806results about How to "Easy to hold" patented technology

The utility model discloses an embedded block blank lifting appliance which comprises a lifting ring, a pin shaft assembly, upper pull arms, lower clamping arms and a tong head plate and further comprises a limiting rod assembly, the length of the limiting rod assembly can be adjusted, one end of the limiting rod assembly is rotationally connected to the outer wall of one upper pull arm through a pin shaft, and the other end of the limiting rod assembly is rotationally connected to the other end of the limiting rod assembly. And a limiting pin is arranged on the outer wall of the other opposite upper pulling arm, and the other end of the limiting rod assembly can be clamped to the limiting pin, so that a jaw between the two oppositely-arranged tong head plates is opened, and the opening degree is matched with the width of the head of the steel rail inlaid block. According to the embedded block blank lifting appliance, the width of the opening jaw can be adjusted, so that the embedded block blank lifting appliance is suitable for clamping embedded blocks with different width specifications.

This utility model relates to a multi-segment adhesive cutting device, including a frame, a cutting component for cutting the outer layer of copper busbars or cables, a clamping component for holding the copper busbars or cables, a moving component for controlling the movement of the cutting component, and a bracket for supporting the copper busbars or cables. The cutting component is connected to the frame via the moving component, and the bracket is connected to the frame. The moving component is disposed within the frame. The cutting component includes a cutting fixed frame, an upper cutting unit, a lower cutting unit, and a transverse cutting unit. The cutting fixed frame and the moving component are fixedly connected. The upper cutting unit is disposed at the upper end of the cutting fixed frame, the lower cutting unit is disposed at the lower end of the cutting fixed frame, and the transverse cutting unit is disposed at the front end of the cutting fixed frame. The design of this utility model can not only achieve circumferential cutting of copper busbars or cables, but also achieve transverse cutting of copper busbars or cables, and is not limited to stripping the outer layers at both ends of the copper busbars or cables, thus improving the versatility of the device in use.

The invention relates to a welding center and method for platform machining, and belongs to the technical field of welding equipment. The device comprises a rack, a gantry frame is slidably mounted on the upper surface of the rack, an air cylinder is slidably arranged at the bottom of a cross beam of the gantry frame, a mounting plate is fixed to the telescopic end of the air cylinder, and a welding head is mounted on the lower surface of the mounting plate; and fixing cylinders are further included, the two fixing cylinders are fixed to the left side and the right side of the lower surface of the mounting plate, and moving plates are slidably connected to the opposite faces of the two supporting vertical plates. According to the device, a single honeycomb platform is automatically clamped through a motor and a wedge block, a guide plate is matched for abutting, an elastic floating roller is matched for pressing, positioning is stable, a workpiece is not damaged, full-area cleaning and negative-pressure synchronous impurity removal are adopted before welding, welding defects are effectively avoided, initial pre-stretching is conducted in the welding process, and the welding efficiency is improved. And then the progressive secondary stretching is realized along with the linkage of the welding machine head, the stress is dynamically eliminated, the deformation is inhibited, and the flatness and the welding precision are greatly improved.

This utility model discloses a nylon pipe socket connection structure, which includes a connecting sleeve. Extension plates are fixedly connected to both sides of the connecting sleeve. A first groove is fitted into the surface of each extension plate, located inside the groove. A filter plate is fixedly connected inside the groove. A clamping screw is threadedly connected to the inside of the extension plate, and one end of the clamping screw is connected to a clamping plate via a rotating shaft. This nylon pipe socket connection structure, by fitting a filter plate onto the surface of the extension rod, can filter impurities from the liquid. The clamping plate can also be adjusted via the clamping screw, thus adapting to and clamping connecting pipes of various sizes and preventing the pipe from detaching from the connection port. Simultaneously, a reinforcing rod is fixed to the outer wall of the connecting sleeve for protection, and multiple washers are fixed to both sides of the reinforcing rod via fixing screws, thereby preventing excessive water overflow.

The invention consists of a holder for the brush body part (9) of an electric toothbrush, due to its structure having a cup (4) and a clip (2A, 8A), thus being usable as a storage container for the brush body part (9) of an electric toothbrush and as a dry and storage position for the brush body part (9) in the presence of a toothbrush cartridge cup.

The utility model discloses a heat treatment feeding device of mould manufacturing belongs to mould manufacturing technical field, has solved present device through the steel wire rope connection clamping assembly, when moving mould material, the steel wire rope and clamping assembly can sway, inconveniently stabilize mould material, and can easily lead to the problem of mould material falling, including moving frame, the four corners fixed mounting of moving frame bottom surface has the hydraulic cylinder, the below of moving frame is provided with clamping assembly, be provided with adjusting assembly on the moving frame, clamping assembly installs on adjusting assembly, through first drive assembly and drive mobile seat movement, through second screw drive assembly and drive electric push rod movement simultaneously, can adjust the position of clamping assembly and the mould material clamped by it, and third motor can drive clamping assembly rotation, can adjust the angle of mould material, has reached the purpose of being convenient for adjusting the position and angle of mould material, avoided the situation of mould material falling due to sway.

The utility model discloses aluminum alloy ingot processing technical field specifically, and this is a kind of aluminum alloy ingot calendering device, the utility model includes conveying roller, the outside of conveying roller is provided with heating assembly, the upper end left side of conveying roller is provided with blanking plate, blanking plate is ramp type setting, the left side below of blanking plate is provided with calendering assembly, calendering assembly is located the left side below of conveying roller, the outside of blanking plate is provided with anti-offset mechanism. The utility model is through setting up convenient replacement mould mechanism, can be firmly to the mould used in calendering with Limit, to guarantee the stability of aluminum alloy ingot in the process of calendering, the component of mould limiting is moved simultaneously and is adjusted, and it is convenient to clamp and loosen mould, even to replace mould, can according to the production needs the mould of different shape can be quickly replaced, setting up anti-offset mechanism simultaneously, the position of aluminum material after heating can be corrected, make it can accurately blank into the inside of mould.

The utility model discloses a chain type turnover machine suitable for various workpieces relates to turnover machine technical field, and it aims at solving the technical problem of turnover machine only supporting the flat workpiece. Its technical scheme main points are: including four turnover assemblies, and the turnover assembly between same side all is bolted with a crossbeam, and transmission connection has a turnover chain, the bottom of turnover chain passes through crossbeam inside, the turnover assembly includes pedestal, and the pedestal is bolted with a stand, and the stand is rotatably connected with turnover arm through first turnover shaft, and first turnover shaft is rotatably connected in turnover chain, and the drive assembly is arranged on first turnover shaft, and one end of turnover arm is provided with second turnover shaft, and second turnover shaft is rotatably connected in turnover chain, and the top of turnover arm is provided with chain straightening assembly, and the crossbeam is provided with the gyro wheel subassembly for adapting the shape of material. The utility model aims at providing a chain type turnover machine suitable for various workpieces.

The utility model discloses an anti-mosquito mesh bag for a sewer, which relates to the technical field of design of auxiliary equipment of a cover plate for water leakage of a water channel and comprises a well cover base, a cover plate mesh bag fixing and clamping unit and an anti-mosquito mesh bag auxiliary fixing unit, and the upper side of the well cover base is connected with a rain leakage plate through the cover plate mesh bag fixing and clamping unit. The anti-mosquito net bag body is fixed on the lower side of the well lid base through a wire clamp buckle and a fixing iron wire, an anti-mosquito net bag auxiliary fixing unit is arranged in the anti-mosquito net bag body, a connecting protrusion is arranged on the surface of the upper side of the well lid base, and a cover plate net bag fixing clamping unit comprises a rain leakage plate, a limiting cylinder, a supporting clamping block and a connecting clamping hole. The anti-mosquito mesh bag can prevent the water leakage cover plate from being damaged, does not affect the use of a sewer in the sewer, is firm in fixation, can easily contain more heavy objects, and does not affect the collection and use of impurities.

The application discloses a handheld air blower, which comprises a shell, a blowing assembly, an emergency power supply and a circuit board. The shell comprises a receiving cavity, which comprises a first receiving cavity and a second receiving cavity. The shell comprises an air outlet part extending along a first direction and a holding part extending along a second direction. The air outlet part corresponds to the first receiving cavity, and the holding part corresponds to the second receiving cavity. The first direction and the second direction form a preset included angle. The blowing assembly is arranged in the first receiving cavity. The emergency power supply is arranged in the second receiving cavity. The holding part is provided with an emergency interface, which is electrically connected with the emergency power supply and used for emergency starting. The circuit board is arranged in the receiving cavity and electrically connected with the blowing assembly and the power supply. The handheld air blower has the advantages of practical function, compact structure and convenient use, and can be used as an emergency starting power supply.

The utility model relates to the technical field of automobile assembly, in particular to a gearbox gear shifting mechanism tool which comprises a tool body, a clamping groove used for being connected with a gearbox gear shifting poking piece in a clamping mode is formed in the tool body, and a first fixing plate and a second fixing plate are arranged at the two ends of the tool body respectively. The first fixing plate and the second fixing plate are parallel and perpendicular to the tool body, and the first fixing plate and the second fixing plate are both used for abutting against the side wall face of a TCU part in an automobile gearbox. The neutral gear positioning device can assist a worker in determining the neutral gear position of the gear shifting piece in the gear shifting mechanism of the automatic transmission automobile gearbox, and the assembling speed and the assembling precision of the gearbox are improved.

This invention discloses an automatic welding machine, comprising a first welding station, a second welding station, and a transfer mechanism. The first welding station includes a first support and positioning component and a resistance welding machine. The first support and positioning component is provided with a first electrode, and the first electrode is provided with a movable connection structure for movably connecting a pre-welding mounting plate. The resistance welding machine includes a second electrode, which cooperates with the first electrode to weld the mounting plate to the inner wall of the first end of the side plate. The second welding station includes a second support and positioning component and a laser welding machine, used to weld the top end of the second outward flange to the first end of the first outward flange. This automatic welding machine can realize the automatic welding of beam frames, which is beneficial to improving welding quality and welding efficiency, and reducing labor intensity.

The utility model relates to the technical field of toys, in particular to a handheld pinching instrument for stimulating sense organs through touch. Comprising a shell which is made of an elastic material and is of a hollow structure; the multiple cutting planes are distributed on the surface of the shell; the concave-convex pattern is arranged on the cutting plane, and the concave-convex pattern is composed of a convex part and / or a concave part; according to the utility model, the structure is reasonable, the hollow shell has better holding and pinching feelings, the plurality of cutting planes enable the surface of the shell to have distinct edges and corners, nerves are stimulated to promote the body to release enkephalin so as to relax the body, the cutting planes are provided with various three-dimensional concave-convex patterns, the visual sense needs are met, the friction and the hand feeling can be better stimulated, and the effect is good. The entertainment of pinching is further improved, the pressure of the body is released, and anxiety is avoided.

The utility model relates to a handheld device for small mirror surface sand blasting parts, and belongs to the technical field of mirror surface sand blasting clamping. The handheld device for the small mirror surface sand blasting part comprises a grip and a fixing plate, and the fixing plate is fixedly connected to one end of the grip. The clamping mechanism comprises two fixing blocks fixedly connected to the upper end and the lower end of the fixing plate, and a threaded rod is arranged on the inner wall of the fixing block located on the upper portion. The handheld clamp is arranged and matched with the clamping mechanism to clamp a part and then conduct sand blasting, the probability that the part slides off from the hand due to sand blasting counter-acting force is reduced, meanwhile, in the sand blasting process, the part can be driven to rotate through a rotating rod by rotating a second rotary knob, and tiny angle adjustment can be conducted on the part; and the surface sand blasting of the part is more uniform. The part is clamped through the clamping mechanism, the contact time of the glove and the abrasive can be shortened, and the probability that glove fibers fall off to pollute the surface of the part, and consequently micro scratches are caused is effectively reduced.

The utility model discloses a water and soil conservation planting device, which relates to the technical field of water and soil conservation and comprises two arc-shaped pipes, end plates are fixed at two ends of each arc-shaped pipe, first bolts are arranged on two adjacent end plates when the two arc-shaped pipes are circularly placed, the first bolts are used for fixing the two end plates, and the bottoms of the arc-shaped pipes are fixedly communicated with first irrigation pipes. A first embedded rod is fixed to the bottom end of the first irrigation pipe, and a plurality of first irrigation holes are formed in the first irrigation pipe. Water is supplied into the arc-shaped pipe, so that the water flows out along the first irrigation holes in the first irrigation pipe and the second irrigation holes in the second irrigation pipe, the water guided out of the first irrigation holes can soak soil of different depths, and downward growth of tree roots is facilitated; the conveying pipe can enlarge the reinforcing range of the device for the soil layer near the tree by means of the second irrigation holes, and water guided out along the second irrigation holes can soak the soil around the root of the tree, so that the root of the tree can grow all around.

The utility model discloses a chip testing device convenient for rapid clamping, which comprises a testing seat and a testing block, and is provided with a lifting device and a positioning device, a motor controls a bidirectional screw to rotate, the bidirectional screw drives a movable block to move, the movable block moves to push a fixed block to move, and the fixed block drives a lifting block to move. The lifting block moves in the upward inclined direction, when the lifting block moves, the baffle cancels shielding of the positioning groove, the infrared sensor can position the position of the clamping tool, clamping is facilitated, the clamping tool can be conveniently placed and positioned through the arrangement, the time for correcting the clamping tool is saved in the process of putting in and taking out the chip, and the working efficiency is improved. And the test efficiency is improved.

This invention relates to the field of welding fixtures for busbar trunking production, and particularly to a welding fixture for busbar trunking production. The fixture includes a base, a fixed column fixedly connected to the base, a top seat fixedly connected to the top of the fixed column, a welding fixture mechanism rotatably connected to the top seat, a rotating seat rotatably connected to the outer wall of the bottom end of the fixed column, multiple placement frames fixedly connected to the rotating seat, an automatic feeding mechanism rotatably connected to the placement frames, and a movable limiting plate rotatably connected to one side of each placement frame. By setting a bending frame adapted to the shape of the bent busbar trunking, and simultaneously setting rotatable rotating rods at multiple positions on the bending frame, the rotating rods drive the abutment wheel to abut against the inner wall of the bent busbar trunking when rotated, thereby achieving clamping of the bent busbar trunking. This avoids the loosening or deformation problems caused by the unsuitable clamping method of traditional fixtures, thus improving the stability during the welding process.

The invention discloses a binocular camera lens optical center change measuring method and device and electronic equipment, and the method comprises the steps: carrying a measured lens in a positioning device, and determining a first reference point based on at least three contact points formed by the positioning device on the outer diameter of the measured lens; establishing a first coordinate system by taking the first reference point as an original point and taking a direction pointing to the first mark point from the first reference point as a coordinate axis direction, and acquiring a first coordinate of the optical center of the measured lens in the first coordinate system; after the environment test is completed, the tested lens is carried in the positioning device again to determine a second reference point; establishing a second coordinate system by taking the second reference point as an original point and based on the same coordinate axis direction determined in the first coordinate system, and acquiring a second coordinate of the optical center of the measured lens in the second coordinate system; and determining the optical center variation according to the first coordinate and the second coordinate, and judging whether the optical center stability of the detected lens is qualified or not. According to the invention, the stability of binocular camera lens optical center change measurement and the reliability of measurement data are improved.

This utility model discloses an e-liquid refillable electronic cigarette, relating to the field of electronic cigarette technology. The utility model includes a cigarette holder; a cover plate is rotatably connected to the outer side of the atomizer and the outer wall of the cigarette holder; an e-liquid tank is provided inside the cover plate and above the atomizer; a sealing plate is fixedly installed on the outside of the e-liquid tank; a rotary cutting assembly is provided on the upper inner side of the sealing plate; the rotary cutting assembly includes a rotating rod rotatably connected to the sealing plate; a rotary cutting blade is installed at the middle of the rotating rod; a rod sleeve is fixedly installed at the outer end of the rotating rod; the rod sleeve is connected to a pull block via a spring; a sliding groove is opened at the top of the right side wall of the e-liquid tank; a pull-out assembly is provided in the side groove; the pull-out assembly includes a cover plate two disposed on the outer end opening of the side groove; and a pull-out component is provided inside the side groove. This utility model allows the soft plastic bottle used for e-liquid storage to be punctured after being placed into the e-liquid tank via the rotary cutting assembly; and the pull-out assembly accelerates the flow of e-liquid from the soft plastic bottle into the e-liquid tank.

The utility model relates to tobacco cutting machine material feeding positioning deviation rectification technical field discloses a tobacco cutting machine material feeding positioning deviation rectification mechanism, including base and fixed base, the side between of base is provided with guide rod, the right side fixedly connected with fixed base at base top, the inside of fixed base is provided with second reservation groove, the left side fixed mounting of base has the pneumatic cylinder, the right side swing joint of pneumatic cylinder has telescopic link, the inside of telescopic link's right side is fixedly connected with deviation rectification block and is fixedly connected with deviation rectification block in the inside of fixed base, the inside of deviation rectification block is provided with first reservation groove. This tobacco cutting machine material feeding positioning deviation rectification mechanism is provided with deviation rectification block and other spare parts, utilizes position sensor, when sensing that material deviation occurs, can open pneumatic cylinder, utilizes telescopic link and can drive one side deviation rectification block to guide movement on guide rod, thereby makes its material in the middle position of conveying table, and the stable material feeding of convenience solves the problem that it is not convenient to automatically position deviation rectification according to the position of food material.

The utility model provides a mechanical arm clamp which comprises a base, a clamping air cylinder is fixedly connected to the bottom end of the base, an adjusting assembly is arranged at the telescopic end of the clamping air cylinder, and a clamping plate is arranged at the bottom end of the adjusting assembly. The adjusting assembly comprises a fixing frame fixedly connected to the telescopic end of the clamping air cylinder, the inner wall of the fixing frame is rotationally connected with a two-way lead screw, one end of the two-way lead screw extends out of the fixing frame and is fixedly connected with an adjusting motor, and a sliding rod is fixedly connected to the position, below the two-way lead screw, of the inner wall of the fixing frame; compared with the prior art, the clamping device has the following beneficial effects that the two first mounting seats move towards each other or away from each other by adjusting the motor, the two-way lead screw and the sliding rod, and the first transmission plate and the second transmission plate are matched to drive the second mounting seats to slide along the surface of the sliding rod, so that the distance between the clamping plates can be adjusted; therefore, the clamp can be suitable for books of various sizes, and the books are prevented from being bent in the carrying process.

The utility model provides a kind of automatic detection device belongs to the technical field of automatic detection, comprising;Control electric cabinet, the front side and rear side of control electric cabinet top are all fixed with horizontal look board, the front end of control electric cabinet top right side is fixed with operation control panel.The utility model is set through the setting of rotating mechanism, cooperate first motor, speed reducer, rotating component and rotary disc use, play the role of convenient driving workpiece rotation adjustment detection position, pass through the setting of clamping mechanism, cooperate mounting seat, telescopic cylinder, fixed connecting plate, guide sleeve, guide rod, shell, first clamping component and second clamping component use, workpiece can be effectively clamped, also convenient workpiece is rotated in the process of clamping, and workpiece can be adjusted clamping according to size, improve clamping effect, prevent workpiece prone to dump or sliding displacement, effectively improve detection accuracy.

The utility model discloses a bearing press -fitting device of motor shell, include: frame, mounting seat, through vertical guide mechanism slidably be located on the frame, the pressure joint post, vertical fixedly be located on the mounting seat and the bottom stretch mounting seat, and its bottom end is equipped with the positioning axle section of inserting bearing inner ring, clamping mechanism, including the elastic clamping piece of being located in the mounting seat, the elastic clamping piece bottom extends to the side of positioning axle section and is equipped with the clamping part, and the clamping part and positioning axle section center axis distance is less than the outer diameter of bearing, makes the clamping part to bearing outer ring exert radial constraint force, release trigger mechanism, including the blocking portion of being located below clamping mechanism movement path, when the mounting seat down to the preset height, the blocking portion triggers clamping mechanism to remove radial constraint, fixed seat, be located in the bottom of frame for fixed motor shell. The utility model has the advantages of: the cooperation of elastic clamping piece and positioning axle section clamps bearing, and the problem of bearing magnetic because of magnetic attraction is eradicated from the source.

This invention relates to the field of material handling systems, and discloses a fixture and a material handling system. The fixture includes a connecting base, a suction structure, and a clamping structure. The connecting base is used to connect to a robot. The connecting base has suction stations and clamping stations spaced apart. The suction structure is connected to the suction station. The clamping structure is connected to the clamping station and includes at least three grippers distributed circumferentially around the clamping station. The fixture provided by this invention can clamp and fix parts with eccentricity problems through the suction structure, and can also clamp and fix parts with residual iron filings or other debris on the machined surface through the clamping structure. It has a wide range of applications, reduces the gripping difficulty of the fixture, and increases the gripping accuracy of the fixture.

The utility model discloses a kind of civil engineering and building engineering structure gap grouting devices, it is related to civil engineering and building technical field, including grouting gun, filling cavity is opened in the inside of grouting gun, and drive shaft is rotatably arranged in the side of filling cavity, and conveying blade is fixedly covered on the axle wall of drive shaft, control motor is fixed on the outer wall of grouting gun, the output shaft of control motor is fixedly connected with drive shaft, the outlet end of filling cavity is fixedly equipped with fairing, the end of fairing is fixedly equipped with connecting pipe, the nozzle is communicated and equipped with the spout of connecting pipe, the top of grouting gun is fixedly equipped with feed pipe, and the lower end of feed pipe is located in filling cavity, and the inside upper end of feed pipe is equipped with connecting assembly, and the outer wall of grouting gun is fixedly equipped with support ring. The utility model can reduce the volume of grouting device, it is convenient for operator to hold and carry out quick and convenient grouting treatment to the gap located at high place of wall, improve the use convenience of device.

The utility model relates to the technical field of plastic packaging device, concretely is a notebook cover plastic packaging device, including the bottom plate, the front surface of bottom plate is installed with the control panel, the top surface fixedly connected with operation box of bottom plate, the inside bottom wall of operation box is provided with the conveying table body, the back of bottom plate is installed with the support frame, the front surface of support frame is installed with the side, the top surface of side is installed with first air cylinder, the output end of first air cylinder is installed with the adaptive cover plate through the inside of side, the lower extreme fixedly connected with the support seat of adaptive cover plate. The utility model starts second air cylinder through heating roller when the surface movement of notebook, drives the smoothing piece downwards through second air cylinder until the smoothing piece is pasted on the cover of notebook, then also can move in the notebook cover that has been plastic packaged through the smoothing piece, carries out the smoothing operation to the cover of notebook, avoids the quality problem of the situation that the past plastic packaging is not complete.

The utility model provides an aluminum foil tensile strength testing device which comprises a bottom plate, a detection mechanism arranged at the top of the bottom plate, a pushing mechanism arranged at the top of the bottom plate, a moving mechanism arranged at the top of the pushing mechanism, a cleaning mechanism arranged on the moving mechanism, and a sliding groove formed in the rear side of the middle of the bottom plate and provided with an upward opening. A sliding groove is formed in the bottom plate, a sliding block is arranged in the sliding groove, a lead screw penetrating through the sliding block is further arranged in the sliding groove, a first rotating motor connected with the lead screw is arranged on the rear side of the bottom plate, and the first rotating motor is connected with the lead screw through a coupler. According to the tensile strength testing device for the aluminum foil, the basic requirement for testing the aluminum foil can be met, the interior of the clamping mechanism can be cleaned through the cleaning mechanism, workers are prevented from frequently cleaning the interior of clamping equipment, time and labor are saved, and the using requirement of people is met.

The utility model relates to the field of bearing frock, concretely relates to a combined heat treatment bearing frock, including support chassis, be provided with the adjusting base in the support chassis, the top of support chassis is provided with the rotating ring, the top circumference of support chassis is provided with the connecting column, the outside of support chassis is provided with transmission outer tube, the outside of connecting column is provided with the moving block, the moving block is connected with adjusting base, the top of multiple moving blocks is provided with the round head. The utility model discloses through setting up support chassis and realizes the stable support of overall structure, utilizes the linkage between rotating ring and connecting column, drives moving block to carry out the height position of control round head, realizes the accurate positioning to work piece, further, through the cooperation of transmission outer tube and lifting rod, drives the stable board to expand outward, enhances the clamping and fixed effect of external circular ring class work piece, improves overall bearing stability.

This utility model relates to a two-stage manhole cover for gas valve wells, comprising a cover body including a primary manhole cover and a secondary manhole cover. The primary manhole cover is horizontally positioned with a through hole in its center; the secondary manhole cover is horizontally positioned on top of the primary manhole cover and covers the through hole. The advantages of this utility model are its simple structure, reasonable design, and the modular design of the manhole cover, which facilitates operation. It solves the problem of high labor intensity when opening and closing gas valve wells, reduces the frequency of handling and moving heavy manhole covers, thereby protecting the worker's health and improving the efficiency of gas well inspection and daily operation.