METHOD FOR CONTROLLING A SPARKLING MIXTURE
FIELD OF THE INVENTION The present invention relates to a method for controlling a foamed mixture. More particularly it relates to a method for controlling a foamed mixture to produce them in a predefined normal condition when a casting mold, for example a main mold or a core, is produced by injecting the foamed mixture into a cavity of a mold, wherein The frothy mixture is produced by mixing a particulate additive, a binder dispersed in water, and water, and then stirring. BACKGROUND OF THE INVENTION Recently, a method has been proposed to produce a casting mold that uses a binder dispersed in water as a binder of the particulate additive and harden it by heating and evaporating moisture, because the ability to collapse is good. of the mold made by this method. A conventional casting molding machine that produces such a casting mold as above, comprises for example injection means for injecting sand with fluid into a mold that can be raised and lowered, wherein the injection means have a cylindrical hollow that it extends vertically, a plunger that
it is located in the hollow, which can move up and down, and a gate that opens and closes the hole located at the bottom of the cylindrical hollow, where a hole is provided in the middle of the cylindrical hollow and a mixer is installed in the opening to feed the fluid area to the cylindrical hollow (see patent publication J. Appearance No. S55-542441). In addition, the molding machine for conventional casting molds can vary the amount of fluid sand to the cylindrical recess to vary the amount to be injected into the mold by placing the door in the middle of the cylindrical recess, or by changing the location of the recess. cylindrical hollow, bottom hole or plunger. SUMMARY OF THE INVENTION However, the molding machine for conventional casting molds requires water to be added to the mixture and to cause the mixture to mix because the fluidity of the foamy mixture, which is a material for the mold, is reduced. of casting having a binder di spersado in water, and can not be introduced a sufficient amount of the mixture can not be lowered into the cavity of a mold that does not have enough water. In addition, when the viscosity of the foamed mixture is too high, sufficient metering can not be introduced into the cavity of a
molding and so the mixture must again mix. Thus the purpose of this invention is to provide a method for controlling a foamed mixture that can provide a monitor shape and control the condition of the foamed mixture before it is injected into the mold, and which can increase filling efficiency and uniformity of the strength of a casting mass by maintaining the filling condition when the mixture is molded. The method for controlling a foamed mixture of this invention controls the mixture to produce it in a predefined normal condition when a casting mold is made by injecting the mixture into a hot cavity of a mold, where the foamed mixture is produced by mixing the additive. in particles, a binder dispersed in water and water. The method comprises (a) a step of measuring the temperature of the foamy mixture, (b) a step of determining each reference value of one or more of the characteristic parameters that show a characteristic property of the foamy mixture based on the temperature measurement and the predetermined relationship between a characteristic property of a foamy mixture and its temperature (c) a step of measuring one or more of the characteristic parameters
showing the mixing condition of the foamed mixture (d) a step of determining whether each characteristic parameter is within the corresponding reference value, and (e) a step of determining whether the foamed mixture has been made under the normal condition or if the condition needs to be adjusted. Furthermore, the method for controlling a foamed mixture of the invention controls the mixture to produce it in a predefined normal condition when the casting mold is produced by injecting the mixture into the hot cavity of a mold., wherein the frothy mixture is produced by mixing the aggregate of particles, a binder dispersed in water, and water, in the following manner: (a) a step to measure the temperature of the foamy mixture, (b) a step of determining the reference values of the moisture content and the viscosity showing a characteristic property of the foamy mixture based on the measured temperature and the predetermined relationship between the characteristic properties of the foamy mixture and its temperature, (c) a measurement step moisture content showing the mixing condition of the foamed mixture, (d) a step of determining whether the moisture content being measured is
finds within the reference value, (e) a step of measuring the viscosity of the foaming mixture showing the condition in which it is mixed when the moisture content is within its reference value, (f) a step of determining if the measured viscosity is within the reference value; and (g) a determined step if the foamed mixture is in a normal condition. By means of this invention, the strength of a casting mold is uniformized by maintaining the filling condition when the casting mold is produced. BRIEF DESCRIPTION OF THE. FIGURES Figure 1 is a front view of a molding machine for casting molds of this invention with a fragmented sectional view. Figure 2 is an explanatory drawing of the molding machine for casting molds of the figure
1. It shows the situation of injecting a foamed mixture into mixing storage media in a horizontal split mold. Figure 3 is a flowchart of one embodiment of this invention. Figure 4 is a front view of the molding machine for casting molds of this
invention with a fragmented sectional view. DETAILED DESCRIPTION OF THE INVENTION We will now discuss the method for controlling a foamed mixture of this invention based on Figures 1 to 4. The casting mold machine used for this invention has two cylinders 2.2 that push its arms upwards through a machine table 1. In addition, 3.3 guide rods are installed in the four corners of the machine table 1. The piston rods of the two cylinders 2.2 support a lifting frame 4 in its lower surface, wherein the lifting frame 4 can move up and down and its four corners are slidably provided through the four guide rods 3,3. The lower mold 6 has a divided horizontal mold 5 placed on the upper surface of the lifting frame 4. The upper mold 8 of the divided horizontal mold 5 is located just above the lower mold 6 and is supported by four pieces of equipment support 8, 8 which are installed on the upper side of the lower mold 6 through the guide rods 3,3. The guide rods 3,3 support an upper frame 9, which extends horizontally. A medium
Mixture storage 10 which also acts as agitation vessel and as a cylinder for the injections, is provided on the lower right side of 1 roof rack 9 in such a way that the truck does not. 1 11 can move it towards the left side of the upper frame 9. The mixing storage means 10 comprises a hollow cube 12 having a hole that extends vertically through it and a lower plate 14 which is fixed to the hollow cube box 12 to close it and having four holes for the injections 13, 13 through which the mixture is injected. The lower plate 14 has a structure cooled with water in its upper portion and a structure protected against heat in its lower part. An agitating knife mechanism 15 is provided on the upper right side of the upper frame 9. The mechanism mixes the additive in particular, a binder dispersed in water soluble at room temperature, and water which are all put into storage media of the mixture . Then the stirring blades stir the mixture and cause it to foam. The particulate additive can be silica sand for example. The binder dispersed in water that is used for the binder of the additive in
particles can be polyvinyl alcohol. The mechanism of the stirring blades 15 has stirring blades 16 which are connected to the output shaft of a motor 17 through a transmission gear 18. The motor 17 is placed on a support 20 that moves up and down with the expansion and contraction of the cylinder 19. The support 20 has a cover 21 covering the outlet at the upper end of the mixing storage means 10. The stirring blades 16 and the cover 21 move up and down with the expansion and shrinkage of the cylinder 19. Cap means 22 are placed in the ceiling frame 9 just below the mechanism of the stirring blades 15. The plug means 22 cover the injection orifices 13, 13 of the mixing storage means 10. The stopper means 22 has plugs 23, 23 that can be inserted into the injection holes 13, 13 and fixed on a support plate 24, which in turn is fixed on the upper end of a cylinder 25 that extends upwards. The plugs 23, 23 move upwards with the expansion and contraction of a cylinder 25. The cylinder 25 is fixed on the roof frame 9 by means of supports 26, 26.
The injection holes 13, 13 can be cleaned by inserting a plurality of plugs therein. An ejection mechanism 27 is provided in the ceiling frame 9 just above the divided horizontal mold 5. The outward pushing mechanism 27 pushes the mixture into the mixing storage means 10 to inject it through the injection holes 13, 13 The ejection mechanism 27 has a piston 29 that has a plurality of clearance holes and moves up and down with the expansion and contraction of a cylinder 30 that is installed to extend downwardly. A casting mold ejection mechanism 31 is provided on the lower left side of the roof frame 9 so that it can be moved to the left by means of the truck no. 2 32. The ejector mechanism of the casting mold 31 pushes a positioning mold of the upper mold 7. The ejection mechanism of the casting mold 31 has a thrust plate 34 which is fixed to the lower end of the cylinder 35 that extends down. The push plate 34 has a plurality of ejectors for ejecting the casting mold 33. The expulsion pins of the mold
laundry 33 moves up and down with the expansion and contraction of the cylinder 35. Since it is important to control a foamed mixture to produce a mold of a predefined quality, this invention monitors and controls the condition of the foamed mixture before injecting it into mold. In this invention, a casting mold is made by injecting a foamed mixture into the hot mold cavity using the mold molding machine. In particular this invention measures the temperature of a foamed mixture, and then determines each reference value of one or more of the characteristic parameters that show the characteristic property of the foamed mixture based on the temperature measured according to the predetermined characteristic property of the foamed mixture. the foamy mixture (which depends on its moisture content, its viscosity, the type and particle size of the sand, and the type and amount of the binder). The characteristic parameter can be its moisture content or its viscosity. Then the characteristic parameter (s) showing the mixing condition of the foamed mixture are measured, and then by means of the invention
it is determined whether each determined parameter (this is the value of its moisture content or its viscosity) lies within the reference values (for example within an upper threshold and a minimum threshold of the reference values). After this it is determined whether the frothy mixture is in a normal condition or whether it should be adjusted. Depending on the determination, if the foamed mixture is in a normal condition, that is, each of the measured parameters is considered within the corresponding reference value, the foamed mixture will be injected into the hot mold cavity and a flow mold will be produced. In contaste if each of the measured parameters of the foamy mixture is considered not to be within the corresponding reference value, then after adjusting the components related to the viscosity and / or moisture content, the condition of the foamy mixture. We will now discuss the procedures for controlling the method in an embodiment of this invention when referring to Figure 3. (a) As shown in Figure 3, the temperature (T) of a foamy mixture is measured by sensor means (SI stage) ).
The expansive mixture is composed of a particulate aggregate, a binder and water and then mixed, stirred and foamed by means of a driving mechanism of the stirring blades in mixing storage media. The particulate additives can be silica salt, alumina sand, olivine sand, cormite sand, zirconia sand, mulita sand, or various types of synthetic additive. The binder dispersed in water is used for the binder of the particulate aggregate can be a polyvinyl alcohol or its derivatives, for example polyvinyl alcohol or its derivatives with a degree of saponification of 80-95 mol%, and / or a starch, dextrin or its derivatives or saponin or sugars. The binder dispersed in water is mixed in the aggregate of particles for example in 0.3-10% by weight of the aggregate. The water can be any other than alkaline water. The water content can be, for example, 2-10% of the binder dispersed with water. The temperature sensing means may include but are not limited to touch-type and non-contact type temperature sensing means, such as a temperature sensor in the form of a contact type thermocouple, or a temperature sensor using a laser, infrared rays. (thermo graphic) or ultrasound,
as a contactless type. (b) Then the reference values (Ws), (Vs) for the moisture content and the viscosity of the foamy mixture are determined based on the measured temperature and the predetermined relationship between a characteristic property of a foamy mixture and its temperature (Step S2). These values show a characteristic property of the foamy mixture and affect the quality of the molds particularly in this mode. The fluidity and the fraction of bubbles in a foamy mixture vary based on variations in temperature, moisture content or viscosity. According to this the quality of the casting mold, such as the difficulty of introducing the expansive mixture, and the strength of a casting mold, also varies depending on those. Therefore correlations between temperature, moisture content, viscosity, etc., are predetermined as a characteristic property of the mixture by means of those experiments. (c) After that the moisture content (V) which show the mixing condition of the foamed mixture, is measured by means of moisture content measurement means (step S3).
Means for measuring moisture content, but is not limited to a moisture analyzer such as one that uses a method to measure electrical resistance or a method that uses microwaves, or a moisture analyzer that heats the sample of the foamy mixture and to evaporate its moisture and then determine the moisture content when measuring the lost weight. (d) Then, when the moisture content (W) is within the reference value (Ws) is determined. In particular, be that the moisture content
(W) of the foamy mixture is within the value between the upper threshold (Wsuth) and the minimum threshold (Wsdth), the value that represents that is within the reference value (Ws) is determined. The upper threshold (Wsuth) the minimum threshold (Wsdth) can be determined previously by means of some experiments. (e) After this the viscosity (V) showing the mixing condition of the foamed mixture is measured with the viscosity measuring means, to see if the moisture content (W) is within the reference value (Ws) ) (step S5).
The viscosity measuring means may include, but are not limited to, viscosity measuring means such as those using a method that inserts a probe, rotates the probe or inserts and rotates the probe, or means that measure an apparent viscosity . For example, a viscosity detector using the method for inserting a probe measures the viscosity in a relative manner, that is, a spherical or column-shaped part is constructed on top of a rod-shaped probe (this part can be with the rod or made separately), and the upper part of the probe is inserted into a foamed mixture and then the load (resistance) to the insert is determined as the viscosity. A viscosity detector that uses the method of rotating a probe measures the viscosity in a relative manner, that is a spherical or column-shaped part is constructed on the top of a rod-type probe (the part can be the rod or be produced separately), and the upper part of the probe is rotated and inserted into a foamy mixture and then the load (resistance and force moment) of the probe are determined as the viscosity. A viscosity detector that uses the
Method of inserting and rotating a probe measures the viscosity in a relative manner, this is a disc-shaped or fan-shaped part It is built on top of a rod-shaped probe (the part can be done with the rod or separately ) and the upper part of the probe is inserted into a foamy mixture and rotated, and then the load (the force moment) of the test is determined as the viscosity. In addition a viscosity detector that measures an apparent viscosity measures the viscosity in a relative manner, this is a foamed mixture is fed into a cylinder having a given bore diameter, a predetermined pressure is applied and then the velocity upon leaving the cylinder is measured to determine the viscosity. Since the foamed mixture is a non-Newtonian liquid, the viscosity detector that uses a method of inserting the probe and rotating the probe, or inserting and rotating the probe should be more preferred than the one that measures the apparent viscosity. (f) After that, it is determined whether the measured viscosity (V) is within the reference value (Vs) of the viscosity (step S6). In particular if the viscosity of the foamed mixture is within the value between
upper threshold and the minimum threshold, a value that denotes that it is within the reference value of the viscosity. (g) then if the viscosity (V) is within the reference value (VS) of the viscosity, it is determined that the foamed mixture is under normal conditions (step S7) and the molding process is initiated. (h) if the moisture content (W) which is measured in step S4 is not within the reference value (Ws) (between the Wsdth and Wsuth thresholds) of the moisture content, the missing water and the foamy mixture are added it is mixed again and stirred (step S8). (i) If the viscosity (V) which is measured in step S6 is not within the reference value (Vs) (between the thresholds Vsdth and Vsuth), the foamy mixture is stirred and mixed again until it reaches a predetermined viscosity. In this invention the temperature, the viscosity and the moisture content of the foamy mixture are measured respectively by means of the temperature sensor, the viscosity detector, and the moisture analyzer, which are all installed inside or outside the storage means from
mixture . In this invention, the temperature etc. can also be measured in a batch process by taking samples of the foamy mixture from the mixing storage media or in a continuous process when installing the mixing equipment in the storage media for mixing. In this invention, since the values of viscosity and moisture content vary based on the variation of the type of particulate additive and the binder dispersed in water, it is difficult to specify the most appropriate values. However, the reference value of the viscosity should be 0.5-5 Pa-s and the reference value of the moisture content should be 2-10% by weight. If the temperature of the sand is 0-40 ° C for example. Now we will discuss an example of the invention. But the invention is not restricted by this example. EXAMPLE This example uses silica sand as the particular additive and polyvinyl alcohol (produced by Japan Vam &Poval Co. Ltd.) and a starch (dextrin NSD-L made by Nissi &Co., Ltd). As binders dispersed in water. 100 parts by weight of sand
silica (Arena Flattery), 0.2 parts by weight of a polyvinyl alcohol, 0.8 parts by weight of starch, 0.2 parts by weight of a citric acid and 5 parts by weight of water, were mixed, agitated and foamed in such a way that the viscosity it was 2 Pa-s and the moisture content was 4.5% by weight. The temperature was 20 ° C. After the mixture was foamed, the viscosity and moisture content thereof were measured. The viscosity was 0.5-3.5 Pa-s and the moisture content was 2.5-7% by weight. After it was confirmed that these values were within the reference values, a molding process was started. Thus, it was confirmed that this method of controlling a foamed mixture was efficient to maintain the filling efficiency when the mixture is used for molding. We will now discuss the function of the casting molding machine that molds a casting mold according to the invention. As in Figure 1, after the injection holes 13, 13 are plugged with plugs 23, 23 of a plug means 22, then for example silica sand is added as the particulate additive, polyvinyl alcohol as the binder dispersed in water, and water, in the media
Mixing storage 10. Then the hole at its upper end is closed by means of the cover 21. Then, a motor 17 of a paddle stirring mechanism 15 is operated and the stirring paddles 16 are rotated to mix and stir the silica sand , polyvinyl alcohol, and water, and thus the expansible foamy mixture is produced. Then a cylinder 10 pulls its arm to raise the stirring paddles 16 and the cover 21. After this according to the above procedure, it is confirmed that the property of the foamy mixture is in a normal condition when controlling a temperature sensor., a viscosity detector D2, and a humidity analyzer D3, and then a cylinder 25 of plug means 22 pulls its arm and pulls the plugs 23,23 out the injection holes 13, 13 to open the injection orifices 13 , 13. After that, the ejector mechanism of the casting mold 31 moves to the left by means of the truck no. 2 32, and the mixing storage means 10 are also moved to the left by means of a cart no. 1 11, which is located just above the horizontal mold
divided hot 4. Then the cylinder 2 pushes its arm outwards to raise the lower mold 5 with the lifting frame 4 and places the upper mold 7 in the lower mold 66 to place the mixing storage means 10 on the upper mold 7 and making the lower end of the mixing storage means 10 contact the upper end of the upper mold 7. Then as shown in Figure 2, the ejection mechanism cylinder 27 pushes its arm to lower the piston 29. After of allowing air between the piston 29 and the mixture to exit through the outlet ports 28, 28 are closed by means of the valve means not shown, and then mixing in the mixing storage means. they are compressed to be injected into the horizontal mold cavity divided 5. The mixture that has been injected hardens, because the moisture evaporates through the heat of the divided horizontal mold 5. After the injection is completed in the divided horizontal mold 5, the cylinder 30 pulls its arm inward to raise the piston 29, and then the pushing mechanisms for the outside of the casting mold 31 moves to the right by means of a wheelbarrow no. 2 32 and the
Mixture storage means 10 also move to the right by means of the truck 11 no. 1 so that the ejection mechanism of the casting mold 31 returns to the position together above the divided horizontal mold 5 and the mixing storage means 10 returns to the position together below the mechanism of the stirring blades 15. After of this the cylinder 35 of the ejection mechanism 31 pushes its arm to insert the ejection pins of the casting mold 33,33 into the upper mold 8 Then the cylinders 2,2 retract their arms to let the lower cylinder mold lower 6 in such a way that the casting mold is separated from the upper mold 7. After that, a pushing mechanism towards the outside of the mold, which is not shown, pushes the casting mold upwards from the lower mold 6. In the meantime, the silica sand, polyvinyl alcohol and water are introduced into the storage media of the mixture 10, which have returned to the position together below the mechanism of the stirring paddles 15, as required for the next molding. In this example the mixture in the storage means of the mixture 10 is injected into the mold
horizontally divided 5 by means of the piston 29 of the ejection mechanism 27. However, the method for injection of the mixture is not restricted to this, but as in Figure 4, a method in which the mixture is injected by means of compressed air can achieve the same effect. In fact instead of the piston 29, a cover 42 that is air-tight closes the hole in the upper end of the mixing storage means 10 and communicates with a source of compressed air, can be installed in the lower end of the mixing rod. piston of a cylinder 49 in the ejection mechanism 27. When the mixture is injected into the divided horizontal mold 5, it can be supplied to the upper surface of the mixture in the mixing storage means 10. In this case, the mechanism can be combined. of agitation and the mechanism of injection of compressed air.