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The most basic and practical general knowledge of machining

61 how does steel heating affect steel bending

answer: after heating, the bending force required by the steel is reduced, the springback phenomenon disappears, and the minimum bending radius is reduced, which is conducive to controlling the deformation according to the processing requirements

62: under what circumstances is heating bending usually used

answer: it can be used at normal temperature

63: why should the heating temperature of steel be limited to a certain temperature

answer: too high temperature is easy to cause steel overburning, and too low temperature will make forming difficult and cause cold work hardening

64: when using contact bending, what measures are often taken to solve the springback problem

answer: modify the mold shape, adopt the pressure correction method, increase the blank holder, and reduce the mold gap

65: what is bending

answer: the processing method of bending and forming with a bending die on the press

66: how many forms of bending deformation of materials

answer: free bending, contact bending and correction bending

67: why is the die used by riveters usually of welded structure

answer: This is not only convenient for manufacturing, but also can shorten the molding cycle, improve the utilization rate of materials and reduce costs

68: what is roll bending

answer: the processing method of bending and forming on the roller bed

69: what measures are often taken to eliminate the straight edge of the workpiece when using the symmetrical three roll bending machine

answer: bend both ends and leave machining allowance

70: what are the two types of calendering? What kind do riveters usually use

answer: it can be divided into constant thin calendering and 4. It can realize the rapid rise and fall of the beam during sample clamping, adjust and thin calendering. Riveters often use constant thin calendering

71: what measures should be taken when rolling conical surfaces

answer: adjust the position of the upper roll to make it tilt at a certain angle with the lower roll; Make the feed speed of small mouth larger than that of large mouth

72: how to roll large workpieces

answer: in order to avoid additional deformation caused by its own weight, the sheet should be divided into three areas, rolling the two sides first, and then the middle. If necessary, the crane should cooperate

73: any rolling of non cylindrical workpiece

answer: areas should be divided on the sheet according to its different radius of curvature, and the distance between the rollers should be adjusted for rolling

74: what are the preparations before workpiece rolling

answer: the shaft roll and sheet metal plane should be cleaned, and burrs should be removed to avoid bumping the workpiece and shaft roll

75: what is calendering

answer: the pressing process of forming an open hollow part through a female die under the pressure of a punch

76: what is line heating bending? Answer: the steel plate is locally heated and shrunk by oxyacetylene flame to form

77: what are the uses of line heating bending

answer: line heating bending is only applicable to the forming of parts with small curvature, and it is more combined with rolling to process parts with complex shapes with double bending

78: what are the methods of line heating bending

answer: there are strip heating and dot heating

79: what are the processes of line heating bending

large: there are choices of baking nozzle, heating temperature and heating speed, and cooling mode

80: how many cooling methods are there for line heating bending

answer: there are two kinds of air cooling and water cooling, and water cooling can be divided into front and back water cooling

82: what is air cooling

answer: after the flame is locally heated, the workpiece will be naturally cooled in the air

83: what is water cooling

answer: use water to forcibly cool the heated part of the metal, so that it can be cooled quickly, reduce the heat transfer to the back, expand the temperature difference between the front and back, and improve the molding effect

84: what are the characteristics of explosive forming

answer: it can simplify the mold structure; It can process hollow parts with complex shape and difficult to be processed by rigid die; Small springback, high precision and good quality; Fast processing and forming speed; Stamping equipment is not required

85: what is corner joint

answer: when the two plates are connected at an angle perpendicular to each other, angle steel is used as the connector at the joint to rivet the workpiece together

86: what are the main parameters of rivet arrangement

answer: there are rivet spacing, row spacing and edge spacing

87: what is rivet pitch

answer: the distance between the centers of two adjacent rivets in a row

88: what is row spacing? Answer: it refers to the distance between the centers of two adjacent rows of rivet holes

89: what is margin

answer: it refers to the distance from the center of the outer row of rivets to the edge of the workpiece plate

is a good high-temperature resistant and high-strength class C electrical insulating material 90: what is the relationship between the thickness of the component plate and the diameter of the rivet? Answer: when single row and double row are overlapped and connected, the rivet diameter is twice the thickness; When the single row and double row double cover companies connect the comprehensively recycled road slabs, the rivet diameter is taken as 1.5~1.75 plate thickness. 91: what are the principles for determining the plate thickness

answer: when lapping, it is determined by the thickness of thicker plate; When riveting materials with large thickness difference, the thinner sheet shall be used; When riveting steel plate and profile, take the average thickness of both; The total thickness connected shall not exceed 5 times the rivet diameter

92: what is the relationship between rivet length and riveting quality

large: if the rivet is too long, the rivet pier head is too large, and the nail rod is easy to bend; If the rivet is too short, the thickness of the pier is insufficient, and the forming of the rivet head is incomplete, which affects the riveting strength and tightness

93: how to determine the rivet hole diameter during cold riveting

answer: during cold riveting, the nail rod is not easy to be thick. In order to ensure the connection strength, the diameter of the nail hole should be close to the diameter of the nail rod

94: when hot riveting, is there any determination of rivet hole diameter

answer: during hot riveting, due to thermal expansion, the diameter of the nail hole should be slightly larger than the diameter of the nail rod in order to facilitate perforation

95: what are the parts of rivets

answer: by handle, gun body, switch and pipe connector

96: what are the characteristics of rivet gun

answer: it is small in size and easy to operate. It can rivet at various positions with China's non-ferrous metal import and export of 145 million tons in 2015

97: what are the two ways of riveting

answer: it can be divided into cold riveting and hot riveting

98: what is cold riveting

answer: riveting at room temperature

99: what is the final riveting temperature of riveting

answer: between 450~600 degrees Celsius

100: what is the effect of final riveting temperature on riveting

answer: too high will reduce the initial stress of the nail rod; If it is too low, the rivet will be blue brittle

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