JP5173387B2 - Resin coated sand temperature control unit and temperature control device - Google Patents

Description

  The present invention relates to a temperature control unit useful for manufacturing a temperature control device used for temperature control of a resin-coated sand (hereinafter referred to as “RCS”) used in manufacturing a mold by a shell mold method. And a temperature control device manufactured by installing the temperature control unit in a sand hopper of a shell mold molding device (shell mold machine).

  In recent years, in addition to further improving mold productivity, moldability and quality (for example, strength) and eliminating problems related to molding and quality in the winter environment in the molding of shell molds, measures for recent environmental problems (energy saving) In order to reduce the environmental load by lowering the mold temperature in response to the above, and to reduce the thermal strain of the mold by lowering the mold temperature, the heating of the RCS for the shell mold has been reviewed. For example, Japanese Patent Application Laid-Open No. 54-48632 (Patent Document 1, preheating method for shell foundry sand) proposes preheating the RCS for the shell mold prior to the molding of the shell mold.

  However, the preheating device used in the method for preheating the RCS for shell mold as disclosed in Patent Document 1 is large in size because each component is large and fixed as a unit. I needed it. Such a large-scale RCS preheating device for shell molds has a problem in terms of energy saving because it consumes a large amount of energy, and it is not easy to install. Attempts have been made to move to preheaters that can be easily installed in space.

  For example, in an apparatus disclosed in Japanese Utility Model Publication No. 51-116915 (Patent Document 2, coated sand preheating apparatus for shell mold machine), an RCS sand for shell mold that is directly connected in a conventional shell mold molding apparatus. A device for supplying dry hot air is interposed as a preheating device between the hopper and a blow head for supplying shell mold RCS to the mold of the shell mold molding device. Moreover, in the apparatus used by the shell mold molding method disclosed in Japanese Patent Application Laid-Open No. 6-142837 (Patent Document 3, shell mold molding method), the preheating device has a double structure including an inner tank and an outer tank. A shell mold RCS heating device is provided, and the shell mold RCS charged in the inner tank is heated from a plurality of bubbling nozzles arranged at the bottom of the inner tank by heat exchange with steam in the outer tank. By blowing out the intermittent air (3 seconds at 5 second intervals), the air is made to rise upward, fluidized, heated, and then discharged from the lower discharge port of the inner tank to the mold.

JP 54-48632 A Japanese Utility Model Publication No. 51-116915 Japanese Patent Laid-Open No. 6-142837

  However, the preheating devices disclosed in Patent Document 2 and Patent Document 3 are difficult to be installed later and added to a conventionally used shell mold molding apparatus, and are expensive. It was.

  An object of the present invention is to solve the above-described problems in the prior art and to provide a small RCS temperature control that can easily and economically include a temperature control device for preheating the RCS for the shell mold for each shell mold molding device. To provide a unit. Another object of the present invention is to provide a temperature control device that can heat-process a required amount of RCS in small steps and at an appropriate temperature by providing the temperature control unit in the sand hopper of the shell mold molding device. It is in.

  As a result of intensive studies to achieve the above-mentioned problems, the present inventors have attached a heater to an ingot in which a gas passage is formed and used it as a heat exchanger, so that a normal temperature gas can be quickly and appropriately heated. The present inventors have found that it can be heated and heated to warm air, and based on this knowledge, further studies have been made to overcome the intended problem and the present invention has been completed.

According to the first aspect of the present invention, a housing in which a plurality of heated gas blowing holes are formed, and a gas passage that is accommodated in the housing and extends from the gas introduction hole to the gas discharge hole are formed inside. And a heater attached to the ingot for heating the ingot, and the gas supplied from the outside of the housing and introduced into the gas passage through the gas introduction hole is the gas. A resin-coated resin which is heated by heat exchange with the ingot heated by the heater while passing through a passage, and the gas heated by the ingot is discharged from the heated gas blowing hole of the housing. Provide sand temperature control unit.

In the temperature control unit, it is preferable that the gas passage of the ingot extends in a branched manner from the gas introduction hole. Moreover, it is preferable that the shape of the said housing is an abacus bead shape which has the inclined surface which makes an angle more than a repose angle with respect to a horizontal surface in a lower part .

  Moreover, this invention provides the temperature control apparatus of the resin coated sand which installs the said temperature control unit in the sand hopper to which resin coated sand is supplied in the 2nd aspect.

  Preferably, the temperature adjusting device further includes a temperature detector, and the heater is controlled based on the temperature detected by the temperature detector.

The temperature control unit according to the present invention uses an ingot with a gas passage provided therein and a heater attached as a heat exchanger, and covers and protects it with a housing having a heated gas blowing hole. Therefore, the following effects can be provided.
(1) The temperature control unit can be manufactured at low cost and can be miniaturized. In addition, the structure requires little maintenance.
(2) Since heat exchange is performed by direct contact between a heated ingot and a normal temperature gas, the heat efficiency is high and rapid heating can be performed. Further, due to the heat retaining effect by heat radiation from the ingot to the surrounding space in the housing, it is possible to prevent the temperature of the high-temperature heated gas used for heating the shell mold RCS from being lowered.
(3) Since an existing sand hopper can be easily and easily converted into a temperature control device, no special installation space or equipment costs are required.

  Embodiments according to the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a longitudinal sectional view showing an example of a temperature control unit according to the present invention. The temperature control unit U is composed of a metal housing (hereinafter referred to as “housing”) A that can be separated vertically and a heat exchanger B. The heat exchanger B is held between two fixed plates (for example, iron plates) 5 with flanges inside the housing A, and the fixed plate 5 is appropriately fixed by, for example, fastening or welding using bolts and nuts. Fixed to the housing A via a flange. The heat exchanger B is held on the fixed plate 5 via a heat insulating material (for example, a heat insulating board) 6 as shown in FIG. 1 in order to minimize the transfer of heat to the fixed plate 5. However, it is not always necessary to provide the heat insulating material 6. Inside the housing A, a gas supply pipe 1 connected to a gas supply device (not shown, the same applies hereinafter) extends through the top of the housing A and extends from a gas introduction hole of the heat exchanger B. 2 is hermetically connected. The “gas” in the present application includes not only air but also a mixture of an inert gas such as nitrogen gas and air, the inert gas itself, and the like.

  The shape of the housing A is not particularly limited, but considering the smooth replenishment of the RCS to the fluidized heating zone 10 (see FIG. 5) as will be described later, the shape of the housing A is set to the horizontal plane so as to cause a natural flow of the RCS. In other words, the housing A preferably has a slope surface at the lower portion of the repose angle. For example, the housing A has a rhombus, abacus bead, parallelogram, polygon (hexagon or octagon), etc. It can be made into a substantially spindle shape (shape in which both ends of a cylinder are sharp). Among these, from the viewpoint of ease of manufacture, the volume of the fluidized heating zone 10 and the like, a substantially spindle shape having a rhombus or abacus longitudinal section is preferable, and in particular, an abacus shape (an approximately abacus longitudinal section). Spindle type) is preferred. The material of the housing A is generally metal, particularly iron, from the viewpoints of cost and durability, but is not limited to this, and may be, for example, duralumin or aluminum. Further, for example, fiber reinforced plastics such as SMC and BMC may be used. The angle of repose of RCS means an inclination angle measured according to JACT test method S-5 (casting sand fluidity test method).

Further, the inclined wall surface of the lower portion of the housing A has a large number of heated gas blowout holes 4 for supplying hot air, that is, heated gas, for flowing and heating the RCS in the fluidized heating zone 10. It is provided at a desired interval. The heated gas blowing hole 4 is perforated at a right angle or an acute angle (directly below) with respect to the inclined wall surface from the viewpoints of (1) to (3) below, thereby effectively acting on the fluid heating of the RCS. The heated gas can be blown out.
(1) Even if it is the pressure and the air volume of the to-be-heated gas of low flow velocity, RCS can be effectively flowed.
(2) When the blowout of the heated gas is stopped, for example, the inflow of RCS from the sand hopper D into the housing A or the clogging into the heated gas blowout hole 4 hardly occurs.
(3) It is possible to effectively contribute to the flow and heating of the RCS by preventing the occurrence of a short path of the heated gas.
Further, the shape of the heated gas blowing hole 4 is preferably a circular shape because it has a small blowing resistance (pressure loss) and is easy to process, but is not limited thereto. Further, the size (diameter) of the heated gas blowing hole 4 is mainly determined in consideration of the flow state of the RCS, but is preferably about 1.0 to 3.0 mm, particularly 1.0 to 2.0 mm. The range of is preferable.

  The outer surface of the housing A may be subjected to a fluororesin process to promote the flow of RCS. Further, since the housing A itself is heated by heat radiation from the heat exchanger B as will be described later, the heated gas is also applied to the inclined wall surface of the upper portion of the housing A to the extent that it does not affect the original RCS heat treatment. A blowout hole may be provided to perform preheating (primary heating) of the unheated RCS. In addition, when importance is attached to prevention of temperature decrease of the heated gas, the upper part or the whole of the housing A may be covered with a wear-resistant heat insulating material.

  In the temperature control unit U of the present invention, the heat exchanger B is a gas for introducing the gas supplied from the gas supply device through the gas supply pipe 1 and the gas introduction pipe 2 as shown in FIGS. An ingot C in which an arbitrary number of gas passages 9 extending from the introduction hole to the gas discharge hole 3 and an arbitrary number of heat source accommodation holes are formed inside, and a heater 7 used as a heat source is fitted in the heat source accommodation hole It is constituted by. The heater 7 used as a heat source can be, for example, a rod-type electric heater such as a cartridge type or a self-heating element type. The gas supplied to the heat exchanger B having such a structure is heated by exchanging heat with the ingot C heated by the heater 7 while flowing through the gas passage 9 formed inside the ingot C (that is, The air is warmed) and discharged into the housing A from the gas discharge hole 3 opened on the outer peripheral surface (peripheral surface, bottom surface) of the ingot C.

  Since the ingot C used in the present invention is used as a heat exchange medium, it is required that the ingot C be formed from a material that easily transfers heat and is difficult to cool. In addition to this, in consideration of castability, tapping workability, cost, light weight, etc., the material of the ingot C is preferably an alloy mainly composed of non-ferrous metals such as aluminum and magnesium, particularly an aluminum alloy. Is preferred. The shape of the ingot C is not particularly limited. For example, the shape of the ingot C may be a plate shape, a prismatic shape (cube, rectangular parallelepiped shape), a cylindrical shape, a spherical shape, or a solid body (conical frustum, truncated pyramid) obtained by cutting and removing the tip. However, a cylindrical shape is particularly preferable in consideration of ease of design and processing, such as formation of the gas passage 9 having excellent heat exchange properties.

  In such an ingot C, the position where the gas introduction hole is provided is not particularly limited, and an appropriate position on the outer peripheral surface (upper surface, peripheral surface, bottom surface) of the ingot C so as to express the maximum heat exchange efficiency. However, it is preferable that the upper surface of the ingot C is selected from the viewpoint of ease of processing. In addition, the shape of the gas passage 9 that continues below the gas introduction hole is not particularly limited. For example, in order to maximize the heat exchange efficiency, a branched shape (a shape branched into a plurality of gas passages), a spiral shape, What is necessary is just to select a bellows shape etc. suitably in light of the shape of the ingot C. However, a branched passage is particularly preferable from the viewpoint of ease of processing and manufacturing cost. That is, it is preferable to provide the ingot C with one gas introduction hole and a plurality of gas discharge holes 3 so that the plurality of gas passages 9 branch from the one gas introduction hole to reach each gas discharge hole 3. .

In addition, the manufacturing method of the heat source accommodation hole and the gas passage 9 as described above is not particularly limited, and for example, the following methods (1) to (3) can be taken, but the manufacturing is easy. From the viewpoint of sheath heat exchange efficiency, the method (3) that can increase the surface area of the passage by tapping is particularly suitable.
(1) A method of casting a pipe for forming a heat source accommodation hole, a gas passage or the like at the time of ingot casting.
(2) A method of drilling a hole in the ingot C.
(3) A method of further tapping a hole drilled in the ingot C.
The size or size of the gas passage 9 is restricted by the size of the drill blade or the tap blade and is generally selected from the range of 5 to 15 mm, but is preferably about 10 mm.

  Next, with reference to FIG.3 and FIG.4, the illustrative and specific Example of a structure of the heat exchanger B mentioned above is described. FIG. 3 is a perspective view of the heat exchanger of FIG. 1, and FIG. 4 is a longitudinal sectional view of the heat exchanger along line IV-IV of FIG. The ingot C is made of an aluminum alloy, and this ingot has a cylindrical shape with a diameter of 200 mm and a height of 200 mm. As can be seen from FIGS. 3 and 4, a gas introduction hole to which the gas introduction pipe 2 is connected is formed at the center of the upper surface of the ingot C. In addition, in the ingot C, eight gas discharge holes (in the lower part of the outer peripheral surface of the ingot C) formed in the peripheral surface (outer peripheral surface and bottom surface) of the ingot C are branched into eight from the gas introduction hole. A gas passage 9 reaching four gas discharge holes 3 and four gas discharge holes 3 on the bottom surface is formed. Inside the ingot C, four heat source storage holes are further formed at appropriate positions so that the temperature distribution due to the heating of the heater 7 does not vary, and each of the heat source storage holes has an output of 3 kWh. A heater 7 is inserted. The ingot C is maintained at a required temperature (for example, about 150 ± 5 ° C.) by the heating by these heaters 7, and the gas flowing through the gas passage 9 is heated by heat exchange with the ingot C to generate hot air, Heated gas (for example, about 60 ± 5 ° C.) is discharged and supplied into the housing A from the gas discharge hole 3 formed on the peripheral surface of the ingot C.

  Here, a specific method for producing the gas passage 9 and the heat source accommodation hole will be described. First, a gas introduction hole to which the gas introduction pipe 2 is connected is formed at the center of the upper surface of the ingot C, and a position (gas) that forms a cross on the upper surface of the ingot C with the gas introduction hole as a base point as shown in FIG. Eight upper vertical holes (holes extending in the direction of the central axis of the cylindrical ingot C) are formed in two symmetrical positions on the left and right and front and rear sides with the introduction hole interposed therebetween. Next, of the upper vertical holes, one upper horizontal hole formed so that the upper end portions of the four upper vertical holes aligned in the diameter direction and the lower end portions of the gas introduction holes extend in the diameter direction. One lower lateral hole formed so as to extend in the diametrical direction at the lower end of two adjacent vertical holes of the four vertical holes aligned in the diameter direction among the upper longitudinal holes. Communicate. In addition, a short lower vertical hole is drilled on the bottom surface of the ingot C so as to communicate with each horizontal hole formed in the lower portion of the ingot C at a position not aligned with the upper vertical hole extending from the upper surface of the ingot C. To do. Next, the upper end of the upper vertical hole and the both ends of the upper horizontal hole formed in this way are sealed with a plug. Specifically, as shown in FIGS. 3 and 4, eight plugs are embedded in a cross shape on the upper surface of the ingot C with the gas introduction hole as a base point, and on the upper portion of the outer peripheral surface of the ingot C. Four plugs (only one of them is visible in FIG. 3) are buried. As a result of such processing, the two upper horizontal holes, the eight upper vertical holes, the four lower horizontal holes, and the four lower vertical holes form the gas passage 9. Further, the openings of the four lower horizontal holes on the outer peripheral surface of the ingot C and the openings of the four lower vertical holes on the bottom surface of the ingot C form the gas discharge hole 3. Furthermore, in the position where the four heat source storage holes are at an appropriate position where the temperature distribution due to heating of the heater 7 does not vary and avoid the upper vertical hole, so as not to intersect the upper horizontal hole and the lower horizontal hole. It is formed by drilling a vertical hole from the upper surface of the ingot C.

  The conditions of the gas supplied from the gas supply device are not particularly limited, but preferably the blowout to such an extent that the RCS of the fluid heating zone 10 can be maintained in a light flow state, or in some cases a slight blow-up flow state. It only needs to have pressure and air volume. Examples of the apparatus for supplying the gas include a pressure cylinder as well as a compressor and a blower. In particular, in consideration of the flow state of RCS, supply of gas (for example, compressed air) by a compressor is preferable. In addition, although a pressure is determined according to the flow state of RCS in the fluid heating zone 10, it is generally about 0.1-0.5 MPa, Preferably it is 0.1-0.2 MPa. On the other hand, the air volume may be adjusted according to the flow state of the RCS while paying attention to the occurrence of a short path, but is generally about 20 to 1000 L / min. Moreover, as gas supplied, dry things, such as dry air dehumidified by arbitrary dehumidification apparatuses, are preferable. Further, the gas supply may be continuous or intermittent.

  Next, the temperature control apparatus according to the present invention will be described with reference to FIG. FIG. 5 is a longitudinal sectional view showing an example of a temperature control device. In a sand hopper D covered with a heat insulating material in a conventional shell mold molding apparatus (not shown), between the inner wall surface of the reduced diameter portion 11 of the sand hopper D and the outer wall surface of the housing A of the temperature control unit U. The sand hopper D is modified as a temperature control device by installing and fixing the temperature control unit U so that a space is formed as the fluid heating zone 10. According to the temperature control device constructed in this way, the RCS in the sand hopper D is heated by the heated gas (hot air) blown out from the heated gas blowing hole 4 in the inclined wall surface of the lower portion of the housing A of the temperature control unit U. ) Is heated to a predetermined temperature while being slightly fluidized or flowing, and then discharged from the discharge port 12 of the sand hopper D into the blow head (not shown) of the shell mold molding apparatus.

  In the temperature control apparatus of FIG. 5, as described above, the RCS amount of the fluid heating zone 10 is determined by adjusting the distance between the inner wall surface of the reduced diameter portion 11 of the sand hopper D and the outer wall surface of the housing A of the temperature control unit U. The interval is generally adjusted to about 20 to 50 mm, preferably 25 to 35 mm. Usually, the heat treatment of the RCS is determined according to the RCS required amount (2 to 3 times the RCS amount required for molding), and then the temperature of the heated gas (warm air) and the blowing conditions (described above) The flow state of RCS, the heating efficiency, and the like are adjusted by the pressure, the air volume, and the like.

  5 is a mechanism in which RCS is sequentially replenished from the top to the fluidized heating zone 10 as the RCS is discharged after the heat treatment, and therefore follows both continuous molding and intermittent molding. Be able to. In addition, since the heating is repeated by the amount of RCS corresponding to the volume of the fluidized heating zone 10, it is possible to perform the heating process of the RCS quickly and uniformly and more efficiently than the large apparatus. Therefore, a long waiting time unlike a large apparatus does not occur even when the molding work is resumed, and waste of waiting time can be eliminated. In addition, the sand hopper D is covered with a suitable heat insulating material. Thereby, the preheating (primary heating) of RCS by the improvement of the heat processing efficiency in the fluid heating zone 10 and the use of the waste heat of hot air is intended.

As described above, in the temperature adjusting device, the fluid heating zone formed between the inner wall surface of the reduced diameter portion 11 of the sand hopper D and the inclined outer wall surface of the lower portion of the housing A of the temperature adjusting unit U. Since the mechanism for optimizing the temperature of the RCS for the shell mold is adopted, the following effects can be provided.
(1) A required amount of RCS for shell mold is set by adjusting the gap between the inner wall surface of the reduced diameter portion 11 of the sand hopper D and the inclined outer wall surface of the lower portion of the housing A of the temperature control unit U. Compared with a large-sized apparatus, it is heated quickly and uniformly with high heating efficiency, which can contribute to an improvement in work efficiency at the molding site and a reduction in energy costs.
(2) Since the blowing condition of the heated gas is gentle compared to a conventional large temperature control device (preheating device), it is possible to prevent peeling of the resin from the surface due to fluid friction between the RCS for shell molds. Can do.
(3) The fluid heating zone 10 employs a mechanism in which unheated RCS is replenished from the top as the RCS for shell mold after heat treatment is discharged, so that the required amount corresponding to the mold is discharged in small increments. Heat treatment can be performed continuously.
(4) In addition, when restarting after the molding operation is interrupted, the start-up of the operation is easier than that of a conventional large-sized temperature control device, and it contributes to preheating of the upper unheated RCS due to the remaining heat of hot air. It is possible to provide advantages such as that it is not necessary to install new equipment if the existing air piping at the molding site is used as a gas supply source.

  In the RCS temperature control method in the temperature control device of FIG. 5, the RCS temperature measured by the temperature sensor 13 provided in the fluidized heating zone 10 as a temperature detector is converted into an electrical signal (current or voltage), and converted. The obtained electric signal is taken into a temperature control device (not shown), and the operation of the heater 7 provided in the ingot C (heat exchanger B) is controlled by the temperature control device to maintain the ingot C at a predetermined temperature. It is like that.

  Specifically, as the temperature control method, (1) when the temperature of the RCS measured by the temperature sensor 13 is lower than a predetermined set temperature range, the heater 7 is turned on; A method of managing power by on / off command control to turn off the device 7, or (2) a voltage signal output in accordance with a difference between the RCS temperature measured by the temperature sensor 13 and a set temperature, and a temperature control device For example, a method of proportionally controlling the voltage of the heater 7 provided in the heat exchanger B can be exemplified. However, in general, from the viewpoint of temperature control accuracy and equipment cost, it is preferable to employ power on / off control as the heat source management to control the temperature of the ingot C. Thereby, variation in the heating temperature of RCS can be suppressed.

  In the above description, the temperature sensor 13 is provided in the fluid heating zone 10 and the temperature sensor 13 measures the temperature of the RCS in the fluid heating zone 10. However, as shown in FIG. In place of or in addition to the temperature sensor 13 provided in the area 10, the temperature adjustment unit is used by using the temperature sensor 13 attached to the housing A of the temperature range temperature adjustment unit U or the temperature sensor 13 disposed in the discharge port 12. You may make it control operation | movement of the heater 7 so that the temperature of U or the temperature of RCS discharged | emitted from the discharge port 12 may become a predetermined temperature range.

  The RCS is generally heat-treated at about 40 to 70 ° C., preferably about 50 to 65 ° C. by the RCS temperature control apparatus and the temperature control method used therein according to the present invention. Therefore, it is possible to provide an advantage that the original fluidity is restored and the free fluidity is excellent. Therefore, the obtained RCS can stably mold the shell mold without being influenced by the environmental temperature as well as improvement in molding and quality. Further, it is possible to lower the molding temperature, and to reduce the thermal strain and environmental load of the mold.

It is a longitudinal cross-sectional view which shows the structure of a temperature control unit. It is a top view of the stationary plate for hold | maintaining a heat exchanger to a housing used in the temperature control unit of FIG. It is a perspective view of the heat exchanger of the temperature control unit of FIG. It is a longitudinal cross-sectional view of the heat exchanger along line IV-IV of FIG. It is a longitudinal cross-sectional view which shows an example of the temperature control apparatus which installed the temperature control unit in the sand hopper.

Explanation of symbols

A housing B heat exchanger C ingot D sand hopper U temperature control unit 1 gas supply pipe 2 gas introduction pipe 3 gas discharge hole 4 heated gas blowout hole 5 fixing plate 6 heat insulating material 7 heater 8 filling plug 9 gas passage 10 flow Heating zone 11 Reduced diameter part 12 Discharge port 13 Temperature sensor

Claims (5)

A housing in which a plurality of heated gas blowing holes are formed, an ingot that is accommodated in the housing and that has a gas passage extending from the gas introduction hole to the gas discharge hole, and for heating the ingot A heater attached to the ingot, and heated by the heater while the gas supplied from the outside of the housing and introduced into the gas passage through the gas introduction hole passes through the gas passage. A temperature-adjusted unit for resin-coated sand, which is heated by heat exchange with the ingot, and the gas heated by the ingot is discharged from the heated gas blowing hole of the housing. .   2. The resin-coated sand temperature control unit according to claim 1, wherein the gas passage of the ingot extends in a plurality of branches from the gas introduction hole. 3. The resin-coated sand temperature control unit according to claim 1 , wherein the shape of the housing is an abacus shape having a slope surface at an angle equal to or greater than an angle of repose with respect to a horizontal plane .   The temperature control apparatus of the resin coated sand characterized by installing the temperature control unit as described in any one of Claims 1-3 in the sand hopper to which resin coated sand is supplied.   5. The resin-coated sand temperature adjusting device according to claim 4, wherein the temperature adjusting device further includes a temperature detector, and the heater is controlled based on a temperature detected by the temperature detector.

Images