Furan resin self-hardening sand is used for casting all kinds of metal castings, such as machine tools for machining, gas turbines for ship manufacturing and other cast iron parts can be produced by self-hardening resin sand process because of its compact and hard sand, easy to control and high accuracy of casting size. Today, is the rapid development of computer automation control to accelerate the development of self-hardening resin sand process applications. But furan resin sand has its own defects, can use time and starting time and final strength by the temperature and humidity changes, easy to cause the instability of the production, to bring adverse effects on the workshop production. sanzhuji according to the characteristics of furan resin sand (self-hardening sand) casting process and sand processing equipment, the study of low temperature environment furan resin and benzene sulfonic acid curing agent different ratios of hardening curve, determine The best ratio, and on this basis to explore the hardening trend of resin sand for wooden and metal molds, and summarize the method to accelerate the hardening of the starting mold, in order to guide the foundry enterprises for casting production.

Mainly based on the relationship between the usable time, mould starting time and strength of furan resin sand under low temperature environment, the following was derived from several casting experiments on resin sand moulding line.

1、The amount of curing agent added is controlled at 30%~50%, with the increase of curing agent, the strength of thermal regeneration sand gradually increases, reaching the maximum at 45%; the strength of mechanical regeneration sand gradually decreases, and the best curing agent is added at 30%.
1.1 curing agent added to control the amount of 30% to 50%, with the increase of curing agent, thermal regeneration sand and mechanical regeneration of sand available time are gradually reduced, the maximum available time curing agent added at 30%.
1.2 curing agent added to control the amount of 30% to 50%, with the increase of curing agent, thermal regeneration of sand and mechanical regeneration of sand starting time are gradually shortened, which curing agent added to 50% of the starting time is only 30% of the amount added 1/3 to 1/2.　　

2、the requirements of the model sand.
2.1 sand to maintain a certain final strength (small castings ≥ 2.0MPa, large castings ≥ 3.0MPa) to reduce the core deformation, to prevent sand trapping castings.
2.2 To ensure the necessary operable time for placing the core iron, cold iron and compacting operation.
2.3 To ensure smooth production on site, the core starting time should be as short as possible to improve production efficiency.
2.4 In the case of meeting the production requirements, the amount of binder added should be as low as possible to save costs and reduce the gas generated by the burning of organic binder during pouring, improve the quality of castings and protect the environment.

3、Comprehensive above factors, sanzhuji according to the self-hardening sand regeneration characteristics, through continuous sand mixer mixed regeneration sand best liquid material ratio of resin 1.0% (accounting for sand weight), curing agent 30% (accounting for resin); thermal regeneration sand best liquid material ratio of resin 1.0% (accounting for sand weight), curing agent 45% (accounting for resin). sanzhuji combined with the foundry according to the self-hardening sand casting workshop The use of wooden mold and metal mold starting time differences in casting based on the use of wooden core box and metal core box samples, every 1h measurement of compressive strength, record the first 6h strength change trend and 24h final strength, the same in 5 ℃ environment, resin, curing agent added to a certain ratio when.
3.1 wood mold molding starting time of about 2 ~ 3h can be cast from the mold to remove (1.5MPa), cast hardening to achieve sufficient strength, will not be deformed; metal mold need 5h to remove, too early to remove the internal not fully hardened, will produce extrusion deformation, the final strength is basically the same, in about 3MPa.
3.2 simply increase the curing agent acidity value can not significantly improve the speed of hardening and shorten the starting time of the mold.
According to this hardening trend, on-site production can be reasonably arranged according to different model starting time, to avoid starting too early in the core sand hardening strength is not enough to cause core deformation, cracking, too late to start the core strength, and mold bonding tight, difficult to start the mold, resulting in poor surface quality and delay on-site production.
　
4、in the low temperature environment, furan resin and benzene sulfonic acid curing agent for the binder modeling production, summarized the following conclusions.
4.1 mechanical regeneration sand best liquid material added to the resin 1.0% (accounting for sand weight), curing agent 30% (accounting for resin); thermal regeneration sand best liquid material added to the resin 1.0% (accounting for sand weight), curing agent 45% (accounting for resin).
4.2 The rest of the conditions remain unchanged, simply increasing the total acidity value of the curing agent does not significantly shorten the mold starting time. You can increase the temperature of the model, cold iron and tooling temperature to accelerate the internal reaction and accelerate the hardening.
4.3 When the conditions are the same, the wood mold compared to the metal mold starting time is significantly reduced, the former is 1/2 of the latter.

Qingdao Sanzhuji Equipment Manufacturing Co., Ltd. specializes in the production of sand reclamation equipment,foundry machines,Sand casting equipment,GS high efficiency rotary mixer,no-bake resin sand mixer,Jolt squeeze molding machine/Jolt-squeezing moulding machines,Multi- Piston Moulding Machine/Hydraulic multi-piston moulding machine,foundry molding machine,flaskless moulding machine,shot blasting machine,dust collector,according to the amount of old sand recovered Carry out plan customization, and provide sand reclamation equipment installation, commissioning, and training. Welcome guests to visit the factory.