Service HotlineUsually, the forming of the bolt head adopts cold heading plastic processing. Compared with the cutting process, the metal fiber (metal wire) is continuous along the shape of the product, and there is no cut in the middle, thus improving the strength of the product, especially the mechanical properties. The cold heading forming process includes cutting and forming, single-station single-click, double-click cold heading and multi-station automatic cold heading. An automatic cold heading machine performs multi-station processes such as stamping, heading forging, extrusion and diameter reduction in several forming dies. The processing characteristics of the original blank used by the single-station or multi-station automatic cold heading machine are determined by the size of the bar with a length of 5-6 meters or the wire rod with a weight of 1900-2000KG, that is, the characteristics of the processing technology. The point is that cold heading does not use pre-cut single blanks, but uses the automatic cold heading machine itself to cut and upset (if necessary) blanks from bars and wire rods. Before extruding the cavity, the blank must be shaped. A blank that meets the technological requirements can be obtained by shaping. Before upsetting, reducing and positive extrusion, the blank does not need to be shaped. After the blank is cut, it is sent to the upsetting and shaping station. This station can improve the quality of the blank, reduce the forming force of the next station by 15-17%, and prolong the life of the die, and the bolts can be made with multiple diameter reductions. The precision that can be achieved by cold heading is also related to the selection of the forming method and the procedure used. In addition, it also depends on the structural characteristics of the equipment used, the process characteristics and its state, the precision of the tool and die, the life and the degree of wear. For high-alloy steel used in cold heading forming and extrusion, the roughness of the working surface of the cemented carbide mold should not be greater than Ra=0.2um. When the roughness of the working surface of this type of mold reaches Ra=0.025-0.050um, it has the highest life.
Washers are divided into: flat washer-C, large washer-A and C, extra large washer-C, small washer-A, flat washer-A, flat washer-chamfer-A, steel structure high Strength washer, spherical washer, cone washer, square bevel washer for I-beam, square bevel washer for channel steel, standard spring washer, light spring washer, heavy spring washer, internal tooth lock washer, internal serrated lock washer, External tooth lock washer, external tooth lock washer, single ear stop washer, double ear stop washer, outer tongue stop washer, stop washer for round nut.
2. Low cycle fatigue Low cycle fatigue means that the fatigue stress is close to or exceeds the yield limit of the material. The material has a certain amount of plastic deformation in each strain cycle. The life is generally in the range of 102 to several times 104, and the fatigue curve is generally used. ε-N curve representation. The finite element calculation results show that after the bolt is screwed into the lock nut, the stress at the root of the threaded piece is large, and part of the surface area is in a yield state, while the strain in the central area of the root of the threaded piece is small, and the strain situation is more complicated. The area with high strain at the root of the thread piece experiences reciprocating loading, which is prone to low cycle fatigue, which reduces the pressure of the thread piece and reduces the screw-out torque.
The core rivet is another type of single-sided riveting. When riveting, the head of the rivet is hit with a hammer to expose the core, so that it is flush with the end face of the nail head, that is, the riveting operation is completed, which is very convenient, especially suitable for inconvenient Riveting occasions using ordinary rivets (which must be riveted from both sides) or blind rivets (lack of a rivet gun). Usually use flat head rivets, countersunk head rivets are suitable for occasions where smooth riveting is required on the surface. Some rivets can also be matched with clothing, becoming a popular element today, mostly the representative of punk style. In addition, there are paired rivets, which are special. Divided into two parts, the thicker section of the rod with a cap has a hole in the center, and the other section of the rod with a cap is an interference fit. When riveting, drive the thin rod into the thick rod.
Two combination screws are also called two combination screws. As the name suggests, it consists of a screw with a spring washer or only a flat washer. After the thread rolling, the two components are combined together. Two combination screws are available in iron and stainless steel. For iron, there are screw materials such as screw wire 1010, 1018, 10B21, etc. The general iron pier needs to be electroplated, and electroplating is divided into environmental protection and ordinary. For example, there are environmentally friendly color zinc, environmentally friendly blue zinc, white zinc, color zinc, white nickel and other electroplating. Stainless steel two combination screws. The material is stainless steel 304.
We have many years of experience in the production and sales of screws, nuts, flat washers, etc. The main products are: C-type spring steel washers, hexagonal long nuts, alloy steel bolts, one rounded and one chamfered positioning pins and other products, we can provide you with suitable products Your fastener solution.
