidied and then are flattened, recovery deformation of the raw materials in the packaging process is reduced, and the defect that the packaging space is large due to deformation recovery is overcome.

The invention relates to an auxiliary device for hip joint replacement operation. The device comprises a bedstead and a bed plate, wherein the middle part of the top end of the bedstead is provided with a buttocks-supporting plate which can move back and forth and lift; the left and right sides of the bedstead are respectively and slidably connected to sliding plates capable of sliding forwards and backwards, the top end of each sliding plate is hinged to a working plate, the bottom of each working plate is provided with leg supporting rods with adjustable height, the inner sides of the working plates are provided with jacking plates capable of moving leftwards and rightwards and inclining forwards and backwards, and the top end of each jacking plate is provided with a push plate and a folding plate which can independently adjust the inclination angle and are hinged to each other; and the left and right sides of the rear end of the bedstead are hinged to telescopic lifting plates, thetop ends of the lifting plates are hinged to bridge plates, the inner ends of the two bridge plates are movably connected and slidably connected to a moving plate, a rotating plate capable of horizontally rotating and moving up and down is arranged on the moving plate, and two leg lifting clamps hinged to each other are arranged at the bottom end of the rotating plate. The device effectively solves the problems that: the body position cannot be changed in the prior hip joint replacement operation, the body position of a patient cannot be firmly fixed in the operation, and the part to be operated cannot be fully exposed.

The invention discloses a lifting frame adopting an independent framework foundation and an operating method. The lifting frame comprises a steel frame, bottom square steel and two pieces of channel steel; a rectangular frame formed by welding four pieces of square steel is arranged at the top end of the steel frame, the four vertexes of the rectangular frame are perpendicular to four pieces of vertically-downward square steel welded to the plane of the rectangular frame respectively, and two pieces of parallel square steel are arranged at the bottom end of the steel frame and each welded between the ends of one pair of square steel perpendicular to the plane of the rectangular frame; a plurality of bolt holes are formed in the two pieces of square steel arranged at the bottom end of the steel frame at equal intervals; the bottom square steel is perpendicularly fixed between the two pieces of square steel arranged at the bottom end of the steel frame through bolts; the two pieces of channel steel are installed on the lower end faces of the bottom square steel located on the two sides of the bottom end of the steel frame through bolts respectively in the modes that channel openings face upwards. According to the lifting frame, the structure that the steel frame formed by welding the square steel is detachably connected with the bottom square steel and the channel steel is adopted, the lifting frame is provided with lifting points itself to achieve lifting, the number of the bottom square steel can be freely regulated according to a model structure, the lifting process is stable, and the safety performance is high; in addition, operation is convenient, and the working efficiency is high.

The invention discloses an incubator inside turn-over device for a newborn baby. The incubator inside turn-over device comprises an incubator and a mattress, wherein the mattress is arranged in the incubator, a rotating shaft is arranged at one side of the mattress along an axial direction and is inserted in the mattress, the mattress is divided into a headrest, a back cushion and a leg rest alongthe axial direction, and the back cushion is fixedly arranged in the incubator. The incubator inside turn-over device further comprises lifting devices, wherein the lifting devices are separately arranged below the headrest and the leg rest, sliding grooves are separately formed in bottoms of the headrest and the leg rest and are vertical to the rotating shaft, each lifting device comprises an air cylinder and a link, the air cylinders are fixedly arranged at the bottom of the incubator, one end of each link is connected with the corresponding air cylinder, and the other end of each link is in slip connection with the corresponding sliding groove. The incubator inside turn-over device for the newborn baby can assist medical care personnel turning over the baby and provide a support, so that the working strength of the medical care personnel is alleviated, and physical force is saved.

The invention provides an automatic detecting device of a three-reference-circle screw hole of a hydraulic torque converter. The automatic detecting device comprises a mounting bottom plate; a supporting mechanism, a lifting mechanism and a positioning mechanism are arranged on the mounting bottom plate; and the supporting mechanism is arranged between the mounting bottom plate and a detecting mechanism mounting plate. A detecting mechanism and a compressing mechanism are arranged on the detecting mechanism mounting plate. A workpiece hydraulic torque converter is arranged on the supporting mechanism. According to the invention, the hydraulic torque converter can be lifted stably and accurate angular positioning can be carried out on the hydraulic torque converter; simultaneous detection of different-reference-circle screw holes of the hydraulic torque converter is realized; quick and automatic switching is realized for different reference circles; and mixing-production line productionof same kinds of products with different types is realized while the efficiency is improved, the cost is saved, and the stability is improved.

The invention discloses a lifting mechanism of a frame splitting machine for industrial aquaculture. The lifting mechanism comprises a lifting body, a sliding block body and a lifting screw rod assembly, wherein the lifting body is connected with the sliding block body, the sliding block body is positioned on the lifting screw rod assembly, and the lifting screw rod assembly drives the lifting body to slide up and down through the sliding block body. According to the lifting mechanism, the overall structural design is ingenious and reasonable, a driving motor drives a lifting screw rod to rotate through a gear conversion box, so that the lifting of the sliding block body is achieved to drive the lifting of the lifting body, the step-by-step separation between a lower culture frame and an upper culture frame stack is achieved, the assembly and disassembly of the culture frame stack is more convenient, the assembly line operation of cocoon collection in the culture frame is achieved, thewhole operation is more automated, and the labor intensity of workers is effectively reduced; and the lifting screw type lifting is adopted, the stability in the lifting process of the lifting body can be effectively guaranteed, the lifting process of the lifting body is more smooth and stable, collision caused by swinging of the lifting body in the lifting process is avoided, and the operation safety performance is improved.

The invention discloses a hydraulic cage stabilizing and supporting wobble platform provided with a floating rocker arm, which belongs to a cage supporting device for a vertical shaft in a mine. The wobble platform comprises a frame, a rocker arm, support claws, an adjustable weight box, a driving tension arm, a rocker arm oil cylinder and a support claw oil cylinder, wherein the rocker arm is fixed at the upper part of the frame through a main shaft; the support claws are arranged at the lower part of the front end of the rocker arm and are positioned on both sides of the frame; the adjustable weight box and the driving tension arm are arranged at one end of the rocker arm close to the main shaft; the rocker arm oil cylinder is connected with the driving tension arm and a base of the frame so as to drive the rocker arm to swing up and down; the support claw oil cylinder drives the support claws to move along a cambered surface; the rocker arm comprises rocker tips and angular two-sided cage stabilizing devices; the rocker tips are arranged at the front end of the rocker arm and are positioned in V-shaped grooves for a cage; the angular two-sided cage stabilizing devices are distributed on the both sides of the rocker tips; the angular two-sided cage stabilizing devices comprise reinforcement plates, cage stabilizing channel steel, cage stabilizing rollers and stop blocks; the cage stabilizing channel steel is arranged on the outer edges of the reinforcement plates and is provided with cage stabilizing support saddles; and the stop blocks are provided with cambered surfaces. The hydraulic cage stabilizing and supporting wobble platform provided with the floating rocker arm can lead the cage to be positioned from four sides after stopping, the rocker arm can float, the structure is compact, the operation is smooth, and the maximum uplifting angle of the rocker arm can reach 55 degrees.

The invention discloses an outer pipeline detection robot and a walking method, the outer pipeline detection robot comprises an outer wall assembly and an inner wall assembly, the outer wall assembly and the inner wall assembly each comprise a plurality of electric control adsorption devices, and the electric control adsorption devices can be adsorbed on the outer wall of a detected pipeline; the outer pipeline detection robot further comprises a main shaft and a transmission assembly connected with the main shaft. When the main shaft rotates forwards, the transmission assembly drives the outer wall assembly to advance and drives the electric control adsorption devices on the outer wall assembly to alternately move close to and away from the detected pipeline; when the main shaft rotates reversely, the transmission assembly drives the inner wall assembly to advance. According to the outer pipeline detection robot and the walking method, the problem that in the prior art, a crawling robot is not suitable for long-distance oil and gas conveying pipeline outer wall detection is solved, and the purpose that the characteristics that the long-distance oil and gas conveying pipeline is gently arranged, long-distance operation is needed and the like can be achieved.

The invention relates to a parking craning method for vibration sinking construction of steel cylinders, in particular to a method by which a cargo ship is parked by an anchoring device and fixed point parking and craning of the cargo ship and moving of craned objects are realized by comprehensive anchoring modes such as crossed traction cables. The method comprises the steps of after the cargo ship carried with the steel cylinders arrives at a parking position, performing four-point mooring on the cargo ship by the anchoring device; anchoring and positioning by driving a floating crane ship to the craning position at the side body of the cargo ship, and forming stable connection between the crossed traction cables at the head of the float crane ship and the head and tail of the cargo ship; craning the steel cylinders by the float crane ship; smartly adjusting the direction of the float crane ship by the anchor cables; controlling the float crane ship to drive to the craning position at the side body of a steel cylinder mounting positioning pier for anchoring and positioning; craning the steel cylinder to the vibration sinking designed position of the steel cylinder in a fixed point mode by the positioning pier through the float crane ship and realizing the vibration sinking location of the steel cylinder by the positioning pier.

The invention provides a self-lifting cabinet. The self-lifting cabinet comprises a cabinet main body and a lifting foot stand; the lifting foot stand is fixed at the bottom of the cabinet main body;the lifting foot stand can deform to lift the cabinet main body to a preset height relative to the ground; the cabinet main body comprises a surrounding frame; the surrounding frame is arranged at thebottom of the cabinet main body; the surrounding frame surrounds the bottom to form an accommodating cavity at the bottom of the cabinet main body; and the lifting foot stand is arranged in the accommodating cavity. According to the self-lifting cabinet of the invention, the cabinet main body can be stably lifted or descended; the cabinet main body leaving the ground can be convenient to carry, so that the self-lifting cabinet can be moved to a required position. In addition, the invention provides a self-lifting cabinet moving system.

The invention provides a lifting mechanism of a 3D printer, and aims at solving the problem of poor lifting effect of the lifting mechanism in the prior art. The lifting mechanism of the 3D printer is characterized in that the 3D printer comprises a base, wherein a plurality of mounting holes in which vertical columns are fixed are formed in the base; an ink-jet printing head for printing is arranged between every two vertical columns; the lifting mechanism capable of controlling the ink-jet printing head to lift up or lift down is arranged between each ink-jet printing head and the corresponding vertical column; each lifting mechanism comprises three lifting tracks which are fixed to three vertical columns; three lifting blocks are correspondingly matched with the three lifting tracks; four pulleys which are in match with the lifting track sleeve the lifting block; each lifting block is provided with two outward bulging parts, and each bulging part is provided with a hinging hole; the lifting blocks can be hinged with the upper ends of control arms through first hinging columns; the lower ends of the control arms are connected to the corresponding ink-jet printing heads; a telescoping rod which can be telescoped is arranged in the middle of each control arm. The lifting mechanism of the 3D printer has the advantage that the lifting effect is good.

The invention provides a buttock lifting and sterile drawsheet laying device for a gynecological operating bed. Lifting devices which are in angle adjustable connection with corresponding side leg supports are arranged on the frames at two sides of the tail part of the operating bed; the lifting devices drive the leg supports and the legs of the patient positioned on the leg supports to move upwards or downwards to realize the lifting or falling of the buttocks of the patient; the sterile drawsheet laying device which can move along the length direction of the frames of the operating bed is arranged on the frames at the tail part of the operating bed; the front end and the rear end of the sterile drawsheet laying device are positioned at the two sides of the buttocks of the patient and arerespectively and fixedly connected to the right angles at the left end of a sterile drawsheet; and the sterile drawsheet laying device drives the sterile drawsheet to move leftwards to realize the laying of the sterile drawsheet after the buttocks of the patient are lifted. The device realizes the laying of the sterile drawsheet after the buttocks of the patient are lifted, solves the problem that the medical staff difficultly lift the buttocks of the patient when the self-control of the patient is inconvenient, is convenient for the medical staff to observe the focus before the operation, reduces the difficulty of laying the sterile drawsheet under the buttocks of the patient, and reduces the discomfort caused by the fact that the buttocks of the patient is lifted too high.

The invention discloses a clamping and positioning assembly line, and relates to the technical field of electronic product machining auxiliary equipment. The clamping and positioning assembly line comprises a first assembly line and a second assembly line, each of the first assembly line and the second assembly line is provided with a positioning and conveying device, a first picking device is arranged over the first section of the first assembly line in a direct facing mode, an overturning device is arranged between the tail section of the first assembly line and the head section of the second assembly line, a second picking device is arranged over the overturning device in a direct facing mode, and a third picking device is arranged over the tail section of the second assembly line in a direct facing mode; the positioning and conveying device comprises a positioning and clamping assembly and a conveying assembly; the first picking device, the second picking device and the third picking device are identical in composition structure; and each of the first picking device, the second picking device and the third picking device comprise two picking heads, and each picking head comprises an air cushion. The clamping and positioning assembly line has the advantages of high automation degree, wide application range and high machining efficiency.

The invention discloses turnover hoisting equipment for an electrical cabinet. The turnover hoisting equipment comprises a fixed seat, wherein a fixed rod and a support located at one side of the fixed rod are rotationally arranged at the top side of the fixed seat; the support is rotationally provided with a winch; a boom is fixedly arranged at the top side of the fixed rod along a horizontal direction; a roller is rotationally arranged at one side of the boom; the roller is in transmission connection with a hoisting rope; one end of the hoisting rope is fixedly connected to the winch; one end, which is far away from the winch, is fixedly connected with a first sleeve rod which is arranged along the horizontal direction; grooves are formed in both two ends of the first sleeve rod; first sliding grooves are formed in the grooves along the horizontal direction; first sliding rods are arranged in the grooves in a sliding way. The turnover hoisting equipment disclosed by the invention canbe flexibly adjusted according to the size of the electrical cabinet which requires to be hoisted, the electrical cabinet can be clamped, stable and firm hoisting can be realized, and a rope requiresnot to be additionally sleeved on the electrical cabinet, so that hoisting work is simpler and more convenient, and the working efficiency is improved.

The invention discloses a nursing device for an anesthesia recovery period. The nursing device comprises a bed plate; an adjusting assembly and a jacking assembly are arranged on the bed plate; the adjusting assembly is provided with an adjusting plate; an arc-shaped guide plate is fixed to the lower end face of the adjusting plate; a vertical plate is arranged at the end of the bed plate; a rotating shaft is arranged on the end face of the vertical plate and is connected with the guide plate through an L-shaped connecting handle; the adjusting plate, the guide plate and a connecting plate can rotate along with the rotating shaft; the center line of the rotating shaft and the upper end face of the bed plate are coplanar; a guide groove is formed in the guide plate and is of an opening structure at the edge of the guide plate; the jacking assembly is arranged on the portion, located on the inner side of the adjusting assembly, of the bed plate and comprises a jacking block; the upper end of the jacking block is provided with an arc-shaped structure; a transverse rod is arranged on the end face, facing the adjusting plate, of the jacking block; and when the adjusting plate is in a horizontal state, the jacking block moves up and down to enable the transverse rod to be clamped into a guide groove from the lower portion. According to the invention, the nursing effect can be effectively improved, and the labor amount is reduced.

The invention provides automatic welding equipment for fishing gear box accessories, and relates to the technical field of fishing gear box machining. The automatic welding equipment for the fishing gear box accessories comprises a lower working frame, a mounting table is fixedly connected to the upper surface of the lower working frame, two rows of conveying assemblies are fixedly mounted on theupper surface of the mounting table and are symmetrically arranged, one row of conveying assemblies are in transmission connection through chains, a carrying plate is arranged above the two rows of conveying assemblies in a rolling mode, and a non-adhesive plate is embedded in the upper surface of the carrying plate. According to the equipment, a driving motor is started and drives one of rotatingshafts to rotate through a belt, due to the fact that the multiple rotating shafts are in transmission through the chains, the conveying assembly drives the carrying plate to move from left to right,products can be continuously conveyed to the position below the hot-pressing welding mechanism for welding operation, the welding effect is improved, and batch production of enterprises is facilitated.

The invention relates to the technical field of heaters, in particular to a heater with a lighting function. The heater comprises a heater body, a control switch, a fixing bottom plate, fixed columns,clamping grooves, limiting columns, through grooves and limiting teeth, and a permanent magnet is arranged on the lower end of the fixed columns and the inner wall surface of the clamping grooves. The device is reasonable in structural design, the fixing columns and the limiting columns are arranged at the bottom of the heater and are connected with the fixing bottom plate in a matched mode, thefixing columns and the limiting columns are inserted into fixing grooves and the limiting grooves, the limiting teeth of the limiting columns are connected with tooth grooves in the limiting grooves in a clamped mode, fixing plates slides to one end of the fixing columns and penetrates through the through grooves until the fixing head are inserted into the clamping grooves, the lower end of the fixing columns and the inner wall of the fixing grooves are provided with permanent magnets, and the fixing head and the inner wall of the clamping groove are provided with permanent magnets, the permanent magnets attract each other and can be fixed to each other, a lifting device can slide pulleys through electric push rods, the height of the heater can be adjusted through a linkage lifting rod, meanwhile, a supporting pad has a damping buffering function, so that the lifting process can be more stable.

The invention discloses a multifunctional chair which comprises a back supporting piece, a seat supporting piece, a supporting frame and a transmission rod. A connecting rod mechanism is arranged between the back supporting piece and the supporting frame, and the back supporting piece can tilt relative to the supporting frame through the connecting rod mechanism. A rotating supporting rod which enables the seat supporting piece to be lifted upwards relative to the supporting piece is arranged between the rear end of the seat supporting piece and the supporting frame; a sliding guide mechanism is correspondingly arranged between the front end of the seat supporting piece and the supporting frame; and one end of the transmission rod is hinged to the back supporting piece or the connecting rod mechanism, and the other end of the transmission rod is hinged to the seat supporting piece or the rotating supporting rod. The back supporting piece tilts to drive the transmission rod to move, and then the transmission rod drives the seat supporting piece to be synchronously lifted relative to the supporting frame. A locking mechanism is arranged in the sliding guide mechanism; and under the action of the locking mechanism, the seat supporting piece can be lifted up relative to the supporting frame and stay at any lifting position, and the back supporting piece stays at the corresponding tipping position.

The present invention relates to the technical field of fruit processing devices and particularly to a fruit treatment device. The fruit treatment device comprises a vertically arranged dicing knife and a washing cover being arranged together with the dicing knife, a cover body of washing cover is opened with a spraying nozzle joint to connect a hard water supply pipe and a spraying nozzle, a toppart of the dicing knife is fixed with a rotating shaft, the water supply pipe is in transmission connection with the rotating shaft, the rotating shaft is driven to rotate by a driving motor, thus one edge of the rotating shaft drives the dicing knife to rotate to lift up and one edge of the rotating shaft drives the water supply pipe to conduct lifting up with the same angle. When the dicing knife needs to rotate and lift up due to avoidance or inclined cleaning and other reasons, the rotating shaft provides the dicing knife with a rotating and lifting force from a top part, besides, the hard water supply pipe also applies a lifting-up force to the washing cover and the washing cover thus transmits the lifting-up force to the dicing knife. The dicing knife is simultaneously subjected tothe lifting-up forces exerted by the rotating shaft and the hard water supply pipe, wherein the hard water supply pipe plays a role in assisting in applying the lifting-up force, so that more stable support is provided for the dicing knife.

The invention discloses a liftable traditional Chinese medicine sorting cabinet, which comprises a cabinet body, a plurality of bottom storage cabinets are arranged at the bottom of the cabinet body, several rows of several bottom common traditional Chinese medicine sorting cabinets are arranged above the bottom storage cabinets, and a plurality of bottom common traditional Chinese medicine sorting cabinets are arranged above the bottom storage cabinets. There are several rows of commonly used traditional Chinese medicine sorting cabinets in the middle, and a row of several middle commonly used tool display cabinets is arranged in the middle of the middle commonly used traditional Chinese medicine sorting cabinets, and several rows of several top special traditional Chinese medicine sorting cabinets are arranged above the middle commonly used traditional Chinese medicine sorting cabinets , the two sides of the cabinet are provided with side plates, the side plates are provided with a lifting device, the bottom of the lifting device is provided with a bottom plate, the end of the bottom plate is provided with a baffle, and an inner wall is formed between the bottom plate and the baffle. cavity, the lifting device is arranged in the inner cavity, and the cabinet moves up and down relative to the bottom plate according to the lifting device. The invention has the characteristics of convenient use, simple structure, convenient operation and more convenient access to the medicinal materials on the top.

The invention discloses an automatic rotary locking switch system which comprises a perfume bottle and a base, and further comprises an automatic rotary locking mechanism. The automatic rotary lockingmechanism arranged between the perfume bottle and the base comprises a first limiting block, a handle assembly and a second limiting block, wherein the handle assembly is composed of a stand and a rotary support, the rotary support is half clamped on the stand and drives the stand to rotate, one end of the rotary support is provided with a handle matched with the base, an iron bar is fixedly connected with the middle of the bottom of the rotary support, the iron bar is movably connected with the base, the bottom of the other end of the rotary support is connected with a plurality of springs,the springs are sleeved with screws installed on the rotary support, a torsional spring is arranged between the handle assembly and the second limiting block, and a magnet is arranged on one side in the second limiting block. The automatic rotary locking switch system is smooth and natural to use, the handle can be automatically locked in a groove after being rotated, it is avoided that a perfumeswitch system is accidentally touched and opened, and the waste phenomenon caused by high-grade perfume loss is avoided.

The invention relates to a device for supporting an independent container (2) for cryogenic media, particularly LNG, in a vertical position in a ship (1) or a stationary facility (1). The device comprises a support for the container (2), which supports the container (2) on a corresponding foundation (10) of the ship (1) or the facility (1) through a thermally insulating layer (7) and which enables a horizontal relative motion between the container (2) and the foundation (10).

The invention discloses a multi-stage lifting and feeding device of an automatic bamboo breaking machine. The multi-stage lifting and feeding device comprises a lifting device body, wherein the lifting device body comprises a plurality of lifting device bodies, and the lifting device single body and the adjacent lifting device single body are distributed in a step mode; and a bamboo barrel is automatically rolled to the upper part of a lifting plate through a slope, and the bamboo barrel is lifted to the upper-stage lifting device single body through the lifting plate, and is automatically rolled up to the upper part of the lifting plate of the upper-stage lifting device single body, so that the purpose of automatically lifting and conveying the bamboo barrel is achieved. The lifting and conveying process of the multi-stage lifting and feeding device of the automatic bamboo breaking machine is more stable, the bamboo barrel does not need to be paved in the material stacking area of thebamboo barrel, even if the bamboo barrel is stacked in the material stacking area, normal lifting and conveying of the bamboo barrel cannot be influenced, the conveying of the bamboo barrel basicallyhas no mistakes, and therefore the working efficiency of the automatic bamboo breaking machine is improved, so that the processing time of bamboo breaking is saved.

The invention discloses a cutting tool which comprises a base assembly and a cutting work head. The base assembly comprises a base and a rotating support, wherein the rotating support is arranged above the base. The cutting work head comprises a saw blade, a motor, a transmission mechanism and a head shell, wherein the motor and the transmission mechanism are arranged in the head shell and drive the saw blade so that the saw blade can achieve one or more of pivoting movement, linear reciprocating movement and curve reciprocating movement. The head shell and the rotating support are in hinged joint, the head shell comprises at least one power assistance sleeve with the opened bottom end and the sealed top end, and a spiral spring is arranged in the power assistance sleeve, wherein the top end of the spiral spring butts against the head shell, and the bottom end of the spiral spring butts against the rotating support. The cutting tool has the advantages that the spiral spring is adopted for assisting the cutting work head to be bounced, and a top end assembling part of the power assistance sleeve is arranged so that the top end of the spiral spring can be curved forwards and backwards respectively when the cutting work head is located at a downward pressing position and a lifting position to assist the operation of a user.