1165results about How to "Adjustable tightness" patented technology

The invention discloses a power battery. The power battery comprises a cell and a shell surrounding the outside of the cell; the power battery further comprises an elastic plate which is arranged between the cell and the shell, due to the adoption of the elastic plate, variable tension exists between the cell and the shell, so as to adjust the distance between a positive pole piece and a negative pole piece in the cell. According to the power battery, due to the adoption of the elastic plate, the tightness in the battery can be adjusted in time according to the actual charge and discharge situations, so as to effectively improve the situation of changed assembling ratios caused by the expansion of the battery, and therefore, the usability of the battery is improved. At the same time, due to the effective control to the assembling ratio, the thickness of the shell when the battery is at a discharge peak value can be reduced, and thus the size of the battery is controlled effectively.

The shoes with socks of the present invention are a combination of two shoes and two socks. The shoes with socks of the present invention can generate unique style per se; optionally, they may match with a user's clothes to provide additional stylish appearances. A front lace section is provided on the front portion of the top portion and a rear lace section is provided on the rear portion of the top portion. The rear lace section passes the opening and goes through the back wall of the top portion. In use, the rear lace section is fixedly attached to the corresponding sock through the engagement of two engagement units. In addition, a fastening unit, which is stylish, is provided on both the front lace section and the rear lace section to allow a user to adjust the tightness of either lace sections and easily and quickly.

The invention relates to a twisting machine, in particular to a twisting machine used for compound double twisting. The twisting machine comprises a frame, wherein the frame is provided with a driving transmission mechanism, at least one twisting device and a yarn winding device corresponding to the twisting device; the twisting device contains at least two double twisting spindles and one compound twisting spindle, the double twisting spindles are parallel to each other and fixed on the mounting plate of the compound twisting spindle; a first-twist bolster is fixed on the mounting plate, a compound twisting spindle whorl is driven by the driving transmission mechanism, the compound twisting transmission wheel is connected with a a first-twist spindle whorl which rotates in the reverse direction of the compound twisting transmission wheel, through a transmission belt; and parallel grooves are arranged on the external circumference of at least one of the compound twisting transmission wheel and the first-twist spindle whorl. The invention mainly provides the twisting machine used for compound double twisting which has simple structure and can perform four processes to multiple strands of raw material yarn on the same platform simultaneously, namely first-twist and double twisting, combination, compound twisting and double twisting in reverse direction, and winding; the production process flow is greatly shortened, the working time is reduced, the production cost is saved, the yarn quality is remarkably increased; and the technical problems of the prior art that the twisting machine can only perform one process, the structure of the integrated twisting machine is huge and complicated and the degree of twist is inconvenient to adjust, can be solved.

The invention discloses a method and device for in-situ real-time detection of the filter characteristic of a mask filter material on particles with different particle sizes. The device comprises a filter flow, temperature and humidity real-time monitoring device, a mask clamping device and a mask inhalation resistance measuring device. By means of the method and the device, the filter efficiency, the classified filter efficiency and the pressure drop of a mask on aerosol particles with different particle sizes and the particle size distribution condition of the filtered aerosol particles can be quickly detected in real time. The method and the device have the advantages that the mask is easy to replace, operation and maintenance are easy and convenient, investment expenses are low, and the method and the device are suitable for practical environment measurement, high in measurement accuracy and the like.

The invention discloses a soil improvement agent capable of preventing and controlling a soil-borne disease and a preparation method thereof. The soil improvement agent is prepared from the following raw materials in parts by weight: 20-25 parts of furnace dust, 8-10 parts of biogas residues, 4-6 parts of crop straw, 2-4 parts of waste gelatine powder, 2-3 parts of calcium magnesium phosphate fertilizers, 3-5 parts of bentonite, 1-2 parts of potassium fulvate, 4-6 parts of active yeast liquid, 1-2 parts of waste molasses, 4-6 parts of sheep and cow dung, 1-2 parts of alum powder, 2-4 parts of polyvinyl alcohol, 0.1-0.2 part of composite microbial agents, 1-2 parts of phosphogypsum, 2-3 parts of traditional Chinese medicine residues, 2-3 parts of gamma-polyglutamic acid and 3-4 parts of sterilizing agents, wherein the sterilizing agents are prepared from the following raw materials in parts by weight: 2-4 parts of camellia sinensis, 8-12 parts of tobacco stem powder, 8-10 parts of weathered coal, 2-3 parts of urea, 1-2 parts of garlic powder, 1-2 parts of tourmaline powder, 4-5 parts of hectorite powder and 2-3 parts of nanometer chitosan. The soil improvement agent disclosed by the invention can not only be used for effectively preventing and controlling the soil-borne disease and accelerating the healthy growth of a plant, but also be used for well regulating the soil compactness, reducing the soil bulk density, increasing the soil organic matter and enhancing the soil porosity, thereby being favorable to the maintenance of moisture and nutrient elements.

The invention discloses a bionic doctor finger system for TCM (traditional Chinese medicine) pulse diagnosis and a signal collecting method, relating to the field of TCM pulse diagnosis informationization. The bionic doctor finger system comprises bionic fingers (1), a bionic finger locating and driving mechanism (2), a wrist fixing mechanism (3), a shell support structure (4), a fingering signal input end (5) and a pulse condition signal output end (6), wherein the bionic fingers (1) are encapsulated in the shell support structure (4), and realize locating and fixing through the bionic finger locating and driving mechanism (2) arranged in the shell support structure (4), and the shell support structure (4) is fixed above the wrist fixing mechanism (3). The signal collecting method comprises the following specific steps: fixing the wrist of a patient, locating the cun, guan and chi acupuncture points, and simulating the pulse diagnosis fingering movements of a traditional Chinese medicinal doctor. The system simulates the flexible mechanism of the fingers of the doctor, and accurately collects the pulse condition information of cun, guan and chi acupuncture points of the patient.

An inductive breathing mask is provided, which comprises a covering shell, a mask pad, and a pressure inductive unit, wherein the pressure inductive unit comprising at least one pressure inductive part, and the pressure inductive part is disposed on the mask pad where corresponds to at least one of the user's nasion, left cheek beside nose, right cheek beside nose, and chin for detecting the pressure of the user's nasion, left cheek beside nose, right cheek beside nose, and chin generated by the mask pad. In addition, the inductive breathing mask of the present invention may further be integrated with other functional elements for constructing a respiratory care system having warning and / or monitoring functions.

The invention discloses an interventional medical instrument delivering system. The system comprises a catheter with a hemostasis valve of which an opening is adjustable, the catheter comprises a pipe fitting and a hemostasis valve main body, and the near end of the pipe fitting is connected with the far end of the hemostasis valve main body; the system further comprises a silica gel ring and a screw cap, the screw cap is connected with the hemostasis valve main body through a thread at the near end of the hemostasis valve main body, and the size of an opening formed in the near end of the hemostasis valve main body is adjusted by rotatably compressing or loosening the silica gel ring through the thread; the side face of the hemostasis valve main body is provided with a side hole used for being connected with a hose and a three-way valve, and an injection syringe can be connected to the hemostasis valve main body through the three-way valve to inject medicine. According to the interventional medical instrument delivering system, adjusting operation on the opening of the hemostasis valve of the catheter is easy and convenient, the condition that blood overflows and gas enters the body of a patient in the using process can be avoided, an operator can conveniently inject medicine to the patient in case of need, therefore, the catheter intervention treatment effect can be effectively improved, the operation safety is improved, and the operation success rate is increased.

The invention discloses a brush adjusting device and method. The brush adjusting device comprises a bottom plate, wherein two side plates are slidably mounted on the top of the bottom plate; the adjacent sides of the two side plates are provided with sliding slots; slide blocks are slidably mounted in the two sliding slots; the same mounting plate is slidably mounted on the adjacent sides of the two slide blocks, and is provided with a mounting hole; a sleeve is movably mounted in the mounting hole; one end of a spring is fixedly mounted in the sleeve; a brush is fixedly mounted on the other end of the spring; two connecting blocks are fixedly mounted on the bottom of the mounting plate; and the same connecting plate is fixedly mounted on the bottoms of the two connecting blocks. The brushadjusting device facilitates the adjustment of the tightness of the spring, avoids a phenomenon of poor contact of the brush, can remind a user when the spring reaches a limit, can adapt to differentsizes of brushes by adjusting the distance between the two side plates, and can easily remove and replace the brush.

The invention relates to a preparation method of a biological soil conditioner, belonging to the field of soil conditioner preparation. The preparation method comprises the following steps: adding an auxiliary into sludge with high water content, and performing aeration treatment to obtain a sludge mixture; performing composting treatment of the waste mushroom bran, corn straws and the like and the sludge mixture; performing pretreatment and pyrolysis on pig bones to obtain biochar; and finally pulverizing bentonite and the like and then mixing with the compost and the like and drying to obtain the biological soil conditioner. According to the preparation method, the prepared conditioner realizes a long-term soil conditioning effect and can supplement various nutrient elements short in soil and adsorb and fix heavy metal ions in soil; moreover, the soil conditioner can regulate the soil tightness, reduce the soil bulk density, increase the soil organic matters and improve the soil porosity; and meanwhile, the preparation method provided by the invention is easy to operate, the raw materials are cheap and easily available, and the waste can be effectively utilized to alleviate environmental pollution.

The invention discloses an active reciprocating no-tillage anti-blocking unit, and belongs to the technical field of agricultural machinery. The structure of the unit consists of a furrowing device and an anti-blocking device. A furrow opener is fixed at the lower end of a shovel shaft of the furrow opener to form the furrowing device with concave structure. The anti-blocking device consists of an upper retaining plate and a lower retaining plate which are fixed on the shovel shaft of the furrow opener face to face, as well as a long shaft, a short shaft, an upper chain wheel, a lower chain wheel, a plectrum chain and the like. The anti-blocking plectrum chain is provided above the furrow opener, and long shafts of all anti-blocking unit bodies are connected by couplings. The active reciprocating no-tillage anti-blocking unit has the advantages: the plectrum chain is provided above the furrow opener, which is favorable for cleaning the deposit during furrowing by the furrow opener, reducing the seeding resistance and is good for the trafficability characteristic of a machine; power-drive blockage prevention is adopted, which enhances the blockage prevention effect obviously by regulating the rotary speed of the plectrum chain device; and the unit bodies are connected by the couplings, can realize the adjustability of the seeding row spacing and are applicable to operations at various areas. The active reciprocating no-tillage anti-blocking unit is applicable to the no-tillage seeding machine for wheat and corn.

The invention discloses double polishing equipment for inner and outer walls applied for magnetic ring processing and an operating method thereof. The double polishing equipment for the inner and outer walls applied for magnetic ring processing comprises a base, an inner wall polishing mechanism, an end face polishing mechanism, an outer polishing belt, a magnetic ring, a placing plate, and a clamping mechanism. One end of the top of the base is fixedly provided with the inner wall polishing mechanism. The other end of the top of the base is fixedly provided with a fixing base. The top of thefixing base is fixedly provided with the end face polishing mechanism. The interior of the fixing base is fixedly provided with a sixth air cylinder. The double polishing equipment pushes the clampingmechanism to lift through a fifth air cylinder, places the placing plate on a clamping plate, and pushes clamping blocks to move, so that the placing plate is fixed by the clamping blocks and rubberpads, the clamping blocks are fixed by inserting a bolt into a bolt hole and a screw hole, and the placing plate can be detached conversely. The double polishing equipment for the inner and outer walls applied for magnetic ring processing is conducive to the installation and disassembly of the placing plate, so as to polish the magnetic ring driven to rotate and clean up debris collected on the placing plate, which is more environmentally friendly.

Provided is a self-photographing support used for a digital camera and a mobile phone. According to the self-photographing support, 6 connection rods and a clamping plate are connected through hexagonal screws, the mobile phone clamping plate is used for clamping the mobile phone through an upper plate and a lower plate, and a camera clamping plate is used for clamping the camera through a spring leaf. During photographing, a user needs to find a supporting body (such as a tree trunk, a street lamp pole, a telegraph pole and a stele) with an appropriate size, then the support is clamped on the supporting body, the support is adjusted and matched with the time delay function of the mobile phone, and self-photographing is achieved conveniently. The self-photographing support is folded after use, thereby being very small in occupied space and convenient to use.

The invention discloses a method for obtaining the pulse wave velocity of aorta by using pulse wave of radial artery, relating to the field of cardiovascular medicines in biomedicine. In the invention, based on the waveform at one point of radial artery, the pulse wave transit time of the aorta can be analyzed and obtained, further, the pulse wave velocity of the aorta can be calculated, and the calculation formula is as follows: the pulse wave velocity of the aorta (aoPWV)is equal to a result that the time difference (delta t) between the main wave and the reflected wave of the pulse wave ofthe radial artery is divided by two times of the length of the aorta, that is, aoPWV=2L / delta t; in the invention, the transmit theory of the pulse wave is firstly applied in the calculation of the PWV, two acquisition points are simplified to form one point, the acquisition position is changed to the radial artery from carotid and femoral artery, signal acquisition difficulty is decreased, the testing procedure is simplified, and no hazard exists. A pulse measuring device in the invention is a pulse clip fixed-pulse sensor, so that the acquisition of the pulse wave of the radial artery is easier; besides, the operation is convenient, and the requirement for operators is low.

The invention relates to the field of car dismounting conveying devices, in particular to a plate link chain belt conveyor. The device at least comprises a rack and a conveying assembly, and the conveying assembly comprises a conveying belt and a power part; the conveying belt is a plate link chain conveying belt, the surface of the conveying belt is covered with a rubber mat layer serving as the working face of the conveying belt, and the rubber mat layer at least covers fit clearances which form link plates of the conveying belt; the conveying belt comprises chains and a driving tooth roller, the link plates are erected between two closed loop chains, and a gap is reserved between every two adjacent link plates; the appearance of the rubber mat layer is of a closed loop belt-shaped structure, the inner annular face of the rubber mat layer is attached to the surfaces of the link plates and is sequentially connected with the link plates to form an integrated structure, and installation holes are formed in the link plates; and fastening bolts penetrate the installation holes of the link plate and penetrate the rubber mat layer to be fixedly connected through threads. By means of the plate link chain belt conveyor, on-line conveying requirements of waste after a car is dismounted can be stably achieved, and the self service life and the working efficiency can be effectively guaranteed.

The invention provides a novel tensioning transmission device capable of realizing the automatic tensioning without artificial regulation on the tightness of a chain, which comprises a guide rail, a driving shaft and a driven shaft, wherein the driving shaft and the driving shaft are driven by a driving device, chain wheels are respectively fixedly arranged in the middles of the driving shaft and the driven shaft, both ends of the driving shaft and the driven shaft are fixed with guide wheels matched with the guide rail, box pushing pulling fingers are fixed between the chain wheels and the guide wheels, and a spring tensioning device is arranged on the driven shaft. The novel tensioning transmission device adopts the stainless steel chain, the device per se cannot be influenced by the temperature, and the temperature of the cleaning media can be raised to be higher than the sterilization temperature specified by the food industry. The tightness of the chain can be effectively regulated through the spring tensioning device, so the transmission device can more perfectly act. The transmission device has the advantages that rolling friction is adopted between the guide wheels and the guide rail, the friction is greatly reduced, and the service life of the chain and the service life of the guide rail are prolonged. After the new belt tensioning transmission device is adopted, the cleaning effect can be improved by about 50 percent, simultaneously, the fault rate is reduced, in addition, the maintenance is convenient, and the work efficiency is improved by about one time.

The invention discloses a virtual reality glasses, and the glasses comprises a glasses body; a head band, wherein two ends of the head band are respectively connected to two ends of the glasses body, and the head band and / or the glasses body are / is provided with at least one pressure detection module which is used for detecting the pressure on a head from the head band and / or the glasses body; a drive module for tensioning and loosening the head band; a control unit which communicates with the pressure detection module and the drive module, so as to control the drive module to tension or loosen the head band according to the pressure on the head from the head band and / or the glasses body. According to the embodiment of the invention, the degree of tightness of the head band can be automatically adjusted in real time according to the wearing condition, thereby greatly alleviating the use inconvenience for the disabled.

A dental wrench device to loosen and extract teeth, comprising a handle with a fixed tapered jaw. A moveable jaw is also coupled to the handle. The tapered jaw is positioned along the root of a tooth selected to be extracted. The moveable jaw has a blunt contoured shape configured to grasp the gum and bone on the opposite side of the selected tooth at a level below the crown of the tooth. The device is applied and tightened around the selected tooth by turning a thumbscrew, or other jaw movement interface, that moves the moveable jaw end closer to the fixed tapered jaw end until the tooth is tightly gripped by the device. Once the wrench is locked into position, force may then be applied to extract the tooth. The device may also incorporate an optional force feedback gauge to warn the operator when excessive force is being applied.

The invention discloses an intelligent adjustable foot-drop rehabilitation orthotic device which comprises a foot fixing component, a leg fixing component and a control unit. The control unit is used for controlling the foot fixing component to rotate relative to the leg fixing component through a pulling mechanism to make the foot fixing component in one of an initial state, a dorsiflexion state and a toe flexion state relative to the leg fixing component. The foot fixing component comprises a foot holder, the leg fixing component comprises a leg supporting rod, and the foot holder and the leg supporting rod are connected through an elastic part and capable of rotating in opposite directions under the action of the elastic part. The bottom of the foot fixing component is provided with a rope wheel corresponding to a forefoot position, a pulley is arranged at the rear end of the foot holder, and one end of a rope part is fixed to the leg fixing component while the other end of the rope part is connected with the rope wheel through the pulley. A power end of a driving motor is connected with the rope wheel, and the rope wheel is driven to rotate by the driving motor to adjust a relative position of the foot holder to the leg supporting rod. The intelligent adjustable foot-drop rehabilitation orthotic device has advantages that switching between dorsiflexion and toe flexion states of a foot can be automatically adjusted according to walking states of a user.

A buttock shaping and training apparatus includes a seat and two pedals. Each pedal has an end of a lower section thereof pivotally disposed to the seat and the other end provided with a roller, such that the pedals are allowed with movements along pre-defined tracks at the seat using pressing motions of human legs. The seat is installed with a counter. Using the aforesaid design, not only decomposition of fats at legs and buttocks but also metabolism at parts being exercise is promoted. Wherein, tightness between the pedals is adjustable using an elastic body fixed between the two pedals and a connecting member extended from the elastic body, as well as with coordination turning of a hexagonal column and a triangular bolt that change tightness with the elastic body, thereby accomplishing tightness adjustment requirements of a user as desired and offering multi-stage exercise effects.

A shaft structure located aside the coupled portion of two objects comprises a pivot shaft, a sleeve barrel and a connecting part. The pivot shaft further includes a retaining terminal and a rotary section. The inner surface of the sleeve barrel is provided with a slot for retaining the rotary section when it is inserted therein, whereby the two objects connected by the retaining terminal and the connecting part may have a relative pivotal motion. Further, the retaining terminal of the shaft and the connecting part may have various shapes according to the objects they are connected with. The tightness between the sleeve barrel and the rotary section can be adjusted to achieve a variety of damping. Therefore, the shaft structure is simple and versatile.

The invention discloses a continuous type garbage compressing and dewatering device. The continuous type garbage compressing and dewatering device comprises a hollow barrel-shaped dewatering cabin body, a main pressing oil cylinder and a feeding device, and the hollow barrel-shaped dewatering cabin body is enclosed by a rack. The dewatering cabin body is composed of a pre-pressing cabin and a main pressing cabin. A feeding inlet is formed in the top of the pre-pressing cabin. The feeding device is arranged above the feeding inlet. The main pressing oil cylinder is installed at one end of the pre-pressing cabin and connected with a main pressing head. The main pressing head is located inside the pre-pressing cabin. The motion direction of a piston rod of the main pressing oil cylinder is parallel to the axis direction of the pre-pressing cabin. The other end of the pre-pressing cabin is connected with the main pressing cabin. The main pressing cabin comprises a top plate, a bottom plate and two side pressing plates, wherein the top plate is fixedly connected with the pre-pressing cabin, and the two side pressing plates are hinged to the pre-pressing cabin. The outlet end of the main pressing cabin is a discharging outlet. The side pressing plates are driven by side pressing oil cylinders. The motion direction of piston rods of the side pressing oil cylinders is perpendicular to the axis direction of the pre-pressing cabin. According to the continuous type garbage compressing and dewatering device, the structure is simple, feeding and discharging can be conducted continuously, pressure is uniform and controllable, and operation is flexible and variable.

A shoelace with a shoelace fastener includes a first retaining base at an end of a first lace and / or a second retaining base at another end of the first lace, and a ratchet and an elastic plate are disposed in the first retaining base and the second retaining base respectively, such that the ratchet can be pressed at an end of the elastic plate, and the ratchet is pressed by the elastic plate into a normal slantingly pressed down status. When use, a fabric shoelace or a serrated plastic groove is passed into the retaining base, and ends of the ratchets are provided for clamping a surface of the fabric shoelace or plastic shoelace to facilitate adjusting the tightness of the shoelace.

The invention relates to a foamed brick cutting device capable of reducing cutting resistance. The foamed brick cutting device comprises a track, a supporting plate mounted on the track in a slideable manner, a foamed brick placed on the supporting plate, a transverse cutting device and a vertical cutting device, wherein the supporting plate carries the foamed brick to sequentially pass through the transverse cutting device and the vertical cutting device; the transverse cutting device comprises a third fixing block, a fourth fixing block and a plurality of transverse cutting steelwires; the third fixing block and the fourth fixing block are respectively arranged on two sides of the track; the transverse cutting steelwires are mounted between the third fixing block and the fourth fixing block; the vertical distances between the adjacent transverse cutting steelwires are the same; the horizontal distances between the adjacent transverse cutting steelwires are also the same and are equal to the transverse length of the foamed brick. The foamed brick cutting device can be used for cutting foamed bricks line by line and prevents the transverse cutting steelwires from being in contact with the foamed bricks simultaneously, thereby avoiding insufficient driving force of the supporting plate and lowering the demand on the power of a motor used for pushing the supporting plate.

The invention relates to a transverse cutting and forming device used for sliced noodles. The transverse cutting and forming device comprises a transverse cutting device and a forming device body. The forming device body comprises fixed bases and mechanical arms. The transverse cutting and forming device is characterized in that each mechanical arm comprises clamping arm bodies, an actuation piece and an actuation cylinder; hinge holes are formed in the clamping arm bodies, the clamping arm bodies are hinged to the fixed bases through the hinge holes in the clamping arm bodies; section gear pieces with the hinge holes as the centers are arranged on the clamping arm bodies; a plurality of tooth grooves are sequentially formed in the actuation pieces in the axial direction of the actuation pieces; the section gear pieces of the actuation pieces are meshed with the tooth grooves; the actuation cylinders are fixed to the fixed bases, are connected with the actuation pieces and control the actuation pieces to move; the transverse cutting device comprises a roller, blades arranged on the roller, and a knife rest used for separating the noodles; the blades are fixed to the roller; a rotating shaft is arranged on the knife rest; the rotating shaft penetrates through the blades and can make the knife rest rotate with the rotating shaft as the center. The transverse cutting and forming device is simple in structure, reasonable in design, high in efficiency, high in shape consistency and not prone to adhesion.

The invention discloses an intermittent chain wheel conveyor line. The intermittent chain wheel conveyor line comprises an aluminum supporting frame, a stepping motor, a bottom groove plate, two chain wheel assemblies arranged side by side and a chain wheel supporting plate arranged on the side edges of the chain wheel assemblies. The chain wheel supporting plate is provided with a main wheel hole, a sliding bar hole and an adjusting groove. The main wheel hole and a driving chain wheel are erected on the aluminum supporting frame through a rotating shaft. The rotating shaft is connected with the stepping motor through a synchronous belt. A chain wheel fetching frame is arranged at the front end of the adjusting groove and comprises a fixing piece, a vertically arranged V-shaped positioning block and a clamping piece. The intermittent chain wheel conveyor line has the following advantages that as the chain wheel fetching frame is arranged, subsequent chain wheel fetching and clamping procedures can be facilitated, the chain wheel assemblies will not be touched in the clamping process, and therefore shaft parts are prevented from being overturned; as a supporting piece is arranged, the shaft parts can be placed on the supporting piece, and steps on the shaft parts can be clamped through the supporting piece, axial displacement is prevented, and the effect of initial positioning is achieved.

The invention discloses an automatic tool conveying assembly line. The automatic tool conveying assembly line comprises assembly line supports. A motor power assembly, a shaft driving assembly and a plurality of transmission shaft assemblies which are arranged side by side are mounted on the assembly line supports. Each transmission shaft assembly comprises a transmission shaft. The shaft drivingassembly comprises a power transmission piece, a shaft connecting piece and a transmission friction assembly. The transmission friction assembly is connected with the power transmission piece and theshaft connecting piece through frictional transmission. The frictional transmission force of the transmission friction assembly is smaller than or equal to the maximum power load of the motor power assembly. When the frictional force exceeds the maximum frictional force of the transmission friction assembly under the condition that a tool is blocked or gets stuck, power transmitted through friction is cut off, the power transmission piece still rotates, and the load of the motor is not changed, so that the motor is prevented from being burnt down; and meanwhile, the cut-off power stops the transmission shaft from rotating, and thus, abrasion of the tool is avoided. Thus, abnormal abrasion between transmission wheels and the tool is prevented, and the operating stability of the assembly line is improved.