Causes And Solutions Of Surface Sandhes On Auto Casting Part

Causes and Solutions of Surface Sandhes on Auto Casting Part
Usually in the Auto Casting Part surface sticky with a layer of sand is difficult to remove, known as sticky sand. Sticky sand is divided into mechanical sticky sand and chemical sticky sand: mechanical sticky sand is part or the whole surface of Auto Casting Part, adhere to a layer of sand and metal mechanical mixture, clear shovel sand layer can see the metal luster; Chemical sticky sand is part of the Auto Casting Part or the entire surface of a layer of metal oxide adhesion, sand and clay interaction and the formation of low melting compounds, high hardness, only with a grinding wheel to wear.
1, sticky sand causes:
In the metal liquid and the wall between the surface of the role of thermal or thermal chemical reaction will form sticky sand. After physical or thermochemical effects, will cause the Auto Casting Part part of the surface or the entire surface to produce varying degrees of sticky sand. Auto Casting Part is a long time, Auto Casting Part thick wall or hot section, poor heat dissipation conditions (concave angle, elongated hole, narrow groove, etc.), metal liquid static pressure, high pouring temperature, The more coarse, it is easy to stick sand.
2, to solve the sticky sand method:
(1) Auto Casting Part wall thickness to be uniform, appropriate to increase the fillet radius, try to reduce the hot ring, the use of cold iron.
(2) According to the thickness of Auto Casting Part and the pouring temperature of molten metal, the proper selection of the original sand grain size, surface sand and binder is higher and the refractoriness is higher, the sand compactness should be uniform, the refractory degree of the coating layer is higher, the thermochemical stability Sex is good, sand to dry.
(3) to improve the quality of metal, appropriate to reduce the casting temperature, casting speed.
The deformation of the Auto Casting Part is a defect caused by the casting stress. The thermal stress is the main cause of the deformation of the Auto Casting Part. The Auto Casting Part structure is unevenly uneven, and the cooling shrinkage of each part is inconsistent and the cooling is slower And the inner layer) has a residual tensile stress; the faster cooling (thin wall and outer layer) has a residual compressive stress in the stress state of the Auto Casting Part, trying to change from this unstable state to a steady state, can be spontaneously deformed Reduce internal stress.
Auto Casting Part Reason:
1.Auto Casting Part structure design is irrational, uneven wall thickness.
2. Improper cooling, uneven shrinkage.
When the Auto Casting Part is cooled to 250-450t in the sand, remove the pins, bolts, box, iron and plucking of the tightening box. Small Auto Casting Part with artificial lift on the type; large and medium-sized Auto Casting Part with a crane to mention the type. Move the upper side to the side to remove the sand inside the upper type, and then empty the empty box on the open space. When the Auto Casting Part is exposed to the lower form, the steel block is used to remove the large sand block from the Auto Casting Part, and the Auto Casting Part falls. Pound the sand in the sand, the sand box will be stacked. At this point, hand the end of sand.
The first to remove the positioning device or fastening the mold of the device, the sand hanging to the sand on the vibrating grid, open the upper type, boot on the sand and Auto Casting Part for severe vibration, sand, and then the sand Box and Auto Casting Part were suspended from the sand machine, and then further clean up the Auto Casting Part.
Some of the data, the results of long-term measurement of the investment and Auto Casting Part size show that in the length of the Auto Casting Part, for the length of 25mm, the offset deviation accounts for more than 50% of the total deviation of the Auto Casting Part; when the Auto Casting Part size When the increase, the impact of the investment is relatively reduced, for a long 250mm, the total deviation of the total deviation of about 40% of the total deviation. The size of the die is mainly caused by the instability of the molding process, such as the size of the force, pressure, pressure, pressure, pressure, Fusion size deviation. As a result, the die size accuracy has a significant effect on Auto Casting Part accuracy.