There are two typical pin shearing fixture tooling, among which the traditional fixture shown in Fig. 1 is more complicated and consists of fixture, spacer, washer and shearing block guide post, hardened bushing, shearing block and so on. The cylindrical pin is installed in the hardened bushing, and the axial load is applied through the shear block to complete the shear test. The fixture is complicated in manufacture and has many consumables, because the size of the hardened bushing is similar to that of the cylindrical pin. , and to keep the notch of the cylindrical pin upward, it is difficult to install before the test, and the broken cylindrical pin after the test remains in the hardened bushing and is difficult to remove.
④ Screw tooth type A: Self-tapping sharp tail (Japanese standard type 1) sparse AB: Self-tapping sharp tail (Japanese standard type 4) dense; B: Self-tapping flat tail (Japanese standard type 2) sparse; C: Self-tapping Tapping flat tail (the third type of Japanese standard) dense; P: double wire teeth Type triangle teeth CCT: C type triangle teeth PTT: P type triangle teeth STT: S type triangle teeth
Electrical contact element is a kind of low-voltage electrical products and household electrical products widely used in switches, relays, thermostats, circuit breakers, contactors, controllers, timers, etc. There are mainly three types of electrical contact elements. 1. Riveting parts , riveting the rivet on the copper piece; 2. Welding piece, welding the sheet contact on the copper piece; 3. Stamping piece, punching the composite tape into components. Existing rivet contacts on the market at present are usually all made of precious metals, such as a simple metal matrix such as gold or silver. Its electrical contact performance is limited by a single metal material, and its electrical contact performance is poor; and due to certain requirements for metal purity in production, production efficiency is low, and production costs are high, resulting in the production of products that cannot be sold on a large scale in the market. and application.
People often think that magnets attract stainless steel to verify its pros and cons and its authenticity. If it does not attract non-magnetism, it is considered to be good, and it is genuine; if it is magnetic, it is considered to be counterfeit. In fact, this is an extremely one-sided, unrealistic and wrong identification method. There are many kinds of stainless steel screws, which can be divided into several categories according to the organizational structure at room temperature: 1. Austenite type: such as 304, 321, 316, 310, etc.; 2. Martensite or ferrite type: such as 430, 420, 410, etc.; Austenite type is non-magnetic or weakly magnetic, and martensite or ferrite is magnetic. Most of the stainless steel usually used for decorative tube sheets is austenitic 304 material, which is generally non-magnetic or weakly magnetic, but may also appear magnetic due to fluctuations in chemical composition or different processing conditions caused by smelting, but this cannot be considered as a Counterfeit or substandard, what is the reason for this? As mentioned above, austenite is non-magnetic or weakly magnetic, while martensite or ferrite is magnetic. Due to component segregation or improper heat treatment during smelting, a small amount of martensite or ferrite in austenitic 304 stainless steel will be caused. body tissue. In this way, 304 stainless steel will have weak magnetism. In addition, after cold working of 304 stainless steel, the structure will also be transformed into martensite. The greater the cold working deformation, the more martensite transformation, and the greater the magnetic properties of the steel. Like a batch of steel strips, Φ76 tubes are produced without obvious magnetic induction, and Φ9.5 tubes are produced. The magnetic induction is more obvious due to the large deformation of the bending and bending. The deformation of the square rectangular tube is larger than that of the round tube, especially the corner part, the deformation is more intense and the magnetic force is more obvious. In order to completely eliminate the magnetic properties of 304 steel caused by the above reasons, the stable austenite structure can be restored by high-temperature solution treatment, thereby eliminating the magnetic properties. In particular, the magnetic properties of 304 stainless steel caused by the above reasons are completely different from those of other materials such as 430 and carbon steel, which means that the magnetic properties of 304 steel always show weak magnetic properties. This tells us that if the stainless steel strip is weakly magnetic or completely non-magnetic, it should be judged as 304 or 316 material; if it is the same as carbon steel, it shows strong magnetism, because it is judged as not 304 material.
Most of the existing belts control the length of the belt by fixing the other end of the belt by the buckle, and the period that is often buckled by the buckle will be deformed and damaged after long-term use, and the user may change the position from standing to sitting or after meals. The circumference of the belt can be adjusted, and micro-adjustment is not necessarily possible when adjusting the tightness of the pin buckle type or buckle plate type belt buckle. In order to solve this problem, it is necessary to design a belt that is relatively suitable for the waist of a person.
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