43results about How to "Avoid misplaced movement" patented technology

The invention belongs to the technical field of all-fiber current transformers, and particularly relates to a high-precision high-reliability and all-fiber current transformer. A redundancy design method adopting active optical devices is applied so that output optical power of light source units is enabled to be more stable and stability of light source average wavelength is enhanced. A depolarization head is additionally arranged in an optical path system so that stability and measurement precision of the optical path system can be enhanced. Two beams of light are converted into electric signals to be transmitted to a signal processing unit by utilizing correlation of output light of the two output ends of a second single-mode coupler through a digital signal processing unit, and suppression of light source intensity noise is realized by utilizing a digital circuit subtraction method so that signal-to-noise ratio is enhanced and measurement precision of the system is enhanced. A low birefringence optical fiber Verdet constant and a transformation ratio error generated by change of wave plate phase delay along with temperature are enabled to be mutually compensated via an all-fiber current transformer transformation ratio temperature error automatic compensation technology so that full-temperature measurement precision of the system is enhanced.

The invention discloses a dense grid solder strip pressing device. The dense grid solder strip pressing device comprises a frame, a pressing strip, spring pressing mechanisms and a solder strip clamping groove; the frame is internally provided with the pressing strip, and the spring pressing mechanisms are arranged at both ends of the frame; and the solder strip clamping groove is formed in the pressing strip. The invention further provides a dense grid battery string welder including the dense grid solder strip pressing device and a string welding method thereof. The dense grid solder strip pressing device is provided with the solder strip clamping groove which is used for clamping a solder strip so as to press the solder strip to a welding spot of a battery piece, the coincide of the solder strip and the welding spot of the battery piece is effectively kept, so that the solder strip is prevented from moving misalignedly, and the phenomenon of poor soldering is avoided.

To provide a method of firing a ceramic plate by which the occurrence of the warpage or waviness of the ceramic plate after firing can be prevented.The ceramic plate 2 is arranged on a zirconia setter 1 between opposed zirconia setters 1 and 5. The periphery part of the ceramic plate 2 is surrounded by a surrounding member 4 composed of a ceramic material having the sane composition as the ceramic plate 2 and the ceramic plate 2 is fired. As a result, lead in lead titanozirconate is released into a gap S between the ceramic plate 2 and the zirconia setter 5 from each surrounding member 4. The evaporation of lead in the lead titanozirconate from the ceramic plate 2 is suppressed and the concentration of lead in the gap S is kept uniform during the firing. Then, the occurrence of the warpage or the waviness of the ceramic plate 2 after firing can be prevented. (C)2005,JPO&NCIPI.

The invention discloses an energy-saving and environment-friendly fabricated wall and an assembly method thereof, and belongs to the field of fabricated buildings. The energy-saving and environment-friendly fabricated wall comprises two supporting columns, a plurality of groups of first wall bodies, second wall bodies and third wall bodies are arranged between the two supporting columns, and the first wall bodies, the second wall bodies and the third wall bodies are connected in a spliced mode, a partition plate is arranged between the two supporting columns and located between every two adjacent sets of the first wall bodies, the second wall bodies and the third wall bodies, inserting grooves are formed in one sides of the first wall bodies and one sides of the second wall bodies, and first inserting blocks matched with the inserting grooves are fixedly connected to one sides of the second wall bodies. Rapid installation of fabricated wall can be achieved, the area and the weight of asingle wall body are reduced, hoisting equipment is not needed, the installation cost is saved, positioning connection between the wall bodies is achieved through inserting connection of the inserting blocks and the inserting grooves, direct inserting can be achieved during installation, dislocation movement of the wall bodies is prevented, and in-place installation is ensured.

The invention discloses a manufacturing method of a split type composite propeller and a product, and the manufacturing method comprises 1) a propeller hub manufacturing step including 1-1) a propeller hub pre-forming step: namely laying prepreg sheets according to a predetermined method to obtain a propeller hub pre-formed body; and 1-2) a propeller hub forming step: namely putting the propellerhub pre-formed body into a propeller hub forming mold, and carrying out heating and pressurizing to obtain a propeller hub; 2) a paddle manufacturing step including 2-1) a paddle pre-forming step: namely paving prepreg sheets according to a predetermined method to obtain paddle pre-formed bodies; and 2-2) a paddle forming step: namely putting the paddle pre-formed bodies into a paddle forming mold, and carrying out heating and pressurizing to obtain paddles; and 3) a bonding step: namely, respectively gluing the faying surfaces of the paddles and the first concave part of the propeller hub, then butting the faying surfaces of the more than two paddles and the first concave part of the propeller hub one by one, then performing fixing, and finally performing baking to obtain the product. Themethod has the characteristics of convenience in manufacturing, high production efficiency and good connection stability.

The invention discloses a novel motor rotor structure. The novel motor rotor structure comprises rotor punching pieces, magnetic steel, rotor magnetic steel pressure plates, fastening bolts and a locking mechanism, wherein the locking mechanism comprises aluminum-casting end rings and mouse cage strips which are integrally formed, each aluminum-casting end ring is a round ring, and movable balancing holes are formed in the round ring; the magnetic steel is mounted on outer arc surfaces of the rotor punching pieces, the rotor magnetic steel pressure plates are respectively arranged on two sidesof the rotor punching pieces, and one aluminum-casting end ring is arranged on the inner side of each rotor magnetic steel pressure plate; a plurality of bolt holes and a plurality of mouse cage holes are formed in the rotor magnetic steel pressure plates and the rotor punching pieces; the fastening bolts penetrate through the rotor magnetic steel pressure plates and the rotor punching pieces andare used for locking the rotor magnetic steel pressure plates and preventing the axial movement of the magnetic steel; and the mouse cage strips and the aluminum-casting end rings are connected withthe rotor punching pieces through interference fit. According to the novel motor rotor structure, the problems that silicon steel sheets are staggered and moved in the carrying and transportation processes can be solved.

The invention discloses a sound production device. The sound production device comprises an outer shell, and a vibration system and a magnetic circuit system connected with the outer shell, wherein the magnetic circuit system comprises a magnetic conductive yoke, the magnetic conductive yoke is provided with a magnetic conductive body and a connecting flange, the magnetic conductive body faces a vibrating diaphragm of the vibrating system, the connecting flange is formed by bending the magnetic conductive body towards one side where the vibrating diaphragm is located, and a plurality of air holes are formed in the connecting flange; and a leakage opening is formed between the outer shell and the magnetic conductive body, and the connecting flange completely covers the leakage opening. According to the sound production device, the reject ratio of products can be reduced.

The invention discloses a positioning and temporary supporting stable unloading device for net rack hoisting. The positioning and temporary supporting stable unloading device comprises a support frame, connecting bases, H-shaped support beams, cushion blocks, support limiting plates and jack assemblies; the connecting bases are welded and fixed on the top surface of the support frame, the H-shapedsupport beams are welded and fixed at the two side ends of the top surfaces of the connecting bases; U-shaped supporting bases are fixedly welded to the two H-shaped supporting beams; and the cushionblocks are clamped in U-shaped clamping grooves of the two U-shaped supporting bases. The using method comprises the following steps that 1) a butt joint part device is installed; 2) an unloading part device is installed; 3) net rack roof high-altitude butt joint is conducted in a subsection mode; and 4) synchronous unloading operations are carried out. According to the positioning and temporarysupporting stable unloading device for net rack hoisting, by means of the device, the installation accuracy of the net rack roof during segmented hoisting can be guaranteed, meanwhile, step-by-step graded unloading is achieved during unloading, the phenomena that due to an improper unloading scheme, a net rack structure generates large lower deflection, local rod pieces are overstressed, and nodeconnection is damaged and collapsed can be effectively avoided, and the stability and the safety of the whole unloading process are ensured.

The invention discloses a sealant formula specially used for watertight-typed cables and a preparation method thereof. The sealant comprises following components, by weight, 90-100 parts of neoprene, 50-60 parts of coumarone resin, 3-5 parts of zinc oxide, 5-8 parts of light-weight magnesium oxide, 0.5-0.8 parts of ethylene thiourea, 0.6-1 part of dihydroxylpolydimethylsiloxane, 3-4 parts of calcium stearate, 0.8-1 part of a 2,2,4-trimethyl-1,2-dihydrogenated quinoline polymer, 2-3 parts of fused magnesite, 1-2 parts of chlorhexidine, 2-4 parts of conch shell powder, 1-2 parts of silicon carbide, 10-15 of high-wear-resistant carbon black, 2-3 parts of perluorooctyl acrylate, 0.4-1 part of 8-hydroxylquinoline and 120-130 parts of calcium carbonate. The sealant is good in waterproof performance, is strong in adhesive force, is east to coat, is quite strong in the adhesive force and stability among each layer of the cable, can effectively prevent dislocation and movement in each layer of the cable under a high water pressure and can ensure a safety performance.

The invention belongs to the technical field of lithium ion batteries, particularly relates to a method for testing a button type half battery made of a lithium ion battery electrode material, and belongs to the field of lithium batteries. The technical scheme adopted by the invention is as follows: the method comprises the processes of manufacturing a pole piece and assembling a button type half cell, namely putting a clean base material on an infrared flat plate coating machine, uniformly coating slurry on the base material, drying the pole piece by the coating machine, baking by a vacuum oven to remove moisture, cutting off a blank base material, sequentially rolling the pole piece once at roller gaps of 50mu m, 40mu m and 30mu m of a double-roller machine, and assembling the button type half cell after the pole piece is rolled once at the roller gaps of 50mu m, 40mu m and 30mu m of the double-roller machine. Making the pole piece into a circular pole piece, pasting the circular pole piece on a gasket by using a small amount of conductive adhesive, drying the circular pole piece to serve as a pole piece sheet, placing the negative pole shell of the button-type half cell on a flat operation table in a closed environment, and putting an elastic sheet into the operation table; after six drops of electrolyte are added, a gasket and a pole piece are added, then three drops of electrolyte are added to wet (increase) a pole piece dressing, a diaphragm is attached to the pole piece, a lithium piece is placed and slightly pressed, a positive pole shell is covered, the lithium piece is placed in a sealing machine to be sealed at the pressure of 800 psi, and the button type half-cell sample for material testing is obtained.

The invention provides an automatic pressing system for a wood ecological composite board. The automatic pressing system comprises a bottom plate, a pressing module, an auxiliary unit and a rolling device; the pressing module is arranged at an upper end of the bottom plate, the auxiliary unit is arranged in the middle of the upper end of the bottom plate and located in the pressing module, and therolling device is arranged at the upper end of the pressing module in a sliding fit mode. The problems that, in the pressing process of a wood composite board, core materials are mainly mixed betweentwo boards, in the hot pressing process through a hot press, due to uneven hot pressing, the core materials in the wood composite board are prone to loosening, and in the hot pressing process throughthe hot press, the core materials are prone to loosening due to uneven mixing of the core materials can be solved. The problems that a gap is likely to exist when a core material in the plate is pressed, the hollowing phenomenon causes that the heat preservation performance of the composite board is reduced, the heat insulation effect becomes poor, and the pressing quality of the board is affected are solved.

The invention discloses a waste heat energy recovery device for an underwater vehicle. An inner connection layer is arranged outside an underwater vehicle high-temperature shell, an outer connection layer is arranged outside the inner connection layer, a thermoelectric module is stuck on the outer surface, between the inner connection layer and the outer connection layer, of the inner connection layer, and a heat insulating layer fills a position between the inner connection layer and the outer connection layer. The thermoelectric module is utilized to be stuck at a position between the outside of the underwater vehicle high-temperature shell and the outer connection layer, then isolation is performed by virtue of the heat insulating layer, an underwater vehicle shell is taken as a high temperature surface, heat is conducted to a heat surface of the thermoelectric module by virtue of a connection surface, a water layer provides a low temperature surface for the thermoelectric module byvirtue of the connection surface, the thermoelectric module converts temperature difference of a high temperature end and a low temperature end into an electrical parameter and outputs the electricalparameter, a fact that a hot spot of the thermoelectric module is far away is utilized, and waste heat of the underwater vehicle is converted into electric energy to be recycled. The device disclosedby the invention is simple in structure; the thermoelectric module does not contain a moving part, thus a recovery structure is stable; and the waste heat of the vehicle is converted into the electric energy, thus energy utilization efficiency of the underwater vehicle is improved.

The invention relates to a handcart type DC circuit breaker and a connection contact thereof. The connection contact comprises a conductive connection seat, a front slot, a rear slot and a fixed connection structure, wherein the front slot is used for being inserted by a main loop busbar matched with the switch cabinet, front watchband contact fingers are installed on the slot walls on the two sides of the front slot respectively, and the front watchband contact fingers are used for making conductive contact with the main loop busbar; incoming and outgoing line ends of the handcart-type direct-current circuit breaker are inserted into the rear slot, and rear watchband contact fingers are installed on the slot walls on the two sides of the rear slot respectively and used for making conductive contact with the incoming and outgoing line ends of the handcart-type direct-current circuit breaker; and the fixed connection structure is arranged on the conductive connection seat and is used for fixedly assembling the wire inlet and outlet ends and the conductive connection seat together. According to the connection contact of the handcart type direct-current circuit breaker provided by the invention, the conductive connection of the incoming and outgoing line ends and the main loop busbar in the adaptive switch cabinet is realized by utilizing the conductive connecting seat and the front and rear watchband contact fingers arranged in the conductive connecting seat, the through-current capability is conveniently and effectively ensured, the overall structure is relatively simple, processing and manufacturing are convenient, and processing cost is low.

The invention relates to the technical field of cold chain equipment, and discloses a novel protective structure of medical cold chain equipment. The novel protective structure comprises a cold chainbox body and a box cover, the rear side wall of the box cover is rotatably connected with the edge of the upper end of the rear side of the cold chain box body through a hinge, the upper end of the box cover is fixedly connected with a positioning clamping block, a positioning clamping plate is fixedly connected to the lower end of the cold chain box body, a positioning clamping groove matched with the positioning clamping block is formed in the lower end of the positioning clamping plate, T-shaped fixing rods are fixedly connected to the left side and the right side of the lower end of the cold chain box body correspondingly, and inserting rods are arranged below the two T-shaped fixing rods correspondingly. By means of the novel protective structure of the medical cold chain equipment, positioning and stacking can be conducted during stacking, the stacking uniformity and stacking stability are improved, meanwhile, the situation that two adjacent cold chain boxes move in a staggered mode due to emergency brake inertia during transportation can be prevented, collision damage to the cold chain boxes and objects in the cold chain boxes due to large displacement is avoided, and the anti-collision performance of the cold chain boxes can be improved.

The invention relates to a near-surface short-time wind-sand flow sand collection tester. The tester comprises a sand collection box, a sand collection cylinder and a collection device. The sand collection box is vertically arranged. The sand collection cylinder is transversely arranged on the sand collection device. The first end of the sand collection cylinder stretches out of the interior of the sand collection box, and the second end of the sand collection cylinder is arranged in the sand collection box. The collection device is magnetically connected to the second end of the sand collection cylinder. According to the invention, by magnetically connecting the collection device and the sand collection cylinder, disassembly and assembly convenience is improved and test precision and work efficiency are improved.

The invention provides a mud scraping foot pad which comprises a pad frame, four rubber surrounding edges and a treading cleaning mechanism. The four rubber surrounding edges are fixedly connected to the surface of the pad frame, the surface of the pad frame is rectangular, the four rubber surrounding edges are fixedly connected with the four side surfaces of the pad frame respectively, the surfaces of the four rubber surrounding edges are all in an arc shape, the interior of each rubber surrounding edge is in a hollow shape, and each rubber surrounding edge relates to the field of articles of daily use. According to the mud scraping foot pad, a special elastic structure is designed according to the problems that an existing foot pad is prone to slipping off, the cleaning space is small, and dust is difficult to remove, a traditional dust removing mode is changed through special deformation, the cleaning effect is enhanced, and therefore the problems that when a common foot pad is used, the foot sole of a person needs to slide on the pad, the lower pad is prone to slipping and shifting and the cleaning space hinders removal of dust on the foot sole, and a cleaning effect of the foot pad is influenced to a certain extent are solved.

The invention provides a post-forming machining system in production and manufacturing of plywood. The system comprises a moving trolley, a stacking unit, a lapping unit and a fixing unit, and can solve the following problems that plywood usually needs to be placed on the ground to be naturally aired after being glued; the plywood subjected to natural airing treatment needs to be manually stacked,but the manual stacking efficiency is low; the plywood is difficult to lift manually when being flattened on the ground; when the plywood is manually carried and stacked, the corners of the stacked plywood are difficult to keep neat; the stacked plywood at the lowermost end is difficult to adjust and trim manually under the influence of gravity; and the plywood is easy to fall off to be crushed and damaged due to fatigue errors in the process of manually carrying the plywood.

The invention relates to a rail set railway fixing device. A rail set is a three-way rail set and comprises a common rail, a left non-common rail and a right non-common rail, an iron backing plate isinstalled between the bottoms of the left non-common rail and the right non-common rail and a rail set sleeper, and the top face of the iron backing plate is in a ladder shape; a fastening device is fixedly installed between the left non-common rail and the right non-common rail; and a fastener A is installed on the outer side of the rail bottom of the left non-common rail, a fastener B is installed on the outer side of the rail bottom of the right non-common rail, and the fastener A and the fastener B are arranged in a staggered or symmetric mode. The rail set railway fixing device is low inproduction cost, convenient to maintain and high in safety.

The invention discloses a cold-resistant cable with a compression-resistant protection structure. The middle part of a cold-resistant cable body is provided with an internal cable for electric conduction, the middle part of the internal cable is provided with a tensile steel rope, the outer side of the tensile steel rope is provided with a conductive core, the outer sides of the tensile steel rope and the conductive core are wrapped by a fireproof wrapping layer, a the outer side of the fireproof wrapping layer is wrapped with an armor layer, the outer side of the armor layer is wrapped with a rubber insulating layer, the outer side of the cold-resistant cable body is provided with a protective sleeve, and the middle part of the protective sleeve is provided with a through sleeve hole for the internal cable to pass through. According to the cold-resistant cable with the compression-resistant protection structure, when the cable is installed and laid, the middle of the cable protective sleeve is filled with inert gas, the protective sleeve is expanded outwards to abut against the inner wall of the laying pipe, the cable is limited, the cable is prevented from being dislocated in the laying process, and meanwhile the cable is prevented from being damaged by the inert gas through the protection sleeve and the filled inert gas, so the cold-proof effect of the cable can be improved.

The invention relates to a novel color 3D printer, comprising a printer base, vertical supports arranged on the two sides of the base, a controller arranged on one side of the base, a transverse rod arranged at the upper ends of the supports and capable of horizontally moving front and back relative to the supports, and a spray head base arranged on the transverse rod and capable of horizontally moving relative to the length direction of the transverse rod. A printing platform is arranged on the base; a main spray head and an auxiliary spray head are fixedly arranged on the spray head base; a mixing unit is arranged at the feeding port end of the main spray head, and is connected with an RGB three-color feeding barrel and a first resin feeding barrel; the auxiliary spray head is connected with a second resin feeding barrel; resin in the first resin feeding barrel is thermosetting resin; and resin in the second resin feeding barrel is thermoplastic resin. According to the novel color 3D printer, the color mixing proportion of the RGB three-color feeding barrel is controlled through a switch, so that resin with the needed color can be obtained; and the thermoplastic resin sprayed by the auxiliary spray head serves as a removable supporting material, so that printing forming of an embedded non-supporting structure can be implemented.

Disclosed is a metal grid touch panel with winding nodes which comprises a bottom box, a packaging bottom plate is fixedly installed on the bottom box, a supporting plate is fixedly connected to the packaging bottom plate, limiting strips are fixedly installed on the supporting plate, an optical film plate is fixedly connected to the limiting strips, an ink layer is fixedly connected to the optical film plate, and the ink layer is fixedly connected to the packaging bottom plate. A glass cover plate is fixedly connected ont the ink layer. the winding nodes are used on the optical film plate to serve as a guide arrangement structure of a metal grid, a hidden structure is adopted, the sockets are used for independently fixing the single winding nodes, the winding nodes can be effectively prevented from moving in a staggered mode, and normal use of the touch panel is guaranteed; through the preparation method of the metal grid touch panel with the winding nodes, the operation process can be simplified, packaging of the touch panel can be rapidly completed, maintenance space is reserved in the packaging process, and deep disassembly of the touch panel is not needed.

The invention discloses a range-adjustable agriculture and forestry irrigation device, and particularly relates to the technical field of agriculture and forestry irrigation, the range-adjustable agriculture and forestry irrigation device comprises a diversion canal, a floating platform floats on the water surface of the diversion canal, a water suction pump is mounted on the top surface of the floating platform, and a stabilizing mechanism is mounted on the top surfaces of the floating platform and the diversion canal; the piston rod of the linear air cylinder pushes the mounting column to move upwards, the hose is pulled to stretch out and draw back during movement, then the range height of the spray head is adjusted, the electric push rod stretches out and draws back, the mounting column is rotationally hinged to the piston rod of the linear air cylinder, and then angle deviation of the mounting column is achieved; crops planted in the planting area are subjected to spray irrigation through the multiple sprayers, the spray irrigation range is changed, and the spray irrigation requirement of the planting area is met. The placing seat is arranged on the outer surface of the mounting column in a sliding and sleeving manner under the matching of the guide block and the guide groove, so that the dislocation movement of the placing seat and the mounting column is avoided; and the stability of the floating platform is improved through the stabilizing mechanism.

The invention discloses a linear type movable pipe peristaltic pump. The linear type movable pipe peristaltic pump comprises a pump body assembly, a pipeline assembly, a closure assembly, a pipe pressing assembly and at least one linear reciprocating motion assembly, wherein the closure assembly is used for clamping and loosening the pipeline assembly; the linear reciprocating motion assemblies and the pipe pressing assembly are both installed on the pump body assembly; the pipeline assembly is connected with the linear reciprocating motion assemblies; along with reciprocating motion of the linear reciprocating motion assemblies, the pipeline assembly conducts reciprocating motion; and the pipe pressing assembly extrudes the pipeline assembly conducting reciprocating motion, and thereforematerial pumping metering is completed. The linear type movable pipe peristaltic pump has the beneficial effects that the structure is simple, the service life of an elastic hose is long, the fillingefficiency is high, and the metering precision is stable.

The invention discloses a die-cutting machine for avoiding printing film adhesion and its use method, comprising a die-cutting machine body, a feeding frame, a rotating shaft, a feeding roller, a printing film, a winding frame, a winding roller, and a die-cutting table , a support frame, a top plate, a control box, an air cylinder and a stepping motor, a discharge rack is arranged on one side of the die-cutting machine body, and a discharge roller is arranged on the inside of the discharge rack through a rotating shaft, and the discharge roller is provided with There is a printed film, and the printed film is connected to the winding frame on the other side through the die-cutting table on the die-cutting machine body, and the middle part of the upper surface of the top plate is provided with a cylinder, and the telescopic end of the lower part of the cylinder is connected to the mold through bolts. The connecting sleeve on the top of the cutting frame is connected. The die-cutting machine for avoiding printing film adhesion and its use method, through the improvement of the structure of the existing die-cutting machine, effectively prevent the adhesion of the film finished product on the die-cutting frame, and at the same time, it is convenient for cutting tools on the die-cutting frame Adjustment and replacement of the distance between.

The invention relates to a rubber track chassis, a rubber track chassis derailment prevention device and a track vehicle. The rubber track chassis comprises a frame and a rubber track; a driving wheeland a supporting wheel are arranged on the frame; internal engaging teeth in transmission connection with the driving wheel are arranged on the internal wall of the rubber track; the rubber track chassis further comprises a derailment prevention device arranged on the frame; the derailment prevention device comprises a frame connecting structure and a stopping structure, wherein the frame connecting structure is used for being connected with the frame, and the stopping structure is in stopping fit with the rubber track in the width direction of the rubber track; and the length dimension of the stopping structure in the length direction of the rubber track is larger than the spacing distance between the two adjacent internal engaging teeth. In the steering process of the rubber track chassis, the derailment prevention device and the rubber track are limited in a stopped manner. Compared with the prior art, the rubber track chassis has the advantages that the safety of the rubber trackchassis is enhanced to prevent damages of other members caused by derailment.

The invention provides an automatic pressing system for wood ecological composite boards, comprising a bottom plate, a pressing module, an auxiliary unit and a rolling device; The auxiliary unit is located inside the pressing module, and the rolling device is arranged on the upper end of the pressing module through a sliding fit; the present invention can solve the problem that the core material mainly exists in the process of pressing the wood composite board. During the hot pressing process between the plates, the inner core material is easy to loose due to uneven hot pressing, and the inner core material is easily loosened due to the uneven mixing of the core material during the hot pressing process, which causes the inner core material to be pressed. The core material is easy to have gaps, and the phenomenon of hollowing out leads to the reduction of the thermal insulation performance of the composite board and the deterioration of the heat insulation effect, which affects the pressing quality of the board and other problems.