JPH0562015B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a casting method that is applied to manufacturing cast products such as engine cylinder blocks, for example.

(Prior art) The casting method, which is widely used in the production of various metal products, involves creating a cavity in the mold that corresponds to the shape of the product;
A runner communicating with the cavity is provided, and a molten metal is injected into the cavity through the runner, and the molten metal is solidified within the cavity to obtain a product in a predetermined shape.

By the way, in such a casting method, a sand mold made of solidified casting sand is usually used as the mold, but in this case, the flow of molten metal that occurs at the introduction part from the runner to the cavity during pouring, etc. Due to this turbulence, the casting sand around the runner or cavity may be pulled off by the flow of molten metal, and if this is brought into the cavity, a product containing sand will be generated. . Therefore, problems such as damage to the cutter occur during machining of the product, for example.

To solve this problem, it is possible to slow down the pouring speed to avoid turbulence that could entrain foundry sand during pouring, but in this case, the pouring process will take a long time, and It is conceivable to slow down the pouring speed only at the start of pouring, when turbulence is likely to occur, and then gradually increase the speed, but changing the pouring speed midway in this way is extremely troublesome, so it is recommended to automate pouring. If so, the control becomes complicated.
In addition, a space is provided in advance at the entrance from the runner to the cavity in the mold to collect foreign matter, and the casting sand stripped from around the runner during pouring is collected in the space. There is a method to prevent the product from being brought into the cavity, but this method creates a fleshy part in the product that corresponds to the space, and requires extra processing to remove this part.

(Objective of the Invention) The present invention addresses the above-mentioned problems regarding the casting method, and is capable of pouring molten metal into a cavity through a runner provided in a mold without causing any disturbance in the flow of molten metal. To realize a method for quickly pouring hot water. This eliminates casting sand from being brought into the cavity due to turbulence generated during pouring, without complicating pouring work or deteriorating efficiency, and prevents sand-containing products from being produced. With the goal.

(Structure of the Invention) That is, the present invention provides a casting method in which molten metal is poured into a cavity through vertical runners in a mold, and when the molds constituting the runners are joined, there is a gap between the joining surfaces at a middle height and in the center. The present invention is characterized in that a plate member provided with an opening smaller than the diameter of the runner is interposed so as to be located within the runner. In that case, the plate member is formed of a material that gradually melts due to the heat of the molten metal, such as a tinned steel plate,
Further, the plate thickness is also set so as to obtain the required molten state.

Therefore, when pouring molten metal into the runner, the molten metal initially flows little by little into the lower part of the runner or cavity through the small diameter opening of the plate member, and as the plate member melts. As the diameter of the opening gradually increases, the speed at which the molten metal flows into the cavity increases. In addition, since the plate member has a medium height, even if the casting sand is stripped off around the sprue above the runner, this sand will be captured by the peripheral part of the plate member and transferred to the cavity side. It is prevented from being brought in.

(Effects of the Invention) As described above, according to the casting method of the present invention, when pouring molten metal into the mold, the molten metal initially flows into the cavity little by little, and as the plate member melts, the flow rate gradually increases. This makes it possible to prevent the occurrence of turbulence that would occur if a large amount of molten metal is poured into the cavity from the beginning, and the entrainment of casting sand caused by this turbulence. In addition, cast sand stripped off around the sprue etc. is captured by the plate member and prevented from being carried into the cavity side. In this way, the casting sand forming the mold can be prevented from being brought into the cavity without deteriorating the efficiency of the pouring operation, and the generation of products with sand mixed in can be prevented.

(Example) Examples of the method of the present invention will be described below.
First, the structure of the mold used in manufacturing the cylinder block of the engine to which this embodiment is applied will be explained. In this embodiment, as shown in FIG. 1, a plurality of hollow bore cores 2...2 are arranged in a row to form a plurality of cylinder parts and skirt parts of a cylinder block, and these bore cores 2... A water jacket core 3 that is fitted to the outside of the portion forming the cylinder portion in 2 to form the water jacket of the cylinder block, and front ends disposed at both ends of the rows of the bore cores 2...2, respectively. A core assembly 1 composed of a core 4 and a rear end core 5 is used. This core assembly 1
The two bore cores 2', 2' located in the middle of the bore cores 2...2 are provided with recesses 6a, 6a having a semicircular cross section on their opposing surfaces, and these are joined. A runner 6 is formed that penetrates in the vertical direction (width direction of the core assembly 1). Also,
A relatively shallow counterbore-shaped recess 7 is formed around the upper end opening of the runner 6.

These cores 2 to 5 are set as an assembly 1 as shown in FIG. 2 between a pair of upper molds 8 and lower molds 9 using baseboards 10, thereby producing a product. A cavity 11 having a shape corresponding to a cylinder block is formed. Here, the upper mold 8 is provided with an upper runner 12 that penetrates downward from the upper surface and continues to the upper end of the runner 6 in the core assembly 1, and
The upper end opening of this runner 12 is widened and formed into a sprue 13. Further, the lower mold 9 is provided with a lower runner 14 that communicates the lower end of the runner 6 with the lower part of the cavity 11. The molds such as the cores 2 to 5, the upper mold 8, and the lower mold 9 described above are all sand molds formed by hardening casting sand.

However, when a cylinder block is cast using the mold as described above, a plate member 15 as shown in an enlarged view in FIG. 4 is also used. This plate member 15 is formed of a tin-drawn steel plate having a thickness in the range of 0.5 to 1.2 mm, for example, and has a medium-height overall shape with a conical portion 16 projecting upward and a flange portion 17 around its lower end. In addition, the upper end of the conical portion 16 is an opening 18, and in this embodiment, an insert blade portion 19 is provided on the outer peripheral edge of the flange portion 17 to project upward. The diameter at the lower end of the conical part 16 is the same as that of the upper die 8 and the core assembly 1 (bore core 2'2').
The diameter of the opening 18 is approximately equal to the diameter of the runners 12 and 6 in
The diameter is smaller than that of Nos. 2 and 6.

Next, a casting method using the mold (core assembly 1, upper mold 8, and lower mold 9) and plate member 15 will be described.

First, as shown in FIG. 1, the cores 2 to 5 are assembled to form a core assembly 1, which is then set in the lower mold 9 as shown in FIG. Next, the plate member 15 is placed so as to cover the upper end opening of the runner 6 formed between the facing surfaces of the intermediate bore cores 2', 2' in the core assembly 1. At this time, the plate member 15 is placed so that the conical part 16 protrudes upward, and the flange part 17 is formed in a recess provided around the opening of the runner 6 on the upper surface of the bore cores 2', 2'. It is stored in 7. Finally, the upper mold 8 is placed from above the core assembly 1. As a result, a cavity 11 having a predetermined shape is formed, and from the sprue 13 on the upper surface of the upper mold 8 to the upper runner 12 in the upper mold 8, the intermediate runner 6 in the core assembly 1, and the lower runner in the lower mold 9. A series of runners 20 leading to the cavity 11 via the channel 14 will be formed, but at this time, the plate member 15 is interposed between the core assembly 1, the upper mold 8, and the joint surfaces in the runner 20. I will do it. Incidentally, the plate member 15 is securely fixed between the joint surfaces by inserting the insertion blade portion 19 provided on the outer peripheral edge of the flange portion 17 into the lower surface of the upper mold 8.

After the mold matching is completed in this way, when molten metal is injected from the sprue 13, the molten metal passes through the runners 20 (upper runner 12, middle runner 6, lower runner 14) and enters the cavity 11. At this time, the molten metal passes through the opening 18 of the plate member 15 interposed in the middle of the runner 20 and flows downward. In this case, since the diameter of the opening 18 is smaller than the diameter of the upper runner 12 and the intermediate runner 6 above and below the plate member 15, a large amount of molten metal is injected into the sprue 13. Also, at the beginning of pouring, the molten metal flows into the cavity 11 from the lower part of the runner 20 little by little. Therefore, the flow of the molten metal is not disturbed unlike when a large amount of molten metal is injected into the cavity from the runner at once, and the molten metal flows quietly into the cavity 11. This prevents the casting sand from the bore cores 2', 2' and the lower die 9 that form the surrounding area from being stripped off by the flow of the molten metal at the introduction part from the runner 20 to the cavity 11, etc. gone,
Casting sand is prevented from being carried into the cavity 11.

Then, when the molten metal is continuously injected from the sprue 13, the conical part 16 of the plate member 15 is melted by the heat of the molten metal, and the diameter of the opening 18 in the plate member 15 gradually increases, and eventually the runner It becomes approximately equal to the diameter of 12,6. Therefore, the flow speed of the molten metal into the cavity 11 gradually increases, but after the molten metal has already been injected into the cavity 11 to a certain extent, the flow is not disturbed even if the flow speed increases. Therefore, the casting sand is not stripped off and brought into the cavity 11, and moreover, pouring into the entire cavity 11 is quickly completed.

On the other hand, at the beginning of pouring, the casting sand may be peeled off around the sprue 13, and this casting sand tries to flow downward through the upper runner 12 together with the molten metal. Since the casting sand mainly passes through the periphery of the runner 12, when it falls to the joint between the runner 12 and the intermediate runner 6, it is received by the plate member 15, and the fourth
As shown by the chain line X in the figure, the particles will be deposited between the outer surface of the conical portion 16 of the plate member 15 and the inner surface of the runner 12. This casting sand adheres to the inner surface of the runner 12 at this position and does not fall downward even after the plate member 15 is melted.

In this way, when pouring, the casting sand is poured into the cavity 1.
This prevents the molding sand from being brought into the interior of the mold, thereby preventing the production of products mixed with casting sand. In particular, this method does not require operations such as slowing down the pouring speed or changing the speed midway through, and therefore has the advantage of not complicating the pouring work or deteriorating efficiency. be.

Since the plate member 15 will be melted and mixed into the structure of the product, it is desirable to form it from the same type of material as the molten metal, and the thickness of the plate will depend on the temperature of the molten metal, the amount of injection, etc. will be set.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; Fig. 1 is a perspective view of a core assembly used in casting a cylinder block to which the embodiment is applied, and Fig. 2 shows a state in which molds are assembled. 3 is a sectional view taken along the line of FIG. 2, and FIG. 4 is an enlarged sectional view of a main part. 1, 8, 9... mold (1... core assembly, 8...
upper mold, 9...lower mold), 20... runner (6... middle runner, 12... upper runner, 14... lower runner),
15...Plate member, 18...Opening.

Claims (1)

[Claims] 1. A casting method in which molten metal is poured into a cavity through a vertical runner in a mold, with a runner having a middle height and a central part so as to be located within the runner between the joint surfaces of the mold that constitute the runner. A casting method characterized by interposing a plate member which is provided with an opening smaller than the diameter and is melted by the flow of molten metal passing through the opening, and then pouring the molten metal from above the runner. .