JP4290536B2 - Casting mold preheating method and preheating gas burner - Google Patents

Description

  The present invention relates to a casting mold preheating method and a preheating apparatus for preheating a molding inner surface of a mold used for casting molding to a predetermined temperature before molding.

  For example, in an automobile wheel, an aluminum alloy wheel is generally formed by casting a molten aluminum alloy into a predetermined casting mold. In the case of such casting, the inner surface of the casting mold that forms the cavity into which the molten aluminum alloy is poured is preheated to a predetermined temperature, so that the molten metal is appropriately placed in the cavity. Can be filled. Here, if the preheating of the casting mold is insufficient, or if there is a difference in the preheating temperature within the inner surface of the molding, the filling of the molten metal and the cooling rate become imbalanced, resulting in defects such as sink marks and cracks. Can be. A casting mold having a relatively complicated cavity shape, such as an automobile wheel, tends to cause a temperature difference on the inner surface of the molding due to preheating. Here, the sink mark indicates a form in which a dent or the like is generated on the surface of the casting surface at the time of contraction when the molten metal is solidified.

For this reason, various methods or apparatuses for preheating the inner surface of the casting mold almost uniformly have been proposed. For example, as in Patent Document 1, the lower mold (concave mold) and the upper mold (convex mold) are separated from each other and preheating is performed directly by a burner inserted between the upper mold and the lower mold. A device has been proposed.
JP-A-2-160159

  Further, as shown in FIG. 4, there is also a preheating device 50 in which a preheating gas burner 51 having a large number of burner nozzles 54a, 54b, 54c and 54d is connected to a mixer 52 for sucking and mixing fuel gas and air gas. The The preheating gas burner 51 includes an annular distribution pipe 53 and a plurality of burner nozzles 54a and 54b protruding in the vertical direction over the circumferential direction of the distribution pipe 53, and the annular distribution pipe. 53 is connected to a gas flow pipe 56 through which the mixed gas flows from the mixer 52. In addition, a distribution straight pipe 60 having an annular diameter is also formed inside the distribution pipe 53, and each of the distribution straight pipes 60 protrudes in the vertical direction at the approximate center of the circular ring. Burner nozzles 54c and 54d are provided. Here, each burner nozzle 54a on the upper side is formed along the annular axis direction, and each ejection port 55a is opened upward. Similarly, even in the upper burner nozzle 54d, the jet outlet 55d opens upward. On the other hand, each burner nozzle 54b on the lower side is bent and inclined toward the outer side in the annular radial direction, and each ejection port 55b is opened obliquely downward. Further, the burner nozzle 54c provided at the substantial center of the ring of the distribution pipe 53 is formed with a jet port 55c that opens downward. In many cases, the preheating gas burner 51 is integrated with the mixer 52 via the gas flow pipe 56. The preheating device 50 is arranged so that the burner nozzles 54a, 54b, 54c of the preheating gas burner 51 face the concave mold 20 and the convex mold 21 that are spaced apart in the vertical direction and are in the standby position. Here, the lower burner nozzle 54 b has the jet outlet 55 b facing the side surface of the molding inner surface 22 of the concave mold 20, and the burner nozzle 54 c has the jet outlet 55 c facing the gate 24. And from each burner nozzle 54a, 54b, 54c, 54d, the mixed gas which flowed in from the mixer 52 is ignited and a flame is ejected, thereby forming the molding inner surface 22 of the concave mold 20 and the molding inner surface 23 of the convex mold 21 respectively. Preheat.

  Incidentally, as described above, in the preheating device 50 (FIG. 4) that preheats the concave and convex molding inner surfaces by the preheating gas burner 51 having a large number of burner nozzles, the relatively small burner nozzles 54a, About 30 to 60 b are arranged at almost equal intervals over the inner surface of the molding, and preheating is performed so that a small and gentle flame is ejected from each burner nozzle. As a result, the inner surface of the molding is preheated without locally heating the inner surface of the molding. However, in this preheating burner, a temperature difference may occur between a portion where the flame of the burner nozzle is in direct contact and a portion where it is not. In addition, because it has a large number of burner nozzles and ejects a weak flame, the thermal efficiency acting on the preheating against the combustion energy of the flame is low, the preheating takes a long time, and the fuel is consumed greatly There is. In addition, since the preheating burner is provided with a large number of burner nozzles, there are problems that it takes time to ignite and that maintenance and maintenance inspections become complicated.

  The present invention solves the above-mentioned problems, and proposes a casting mold preheating method and a preheating gas burner that can preheat the molding inner surface of the casting mold almost uniformly and can efficiently perform the preheating step. It is for the purpose.

  The present invention includes a gas outlet channel that communicates at a side portion with a mixer that mixes fuel gas and air gas to generate a mixed gas, and that opens upward and downward, and has an umbrella that expands outward at each opening end. The gas burner formed in the shape of a gas diffusion jet is arranged so that each diffusion jet is opposed to the center of each of the concave and convex shapes spaced apart in the vertical direction and placed in the standby position, and the mixed gas is ignited. A casting mold preheating method is characterized in that the inner surface of the concave mold and the convex mold is heated by radiating a flame formed in this manner from a diffusion jet port.

  In such a preheating method, the air around the jet outlet is heated and fluidized by a flame radiated from the expanded jet outlet, and this heated air (hot gas) is applied to the inner surfaces of the concave and convex molds. They are brought into contact and heated. Here, since the hot gas diffuses in four directions from the diffusion jets arranged at the centers of the concave and convex molds, the hot gas becomes an air flow that flows along the molding inner surfaces of the concave and convex molds. Contact can be made over almost the entire surface. Thus, the concave and convex molded inner surfaces can be heated almost entirely and uniformly. Further, since the preheating method heats the inner surface of the molding by a hot gas stream generated by the flame, the hot gas is heated at a high temperature, a high flow rate, and a strong air current, thereby forming the convex and concave molds. It becomes easier to contact the surface more evenly, the inner surface of the molding can be heated almost uniformly, and the temperature rise rate of the inner surface of the molding is improved, so that it can be heated to the preheating temperature in a relatively short time. . And the outstanding advantage that the combustion energy of a flame required for preheating can be reduced and thermal efficiency can be raised also arises. Here, the hot gas in a strong airflow can be generated by radiating a high-temperature and high-velocity flame from the expansion jet port by flowing a high-pressure mixed gas from the mixer. As described above, the preheating method of the present invention has a conventional configuration in which even when a high-temperature and vigorous flame is ejected using a high-pressure mixed gas, it is heated by a relatively small flame using a large number of burner nozzles. The inner surface of the molding can be heated almost uniformly without local heating.

  Here, as described above, the preheating method of the present invention heats the convex and concave molding inner surfaces by the flow of hot gas generated by the radiating flame. In the meantime, it is desirable to appropriately form an air space for the hot gas to flow. For this reason, not only arranging each diffusion jet port to be the center of each of the concave and convex shapes as described above, but also one of the expanded jet nozzles in the concave insertion air space into which the convex type is inserted, It is preferable to arrange the gas burner so that the position is a predetermined distance away from the concave molding inner surface, and the other expansion jet outlet is a position away from the convex mold by a predetermined distance.

  On the other hand, the present invention is arranged at a central position between a concave mold and a convex mold spaced apart in the vertical direction as a standby position, and a mixer that mixes fuel gas and air gas to generate a mixed gas, Preheating of a casting mold, characterized in that it has gas outflow passages that open at the top and bottom and communicate with each other at the sides, and at each opening end, an umbrella-shaped diffusion jet port that is widened and inclined outward is formed. Gas burner for use.

  In such a preheating gas burner, it can be suitably used in the above-described casting mold preheating method, and is disposed at the center position between the concave mold and the convex mold at the standby position, and from the diffusion injection port. By radiating the flame, the same effects as described above can be produced. In addition, in this configuration, since there are few diffusion discharge ports compared to the conventional configuration having a large number of burner nozzles, ignition work at the start of preheating is easy and maintenance inspection is also easily performed. obtain. Furthermore, since the structure can be made simpler than the conventional configuration, there is an advantage that durability can be easily improved or manufacturing costs can be reduced.

  Here, the diffusion outlet is formed between an outer umbrella portion having an outer inclined surface that expands and inclines outward, and an inner block portion having an inner inclined surface formed along the outer umbrella portion. A configuration is proposed. In such a configuration, the flame is radiated according to the expanding inclination angle between the outer inclined surface of the outer umbrella portion and the inner inclined surface of the inner block portion. And by setting this inclination | tilt angle suitably according to the shape of the shaping | molding inner surface of a concave mold and a convex mold | type, the gas flow of the hot gas which can be made to contact a shaping | molding inner surface appropriately can be formed. In addition, since the flame radiated from such a diffusion jet also heats the inner block part forming the jet outlet, the radiant heat of the inner block part heats the part immediately below and immediately above the inner block part. Can do. For this reason, when the diffusion jet is greatly expanded outward, the contact area of the hot gas, which tends to be reduced, also heats the portion immediately below and directly above the diffusion jet on the inner surface of the molding. It is possible.

  Further, a configuration is proposed in which the diffusion outlet includes a plurality of ejection holes for ejecting the mixed gas from the gas outflow passage. In such a configuration, a relatively small flame with a high ejection speed is radiated from the ejection hole having a relatively small shape as compared with the cross section of the gas outflow path 4. With such a flame, it is possible to enhance the action of heating the air around the diffusion jet outlet and to increase the flow velocity of the hot gas flow, so that the inner surface of the molding can be heated more uniformly, The temperature rising rate of the inner surface of the molding can be improved. Further, even when a high-pressure mixed gas is used, the hot gas can be heated to a higher temperature without locally heating the inner surface of the molding, and a strong air current can be generated. Here, by appropriately setting the hole diameter and the number of holes, the amount of flame radiated from the upper and lower diffusion jets can be adjusted appropriately according to the shape of the inner surface of the concave and convex molds to be preheated. Is possible. In addition, for example, in the case where the wheels have substantially the same shape with respect to the central axis, such as an automobile wheel, the ejection holes are disposed substantially evenly along the circumferential direction of the diffusion ejection port. Is preferred.

  Furthermore, a configuration is proposed in which the gas outflow path includes a communication portion that allows the mixer to be attached and detached. In such a configuration, when preheating is performed, the preheating gas burner of the present invention is connected to a mixer, and in other cases, both are separated and stored separately. For this reason, at the time of preheating, the preheating gas burner may be installed at a predetermined position and joined to a mixer previously installed at the predetermined position, so that workability is improved. Further, by preparing a preheating gas burner according to various shapes of casting molds, there is an excellent advantage that it can be appropriately selected and used. In addition to the configuration in which the preheating gas burner and the mixer are directly connected, a gas circulation pipe may be provided between them so that the preheating gas burner is detachable from the gas circulation pipe.

  As described above, the present invention includes a gas burner which is provided with a gas outflow passage which is open at the top and bottom and communicates with the mixer at the side, and each diffusion jet has an up-down direction. Of the casting mold which is arranged to be opposed to each center of the concave mold and the convex mold which are separated from each other in the standby position, and the inner surface of the molding is heated by radiating a flame from the diffusion outlet. Since it is a preheating method, the flow of hot gas generated by the flame diffuses in all directions, and the inner surfaces of the concave and convex molds can be heated almost entirely and uniformly. In addition, by generating a high-temperature and strong airflow with the high-pressure mixed gas, the temperature rise rate of the inner surface of the molding can be improved and heating can be performed in a relatively short time. And the combustion energy required for preheating can be reduced, and the cost required for the preheating step can be reduced.

  On the other hand, the present invention provides a casting mold preheating gas burner that can be suitably used in the above-described casting mold preheating method, and a central position between the concave mold and the convex mold that are spaced apart in the vertical direction and set as a standby position. And is provided with gas outflow passages that open at the top and bottom and communicate with each other at the sides, and at each opening end, an umbrella-shaped diffusion jet port that is inclined outward is formed. Thus, as described above, the inner surface of the molding can be heated as a whole and uniformly, and the heating rate and thermal efficiency can be increased by using a high-pressure mixed gas. In addition, the workability in the preheating process and the workability in maintenance can be simplified.

  Here, the diffusion outlet is formed between an outer umbrella portion having an outer inclined surface that expands and inclines outward, and an inner block portion having an inner inclined surface formed along the outer umbrella portion. With this configuration, it is possible to appropriately form an air flow that can sufficiently bring the hot gas into contact with the inner surface of the molding. Further, the radiant heat of the heated inner block portion can also appropriately heat the portion immediately above and directly below the inner block portion.

  In addition, in the case where the diffusion outlet has a plurality of ejection holes for ejecting the mixed gas from the gas outflow passage, a relatively small flame with a high ejection speed is emitted from each ejection hole. In addition to enhancing the action of heating the air around the diffusion jet outlet, it is possible to increase the flow velocity of the hot gas flow and to improve the temperature rising rate. Furthermore, even when a high-pressure mixed gas is used, the molding inner surface can be heated more uniformly without the high-temperature flame locally heating the molding inner surface.

  Furthermore, when the gas outflow path is provided with a communication portion that allows the mixer to be attached and detached, the workability of installing the preheating gas burner at a predetermined position can be improved when preheating. Further, by connecting a preheating gas burner corresponding to various shapes of casting molds, it is possible to easily cope with a wide variety of products.

An embodiment of the present invention will be described in detail with reference to the accompanying drawings.
As shown in FIGS. 1 and 2, a casting mold preheating apparatus 1 includes a substantially cylindrical preheating gas burner 2 provided with diffusion jets 3 and 3 on the upper and lower sides, and the preheating gas burner 2. A gas flow pipe 10 that is detachably joined to the side portion and a high-pressure mixer 11 that is joined to the other end of the gas flow pipe 10 and generates a mixed gas are provided. Further, a support device 7 arranged at a predetermined position is fixed to the side surface of the preheating gas burner 2 with bolts or the like, and is supported by four support legs 8 arranged in four directions. In addition, this support apparatus 7 can change the vertical direction height of each support leg 8, and can change a height position suitably according to the metal mold | die for casting.

  Here, in the present embodiment example, as the mixer of the present invention, a high-pressure air-mix type high-pressure mixer 11 that can feed a mixed gas obtained by mixing fuel gas and air at a high flow rate at a high pressure is used. . The high-pressure mixer 11 includes an inlet 12 through which fuel gas flows from a storage tank (not shown) in which a predetermined fuel gas is stored, an air inlet 13 for taking in air, and a coupler that can be attached to and detached from the gas distribution pipe 10. (Not shown). And the fuel gas which flowed in from the inflow port 12 and the air taken in from the air intake port 13 are mixed, and mixed gas is produced | generated. Here, the intake amounts of fuel gas and air can be changed, and the ratio of the fuel gas and air in the mixed gas can be adjusted as appropriate.

  Further, the preheating gas burner 2 includes a gas outlet passage 4 having a circular cross-section opening up and down, and jet nozzles 6 and 6 having diffusion jet ports 3 and 3 screwed or welded to the respective opening ends. Yes. And the gas distribution pipe 10 is joined to the side part of the preheating gas burner 2, and the communication part 5 which connects the gas outflow path 4 and the high pressure mixer 11 is formed. The mixed gas generated by the mixer 11 flows into the gas outflow passage 4 from the gas circulation pipe 10 through the communication portion 5.

  Here, in the ejection nozzles 6, 6, the outer umbrella portion 15 in which an outer inclined surface 14 that is expanded and inclined at a predetermined inclination angle is formed on the outer side of the upper and lower opening ends of the gas outflow passage 4, and the outer side Umbrella-shaped diffusion jets 3 and 3 are formed between the inner block portion 17 and the inner inclined surface 16 formed along the inclined surface 14 (see FIG. 3). Here, in the present embodiment, the outer umbrella portion 15 has a conical umbrella shape and the inner block portion 17 has a conical shape, and the mixed gas flowing out from the cylindrical gas outflow passage 4 is ejected relatively smoothly. I try to do it. As a result, the flame diffuses from the diffusion jets 3 and 3 almost uniformly in the outward direction. In addition, the outer inclined surface 14 and the inner inclined surface 16 may have a configuration in which steps are provided so as to narrow the gap in the middle (not shown).

  The ejection nozzles 6 and 6 are formed with ejection surface portions 18 perpendicular to the inclination angles of the diffusion ejection ports 3 and 3 in the vicinity of the boundary with the opening end of the gas outflow passage 4 (see FIG. 3). . The ejection surface portion 18 is provided with a plurality of ejection holes 19 at substantially equal intervals in the circumferential direction, and the mixed gas flowing into the gas outflow passage 4 is ejected from the ejection holes 19. . Here, each of the ejection holes 19 reduces the area of the ejection ports of the diffusion ejection ports 3 and 3 and ejects the mixed gas separately. Therefore, the flame formed by igniting the mixed gas ejected from each ejection hole 19 has a small fire magnitude (so-called fire column) and a high ejection speed. For this reason, the overall flame radiated from the diffusion jets 3 and 3 also has a high temperature and a high jet speed, although the fire column is small, so that the air around the diffusion jets 3 and 3 is heated to a high temperature. In addition, the air flow of the heated air (hot gas) can be made fast and strong. Further, since the ejection holes 19 are arranged uniformly over the circumferential direction, it is possible to radiate a flame almost uniformly in all directions. The inner block portion 17 is screwed and fixed to the approximate center of the ejection surface portion 18 with a spiral, a bolt, or the like, or is fixed by welding.

  Here, in the preheating gas burner 2 of the present embodiment, the convex mold is preheated in order to have a configuration suitable for preheating a casting mold for casting an aluminum automobile wheel. The inclination angle at which the upper diffusion jet 3 is inclined is set larger than that of the lower diffusion jet 3 that preheats the concave mold.

Next, a process of preheating the casting mold using the above-described preheating device 1 will be described.
First, as shown in FIG. 1, a predetermined casting mold is separated into a concave mold 20 and a convex mold 21 in the vertical direction to be a standby position. Here, the standby position is a position where the distance between the concave mold 20 and the convex mold 21 is set so that the above-described preheating gas burner 2 can be installed at a predetermined preheating position. In general, in a casting mold for an automobile wheel, the concave mold 20 can be further separated into a lower mold and a horizontal mold. However, the concave mold 20 is formed during preheating. That is, the inner peripheral surface of the concave mold 20 is a molding inner surface 22 that forms a cavity of a casting mold. Similarly, even in the convex mold 21, the fitting surface of the convex mold 21 to be fitted into the concave mold 20 is the molding inner surface 23.

  In this way, the preheating gas burner 2 is arranged by the support device 7 so that the diffusion jets 3 and 3 face the respective centers of the concave mold 20 and the convex mold 21 that are in the standby position. Here, in the support device 7, the support legs 8 are respectively fixed to the upper outer surface portion of the concave mold 20, and the diffusion jets 3 and 3 are formed in the mold 20 of the concave mold 20 and the convex mold 21. The height in the vertical direction is adjusted so that the surface 23 is located at a predetermined distance from the portion facing the gate 24. Here, the lower diffusion outlet 3 is arranged in the insertion area of the concave mold 20 into which the convex mold 21 is inserted.

  And the gas distribution pipe 10 joined with the high pressure mixer 11 is joined to the communication part 5 of the preheating gas burner 2 installed as described above. As a result, the gas outflow path 4 of the preheating gas burner 2 and the high-pressure mixer 11 are in communication with each other. Then, by starting the high-pressure mixer 11, the fuel gas flows in from the storage tank (not shown) through the inflow port 12, and air is taken in from the air intake port 13. The fuel gas and air are mixed to generate a mixed gas, and the high pressure mixer 11 sends the mixed gas to the gas outflow passage 4 through the gas flow pipe 10 at a high flow rate at a high pressure. Thus, the mixed gas that has flowed into the gas outflow passage 4 is ejected from the ejection holes 19 of the diffusion ejection ports 3 and 3 at a higher ejection speed. Then, by igniting the mixed gas ejected from each of the diffusion jets 3 and 3, from each of the diffusion jets 3 and 3, a flame having a relatively high temperature and a high jet speed is radiated although the fire column is relatively small. .

  In this way, the flames radiated from the respective diffusion jets 3 and 3 heat the air around the diffusion jets 3 and 3, and an air flow is generated in which the heated hot gas flows with strong momentum in all directions. Become. The air flow of the hot gas generated in this way diffuses according to the inclination angle of the diffusion jet 3 in the concave mold 20 and rises along the inner surface 22 from the bottom surface of the concave mold 20 toward the side surface. Thereby, the shaping | molding inner surface 22 which this hot gas contacted can be heated. On the other hand, even in the convex mold 21, the hot gas diffuses according to the inclination angle of the diffusion jet outlet 3, rises along the side surface from the bottom surface of the convex mold 21, and can heat the molding inner surface 23. As described above, the flame radiated from the diffusion jets 3 and 3 generates an air stream that flows so that the hot gas is brought into contact with the molding inner surfaces 22 and 23, and the molding inner surfaces 22 and 23 are heated by the hot gas. By doing so, the molding inner surfaces 22 and 23 can be heated substantially uniformly. As described above, since a high-temperature type high-pressure mixer 11 is used to radiate a high-temperature flame, the temperature of the hot gas can be increased, and a strong air flow having a high flow velocity can be generated. The heating rate of 23 is increased, and the heating time for a predetermined preheating temperature is shortened.

  On the other hand, the pouring gate 24 immediately below the diffusion jet 3 of the concave mold 20 and the portion of the convex mold 21 just above the diffusion jet 3 are heated by the flow of the above-described hot gas, but other parts. Compared to the above, the heating efficiency by the hot gas tends to be low. However, since the flame radiated from the diffusion jets 3 and 3 also heats the inner block portion 17, it is heated by the radiant heat of the inner block portion 17, assisting the heating action by the hot gas, and molding The inner surfaces 22 and 23 can be heated almost uniformly.

  Thus, in the method of preheating by the preheating device 1 according to the present invention, the concave 20 is formed by the hot gas flow generated by the flame radiated from the diffusion jets 3 and 3 of the preheating gas burner 2. The molded inner surfaces 22 and 23 of the convex mold 21 are heated. For this reason, the molding inner surfaces 22 of the concave mold 20 and the convex mold 21 are brought to a preheating temperature necessary for molding an automobile wheel in which the molten aluminum alloy is properly filled in the cavity and does not cause defects such as sink marks. , 23 can be heated almost uniformly as a whole. Further, unlike the above-described conventional apparatus equipped with a large number of burner nozzles (see FIG. 4), it is not necessary to blow out the mixed gas and suppress the fire so as not to be locally heated. In addition, it is possible to improve the heating rate by radiating a flame having a high ejection speed. For example, the preheating device 1 of the present invention increases the temperature when preheating the concave mold 20 and the convex mold 21 of an automobile wheel as compared with the conventional apparatus (see FIG. 4) provided with many burner nozzles described above. The speed can be improved by about 10% to 20%, and the preheating time can be shortened. Further, the combustion energy per unit time required for preheating can be reduced by about 20% to 30%, and energy saving can be promoted. Thus, the time for the preheating step can be shortened, and the molding cost can be reduced.

  Further, since such a preheating gas burner 2 is provided with diffusion jets 3 and 3 at the top and bottom, flame ignition work, maintenance work, and the like can be performed as compared with the conventional construction having many burner nozzles. There is also an excellent advantage that it can be done easily. Further, since the preheating gas burner 2 is detachable from the gas flow pipe 10 joined to the high-pressure mixer 11, the gas burner 2 can be easily installed. Furthermore, by preparing a preheating gas burner formed according to various casting molds having different shapes, it is possible to easily cope with molding of a plurality of types of automobile wheels. The preheating gas burner 2 according to the present invention is detachable from the high-pressure mixer 11 and thus has an advantage that the automatic equipment can be easily designed even when the preheating work is automated.

  On the other hand, in the above-described embodiment, the upper and lower diffusion jets 3 and 3 of the preheating gas burner 2 are configured such that the upper inclination angle is increased. Can be variously set according to the shapes of the concave mold 20 and the convex mold 21 to be preheated. For example, in a casting mold for an automobile wheel, a relatively small diameter wheel such as 13 inches or 14 inches can be set to a small inclination angle, and a large diameter wheel can be set to a large inclination angle. Also, it is preferable to set the inclination angle appropriately depending on the offset size of the wheel. And it is set as the structure which prepares an ejection nozzle provided with the diffusion jet of such various forms, and makes an ejection nozzle removable by screwing so that the diffusion jet of an appropriate form may be used according to a wheel shape. Is preferred.

  Further, in the above-described embodiment example, the ejection surface portion 18 formed in the diffusion ejection ports 3 and 3 and having the ejection holes 19 formed uniformly in the circumferential direction has a concave shape. 20 and the shape of the convex mold 21 can be set as appropriate. For example, it is possible to provide the ejection surface portions 18 having different numbers of ejection holes 19 in the diffusion ejection port 3 facing the concave mold 20 and the diffusion ejection port 3 facing the convex mold 21, respectively. Further, when the concave mold and the convex mold have an asymmetric shape in the circumferential direction, the number of the ejection holes 19 facing the region having a large area on the inner surface of the molding is increased or the diameter is increased. Thus, the entire inner surface of the molding can be heated uniformly.

  In the above-described embodiment, an umbrella-shaped enclosure that covers the upper side and the side of the convex mold 21 at the upper standby position may be provided. Thereby, the hot gas generated by the flame radiated from the diffusion jetting port 3 on the upper side of the preheating gas burner 2 can be sufficiently brought into contact with the molding inner surface 22, so that the molding inner surface 23 of the convex mold 21 is more appropriate. And it becomes possible to heat efficiently.

  The preheating method and the preheating gas burner 2 of the present invention can be applied not only to the above-described casting mold for automobile wheels, but also to molds for molding various other cast products.

It is side sectional drawing showing the state which installed the preheating apparatus 1 concerning this invention. It is a top view from the top showing the state which installed the preheating apparatus 1 concerning this invention. It is the (a) side sectional view and the (b) bottom view showing the jet nozzle 6 of the preheating gas burner 2 concerning this invention. It is a sectional side view showing the conventional preheating apparatus 50 provided with many burner nozzles.

Explanation of symbols

2 Gas Burner for Preheating 3 Diffusion Jet 4 Gas Outflow Path 5 Communication 11 High Pressure Mixer
14 Outer slope 15 Outer umbrella part 16 Inner slope 17 Inner block part 19 Ejection hole 20 Concave 21 Convex 22, 22 Molding inner surface

Claims (5)

Umbrella-shaped diffusion jets that communicate at the side with a mixer that mixes fuel gas and air gas to generate mixed gas, and that have gas outlets that open up and down, and that open and widen at each open end. A gas burner that forms an outlet,
Each diffusion jet is arranged so as to be opposed to each center of the concave and convex shapes spaced apart in the vertical direction and set as a standby position,
A casting mold preheating method characterized by heating a concave mold and a convex mold inner surface by radiating a flame ignited with a mixed gas from a diffusion outlet. It is arranged at a central position between the concave mold and the convex mold that are separated in the vertical direction and set as a standby position,
Umbrella-shaped diffusion jets that communicate at the side with a mixer that mixes fuel gas and air gas to generate mixed gas, and that have gas outlets that open up and down, and that open and widen at each open end. A gas burner for preheating a casting mold, wherein an outlet is formed.   A diffusion jet outlet is formed between an outer umbrella portion having an outer inclined surface that expands and inclines outward, and an inner block portion having an inner inclined surface formed along the outer umbrella portion. The gas burner for preheating a casting mold according to claim 2, wherein the gas burner is for casting.   4. The preheating gas burner for a casting mold according to claim 2, wherein the diffusion outlet comprises a plurality of ejection holes for ejecting the mixed gas from the gas outflow passage. The gas burner for preheating a casting mold according to any one of claims 2 to 4, wherein the gas outflow path is provided with a communication portion that allows the mixer to be attached and detached.

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