JP2011189403A - Method for casting annular member, and cast annular member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a casting method which solves a difference in hardness in the circumferential direction of annular cast members and a difference in hardness between products in the case of multi-work processing, and obtains products of stable quality, and to provide the products. <P>SOLUTION: Molten metal melted from the side of the central axis in molds having cavities C for annular members is radially filled into the cavities C. Particularly, in a stack mold casting method, a plurality of almost circular molds 11 to 13 provided with cavities C for annular members are stacked with the central axis of the circular shape as a vertical direction, a runner 18 passing through the common central axis of the plurality of molds 11 to 13 is provided to compose a stack mode mold 10, the molten metal is poured from a gate 19 provided at the upper part of the runner 18, the molten metal is introduced into the molds 11 to 13 of each layer stacked via the runner 18, the molten metal is filled from the inside in the radial direction in the cavities C of the respective mold toward the outside, and, after cooling, annular members formed in the cavities are taken out. The mold 12 located at the middle of the plurality of cavities C may be provided with a cooling plate 21. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for casting an annular member, in particular, a casting method for minimizing product quality variation and defects of the annular member, and further minimizing quality variation between the annular members taken by a plurality, and The present invention relates to a cast annular member obtained by the casting method.

  2. Description of the Related Art Conventionally, a casting method for obtaining a product having a desired shape by pouring molten metal into a mold formed of foundry sand so as to have a cavity having a desired shape has been widely used. If it is a large product, one product is obtained from one gate, but if it is a product of a certain size or less, it is connected to multiple product cavities from a water channel branched from the gate, and multiple products are produced by one pouring. In general, the production efficiency is increased by taking out.

  A brake disc material 1 for a vehicle shown in FIG. 6 is also cited as one specific example of an annular member manufactured by such casting. The brake disc material 1 is generally composed mainly of a ring portion 2 that generates a braking force by being sandwiched between friction materials called calipers, and a hub portion 3 that is attached to the axle on the shaft core side and holds the whole. In the illustrated example, a plurality of cooling through holes 4 called ventilated disks are formed in the ring portion 2 radially.

  For example, in Patent Document 1, hot water is poured into a cavity from a weir provided at one point corresponding to the outer periphery of the ring portion 2 of the brake disc material 1, and from here to the entire circumference of the ring portion. It is configured so that hot water can be used. In Patent Document 2, which is an example of taking a plurality of products, hot water is poured into four brake disc cavities from one gate through a runner, and four pieces can be taken. In a mass production type casting plant in which a large number of molds are transported side by side on a conveyor, and the pouring is sequentially performed on the molds, the number of the plurality of molds is limited by the size of the molds that form the molds. In Patent Document 2, four pieces are taken, but depending on the mold size and product size, there are cases where two pieces are limited due to the restrictions of the form. In such a case, the runner diverges into two from the gate and is connected to each brake disk cavity.

  As another method for casting a brake disc material in the prior art, Patent Document 3 discloses a lotos wax method. In the lost wax method, a wax mold imitating a product is formed, sand is piled up around the wax mold and hardened, and then heated to melt only the internal wax mold to obtain a desired cavity. It is known as a method suitable for precision casting.

  Apart from this, a stack mold method is known as one of casting methods. In the stack mold method, a number of flat molds are stacked to form a plurality of layers of cavities in the vertical direction, and hot water is caused to flow into each cavity through a water channel directed downward from a gate provided above. Multiple product collection is possible. For example, Patent Document 4 discloses a method of taking a large number of flat parts in a tree shape at each layer by using a stack mold method. In this way, the stack mold method is mainly used in the case of taking a large number of relatively small products. If small parts are cast by a general casting method, a cavity for small products is formed. Plural arrangements are made in a plane, and the hot water channel extends long, and the number of products obtained by a single pouring is limited for a large area. In the stack mold method, the loss due to the arrangement of such molds is improved by developing in the vertical direction.

JP 2002-59243 A JP 2007-211182 A Japanese Patent Laid-Open No. 08-267176 JP 2001-129640 A JP 62-240140 A

  However, the conventional casting method has a problem. Problems with the above-described brake disk as an example will be described with reference to FIGS. FIG. 7A shows an arrangement pattern (plan view) in the mold when two brake disc materials are taken. In the figure, a pair of cavities 6 for brake discs are arranged on a substantially diagonal line of the mold 7, and a runner 8 and a weir 9 provided near the center of the mold 7 close to both of them are both cavities 6. It is tied to At the time of casting, hot water is poured from the pouring gate 22, and molten metal is poured from the hot water passage 8 through the weir 9 into the cavity 6. After that, the material solidified in the cavity 6 is obtained after waiting for cooling, and is further processed into a product through machining.

  FIG. 7B shows the hardness distribution of the brake disc material obtained as described above. The figure shows the measurement result by Brinell hardness (BHN) and its scale. As is clear from the figure, the brake disc material has a hardness near the runner 8 (weir 9) shown in FIG. 7 (a). Is low (hardness of about 206), and the hardness gradually increases with increasing distance from it, and is the highest hardness (about 215) at the position farthest from the runner 8 in the ring portion 2. Between the two, there is a variation between intermediate hardnesses (206 to 215), and the change in the hardness is in a direction extending from a position close to the runner 8 to the opposite side of the runner 8 across almost the center of the brake disc material. It can be seen that the change is inclined.

  FIG. 8 is a graph showing the relationship between the cooling time (horizontal axis) and the temperature change (vertical axis) of the brake disc material obtained by casting as shown in FIG. As shown in the upper right of the graph, the three points P1, P2, and P3 shown in the one brake disc material 1 are selected, and the relationship between time and temperature is plotted. As a result, the point P1 farthest from the runner 8 draws the most rapid cooling curve, conversely, the point P2 closest to the runner 8 becomes the slowest curve, and the point P3 is in the middle. . Generally, when solidifying by cooling an Fe-C molten metal, the densification of pearlite changes as the cooling rate increases, especially as the cooling rate passing through the A1 transformation point (726 ° C for cast iron) increases. Is known to increase. It can be understood that the difference in hardness depending on the position as shown in FIG. 7B is due to the difference in the cooling rate.

  Actually, in the arrangement in the mold 7 as shown in FIG. 7A, the cooling is promoted as the position away from the runner 8 and closer to the mold 7, and the vicinity of the weir 9 located near the center of the mold 7. Then, it can be easily imagined that the cooling rate is low because the heat dissipation efficiency is low. The same applies to the casting method of the type in which hot water is press-fitted in the vertical direction as shown in Patent Document 1. In FIG. 8, the decrease in the cooling rate once around 730 ° C. indicates the passage of the A1 transformation point described above.

  Such a difference in hardness depending on the position is particularly problematic in a functional component (an important safety component) such as a vehicle brake disc. Generally, the higher the hardness is, the better the wear resistance is. Therefore, when a friction material (caliper) is pressed against the brake disc during braking of the vehicle, this hardness difference becomes a problem. Since the brake disc obtained from the brake disc material 1 shown in FIG. 6 rotates about its own rotational symmetry axis, the ring portion 2 against which the friction material is pressed has a high hardness as shown in FIG. 7B. The part and the low part are mixed. As a result, the amount of wear in the circumferential direction of the ring portion 2 varies due to the long-term repeated frictional action of the friction material. When this is seen from the friction material (caliper) side, it means that the other side (ring part 2) that comes into frictional contact becomes wavy, and pressing the friction material against this causes judder (chatter vibration) and abnormal noise. Cause it to occur. In severe cases, the diffusion of vibration can affect the braking performance itself.

  In order to alleviate such a problem, for example, in Patent Document 2 (four examples are displayed), a hot water path is extended so that hot water flows into the cavity from a plurality of positions of the ring portion of the brake disc material. Yes. However, even with this method, even if a certain degree of improvement is seen, the fact that the distance from the gate is not uniform is unchanged, and of course the heat radiation effect at the position where the cavities face each other and the outer peripheral part close to the formwork Since there is a difference between them, it cannot be a complete solution to eliminate the hardness difference in the ring part of the brake disc material.

  The lost wax method as shown in Patent Document 3 is suitable for casting small items and precision parts as illustrated, but handling of the lost wax itself is troublesome, resulting in inferior mass productivity and cost disadvantages. In particular, it is not suitable for manufacturing large disc brake materials.

  The problem that the hardness difference of the product based on the difference in the cooling rate occurs is a phenomenon that can also be seen in the stack mold method shown in Patent Document 4. The situation is the same as the above casting method that the cooling rate is slow (low hardness) near the gate and high (high hardness) near the formwork. ) Among the molds, there is a problem that the cooling rate is high in the uppermost stage and the lowermost stage, and the product in the mold stacked between the two has a low cooling rate. This is based on the reason that the heat dissipation efficiency is inferior because one of the uppermost and lowermost layers is in contact with the outside air, while the mold in the middle is located close to the hot product on both sides. .

  As described above, the present invention eliminates the hardness difference in the circumferential direction of the cast annular member in the conventional casting method, and also the difference in the cooling rate between the uppermost stage, the lowermost stage, and the both in the stack mold method ( An object of the present invention is to provide a casting method for producing an annular member having a stable quality, and a product obtained by the casting method.

  In the present invention, molten metal is poured from the central axis side of the cavity for the annular member, and hot water is radially filled into the cavity, thereby eliminating the variation in quality of the annular member alone, and the intermediate layer of the stack mold method having multiple stages Solves the above-mentioned problems by disposing the cooling plate to eliminate the difference in the cooling rate of each stage, and specifically includes the following contents.

  That is, one aspect according to the present invention is a casting method for casting an annular member, wherein a pouring gate for pouring water from above is arranged at the center of a mold in which a cavity for the annular member is arranged horizontally, and is connected to the pouring gate. The hot water is introduced into the cavity from the center side of the cavity through the hot water channel, and the hot water is cast from the center side of the cavity toward the outer periphery of the cavity that is radially outward of the annular member. The present invention relates to a casting method.

  According to another aspect of the present invention, there is provided a method for casting an annular member in which an annular member is cast by a stack mold method, wherein a substantially circular mold having a cavity for the annular member is placed with the substantially circular central axis perpendicular thereto. A plurality of stacks, and a stack mode mold is formed by providing a runner that passes through a common central axis of the plurality of molds, and hot water is poured from a spout provided above the runner, and the runner is passed through the runner. The method comprises the steps of guiding hot water into the molds of the stacked layers, filling the hot water from the radially inner side to the outer side in the cavity of each mold, and taking out the annular member formed in the cavity after cooling. The present invention relates to a casting method.

  The casting method can control the cooling of the stacked cavity portions by using the cooling plates for heat dissipation disposed between the cavities stacked in the stack mold.

  According to still another aspect of the present invention, there is provided a stack mold for casting an annular member by a stack mold method, wherein a plurality of substantially circular molds having cavities for the annular member, wherein the substantially circular central axis is provided. A plurality of molds stacked as a common axis with the axes oriented in the vertical direction, a runner formed through each of the central axes of the plurality of molds, and a spout disposed at the upper end of the runner The hot water poured from the gate is introduced into each cavity via the hot water channel, and is filled from the central axis side in each cavity toward the radially outer side. The present invention relates to a stack mold.

  Of the plurality of molds stacked in the stack mold, the mold part located in the middle of the upper and lower cavities is a cooling plate that is at least partially embedded in the part and is not exposed in the cavity. Furthermore, you may provide.

  Still another aspect of the present invention relates to an annular member formed by casting, which is manufactured by the casting method described above or by using the stack mold described above. The annular member can be a vehicle brake disc.

  By carrying out the present invention, the difference in hardness in the circumferential direction within a single annular member is eliminated, and problems associated with uneven wear when used as a functional component are prevented, thereby improving the reliability of the product. In addition, there is no difference in hardness between multiple parts, especially between layers in the stack mold method, and a balanced performance is exhibited when the product is used in combination of a pair or more. Product can be provided.

It is side surface sectional drawing which shows the casting_mold | template structure used with the casting method which concerns on embodiment of this invention. It is a schematic diagram which shows the hardness distribution of the product obtained by the casting method shown in FIG. It is side surface sectional drawing which shows the casting_mold | template structure used with the casting method which concerns on other embodiment of this invention. It is a graph which shows the cooling curve of the product obtained by the casting method which concerns on each embodiment of this invention. It is a graph which shows the hardness distribution of the product obtained by the casting method which concerns on each embodiment of this invention. It is a perspective view which shows the external appearance of a brake disc raw material. It is explanatory drawing which shows the mold distribution example (plan view) of the brake disc raw material by a prior art, and the hardness distribution of the product obtained by this. It is a graph which shows the cooling curve of the product obtained by the casting method by a prior art.

  A casting method according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an outline of a stack mold used in a method for casting a brake disc material according to the present embodiment. The figure shows a cross section of the stack mold 10 according to the present embodiment cut in the vertical direction. In each of the following embodiments, a case where the brake disc material 1 shown in FIG. 6 is cast will be described as an example. However, the casting method according to the present embodiment is not limited to this, It is equally applicable to the production of annular members that preferably have a uniform quality in the circumferential direction.

  In FIG. 1, the stack mold 10 includes a lowermost layer mold 11, four intermediate layer molds 12, and an uppermost layer mold 13 in total, which are stacked in a vertical direction in order from the bottom. It is sandwiched and fixed by a long bolt 17 which is a fixing tool (or other fixing methods such as a clamp and a weight may be used). Each of the intermediate layer molds 12 provides a pattern of the upper surface of the product positioned below on the lower surface side, and provides a support pattern for supporting the intermediate layer mold 12 positioned above on the upper surface side. Further, a support pattern for supporting the intermediate layer mold 12 positioned above is provided on the upper surface side of the lowermost layer mold 11, and a pattern on the upper surface of the product positioned lower is provided on the lower surface side of the uppermost layer mold 13. By stacking them with the central axes aligned as shown in the figure, a stack mold 10 in which cavities C for casting five brake disc materials are arranged in the vertical direction is obtained. In the example shown in FIG. 1, the intermediate layer mold 12 is formed by superposing the lower mold 12 a and the upper mold 12 b with the cavity C in between. It shall be called the layer mold 12.

  In addition, the lowermost mold 11 and the uppermost mold 13 can be made common with the intermediate mold 12 by applying predetermined shapes to the upper and lower pressing plates 14 and 16. Further, in the example shown in the figure, five pieces are taken, but other pieces can be taken by increasing or decreasing the number of intermediate layer molds 12. For example, it is possible to obtain only one piece (in this case, a normal casting method), and it is possible to obtain a number larger than five.

  Each of the molds 11 to 13 is provided with a through hole that extends in the central axis direction at a portion that is a rotationally symmetric axis of the brake disk. By overlapping the molds 11 to 13, the through holes are connected in the vertical direction. A runner 18 is formed. A stack mold 10 is formed by attaching a gate 19 to the upper end of the runner 18. The stack mold 10 is housed in a size cylinder (form frame) 25 conveyed by a conveyor, and the periphery is further surrounded by sand to prepare for pouring. When the molds 11 to 13 are stacked, the dams are formed so that weirs connected from the runner 18 to the cavities C are formed between the molds. In the present embodiment, a weir is provided between the lower mold 12a and the upper mold 12b of the intermediate layer mold 12 (between the lower mold 12a and the lowermost mold 11 in the lowermost stage).

  The operation when using the stack mold mold 10 configured as described above is as follows: molten hot water (molten iron) is poured into the pouring gate 19 of the prepared stack mold mold 10, and the hot water flows along the runner 18. While descending, the cavities C are filled into the cavities C through the weirs of the molds 11 to 13 (not shown). Then, it is allowed to stand until it falls to a predetermined temperature, and after cooling, the size cylinder 25 is removed, the long bolt 17 is removed, the stack mold 10 is disassembled, and the product is taken out. Subsequent processing steps are the same as in the prior art. In order to obtain a stable product, it is preferable to wait until the temperature drops to a temperature below the A1 transformation point during cooling.

  As apparent from the drawings, according to the method for casting the brake disc material 1 according to the present embodiment, the runner 18 is provided at the center of the mold, and the hot water flows through the center of the mold and from there around each cavity. It will be poured into C. The flow of hot water at that time spreads radially from the hub portion 3 at the center of the brake disc material 1 toward the ring portion 2 (see FIG. 6) at the outer periphery. In addition, since the entire periphery of the stack mold 10 is open to the outside air (or is open to the outside air through sand on the outer periphery thereof), the ring portion 2 of the brake disc material 1 that is the product is a circle. The entire circumference in the circumferential direction is evenly cooled. As a result, in the circumferential direction of the ring portion 2, excellent characteristics that cannot be obtained by the prior art are obtained.

  FIG. 2 is a schematic diagram showing the hardness distribution of the brake disc material 1 obtained by the present embodiment. The distribution is a clean concentric circle centering on the central axis, indicating that the distribution is evenly cooled in the circumferential direction from the center to the periphery. In terms of hardness, it spreads between the central side 203 and the outer peripheral side 216 in Brinell hardness (BHN), but it is almost zero or 1 at all in terms of the hardness difference in the circumferential direction of the brake disc material 1. It has a very good hardness distribution. This is consistent with the above-described cooling from the periphery of the ring portion 2 on the outer periphery and spreading sequentially to the central portion.

  When viewed from the usage form of the brake disc, the caliper exerts a frictional force across the ring part 2 of the rotating brake disc, so there is almost no difference in hardness in the sliding direction (rotating direction of the brake disc). Even if the ring portion 2 is worn, the amount of wear is uniform in the circumferential direction. In the radial direction of the ring portion 2, even if a difference in wear occurs due to a difference in hardness, the caliper can easily follow this difference in wear because it is not in the rotational direction. As a result, uneven wear in the circumferential direction (rotational direction) in the ring portion 2 as in the prior art does not occur, and therefore occurrence of judder and abnormal noise can be effectively prevented. In addition, the brake performance is not affected, and a more important effect of eliminating uneven wear and extending the life of the brake disk is obtained.

  When casting an annular member using the stack mold method, a technique of providing a gate and a runner in the center of the annular member and uniformly spreading the hot water radially around the periphery is a unique idea in the present invention. In the prior art, as shown in Patent Document 4, a stack mold method has been widely used when a large number of small parts are arranged in a tree shape to obtain a large number. Further, it is not very common to apply the stack mold method to a relatively large product such as the brake disc material 1, and even when the stack mold method is used for casting of the annular part, the gate is used. In general, the runner is provided outside the annular part (for example, see Patent Document 5). The inventors of the present application have conceived the application of an unprecedented stack mold method based on a new idea, and have found a technique for eliminating the circumferential hardness difference in the annular member.

  In addition, according to the method according to the present embodiment in which the hot water is uniformly distributed radially from the central hub portion to the surrounding ring portion in the cavity, the hot water as in the prior art can be obtained from one direction. It is possible to effectively prevent the occurrence of defects such as “bath” and “bath” caused by flowing to the surroundings (see, for example, Patent Document 1).

  Next, a casting method according to the second embodiment of the present invention will be described with reference to the drawings. FIG. 3 shows an outline of the stack mold 20 used in the method for casting a brake disc material according to the present embodiment. FIG. 3 shows a cross-sectional view of the stack mold 20 cut in the vertical direction. This figure corresponds to FIG. 1 shown in the previous embodiment, and the same elements as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. The stack mold 20 according to the present embodiment is characterized in that a cooling plate 21 is provided on the intermediate layer 12 with respect to the stack mold 10 shown in FIG. Other configurations are the same as those of the previous stack mold 10.

  In the casting method using the stack mold 10 according to the first embodiment, a uniform hardness distribution is obtained in the circumferential direction as shown in FIG. 2, and the conventional technique as shown in FIG. Although this is a significant improvement over the brake disc, this embodiment takes this one step further and provides technology that also suppresses the hardness difference between multiple products obtained by a single casting process using the stack mold method. To do.

  FIG. 4A shows the relationship between the cooling temperature and time of five products obtained by a single casting using the stack mold 10 shown in the first embodiment. X1 to X5 are given to the respective brake disks 1 obtained by the respective cavities C of the stack mold 10 shown in FIG. 1 by the symbols X1 to X5 in the order from the lower stage to the upper stage. . As is clear from FIG. 4A, the cooling of X1 and X5 in the lowermost layer and the uppermost layer is fast, and the cooling of X2 to X4 in the intermediate layer is slow. Referring to FIG. 1, since the lowermost layer mold 11 and the uppermost layer mold 13 of the stack mold mold 10 are opened to the outside and have good heat dissipation properties, reference numerals X1 and X5 located immediately above and immediately below are indicated. It can be understood that the cooling of the brake disc 1 is fast. On the other hand, the brake disc material 1 of X2 to X4 cast by the intermediate layer mold 12 is sandwiched between other high-heat brake disc materials 1 positioned up and down even though the outer periphery is open, and the cooling performance is high. It will be inferior.

  Such a difference in hardness between products obtained in a single casting can have an unfavorable effect on some products. If the product is used as a single product and such variations are within the allowable range, there is no problem at all. However, it can be a problem in products that are used in pairs or in combination. Especially for brake discs for vehicles, when products with such variations are used on both the left and right wheels, there is a difference in the amount of wear due to the difference in hardness between the left and right, resulting in an unbalance in the left and right life. It can also be a distant cause of braking effect.

  The stack mold 20 according to the present embodiment solves such a problem. Returning to FIG. 3, the cooling plate 21 is provided in each intermediate layer mold 12 as a countermeasure. In the present embodiment, an annular cooling plate 21 (by iron plate, casting, sintering, etc.) is used, and this is configured by embedding the intermediate layer mold 12 in the mold. This cooling plate 21 can be reused repeatedly. In the intermediate layer mold 12 according to the present embodiment, the outer periphery of the cooling plate 21 is protruded to the outside from the intermediate layer mold 12, thereby further enhancing the heat dissipation effect. Specifications such as the amount of protrusion to the outside and the thickness of the cooling plate can be appropriately selected according to desired cooling characteristics.

  In the illustrated example, one cooling plate 21 is provided for each intermediate layer mold 12, but a plurality of cooling plates 21 may be provided. Alternatively, the thickness and shape of the cooling plate 21 may be changed according to the position of the mold. Furthermore, without using the cooling plate 21 as an annular member, a large number of rod-like members such as square bars and round bars may be arranged so as to extend radially around the intermediate layer mold 12. The “cooling plate” referred to in the present embodiment includes these members arranged in the intermediate layer mold 12 for the purpose of radiation cooling. The operation during casting is the same as in the previous embodiment.

  FIG. 4B shows a cooling curve of five products obtained by one casting using the stack mold 20 provided with the cooling plate 21 according to the present embodiment. Brake disk materials obtained from the respective cavities from the lower stage to the upper stage of the stack mold 20 are denoted by symbols Y1 to Y5 in the order. As is clear from the figure, only a slight difference is seen in the cooling rate between Y1 to Y5, showing almost the same cooling tendency, and when the cooling plate 1 shown in FIG. 4 (a) is not used. Compared to the cooling curve, the decrease in the variation is very remarkable.

  A further effect obtained by providing the cooling plate 21 is an improvement in cooling performance by heat radiation in the entire stack mold 20. When the cooling plate 21 shown in FIG. 4A is not used, even at X1 and X5 where the cooling rate is relatively fast, the temperature remains at 800 ° C. or higher after 30 minutes. On the other hand, in this embodiment using the cooling plate 21 shown in FIG. 4B, all of Y1 to Y5 are lowered to around 800 ° C. in 20 minutes, and the entire stack mold 20 is cooled. The improvement of sex is clearly shown.

  This improvement in cooling performance can lead to an improvement in productivity. In order to obtain an appropriate and stable material including hardness as a disc brake, it is preferable to wait for the passage of the A1 transformation point to open the mold and take out the product. In the case with the cooling plate shown in FIG. 4 (b), after casting, after about 50 minutes that seem to have passed the A1 transformation point (726 ° C for iron), the frame is released and Removal is possible. On the other hand, in the case of no cooling plate shown in FIG. 4A, it takes about 60 minutes to pass the transformation point even in X1 and X5 having excellent cooling performance, and the transformation of all the disc brakes X1 to X5. It can be assumed that it takes about 90 minutes to pass the point. This improvement in the cooling time leads to a reduction in cycle time in the casting process, and has the effect of increasing productivity.

  FIG. 5 shows hardness measurement results at six points around the brake disc material 1 when (a) the cooling plate 21 is not used and (b) when the cooling plate 21 is used. When the cooling plate 21 is used, it can be seen that the variation among the disc brake materials 1 is eliminated, and at the same time, the variation in hardness among all the five disc plates 1 is converged to a high level. This means that the quality of the brake disc material 1 is stable. Note that the hardness shown in FIG. 5 is represented by Brinell hardness BHD, and a larger value means a lower hardness because it is expressed by the diameter of the indentation. Between the two graphs, the hardness with the cooling plate (Fig. 5 (b)) is lower than the hardness without the cooling plate (Fig. 5 (a)). In the case where there is a cooling plate, the measurement is made after passing through the A1 transformation point, whereas in the case where there is no cooling plate (FIG. 5A), the frame is released before passing through the A1 transformation point, and then rapidly cooled with outside air. As a result, the hardness measurement result is high.

  The cooling plate 21 according to the present embodiment is based on an idea unique to the present application that is not found in the stack mold method according to the prior art. The use of “cooling metal” is known in the prior art, and an example of its use is also found in the stack mold method (see, for example, Patent Document 4). However, the chiller is disposed so as to be exposed inside the cavity and in direct contact with the product, and is intended to locally cool a part of the product to improve the physical properties of the part. In this respect, it is technically different from the cooling plate according to the present embodiment in which at least a part of the mold is embedded in the mold without improving the heat dissipation of the entire mold without being exposed inside the cavity. .

  According to the casting method according to the present embodiment, a stable quality product can be obtained regardless of the arrangement position in the mold even when the stack mold casting method in which a plurality of layers are cast at the same time is used. In particular, even in the case of a product that is used by combining a plurality of products at the same time, the product can be used without being bothered by managing variations among products.

  INDUSTRIAL APPLICABILITY The present invention can be widely used in the technical field of casting and in the technical field of manufacturing, selling, and using machined parts using the cast material.

1. 1. brake disc material, 2. ring part; Hub part, 6. Cavity, 7. Formwork, 8. 8. Yuji, 9. Weir, 10. 10. Stack mold type Bottom layer type, 12. Intermediate layer type, 13. Top layer type 14,16. Mold plate, 18. Yuji, 19. Yuguchi, 20. 21. Stack mold type Cooling plate, 22. Yuguchi.

Claims (7)

In a casting method for casting an annular member,
A pouring gate for pouring from above is arranged in the center of the mold with the cavity for the annular member arranged horizontally,
The hot water is led into the cavity from the center side of the cavity through a hot water passage connected to the gate,
A casting method, wherein casting is performed so as to fill hot water from the center side of the cavity toward the outer periphery of the cavity that is radially outward of the annular member. In the casting method of the annular member for casting the annular member by the stack mold method,
A plurality of substantially circular molds having cavities for the annular member are stacked with the substantially circular central axis being vertical,
A hot water passage penetrating a common central axis of the plurality of molds is provided to constitute a stack mode type,
Pour hot water from a spout provided above the runway and guide the hot water into the molds of the stacked layers through the runway,
Filling the hot water from the radially inner side to the outer side in the cavity of each mold,
A casting method comprising the step of taking out an annular member formed in the cavity after cooling.   The casting method according to claim 2, wherein cooling of the mold is promoted by using a cooling plate for radiating heat disposed between the cavities stacked in the stack mold. In a stack mold for casting an annular member by a stack mold method,
A plurality of substantially circular molds having cavities for the annular member, wherein the plurality of molds are stacked with the substantially circular central axis as a common axis and oriented in the vertical direction;
Runners formed through the central axes of the plurality of molds, and
It is composed of a gate that is arranged at the upper end of the runway,
The hot water poured from the gate is introduced into each cavity via the hot water channel, and is filled from the central axis side in each cavity toward the radially outer side. Stack mold type.   Of the plurality of stacked molds, a mold part located in the middle of the upper and lower cavities is provided with a cooling plate that is at least partially embedded in the part and is not exposed inside the cavity. The stack mold according to claim 4.   An annular member formed by casting, using the casting method according to any one of claims 1 to 3, or the stack mold according to any one of claims 4 to 5. An annular member manufactured by the method described above. The annular member according to claim 6, wherein the annular member is a brake disc material for a vehicle.