Lost mold casting position, pay special attention to 7 key points!
Release time: 2019-05-24 Source:Luoyang Shun Xiang Machinery Co., Ltd. Visits: 409
The development speed of epc in China is ***, because of its many advantages, many factories are using epc technology.
However, because many small and medium-sized private enterprises have not systematically studied the professional knowledge of epc casting, most of the designed casting systems are not perfect, which leads to the inherent defects of casting products, the inability to meet the quality requirements of customers, or the failure to complete orders on time.
Casting products of qualified quality can only be produced with reasonable casting position. Here are 7 key points to pay special attention to.
No. 1
Machining surface
place the working surface, especially the important working surface, face down or vertically. This is the same as in sand casting, because under the action of the static pressure of the metal, the bottom of the casting is easily fed and compacted during solidification. This is especially true for epc casting, because epc is easy to float to the upper surface of the casting when it meets the molten slag generated by the high-temperature metal liquid, and the machining surface can be guaranteed. Ideally, of course, the slag should float up into the riser.
No. 2
Large plane
Second, the shape of the large plane should be placed vertically or tilted. Production practice shows that the inclusion defects formed by pores, pyrolysis and gasification residues mostly appear on the surface facing up, while the surface facing down or the side elevation is usually relatively bright and clean, and the possibility of defects is small. For the epc, such placement can avoid deformation of large plane when filling sand and avoid simultaneous decomposition and gasification in a large area after epc meets high-temperature metal liquid, which can inhibit the gasification speed, reduce the gap between air gap and metal liquid surface, effectively avoid collapse of box and ensure smooth pouring.
No. 3 Open part Third, try to put the open parts (such as Windows, grooves and holes, etc.) on the vanishing mold upward, so as to facilitate sand filling and modeling and ensure compactness. In order to ensure the casting profile and clear edges, the designed straight runner should have the necessary filling pressure head, which is 160 ~ 210mm higher than the upper level of the casting, and has enough rising speed to avoid the defects of the casting, such as wrinkle, cold insulation and slag scar. No. 4 At the bottom of the Fourth, epc usually adopt bottom note type (including side lower part, rain drench type, etc.) pouring system, due to the airtight mold, pouring shape, by the high temperature pyrolysis product of liquid metal and gas gap mainly from sand and gaps between mold and casting out, vertical or inclined to gas and impurities was laid out, avoid sand inclusion scar flaw. In addition, it is necessary to facilitate the opening of exhaust unimpeded, slag removal and pouring riser system. No. 5 Sand box inside Fifth, we should consider the placement of the shape in the sand box, the shape in the sand box position should be conducive to dry sand filling, as far as possible to avoid horizontal or downward non-porous, to ensure that molding sand easy to fill and compact. Prevent molding sand filling or vibration is not tight produce dead Angle, avoid pouring after the formation of swelling sand or nodule defects. The designed pouring system should be reasonable flow direction of metal liquid, short flow, few curves, small resistance, to ensure that the set pouring time can be fully filled with the cavity. In order to have a good slag resistance, slag collection bag and filter net can be considered. This control can only be achieved through field test and verification. The pouring position should be favorable to the arrangement of multi-layer casting shells, and it is convenient to support in real time when filling dry sand, so as to prevent deformation in some parts where it is difficult to reinforce. No. 6 The amount of liquid metal Sixth, the design of the pouring system to smooth the flow of metal liquid, avoid serious turbulence, involved in gas, and high temperature metal liquid excessive oxidation. The linear velocity should not be too high when the liquid metal liquid enters the casting mold. Keep 2/3 of the spout cup filled with liquid metal. No. 7 Principle of alloy solidification Seventh, the principle of alloy solidification must be followed. For epc gray cast iron, usually as far as possible, based on the principles of "sequential solidification" to consider, in addition to wall thickness uniformity of the casting, based on the principles of solidification at the same time to consider, the identified within the sprue position, direction and the number should be in accordance with the principle of "order" of the casting solidification, the thick parts adopt to speed up the cooling, can make its solidification at the same time, try to make rapid and smooth filling, effective feeding. The principle of vanishing mold solidification is to make the cross-section area of the pattern increase gradually from bottom to top, which is beneficial to exhaust and scum, to feed, to eliminate the defects of porosity and shrinkage, and to obtain the excellent casting with dense structure.
