What is the tolerance range of precision screws?
What is the tolerance range of precision screws?
Countersunk head screw, also called countersunk head screw, also known as flat machine screw, is a kind of construction part. The head is a 90-degree cone, similar to common wood screws. The head has tool tightening grooves, such as a zigzag, cross, inner hexagon, plum blossom, pentagon, etc. Screws are all connectors used to connect two objects. Generally, the head of the screw will protrude above the surface of the object to be connected, so that the surface will lose its smoothness. Countersunk head screws can be sunk under the surface to make the surface flat. For hard objects, countersunk holes need to be drilled in the corresponding positions of the countersunk head. In short, the countersunk head is the head of the screw that can keep the surface flat after installation.
Drilling screw is a new invention of people in recent years. A screw is a common term for fasteners, an everyday colloquial language. The tail of the drill tail screw is in the shape of a drill tail or a pointed tail, and no auxiliary processing is required. Drilling, tapping and locking can be directly carried out on the setting material and basic material, which greatly saves construction time. Compared with ordinary screws, its toughness and pull-out force and maintenance force are high, and it will not loosen for a long time after combination. It is easy to use safe drilling and tapping in one operation. Drill tail screw Drill tail screw use: It is a kind of screw, mainly used in the fixing of color steel tiles of steel structures, and can also be used for thin plate fixing of simple buildings. It cannot be used for metal-to-metal bonding. Materials and models The materials are iron and stainless steel, of which stainless steel is divided into various materials. Models are: Φ4.2/ Φ4.8/ Φ5.5/ Φ6.3mm, the specific length can be agreed upon request. According to the different drill tails, it can be divided into: round head rice / cross / plum blossom, countersunk head (flat head) / rice seed / cross / plum blossom, hexagonal washer, round head washer (big flat head), horn head, etc.
Knurled copper nuts are widely used in the following fields: notebook computer plastic casing, desktop computer plastic casing, GPS plastic casing, router plastic casing, mobile phone plastic casing, infinite communication facility plastic casing, home appliance plastic casing, automobile, electrical appliances, medical, electronics, etc. plastic shell.
With the rapid development of electronic technology, the integration of circuit boards is getting higher and higher, and the number of layers of circuit boards is increasing. Press-fit and fix to ensure accurate alignment during riveting and pressing. The rivets used on PCB boards are basically brass rivets. When riveting and pressing multi-layer PCB boards, metal chips are prone to appear, inner layer short circuits or foreign objects between layers, and because of the brass rivets With higher hardness and larger wall thickness, the riveted area of the PCB is thicker than the non-riveted area, which is easy to cause damage to the middle steel plate of the auxiliary tool. At the same time, the protruding rivets hinder the free expansion of the copper foil, which is easy to produce copper foil. wrinkling phenomenon. Now there are improved plastic rivets used to manufacture multi-layer PCB boards. The advantage is that no metal debris is generated, and at the same time, the tool steel plate is not damaged to the greatest extent. However, the existing plastic rivets are insufficient due to the inherent strength of plastics. When the PCB board is riveted and pressed, it is easy to deform, and the positioning is inaccurate, resulting in dislocation between layers, resulting in poor improvement of the product defect rate.
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