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The positioning accuracy of NC machine tool refers to the position accuracy that can be achieved by the movement of each coordinate axis of the machine tool under the control of NC device. The positioning accuracy of NC machine tool can be understood as the motion accuracy of machine tool. Ordinary machine tools are fed manually, and the positioning accuracy mainly depends on the reading error, while the movement of NC machine tools is realized by digital program instructions, so the positioning accuracy depends on the NC system and mechanical transmission error. The movement of the moving parts of the…

The steel grade consists of numbers, letters and numbers. The letter symbols of non oriented and oriented silicon steel are "W" and "Q" respectively The thickness is placed in the front, the letter symbol is placed in the middle, and the iron loss value is placed in the back, such as 30q113. In oriented silicon steel, the letter symbols "g" and "Q" with high magnetic induction are placed together, such as 30qg113 The number after the letter represents 100 times the iron loss value (w / kg). The letter "g" indicates that it is tested at high frequency; If "g"…

Welding steel includes carbon steel for welding, alloy steel for welding and stainless steel for welding. Its brand is represented by adding the symbol "H" to the head of various welding steel brands. For example: "H08", "h08mn2si", "h1cr18ni9" For high-grade and high-quality welding steel, the symbol "a" is added at the end of the brand. For example: "H08A", "08mn2sia".

Bearing steel is divided into four categories: high carbon chromium bearing steel, carburized bearing steel, high carbon chromium stainless bearing steel and high temperature bearing steel. ① For high carbon chromium bearing steel, the symbol "g" is added at the head of the brand, but the carbon content is not indicated. The chromium content is expressed in thousands, and other alloy elements are expressed according to the alloy content of alloy structural steel. For example, the grade of bearing steel with an average chromium content of 1.50% is expressed as "GCr15". ② Carburized bearing steel adopts the brand representation method…

1. Allowable burr height of punching parts (1) limit value of burr of blanking parts It is not allowed that the burr of blanking parts exceeds a certain height. The limit value of burr height of stamping parts (mm) is shown in the table below.  (2) marking requirements for burrs in design drawings *Burr direction: burr side. *Parts requiring burring: coin or coin continue. Generally, do not press all the burrs on the fracture of the whole structural member, which will increase the cost. Try to use it in the following situations: the fracture exposed to the outside; Sharp edges…

Except that the symbol "SM" is added at the head, the representation method of plastic mold steel is the same as that of high-quality carbon structural steel and alloy tool steel. For example, the grade of carbon plastic die steel with an average carbon content of 0.45% is expressed as "sm45"; Alloy plastic die steel with average carbon content of 0.34%, chromium content of 1.70% and molybdenum content of 0.42% is indicated as "sm3cr2mo".

For non quenched and tempered mechanical structural steel, the symbols "YF" and "F" are respectively added at the head of the brand to represent free cutting non quenched and tempered mechanical structural steel and non quenched and tempered mechanical structural steel for hot forging. Other contents of the brand representation method are the same as those of alloy structural steel. For example: "yf35v", "f45v". Tool steel is divided into carbon tool steel, alloy tool steel and high-speed tool steel. ① Carbon tool steel is represented by standard chemical element symbols, symbols specified in Table 1 and Arabic numerals. Arabic numerals…

Free cutting steel is represented by standard chemical element symbols, symbols specified in Table 1 and Arabic numerals. Arabic numerals indicate the average carbon content (in tens of thousands). ① For sulfur free cutting steel and sulfur and phosphorus free cutting steel, the free cutting element symbol is not added after the symbol "Y" and Arabic numerals. For example, the grade of free cutting steel with an average carbon content of 0.15% is expressed as "Y15" ② For sulfur or sulfur and phosphorus free cutting steel with high manganese content, manganese element symbol shall be added after the symbol "Y"…

The grades of stainless steel and heat-resistant steel are indicated by alloy element symbols and Arabic numerals specified in the standard. For cutting stainless steel and free cutting heat-resistant steel, add "Y" at the head of the grade. Generally, one Arabic numeral is used to represent the average carbon content (in thousands); When the average carbon content is ≥ 1.00%, it is represented by two Arabic numerals; When the upper limit of carbon content is less than 0.10%, the carbon content is represented by "0"; When the upper limit of carbon content is ≤ 0.03% and > 0.01% (ultra-low carbon),…

① The grades of alloy structural steel are indicated by Arabic numerals and standard chemical element symbols. Use two Arabic numerals to represent the average carbon content (in tens of thousands) and put it at the head of the brand. The expression method of alloy element content is: when the average content is less than 1.50%, only elements are indicated in the brand, and generally the content is not indicated; When the average alloy content is 1.50% ～ 2.49%, 2.50% ～ 3.49%, 3.50% ～ 4.49%, 4.50% ～ 5.49%,... Write 2, 3, 4, 5... After the alloy element. For example, when…