SU1210954A1 - Method of producing moulds and cores - Google Patents

Description

The invention relates to foundry and can be used in the manufacture of molds and cores from liquid, plastic and bulk self-hardening mixtures based on a liquid binder.

The aim of the invention is to increase the strength of the forms and rods and reduce their fallability.

The essence of the invention is that when filling with a mixture of flasks or core boxes, a proportional amount of liquid or powdered sealer is fed to its stream. Ferrochrome slag, mercury phosphate and phosphoric acid with a density of 1.6 g / cm are used as hardeners,

The introduction of the hardener into the mixture at the moment it fills the flask or the core box ensures, on the one hand, the proportional distribution of the hardener by the volume of the mixture and the form, on the other hand, the flow of the initial stage of physicochemical interaction of the binder material with the hardener directly in the form. From the known methods in the present invention, the complete flow in the form of the first adsorption and second, coagulation stages of strengthening, which are the most effective in strengthening the forms and rods, is ensured. Therefore, during the hardening process, the number of structural bonds in the mixture increases, which leads to an increase in the service (i.e., after hardening) strength of the forms and rods. This makes it possible to reduce the relative content of the binder material, reducing the long hardening process. At the same time, it is possible to use for controlling the forms of highly active hardeners such as aluminum phosphate or orthophosphoric acid, which additionally shorten the process of strengthening the forms, increase their strength with relatively low binder content and thereby improve the embossing of the mixtures from castings.

This is due to the fact that the act: an explicit physicochemical interaction of a highly active hardener with Lodka glass occurs directly in the form with a stationary state of the sheath of components, when the resulting structural bonds are retained without

109542

destruction and predetermine the formation of high strength forms and rods.

The method is carried out with use; Research institutes of both liquid and plastic self-hardening mixtures are in this order.

In the first embodiment of the method, a mixture of all the necessary components is prepared first, for example, from a refractory filler, a binder material of nonstick and technological additives, but without a hardener. Such a mixture possesses a high living honor and does not change its initial properties for a long time. When filled with a mixture of flask or core box, its flow is supplied by any known method, for example, transport 2 (by ter, star feeder or spray, a stream of powder or liquid hardener. At the same time, the uniformity of hardener distribution by volume of the mixture ensures

2J its proportional flow

with respect to the flow rate of the mixture when filling the flask or core box.

The selection of the cost ratio is carried out empirically, based on the type of utilized expendable devices. So, when using a powdered hardener, two metering conveyors can be used, one of which, designed for the hardener, is positioned above the conveyor for the mixture. At the same time, the flow of hardener from it gets into the flask with the mixture flow. It moves at a slower speed than the conveyor. for the mixture, and provides a proportional flow of hardener to the mixture flow that is loaded into the flask. When this weight ratio of the mixture and the hardener is maintained in the ratios given by this invention, the ice hardener is supplied, for example, from a spray bottle to the feed mixture flowing into the flask, the flow ratio of which is supported;

50

In the second variant of the method, the mixture is prepared from all the necessary components, for example sand, liquid clay glass, ferrochromic slag 55 for SRS and for ZhSS. When filling the flask of one of these mixtures, highly active powdered or

40

3

liquid hardener, such as aluminum phosphate or phosphoric acid.

According to the TpeTbeNry variant, the mixture is first prepared without a hardener; when the flask is filled with the mixture, ferrochrome slag is proportionally fed into it with the addition of 0.2-1.5 wt.% Powdered aluminum phosphate.

In the fourth variant, a mixture is first prepared from all components, for example, from sand, liquid glass DS-RAS, ferrochromic slag. When filling the flask with the mixture, 0.2-2.0 wt.% Solution of phosphoric acid (in terms of a density of 1.6 g / cm) is proportionally fed into it.

Testing methods were carried out in the manufacture of molds from liquid and plastic self-hardening mixtures with soda liquid glass having a modulus of 2.8 units. and a density of 1.48-1.52 g / cm3.

The mixtures were prepared in a 1A11 brand-type mixer. Feed the mixture from the mixer to the conveyor to feed it into the flask. At the end of the conveyor, there was a star-shaped dispenser, which was used for feeding. In the flask of the sump, along with the mixture flow. In another embodiment, a liquid hardener was fed to the discharge conveyor from the conveyor stream of the mixture from the spray. After filling the plastic mixtures, the flasks were compacted on a shaking molding machine, and the flasks filled with the liquid mixture were kept for 1-1.5 hours in air for strengthening. From the strengthened forms, the models were removed and, after holding for 0.5 h, they were assembled and filled with metal according to serial technology. In the same order, we prepare rods from plastic and liquid self-hardening mixtures. In the course of making molds and cores, portions of the mixtures were taken to determine strength and flaking.

Strength was determined by the standard method. Moreover, the strength before strengthening was determined by compressing cylinder samples, and after hardening, by stretching eight figures. As a highly active powdered hardener, aluminum phosphate was tested, as a highly active liquid hardener, thermal orthophosphoric acid in the form of an aqueous solution with a density of 1.6 g / cm. When tested, we first believed the effect of the proposed method.

109544

on the strength of forms with the use of widely used powdered hardener - ferrochrome slag in the amount of 2.0-5.0 wt.%, and then 5 highly active powdered aluminum phosphorus in the amount of 0.2-1.5 wt.% by weight of the mixture.

Compare the proposed method with the known auth. No. 514657 is not possible because in a known manner

it is impossible to introduce powdered material into the mixture after zaskki it into the flask through the injector in the model. Phosphoric acid was tested in the amount of

15 0.2 to 2.5 wt.% By weight of the mixture.

Tables 1 and 2 show the comparative results of testing on plastic mixtures.

As can be seen from Tables 1 and 2, the strength of the mixtures with the manufactured ™ forms offered by cnoco6oti after 1 and 3 hours is greater in all cases than with the use of known methods, and crumbling is 5-6 times smaller, respectively. 25 the difference in the absorption of the additive highly active hardener - aluminum. If during the application of a known method with an increase in the phosphate content of 3Q and that the aluminum strength after loops 1 and 3 hours decreases, the strength increases and the crumbiness decreases in cases where the proposed method is applied. In this case, the dependence is established: the higher the strength of the mixture after compaction to a certain limit (up to 1 wt.%), The lower it is after being held in air (i.e. after performing the hardening process) and, conversely, the lower immediately after compaction, the higher after exposure. This is due to the fact that the more liquid glass is consumed for coagulation interaction with the hardener before compaction (for example, during the mixing process in a known method), the less it remains for the formation of structural-strengthening bonds. strengthened to the endurance and the less it becomes official

 (i.e. for resisting metal) durability of molds and rods. As can be seen from Tables 1 and 2, the proposed method provides a lower initial strength.

55 (which is useful for the process of filling the flask and compacting the mixture) and higher service strength. At the same time, a noticeable effect on

40

45

S1

The effectiveness of the forms of the proposed method is manifested when the aluminum phosphate content is 0.2 us, 7- ,. Therefore, for the lower limit, the content of highly active powdered hardener equal to O ,, 2 wt.% Is accepted. When the content of aluminum phosphate in mixtures is more than 1.5 wt.% (For example, 2 wt.%), A decrease in strength and an increase in osterability are observed. Therefore, the upper limit of the content of aluminum phosphate in mixtures is 1.5 wt.%.

The results of testing the proposed method when using a liquid hardener are presented in Tables 3 and 4.

As can be seen from Tables 3 and 4, the fabrication of the samples by the proposed method with ferrochrome slag, as compared with the known, allows to increase the strength by almost 2 times and more than 2 times to reduce crumbling. When using a highly active liquid hardener (orthophosphoric acid), it was not possible to obtain sufficient strength in a known manner, whereas the proposed method allows one to achieve sufficiently high strengths and more so than the content of the liquid hardener. At the same time, it has been established that the hardener additives already have an appreciable effect on the strength of about 0.2 wt. Therefore, 0.2 wt.% Is assumed to be the lower limit of the liquid hardener additives. With increasing content of orthophosphoric acid, strength increases continuously. However, an excessive increase in acid increases the cost of the mixture. Therefore, the upper limit of acid addition is 2.0 wt.%. It has also been established that by reducing the content of liquid glass in mixtures, the proposed method provides for obtaining forms with strength at a level higher than the strength of forms obtained by known methods on mixtures with a higher content of liquid glass.

Thus, the proposed method allows either to increase the strength properties of the molds or to keep them at the level specified by the technical conditions with a reduced content of liquid glass. Reducing the content of liquid glass saves the binder, and its low content in blends provides improved embossability of the molds and cores of castings.

9546

The proposed method, in comparison with the known ones, makes it possible to use in the manufacture of molds powdered and liquid hardeners that are characterized by high activity, which allow to shorten the duration of strengthening of the molds and cores and increase their strength and properties.

Example 1. According to the invention, a mold was made for casting a drum weighing 60 kg. In a 1A12 roller mixer, a mixture was made from sand K0315 with 7 wt.% Liquid glass and 5 wt.% Refractory clay (experiment 1,

j table 1). This mixture from the mixer was conveyed to the flask mounted on the shaking table of the molding machine. At the moment of dropping the mixture from the conveyor onto its current, the ferrochromic slag was fed from the star feeder. Slag consumption was selected according to the mixture consumption at the rate of 5 wt.%. After filling the flask with the mixture, the mixture was shaken.

5 for 10 s. Then removed the model from the form. The mold was kept in air for 1 hour, collected and volley carbon steel. Casting is suitable.

Example 2, the proposed method produced the form of a casting drum In the roller mixer prepared mixture (experiment 2, table 1), containing sand, water glass, clay and ferrochrome ijonax. The mixture was fed through a conveyor to the flask. At the moment of dropping the mixture into the flask, powdered aluminum phosphate was fed into the flask from the star feeder at the rate of 0.2 wt.% To the mixture. Further processing carried out as in example 1.

Example 3. First, prepare the mixture without hardener. When the drum was cast with a mixture of castings, ferrochromic slag with the addition of aluminum phosphate was fed into the flow of the mixture at the rate of 1 wt.%. The remaining operations were performed as in examples 1.

Example 4. First, a mixture of H was prepared (CC in a C-946 continuous mixer with a capacity of 8. The mixture was prepared from components: sand, liquid glass, and ferrochrome slag.

 When dropping the mixture in the flask, an aqueous solution of orthophosphoric acid was supplied to the stream from the spray gun (test 4, Table 3). Further processing0

five

0

five

71210954. 8

The implementation of the invention will allow him to increase the strength of the rods and shapes,

reduce their shedding. Besides,

The proposed method is used to reduce the consumption of liquid glass, make molds and rods shorten the duration of the hardening of self-hardening plastic molds, and reduce the labor intensity of the mixture on knocking out rods and cleaning the casting.

Sand K031583

Liquid glass module 2.8 density 1.48

Ferroshlak5

Clay5

Aluminum phosphate Strength, kgf / cm

after compaction of the form (compression) 0.26 0.22 0.38 0.25 0.42 0.27 0.38 0.28 0.32 0.32 0.21 0.52

after holding for 1 hour (stretch) 0.62 0.97 0.60 0.99 0.56 1.12 0.48 1.18 0.42 1.26 0.12 1.02

after holding for 3 hours (stretching) 0.71 1.250.62 1.32 0.46 1.44 0.42 1.96 0.38 2.15 0.01 1.01

Sapability

after 3 h,% 7.6 1.3 7.9 1.1 8.6 1.1 9.3 0.9 1.2 0.7 0.7 60 1.2

 Note: 1-way according to auth. No. 566672} 2 - proposed

way to.

Table 1

84.8 84.5 84 83.5 83

7 5 5 0.5

7 5

5 1.5

7 5 5 2.0

table 2

87.8 90.7 90.3 89.889.3

7777 7

Blend properties

1 T2 Tz L I j 2 M T 2 I 1 2 Tl j 2 I 1 2

Strength, kgf / cm

in 1 hour (to be stretched) 0.7 1.2 0.120.280.240.360.350.92 0.281.36 0.20 1.61 0.21 1.71

after 3 h

(extension) 1.3 2.1 0.220.550.310.940.451.36-0.22 1.73 0.21 2.19 0.20 1.25

Sapibility through

3 h, Z 2.1 0.7 12.70 3.708.103.558.702.31 12.00 2; 3028.00 1.25 31.00 1.21

Note 1 - method according to the author.№ 566672; 2 - proposed; 3- way by

Aug.St. 514657 (it was not possible to manufacture the samples, since the impregnation of the mold only extended by acid to 5-6 mm}.

88,888.3

Table 4

Indicators by the way

Claims (4)

1. METHOD FOR PRODUCING CASTING FORMS AND RODS from plastic and liquid self-hardening mixtures, including preparing the mixture on a liquid-glass binder, filling it with a rod or molding tool, sealing the mixture, removing the model from a molding or bar tool, characterized in that, in order to increase the strength and rods and reduce their crumbling, when filling the mixture into the equipment, a liquid or powder hardener of a liquid-glass binder is fed into its stream in an amount of 0.2-6.5 wt.% by weight of the mixture. 2. The method according to claim 1, characterized in that as hardener use aluminum phosphate in an amount of 0.2-1.5 wt.% By weight of the mixture. 3. The method of pop. 1, characterized in that the orthophosphoric acid with a density of 1.6 g / cm ³ in a quantity of 0.2-2.0 wt.% By weight is used as a hardener. mixtures. 4. The method of pop. 1, characterized in that the hardener used ferrochrome slag in an amount of 2.0-5.0 wt.% And powdered aluminum in an amount of 0.21.5 wt.% mixtures. SU „1210954