What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
The diameter, length and quantity of the stud bolts shall meet the requirements, and the type and material of the stud bolts shall be determined by the grade. There are two types of commonly used stud bolts (also known as full-threaded studs). The thread is divided into two types: coarse thread and fine thread. The coarse thread ordinary thread is expressed by M and the nominal diameter, and the fine thread ordinary thread is expressed by M and the nominal diameter × pitch. The fastener standard stipulates that M36 bolts use coarse thread, M36 and above diameters can use fine thread, and the pitch is 3. bm=1d studs are generally used for the connection between two steel connected parts; bm=1.25d and bm=1.5d studs are generally used between cast iron connected parts and steel connected parts The connection between the two; bm=2d double-ended stud is generally used for the connection between the aluminum alloy to be connected and the steel to be connected. The former connector has internal threaded holes, and the latter connector has through holes. The threads at both ends of the equal-length studs need to be matched with nuts and washers, and are used for two connected parts with through holes. One end of the welding stud is welded on the surface of the connected piece, and the other end (threaded end) passes through the connected piece with a through hole, and then the washer is put on, and the nut is screwed on, so that the two connected pieces are connected as a whole.
The elastic cylindrical pin, also known as the spring pin, is a headless hollow cylindrical body, which is slotted in the axial direction and chamfered at both ends. It is used for positioning, connection and fixation between parts. The outer diameter of the spring pin is usually slightly larger than the mounting hole. The deformation force generated by the elastic cylindrical pin to be restored to its original state by extrusion ensures the clamping effect of the elastic cylindrical pin. But just because of its clamping effect, it will play a big obstacle to the disassembly of the elastic cylindrical pin. When in use, the open end is extended out of the through hole on the pin shaft, and the open end is flared and separated to prevent the elastic cylindrical pin from sliding off the pin shaft to realize the function of preventing backlash. At present, the disassembly method of the elastic cylindrical pin usually uses a punching machine to remove the cylindrical pin, which easily destroys the equipment installed on the cylindrical pin, and the disassembled elastic cylindrical pin cannot be used again due to damage. One method is to insert the mounting pin with the clearance fit of the mandrel, punch the pin behind the mandrel to clamp the bottom of the cylindrical pin, and then pull out the cylindrical pin, which can only be used when the elastic mounting pin is installed in the through hole, and because it is necessary Applying force to the mandrel increases the difficulty of disassembly and increases the work intensity of the installer. Three methods are done by the installer using two needle nose pliers. Specifically, first use needle-nose pliers to clamp the ends of both sides of the elastic cylindrical pin, and then apply an inward force to the needle-nose pliers, so that both sides of the elastic cylindrical pin rotate in the same direction until the opening becomes smaller, and then Pull it out to remove it successfully. The defects of these existing methods are obvious. The shape of the disassembled elastic cylindrical pin is either unusable or the deformation of the cylindrical pin after disassembly is not uniform, which seriously affects the performance of the elastic cylindrical pin, resulting in waste and increased cost; The method is purely manual work, and sometimes it takes several repetitions to remove the elastic cylindrical pin. Due to the different installation positions of the elastic cylindrical pin, it sometimes increases the difficulty of disassembly, and it is difficult to remove the needle-nose pliers effectively. The pliers are difficult to construct, and the elastic cylindrical pins are easily damaged. If there are too many elastic cylindrical pins to be disassembled, the existing methods are often difficult to meet the needs, which not only consumes a lot of time and physical strength of the installer, but also makes it difficult to ensure the quality.
GBT 3098.19-2004 blind rivets in my country are divided into: GB/T12615 closed oblate head blind rivets; GB/T12616 closed countersunk head blind rivets; GB/T 12617 open type countersunk head blind rivets; T 12618 Open-type oblate head blind rivets; the international standard is DIN7337; there are 1990 versions and 2004. The 2006 version is mainly the 2006 version.
In another embodiment of Guangdong Yueluo Hardware Industry Co., Ltd., the discharge port of the vibrating plate 2 is matched with the screw receiving hole 35, and the screws can enter the screw receiving hole 35 through the discharge port after sorting and sorting in the vibrating plate 2. . Preferably, a guide rail 6 is provided between the discharge port of the vibrating plate 2 and the screw accommodating hole 35 , and the screws enter the screw accommodating hole 43 from the discharge port through the guide rail 6 . The slotting is carried out, which improves the efficiency and saves the labor cost.
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