68results about How to "Smooth scraping" patented technology

The invention belongs to the field of fine chemistry, and in particular relates to a preparation process of special rubber powder for an architectural coating. A one-step dry synthesis process of oxidation, cross-linking and etherification is adopted; and the invention adopts the preferred scheme that: industrial H2O2 for oxidation is adopted in the oxidation reaction, epoxy chloropropane for cross-linking is adopted in the cross-linking reaction, and ClCH2COONa is used as an etherification agent in the etherification reaction. By multiple modifications, the starch has good flowability and storage stability of oxidized starch, has the advantages of strong shearing resistance, acid and alkali resistance, good thermal stability and the like of cross-linked starch, and has the advantages of high paste transparency, good freeze thawing stability, strong ageing resistance and the like of carboxymethyl starch. The prepared rubber powder can be quickly dissolved in cold water; the rubber solution is uniform and granule-free; and the wall painting putty prepared by mixing the rubber solution, talcpowder, heavy calcium powder, water and the like in a certain ratio has the advantages of strong adhesive force, painting smoothness and the like. Moreover, the wall painting putty is environment-friendly and nontoxic, and has obvious social and economic benefits.

The invention relates to aerated concrete block surface mortar.The aerated concrete block surface mortar is characterized by being prepared from, by weight, 60-80 parts of aggregate, 10-20 parts of 42.5 portland cement, 10-20 parts of coal ash, 0.1-0.3 part of a water reducing agent, 2-3 parts of redispersible latex powder, 0.1-0.5 part of cellulose ether, 0.1-0.5 part of wood fibers, 0.02-0.05 part of an air entraining agent and 0.5-3 parts of polypropylene fibers.The aerated concrete block surface mortar is easy to use, capable of saving energy and environmentally friendly and has good cohesiveness and water retentivity, and construction is convenient and fast; the mortar is soft and smooth, and batch scraping can be smoothly performed; the mortar has large adhesive force and high water retentivity, the use amount of the mortar is smaller than that of common mortar, the weight of a wall is reduced, and comprehensive benefits are good.

The invention relates to the field of embossing machines and discloses a full-automatic high-efficiency embossing machine. The embossing machine comprises a machine platform, a running platform, a machine cover and a control module. The running platform is arranged between the machine platform and the machine cover, and the control module is arranged in the machine platform. A walking device, a lifting device, a scraper blade device, a first servo motor and a second servo motor are arranged on the running platform. The walking device comprises walking wheels, a walking shaft and a synchronous pulley. The walking shaft drives the walking wheels to rotate through the synchronous pulley. The lifting device comprises a lifting shaft, a lifting shaft speed reducer, a lifting sliding block, a compression spring location mechanism and a rack. The scraper blade device comprises a scraper blade shaft, a scraper blade shaft speed reducer, a scraper blade guide rail and a scraper. The scraper blade shaft drives the scraper to move on the scraper blade guide rail through the scraper blade shaft speed reducer. Products produced by the embossing machine have the advantages of being stable in quality, free of color difference and high in efficiency.

The invention discloses a main driving device of a material taking machine with a scraper, which comprises a base (1), a driving motor (2), a coupler (3), a reduction box (4) and a crossbeam (10). The driving motor (2) is connected with the reduction box (4) by the coupler, and both the driving motor (2) and the reduction box (4) are fixed onto the base (1). The main driving device is characterized in that a support seat is arranged between the base (1) and the crossbeam (10) and consists of a first fixing base (5), a second fixing base (6), a connecting plate (7), a first shaft (8) and a second shaft (9), and the first fixing base (5) and the second fixing base (6) are respectively fixedly connected by the first shaft (8) and the second shaft (9) via the connecting plate (7). The main driving device of the material taking machine with the scraper is firm in fixation, and cannot rotate easily.

The invention discloses an environment-friendly concrete block edge cutting device aiming at sizes. The device comprises a base, multiple conveying rollers are rotationally mounted at the top of the base, an edge cutting device body is arranged on one sides of the tops of the conveying rollers, a material falling groove is formed in the bottom of the edge cutting device body, the material falling groove communicates with a waste recycling box, the waste recycling box is slidably mounted on one side of the base through a sliding rail, a limiting frame is fixedly connected to one side of the top of the base, an air cylinder is fixedly connected to one side of the top end of the limiting frame, the bottom moving end of the air cylinder slidably penetrates into the limiting frame and is fixedly connected with an edge cutting assembly, the edge cutting assembly is movably mounted in the limiting frame, the bottom end of the outer wall of one side of the limiting frame is fixedly connected with a pushing air cylinder, and the moving end of the pushing air cylinder slidably extends into the limiting frame and then is fixedly connected with a pushing plate.

The invention discloses an energy-saving purification device for sewage treatment, wherein the energy-saving purification device comprises a purification shell; a rectangular groove is formed in the outer wall of the top of the purification shell, a storage shell is mounted on one side of the outer wall of the top of the purification shell, a feeding pipe is inserted into one side of the outer wall of the top of the storage shell, and a liquid adding pipe is inserted into one side of the outer wall of the top of the purification shell; one sides of the inner walls of the two ends of the purification shell are rotationally connected with a same rotating shaft. According to the energy-saving purification device for sewage treatment, through the arrangement of a connecting spring and a rubberpad on a connecting block, scraping of a scraping plate can be smoother; through the arrangement of a sliding ring, the scraping plate can move back and forth on the purification shell, sewage is prevented from entering the storage shell, and the waterproof effect is achieved; through arrangement of a motor, a lead rod and a sliding block, the sliding plate can be driven to move back and forth inthe purification shell, the arc-shaped scraping plate on the sliding plate can be driven to move, sewage at the bottom of the purification shell can be scraped, and deposition is avoided.

The invention discloses a frictional resistance noise elimination device of a windshield wiper. The windshield wiper comprises a main frame and a pressing bar scraper. A pin joint wall is arranged in the center of the main frame, a movable base with a connecting piece connected in the middle is contained in the center of the pin joint wall in an extending mode, a plurality of corresponding transverse actuation holes are formed in the two side walls of the movable base towards the two lateral sides of the connecting piece, by arranging and positioning fixing pins in the two side walls of the pin joint wall in a pivoted and penetrating mode, the movable base is positioned through penetrating of the fixing pins and elastically moves through the transverse actuation holes, the two sides between the movable base and the pin joint wall are opposite to each other to form a pivoting-abutting space to be pivoted with elastic press bodies so that the movable base can be laterally pushed and propped, the movable base is made to be positioned in the pin joint wall to form two-segment separation assembly so that the connecting piece can be made to be connected with a connector of the windshield wiper, and the movable base can make eccentric movement along the transverse actuation holes in the side walls through pushing-abutting elastic pressing of the elastic press bodies on the two sides of the movable base. Thus, resistance and friction force from all directions can be absorbed through frictional resistance generated in the swing process of the windshield wiper at a proper movement angle and deviation pressing and propping, and thus the noise elimination purpose is achieved.

The invention relates to a piece cutting device for vertical conveying of bamboo piece green and yellow faces and belongs to the technical field of bamboo piece processing. The piece cutting device comprises a channel body enabling the green faces and the yellow faces of bamboo pieces to be placed vertically. The channel body comprises a conveying bottom face and conveying blocking edges arranged on the two sides of the conveying bottom face. The conveying blocking edges are provided with outer surface primary processing devices. A bamboo piece conveying line behind the channel body is provided with a vertical piece cutter in a matched mode. A piece dividing conveying rail which is symmetric with the piece cutter as the symmetry axis is arranged behind the piece cutter. A power stabilizing structure is arranged between the piece cutter and the piece dividing conveying rail. By means of the scheme, cutting of multiple bamboo pieces can be achieved through vertical arrangement of the blocking edges. Besides, the bamboo pieces are quickly cut and divided through a thin piece cutter. A front conveying channel used for drawing the bamboo pieces more conveniently and more efficiently is further arranged.

The invention discloses rubber production equipment, comprising a machine body. The machine body is provided with a rotating shaft, a stirring device, a wall scraping device and a magnetic strip; the stirring device is fixed to the surface of the shaft; the wall scraping device is fixed to the end of the stirring device and located on the inner wall of the machine body; the magnetic strip is arranged in the machine body; the inner cavity is formed in the stirrer and located at the end; the magnetic block is fixed to the top of a reset spring; the elastic air bag is arranged in the inner cavity and located at the magnetic block; the magnetic strip is arranged in the stirrer; and the spraying device is arranged in the stirrer and located at the top of an agent storage cavity. The invention relates to the technical field of rubber production. The rubber production equipment achieves the purposes of uniform mixing and adhesion prevention; mixing is performed through spraying, and therefore is rapid and uniform; and sticky substances on the inner wall can be automatically scraped off in time, so that both time and labor are saved, and the use performance is improved.

The invention discloses an inductive LED lamp aluminum profile shell aftertreatment device. A left slide rail is arranged on an operation platform; a movable frame is arranged on the slide rail; a shell clamping device is arranged on the operation platform; the movable frame is provided with a scraping cutter associated with a lifting mechanism; a rack is arranged on the slide rail; a driving shaft is arranged in the movable frame, and is provided with a driving gear engaged with the rack; the lifting mechanism comprises a vertical driving rod, and a lifting sleeve sleeving the driving rod andconnected with the scraping cutter; an inner spiral groove and an upper annular groove, communicating with the upper end of the inner spiral groove, are formed in the inner side wall of the lifting sleeve; a slide pin, extending into the inner spiral groove, is arranged on the side wall of the driving rod; the driving shaft is connected with the driving rod through a transmission mechanism; and when the movable frame moves to an ending position, the slide pin moves from the lower end of the inner spiral groove to the upper end, and slides into the upper annular groove, and the scraping cutteris descended to a scraping position. The inductive LED lamp aluminum profile shell aftertreatment device not only can guarantee the induction precision of rib height sizes, but also can improve the production efficiency in aftertreatment.

The invention discloses a water conservancy project dredging device capable of achieving rapid cleaning. The dredging device comprises a scraping plate and supporting plates, wherein the two supporting plates are fixedly welded on the two sides of the scraping plate, the scraping plate and the supporting plates are arranged in a river channel, dam bodies are arranged on the two sides of the riverway, a mud pumping device and a traction device are arranged on the upper ends of the supporting plates and the upper end of the dam bodies respectively, the mud pumping device comprises a baffle, material conveying pipes, a rotating rod, a screw conveyor blade, a driving motor and a discharging pipe, the baffle plate is welded and fixed to the front side of the upper end of the scraping plate, andthe two material conveying pipes are supported and fixed above the supporting plates through supporting blocks. According to the dredging device, the material conveying pipes are arranged on the twosides of the scraping plate, then the material conveying pipes are driven to move forwards through rolling wheels of the base, sludge at the bottom of the river channel can be scraped up, and the sludge is transmitted to the upper part of the dam bodies through the material conveying pipes, so that the sludge can be cleaned more quickly than the traditional method, the dredging device is practical, and is suitable for wide popularization and use.

The invention relates to the technical filed of a coating, specifically to a waterborne stone effect coating convenient for construction. The waterborne stone effect coating is characterized by comprising the following raw materials, by mass percentage, 60-75% of natural colored sand, 25-40% of a stone effect coating thick liquid, 0.2-0.4% of an amide wax thick liquid and 0.1-0.2% of a modified cellulose thick liquid. During a preparation process, through addition of the amide wax thick liquid and the modified cellulose thick liquid, the adhesive force between the stone effect coating and an outer wall substrate is increased, and the covering power of the waterborne stone effect coating is improved. The coating can flow well during a construction process, is smooth in scraping, and doesn't adhere to a knife, so that the construction performance of the stone effect coating can be greatly improved.

The invention belongs to the technical field of agricultural tools, and particularly relates to an uninterrupted insect removal device for agricultural planting. Aiming to solve the problem that mostenvironment-friendly insect removal devices need people to frequently replace insect removal paper, which are troublesome, the following scheme is provided. The device comprises a supporting frame body; the inner top end of the supporting frame body is connected with an insect trapping box; four servo motors are fixedly connected with the upper end of the supporting frame body; output shafts of the servo motors penetrate through the supporting frame body and are fixedly connected with long screws; lifting blocks are in threaded connection with the long screws; adhesive scraping plates are fixedly connected with the end faces, close to the insect trapping box, of the lifting blocks; adhesive containing boxes are fixedly connected with the end faces, away from the insect trapping box, of thelifting blocks; and each of the adhesive containing boxes is fixedly connected with a gluing spray head through a first electric push rod. According to the uninterrupted insect removal device for agricultural planting, in the ascending process after the adhesive scraping plates downwards scrape off adhesives with insects, the first electric push rods are used for driving the gluing spray heads toget close to the insect trapping box, so that stable spraying can be conducted on the surface of the insect trapping box, and uninterrupted insect removal is achieved.

The invention discloses a clamp type pig hair double-edge scraping knife. The scraping knife comprises a handle and a clamp body formed by machining a single elastic steel sheet. A left clamp part and a right clamp part of the clamp body are provided with a left handle and a right handle respectively, and the left handle and the right handle are formed by machining elastic steel wires. The right side of the bottom of the left clamp part is provided with a left blade. A left boss is arranged in the middle of the left blade in the length direction. The lower end of the left side of the left boss is provided with a left knife edge. The left side of the bottom of the right clamp part is provided with a right blade. A right boss is arranged in the middle of the right blade in the length direction. The lower end of the right side of the right boss is provided with a right knife edge. The width of the left boss and the width of the right boss both range from 0.1 mm to 0.5 mm so that the distance between the left knife edge and the right knife edge can be from 0.2 mm to 1.0 mm when the bottom of the left clamp part and the bottom of the right clamp part are closed. By adopting the clamp type pig hair double-edge scraping knife, pig hair can be scraped off easily, and the pig hair left between the left knife edge and the right knife edge can be taken out easily.

The invention discloses a batch recovery process and equipment for preparing a membrane electrode catalyst by a spraying method. According to the invention, a catalyst exceeding a spraying area in a spraying process is recovered; before the catalyst layer is prepared, the auxiliary equipment is completely coated with a carrier sheet, it is guaranteed that catalyst slurry completely falls on the carrier sheet outside an effective area, and then efficient recovery of the catalyst adhering to hardware auxiliary equipment such as a clamp is achieved through the procedures of soaking, scraping, collecting, washing and vacuum drying. The cost is reduced, and meanwhile, the air environment pollution is reduced. Meanwhile, the invention further discloses batch recovery equipment for the fuel cellcatalyst, which can achieve batch work of the catalyst recovery method, improve the working efficiency, increase the utilization rate of raw materials in production, and reduce the manufacturing cost.

The invention provides a wild jujube pulp removing device which comprises a pre-cooling bin for pre-freezing wild jujubes of which pulp is to be removed, the wild jujube pulp removing device further comprises a conveying part and a removing unit, the conveying part is used for receiving wild jujubes output by the pre-cooling bin so as to carry the wild jujubes to advance, and the removing unit is located on the advancing path of the wild jujubes and comprises a scratching part, a scraping part and a brushing part arranged in sequence so as to sequentially form the operations of scratching the peel of the wild jujube, scraping the pulp of the wild jujube and brushing the residual pulp of the wild jujube. According to the wild jujube pulp removing device, the problem of water pollution in the wild jujube pit processing process can be solved.

The invention provides a peeling device convenient for peeling sugarcane joints, and relates to the technical field of sugarcane peeling equipment. The peeling device comprises a feeding outer shell,a feeding cylinder fixing piece, a sugarcane feeding cylinder, a sugarcane joint detection mechanism, an access cover, an upper scraper mechanism, a top cover, a tightening wheel, a bagasse cleaning cover, a sugarcane outlet, a rotating shaft, a support, a driving motor, a driving motor supporting plate, a residue outlet, a lower scraper mechanism and a belt B, wherein the feeding outer shell is fixedly installed on the left side of the support, the feeding cylinder fixing piece is fixedly installed at the inner bottom part of the feeding outer shell, the sugarcane feeding cylinder is fixed inthe feeding cylinder fixing piece, and the sugarcane joint detection mechanism is arranged on the right side of the feeding cylinder fixing piece. When the peeling device is used, an operator only needs to unscrew the tightening wheel to open the bagasse cleaning cover and the top cover at the same time, the operator can conveniently clean the upper scraper mechanism, the lower scraper mechanismand bagasse generated in the scraping process, and meanwhile the upper scraper mechanism and the lower scraper mechanism can be conveniently replaced and maintained.

The invention discloses anti-exposure mine magnetic separation equipment, which comprises a frame body, supporting legs, a top plate, a glass sheet and a feeding port, wherein the supporting legs arefixedly connected to the left side and the right side of the lower end of the frame body, the top plate is fixedly connected to the upper side of the frame body, the glass sheet is fixedly connected to the upper surface of the top plate, the feeding port is fixedly connected to the right side of the frame body, a mounting frame is fixedly connected to the left side of the frame body, a first motoris fixedly connected to the interior of the mounting frame, and a mounting cabinet is fixedly connected to the upper side of the inner wall of the frame body. According to the invention, when the anti-exposure magnetic separation equipment for the mine is used, the effect of convenient sun shading is achieved through cooperative use of structures such as the mounting cabinet, the sliding block, the elastic sun shading cloth and the like; the effect of secondary separation is achieved through cooperative use of structures such as the fan blades, the material guide block, the filter screen andthe like; and the effect of stable scraping is achieved is achieved through cooperative use of structures such as the conveying belt, the magnetic induction belt, the brush block and the like.

The invention discloses a dry surface-mortar additive material. The dry surface-mortar additive material is characterized by being prepared from, by weight, 10-15 parts of hydroxypropyl methyl cellulose being 80-120 thousand in silicic acid viscosity, 50-70 parts of redispersible emulsion powder, 2-5 parts of an organic silicon water repellent, 2-5 parts of starch ether, 2-5 parts of calcium formate, 5-10 parts of polycarboxylate superplasticizer, 10-20 parts of polyvinyl alcohol, 5-10 parts of modified lignocelluloses and 5-10 parts of modified PVAC (polyvinyl acetate). Surface mortar prepared from the surface-mortar additive is firm in adhesion with boards, high in flexibility, crack resistance and impact resistance and great in waterproof performance and alkali efflorescence resistance. In addition, convenience in construction, high sagging resistance, smoothness in batch scraping, freeness of stickiness to blades, easiness in mortar collection and high mortar utilization rate are realized.

The invention relates to rice noodle making and drying equipment. The equipment comprises a bottom plate, a stand column, a sliding base, a heating base, heating pipes and a buckling cover. An electric appliance cabinet is mounted on the left side of the top surface of the bottom plate; at least a temperature control assembly and a power supply assembly are arranged in the electric appliance cabinet; the stand column is welded to the middle of the top face of the bottom plate; the outer side of the stand column is sleeved with a large spring; three guide sleeves are welded on the top surface of the bottom plate; a guide column is inserted into each guide sleeve in a sliding manner; the heating base is welded on the top faces of the guide columns; the heating pipes are mounted at the bottomface of the heating base; a valve type drain pipe penetrates through the outer side of the bottom of the heating base; the large spring is located between the sliding base and the base plate; a spring pin is mounted at the right side of the sliding base; and three lower crank rods are also welded to the top end of the sliding base. The rice noodle making and drying equipment has the advantages ofbeing compact in integral structure, easy to operate, high in functionality and small in occupied area and adapts to household environments, and the rice noodle processing efficiency can be improvedby the aid of a three-station structural style.

The invention discloses novel lightweight compression-resistant foam concrete and a preparation method thereof. The concrete is prepared from the following raw materials in parts by mass: 35-45 partsof cement, 25-30 parts of fly ash, 20-25 parts of lime powder, 12-18 parts of asbestos fiber, 10-20 parts of glass fiber, 2-5 parts of foaming agent, 1-3 parts of calcium stearate, 2-4 parts of polycarboxylic acid water reducing agent and 40-50 parts of water;. The compressive strength of the concrete is improved by adding the asbestos fibers and the glass fibers into preparation raw materials ofthe concrete, the concrete is high in compressive capacity, slurry can be evenly distributed in the mold by swinging the supporting plate and the mold, the slurry is scraped to be flat through the scraping plate, the surface of the prepared concrete can be smooth, the quality of the concrete is guaranteed, construction is facilitated, the concrete with different sizes can be leveled, and the applicability is high.

The invention relates to the technical field of papermaking equipment, and discloses a vacuum pulp washer for papermaking. The vacuum pulp washer comprises a machine body, wherein a pulp inlet is formed in one side of an inner cavity of the machine body, and a pulp outlet is formed in the other side of the inner cavity of the machine body. According to the vacuum pulp washer for papermaking, the air inlet pipe is matched with an air storage tank, the air storage tank is matched with a partition cavity formed by a second ventilation piston, and a first ventilation piston and a partition plate, a permanent magnet is arranged at the matched position of the first ventilation piston and a ventilation arc plate; magnetic poles are arranged left and right; the bending direction of a bent groove is matched with a scraper; after the first ventilation piston is matched with the ventilation arc plate, the bent groove cannot rotate along with the rotation of a shaft sleeve; and the exhaust direction of the bent groove is always matched with the scraper, namely, air in the bent groove is injected into a cavity formed by every two partition plates in sequence under the rotation of the shaft sleeve, and when air is injected into the cavity, the scraper is used for scraping pulp on the drum surface of an air injection cavity, so the scraping difficulty of the scraper is reduced, and the pulp can be smoothly scraped.

The invention relates to a cutting head component for scraping intestinal mucosa. The cutting head component is arranged on a handle for scraping the intestinal mucosa; the innovation point is that the cutting head component comprises a scraper head and an annular air storage cabin; a handle connecting section, a scraper section and a circular platform section are arranged on the outer surface ofthe scraper head; an annular scraper plate is arranged on the outer periphery of the scraper section; a cylindrical concave chamber with an internal thread is arranged at the center of the first end surface of the scraper head; the annular air storage cabin is jointed in the cylindrical concave chamber; a plurality of water spraying channels and air channels connected with the water spraying channels are uniformly distributed on the scraper head; the air channels are connected with the annular air storage cabin; the water spraying channels are communicated with an inner water supply joint. Thecutting head component has the advantages that air is utilized to drive water in the water spraying channels to impact the inner wall of the small intestine of the pig at certain speed, the sprayingis more uniform, the soaked intestinal mucosa layering is loose and the separation is thorough, and meanwhile, the inner wall of the small intestine of the pig is lubricated, the scraping is more smooth and the scraping efficiency is improved.

The invention discloses a separation material returning type blocky food forming mold which comprises a base, a mold plate, an elastic supporting mechanism, a material returning column and a separation abutting mechanism. The base and the die plate are controlled to be in a relative floating or positioning state through the separating and abutting mechanism, when material returning is needed, the base and the die plate are controlled to float relative to each other, the whole structure is inverted, the base is pressed, and the material returning column extends into the die groove to abut against materials for material returning; the positioning between the base and the die plate is controlled, so that the rotating scraping plate or pressing plate on the upper side of the die plate can stably scrape or press materials, flexible and changeable operation modes and structural design are achieved, and the material returning efficiency is improved.

The invention discloses a clamp type pig hair double-edge scraping knife. The scraping knife comprises a handle and a clamp body formed by machining a single elastic steel sheet. A left clamp part and a right clamp part of the clamp body are provided with a left handle and a right handle respectively, and the left handle and the right handle are formed by machining elastic steel wires. The right side of the bottom of the left clamp part is provided with a left blade. A left boss is arranged in the middle of the left blade in the length direction. The lower end of the left side of the left boss is provided with a left knife edge. The left side of the bottom of the right clamp part is provided with a right blade. A right boss is arranged in the middle of the right blade in the length direction. The lower end of the right side of the right boss is provided with a right knife edge. The width of the left boss and the width of the right boss both range from 0.1 mm to 0.5 mm so that the distance between the left knife edge and the right knife edge can be from 0.2 mm to 1.0 mm when the bottom of the left clamp part and the bottom of the right clamp part are closed. By adopting the clamp type pig hair double-edge scraping knife, pig hair can be scraped off easily, and the pig hair left between the left knife edge and the right knife edge can be taken out easily.

The invention discloses a dust removal device special for a resistive load box. The dust removal device comprises a discharge groove and a blocking collecting mechanism; the blocking collecting mechanism is arranged in a fixing frame, a motor is electrified to work to drive a recovery roller to rotate, and accordingly, the recovery roller releases the winding of blocking cloth; the blocking clothis driven to move towards the lower end through the gravity of a balancing weight, then the blocking cloth blocks the discharge groove, then a draught fan pumps dust, the dust is blown to the upper end of the blocking cloth and falls into a collecting frame to be collected, meanwhile, air flow is exhausted through an air exhaust groove, and the advantage of preventing the dust from flying away isachieved; and a scraping mechanism is arranged at the upper end of the blocking collecting mechanism, a scraping piece makes contact with the left end of the blocking cloth, when the blocking cloth isretracted towards the upper end, the scraping piece can scrape away dust adhering to the upper end of the blocking cloth, and the advantage that dust can be stably scraped away is achieved.