Introduction to bushing
Bushing is a supporting part used outside mechanical parts to achieve sealing, wear protection and other functions. It refers to the ring sleeve that acts as a gasket. In the field of valve application, the bushing is in the bonnet, and generally uses corrosion resistant materials such as polytetrafluoroethylene or graphite for sealing.
In moving parts, the wear of parts is caused by long-term friction. When the clearance between the shaft and the hole is worn to a certain extent, the parts must be replaced. Therefore, the designer selects the material with lower hardness and better wear resistance as the shaft sleeve or bushing in the design, which can reduce the wear of the shaft and seat. When the shaft sleeve or bushing is worn to a certain extent, it can save the cost of replacing the shaft or seat. Generally speaking, The bushing and the seat adopt interference fit, while the bushing and the shaft adopt clearance fit. Because wear can not be avoided in any case, it can only prolong the service life, and the shaft parts are relatively easy to process; There are also some new designers who do not like this design. They think that this is to increase the cost during manufacturing, but after a period of use, they still need to be modified in this way during maintenance. However, it is easy to reduce the accuracy of the equipment due to the simple reason. The secondary processing can not guarantee the position of the center of the seat hole. The shaft sleeve has a low speed in some parts, Places with high radial load and high clearance requirements (such as camshaft) are used to replace the rolling bearing (in fact, the shaft sleeve is also a sliding bearing). The material requirements are low hardness and wear resistance. The inner hole of the shaft sleeve can be ground and scraped to achieve a high fitting accuracy. There must be an oil groove on the inner wall. The lubrication of the shaft sleeve is very important. In case of dry grinding, the shaft and shaft sleeve will soon be scrapped. It is recommended to scrape the inner hole wall of the shaft sleeve during installation, In this way, many small pits can be left. The enhanced lubrication bushing and shaft sleeve are selected according to different industrial and mining conditions. The most important conditions are: pressure, speed, pressure-velocity product, lubrication state, and load property. The automatic type selection of bushing is included.
Wrap the valve rod, which is worn and can be replaced easily. If the bushing is not used, the parts will be replaced after wear. Therefore, the replacement is to replace the bushing (during the design, the hardness of the bushing will be reduced to make it become a wear part in the friction pair). Because of its convenient processing, low replacement cost and easy replacement. Of course, there are guiding functions, which are secondary.
Characteristic
Miniature linear bushing bearing is a very small linear motion guide machine with a diameter of 3~5mm, which rotates with the shaft, and the contact edge moves infinitely in a straight line in the direction of the shaft. Features:
1.Low friction impedance: the steel ball can move stably in a straight line with a small friction impedance due to the correct orientation of the retainer.
2.Stainless steel: stainless steel series is also available, which is suitable for the purpose of corrosion resistance.
3.Exquisite design: small size, can be designed in delicate mechanical equipment.
4.Rich changes: In addition to the standard type, there is also a series of high-rigidity long type, which can be selected according to the purpose.
Role of bushing
Bushing has high flexibility and can play a lot of roles. Generally speaking, bushing is a kind of component to protect equipment. The use of bushing can reduce the wear, vibration and noise of equipment, and has the effect of corrosion prevention. The use of bushing can also facilitate the maintenance of mechanical equipment and simplify the structure and manufacturing process of equipment.
The role of bushing in practical work is closely related to its application environment and purpose. In the field of valve application, the bushing is installed in the valve cover to cover the valve stem, so as to reduce the leakage of the valve and achieve the sealing effect. In the field of bearing application, the use of bushing can reduce the wear between bearing and shaft seat and avoid the increase of clearance between shaft and hole.
Material of bushing
Bushings are mostly made of soft metal, rubber, nylon and non-metallic polymers. These materials are relatively soft and have low cost. In various harsh working environments, the bushing bears vibration, friction and corrosion to protect the wrapped parts, while the bushing itself is easy to replace after damage, with low cost and good economy.
Bushing selection factors
La douille a une large gamme d'applications et une grande variété de types. Pour sélectionner une douille appropriée, il est nécessaire de tenir compte de son objectif d'utilisation et de sélectionner différents types de douilles dans différentes conditions de travail. Les principales conditions à prendre en compte dans le choix de la traversée sont la pression, la vitesse, le produit pression-vitesse et la propriété de charge que la traversée doit supporter. De plus, le fait que la douille soit lubrifiée ou non détermine son effet de service et sa durée de vie.
Application pratique
Application: machines d'emballage, machines textiles, machines minières, machines métallurgiques, machines d'impression, machines à tabac, machines à forger, diverses machines-outils et connexion de transmission mécanique interchangeable. Par exemple : poulie, pignon, engrenage, hélice, grand ventilateur et autres connexions diverses ; Caractéristiques : couple élevé, haute précision, montage et démontage pratiques et rapides, fonctionnement simple, bon positionnement, faible taux de rebut de l'arbre et du moyeu assortis, réutilisable et aucun dommage à la surface de contact, ce qui est le choix le plus idéal et économique à l'heure actuelle. .
1.Installation : la douille a été enduite d'huile lubrifiante avant de quitter l'usine et peut être directement installée et utilisée. Lors de l'installation, vissez d'abord trois boulons dans le trou de vis de la bride de l'autre pièce uniformément réparties le long de la circonférence, puis écartez le manchon intérieur et le manchon extérieur. Ensuite, placez le manchon d'expansion dans le trou du moyeu à la position de conception et serrez les boulons avec une clé de mesure de force. La méthode de serrage est que chaque boulon n'est serré qu'à 1/4 du couple nominal à la fois. La séquence de serrage est délimitée par l'ouverture, et la gauche et la droite sont serrées symétriquement et en croix afin de s'assurer que la valeur de couple nominal est atteinte.
2. Démontage : desserrez tous les boulons de plusieurs tours avant le démontage. Ensuite, vissez le dessus du boulon et desserrez le manchon d'expansion en croix dans le trou de vis retiré.
3.Protection : empêche la pollution du manchon d'expansion lors de l'installation. Sur les machines fonctionnant à l'air libre ou dans un environnement de travail médiocre, de la graisse antirouille doit être régulièrement appliquée sur la face d'extrémité exposée du manchon de dilatation et des boulons, et le type de manchon de dilatation avec une bonne propriété antirouille doit être sélectionné. Le manchon d'accouplement à expansion est un composant de base mécanique nouveau et avancé à l'époque moderne. Il s'agit d'un nouveau type de dispositif d'accouplement sans clé largement utilisé dans le monde aujourd'hui pour réaliser la connexion entre les pièces de machine et les arbres, et réaliser la transmission de charge en resserrant la pression et le frottement générés entre les surfaces de confinement en serrant les vis à haute résistance 12.9.
