What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Common fastening screws include self-tapping screws, fine-pitch drywall screws, traditional wood screws, and fiberboard screws. The following are the characteristics of commonly used screws, everyone should choose them reasonably. Self-tapping screws The correct application of self-tapping screws should be used for the fastening and connection of metal materials with pre-drilled holes. It has the function of automatically tapping out the internal thread on the metal body, and can complete the thread engagement with it to play a tightening role. However, due to its high thread bottom diameter, when it is used in wood products, the cut into the wood will be shallower; and because the thread pitch is small, there is less wood structure between every two threads. Therefore, it is unreliable and unsafe to use self-tapping screws for wood mountings, especially loose wood. Drywall Screws The proper use of fine-pitch drywall screws is for fastening and joining between metal studs and plasterboard. It suffers from similar drawbacks as self-tapping screws when used on wood mountings. Moreover, due to the large diameter of the head of the dry-wall screw, the embedding of the head is poor, and it is easy to cause unevenness between the head of the screw and the surface of the mounting part after installation. Traditional wood screws Before using traditional wood screws, pre-drilling holes are required on the wooden mounting parts, otherwise it is easy to cause wood cracking. In addition, since the traditional wood screws are not heat-treated, the use of electric tools can easily cause the groove shape to be damaged, and manual installation is very laborious. Fiberboard screws are relatively new types of wood screws, suitable for power tool installation. However, due to its relatively simple thread design, it still cannot effectively solve the stubborn problem of easy cracking when used on hardwood, and it does not have any advantages in screwing speed and screwing torque. [2]
T-bolt with a spring, used for undercutting the opening of the outer closed cavity, including a head and a rod part connected in one piece, and also including a strip spacer, a spring and a pull rod, and the length of the strip spacer is greater than The opening, the connecting part of the head and the rod part are set as polygonal anti-rotation blocks, and the strip-shaped spacer is provided with anti-rotation holes for inserting the anti-rotation blocks, and the shape and size of the anti-rotation holes are the same as The size of the anti-rotation hole is smaller than that of the head; the spring is threadedly matched with the rod part, and is fixedly connected with the pull rod, and the pull rod moves away from the rod part along the axial direction of the rod part One side of the head extends. The utility model can be easily and reliably buckled in the opening of the airtight cavity, thereby facilitating the installation and connection of external parts.
rivet is a nail-shaped object used to join two parts or components with a through hole and a cap on one end. In riveting, the riveted parts are connected by their own deformation or interference. There are many types of rivets, and they are informal. In today's product production, the slot holes on the same mounting surface often have different mounting slot depths. If a mechanical tool is used for quick screwing and installation, it will directly bring destructive effects to the brittle products, resulting in When the product is cracked and damaged, when connecting plastic shells, lightweight boards, insulating materials, circuit boards, or any other thin and light materials, the requirements for the installation process are also relatively high. The gripping force and bonding force of rivets are weaker than those of rivets that are screwed and installed by machinery. The bonding strength of rivets used in manual operations needs to be enhanced. The rivet structure needs to be improved and enhanced when installing thin, light-weight materials.
The self-tapping locking screw is composed of three parts: the head, the stem and the end of the stem from beginning to end. The composition of each self-tapping screw has four major elements: head shape, wrenching method, thread type, and end type. Head Shapes - Head shapes come in all shapes and sizes. There are round head (semi-round head), oblate head, round head flange (with pad), oblate head flange (with pad), pan head, pan head flange (with pad), countersunk head, semi-countersunk head, Cylinder head, spherical cylinder head, horn head, hexagonal head, hexagonal flange head, hexagonal flange (with gasket), etc. Wrench Styles - There are various ways of wrenching. External wrench: hexagonal, hexagonal flange, hexagonal flange, hexagonal flower shape, etc.; internal wrench: slotted, cross groove H type (Phillips), cross groove Z type (Pozidriv), cross groove F type (Frearson) , Square groove (Scrulox), compound groove, internal spline, internal hexagon flower (plum groove), internal triangle, internal hexagon, internal 12-angle, clutch groove, six-blade groove, high torque cross groove and so on. Thread Types - There are many types of threads. There are self-tapping threads (wide thread), machine threads, drywall screw threads, fiberboard screw threads, and some other special threads. In addition, the thread can be divided into single lead (single head), double lead (double head), multi-lead (multiple head) and high and low thread double head thread. End type - The end type mainly includes saw end and flat end. However, according to the function of use, grooves, grooves, incisions or parts with a cutting function can be processed. In some standards, the same saw end or flat end, there are different forms. There are various changes in the head shape, wrenching method, thread type and shank end type of self-tapping screws. They can be combined with each other to show many different products belonging to the category of self-tapping screws.
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