01
Application of coated sand
description2
Iron mold sand molding process
1.1 Preparation of raw materials
The sand should be of moderate strength, fine grain size and low outgassing.
1.2 Preparation before molding
①Check whether the work equipment is intact, whether the work station apparatus is complete, and placed in the designated position;
②Check whether the traveling crane, sand bucket, etc. are in normal use;
③Check whether the materials such as sand, mold release agent, etc. are available and placed in the designated position;
④Turn on the gas source, water source, and check whether the various actions of the molding machine are normal;
⑤Check whether the sand injection plate of the core box is mounted in place and intact;
⑥Check whether the heating pipe is firm and not loosened; ⑦ Regularly check the box pin, positioning pin (set) whether deformation, wear, etc., can not be used in a timely manner to replace.
1.3 Modeling
1.3.1 Requirements for the use of coated sand
In order to prevent the sand shot hole is not smooth or affect the strength of sand molding, all the recycled sand must be strictly sifted with fine mesh.
1.3.2 Requirements for selecting parameters of sand shooting process
Generally speaking, the actual heating temperature is 220~280℃, curing time is 60~300s, and the pressure of sand injection is 0.2~0.6MPa. The specific parameters should be adjusted by the operator according to different situations. The thickness of sand layer is 5~10 mm.
1.3.3 Operation requirements
① sand injection box before the sand injection hole should be kept open, the plate should be blown clean;
② mold release agent should be sprayed uniformly, and as long as the mold can be normal, the number of times you should try to reduce the spray release agent. Generally 8 to 10 times per modeling spray is appropriate;
③ strictly in accordance with the equipment operating procedures for operation.
1.4 Lower core
① not to use the bad type;
② before the core must carefully check the quality of the core, deformation, insufficient baking or serious damage shall not be Use:
③ under the core to be stuck tight, flat, under the right, under the whole, under the end;
④ sand box off the set of change direction without core.
1.5 Close the box
① operator in the box before the box must again check the box pin and sand box with the situation, inappropriate to be replaced in a timely manner;
② sand box parting surface excess sand must be shoveled and blown clean;
③ on the box should be lifted flat, box should be balanced;
④ to move a good box of sand must be carried out with the pin.
1.6 Coupling pair
In order to ensure accuracy, easy to find problems, the requirements of the upper and lower sand box box pin set coupling and pairing, must be strictly enforced.
1.7 End of work
① shut down the gas source, power supply, clean up the model, blowing clean molding machine table;
② timely recovery of scattered sand, to ensure that the ground is clean and smooth.
Hot core box core making process
Raw material preparation
2.1
According to the complexity of the sand core to choose different types of coated sand. For multi-cylinder cylinder head core and cylinder water jacket core should be selected for high strength, coarse particle size, low gas generation coated sand, for 2 cylinder cylinder head core should be selected for lower strength, moderate particle size, low gas generation coated sand.
2.2 Preparation before core making
① check whether the core tool is complete, and placed in the designated location;
② check the traveling crane, hanging sand bucket is normal;
③ check the film sand, molding agent, core repair paste and other materials, to ensure that all ready and placed in the designated location:
④ check the operating platform, the core box is neat and tidy and stored neatly;
⑤ open the gas source, water, check whether each action of the core machine is normal;
⑥ check the core box shot sand plate is installed in place intact (focus on checking the shot sand mouth sealing rubber pad sealing sand is good, the core box track positioning pin wear and tear in the cold state of opening and closing is smooth);
⑦ check the heating tube, temperature measurement head is firm and no loose;
⑧ the last power heating to the temperature control meter adjusted temperature, pay attention to the process of heating should be checked at any time to see whether the temperature rise is normal, the temperature control meter display Whether normal;
⑨ check the hot state of the core box open and close smoothly, found that there are abnormalities, should be adjusted in a timely manner.
2.3 Core shooting operation
2.3.1 Requirements for the use of coated sand
① In order to prevent the shooting of sand holes or affect the strength of the sand core, all the recycled sand must be strictly sifted with a fine mesh.
② Shooting system multi-cylinder cylinder head body core and cylinder water jacket core should use high strength coated sand, shooting the rest of the sand core always use general coated sand or recycled sand.
2.3.2 Core shooting process parameters selection requirements
Generally speaking, the actual heating temperature is 220~280℃, curing time is 60~300s, and the injection pressure is 0.3~0.6MPa. The specific parameters should be adjusted by the operator according to different situations, and the principle is that: for the core with simple shape and good filling, the coarser size of the coated sand should be chosen to have smaller injection pressure (not the higher the better, but the higher the pressure is, the higher the pressure, which may sometimes cause local over-voiding): for thin sand core, choose the lower injection pressure, and the lower injection pressure should be chosen. Thin sand core selection of lower heating temperature, or low heating temperature can be appropriate to extend the curing time, and so on, and vice versa.
2.3.3 Operation requirements
① In order to bake through, should master the appropriate production beat, to do in each cycle, according to the average time to determine the beat or observe the curing color to determine the beat. The normal situation is: the appearance of the sand core should be a uniform yellow-brown, yellow in the center; overcooked appearance is brown or even black; hardening is not enough appearance of yellow, white in the center. As the initial temperature of the curing reaction of the sand curing reaction is relatively high, its softening point is higher than 90 ℃, so the use of residual heat to continue to harden the effect is not significant. In order to make the center fully hardened, it is advisable to exhaust the gas production during the polymerization reaction as much as possible.
To fully harden the center, it is desirable to exhaust the gas production during the polymerization reaction as much as possible, and reduce the amount of sand core gassing when the casting solidifies. The main cylinder head core should make the surface was dark yellowish brown, finger scratching the surface is not easy to shed grains of sand is appropriate: for the intake and exhaust channel core, valve top rod core and other auxiliary core should be darker than the main core color.
② as long as the core can be normal, should minimize the number of times the spray parting agent. Generally 8 to 10 sets of cores out of each set of spray is appropriate.
③When taking the core, use the special clamp to hold it gently. Therefore, the residual stress inside the core is not uniformly distributed and it is easier to break.
2.4 Sand core trimming
To trim the burrs, phi seams and sand shooting rods with the type, the part which is not solid or lacks flesh due to sand shooting should be trimmed with putty and then brush the paint.
2.5 End of core shooting
①Shut off the gas source, power supply, clean up the core box, blow clean core shooting machine table. Cooling water will be turned off to maintain a small flow of about 1L/min without stopping the flow, the estimated temperature is lower than 100 ~ 150 ℃ and then turn off the water supply. Recover the scattered sand in time, and make sure the ground is clean and smooth.
2.6 Second baking of sand core
The cylinder head body core and airway core must be boxed and sent to the electric kiln for secondary baking, and keep warm for 1~1.5 h within the temperature range of 200~220 ℃.
3 Conclusion
As the level of science and technology continues to improve, high strength, low gassing and other high-quality performance coated sand continues to appear, making the application of coated sand will be more extensive.