JPS61235039A - Casting method - Google Patents

Abstract

PURPOSE:To prevent the exfoliation of molding sand and the carry over of the exfoliated molding sand into a cavity by interposing a plate material which is bulged in the middle and has an aperture smaller than runners between the joint surfaces of the runners in upper and lower directions in a casting mold. CONSTITUTION:A core assembly 1, a cope 8 and a drag 9 are assembled and thereafter a molten metal is poured into the mold through a sprue 13. The molten metal is poured through a runner 20 into a cavity 11. The molten metal passes the aperture of the plate material 15 interposed in the midway of the runner 20 and flow downward. The diameter of the aperture is smaller than the diameter of the upper runners 12 above and below the material 15 and the intermediate runner 6 and therefore even if a large amt. of the molten metal is poured into the sprue 13, the molten metal flows gently by each small amt. into the cavity 11 from the lower part of the runner 20 for the beginning when the pouring is started. The exfoliation of the molding sand is thus obviated from the runner 20 up to the cavity 11. The material 15 is thereafter melted and the diameter of the aperture is gradually increased, by which the molten metal speed is increased but some amt. of the molten metal is already poured into the cavity and therefore there is no disturbance of the flow and the exfoliation of the molding sand is obviated.

Description

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

(Conventional technology) A casting method widely used for manufacturing various metal products involves providing a cavity corresponding to the shape of the product in a mold and a runner leading to the cavity, and pouring molten metal into the cavity through the runner. A product having a predetermined shape is obtained by injecting the molten metal and solidifying the molten metal within the cavity.

By the way, in such a casting method, a sand mold made of hardened casting sand is usually used as the mold, but in this case, the molten metal generated at the introduction part from the runner to the cavity during pouring, etc. Due to the turbulence of the flow, the casting sand around the runner or the cavity may be pulled off by the flow of the molten metal, and if this is carried 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, and it is difficult 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 that is peeled off from around the runner during pouring is collected in the space. There is a method to prevent the above-mentioned space from being brought into the cavity, but this method creates an interior in the product that corresponds to the above-mentioned space, and requires extra processing to remove this.

(Purpose of the Invention) The present invention addresses the above-mentioned problems regarding the casting method, and provides a method for pouring molten metal into a cavity through a runner provided in a mold without causing turbulence in the flow of molten metal. ,
Moreover, a method for quickly pouring hot water is realized. The purpose of this is to prevent casting sand from being brought into the chamber by the turbulent flow that occurs during pouring, and to prevent the generation of sand-containing products, without complicating pouring work or deteriorating efficiency. shall be.

(Structure of the Invention) That is, the present invention provides a casting method in which molten metal is poured into a cavity through a vertical runner in a mold. A plate member having an opening smaller than the diameter of the runner in the center is interposed within the runner.In this case, this plate member is heated by the heat of the molten metal such as a tinned steel plate. formed by a material that gradually melts,
Further, the plate thickness is also set so as to obtain the required molten state.

Therefore, when molten metal is poured into the runner, the molten metal initially flows into the lower part of the runner or the cavity through the small-diameter opening of the plate member, and as the plate member melts, the opening opens. As the diameter of the cavity gradually increases, the flow rate of the molten metal 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 is captured by the peripheral part of the plate member and brought into the cavity side. This will be prevented.

(Effects of the Invention) As described above, according to the casting method of the present invention, when pouring into the mold, the molten metal initially flows into the cavity little by little, and gradually as the plate member melts. The inflow speed becomes faster, thereby preventing the generation of turbulent flow 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 turbulent flow. In addition, cast sand stripped off around the sprue etc. is captured by the plate member and prevented from being brought into the cavity side. In this way, the casting sand forming the mold can be prevented from being carried 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 a mold used in manufacturing a cylinder block of an 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 a skirt part of a cylinder block, and a plurality of hollow bore cores 2...2 are arranged in a row to form a plurality of cylinder parts and a skirt part of a cylinder block, and A water jacket core 3 that is fitted to the outside of the portion forming the cylinder portion of the core 2...2 to form the water jacket of the cylinder block, and a water jacket core 3 that is fitted to the outside of the portion forming the cylinder portion of the core 2...2, and a water jacket core 3 that is fitted to the outside of the portion forming the cylinder portion of the core 2... A core assembly 1 is used which is composed of a front end core 4 and a rear end core 5 that are arranged. In this core assembly 1, the two bore cores 2', 2' located in the middle of the bore cores 2...2 have a recess 6 having a semicircular cross section on their opposing surfaces.
a, 6a are provided, and by joining these, a runner 6 that penetrates in the vertical direction (width direction of the core assembly 1) is formed.
is formed. Further, a relatively shallow recess 7 in the shape of a counterbore is formed around the upper end opening of the S path 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 a core 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 a lower 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 to form a sprue 13. The lower mold 9 also includes a lower end portion of the runner 6,
A lower runner 14 communicating with the lower part of the cavity 11 is provided. 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 casting a cylinder block using the mold as described above, a plate member 15 as shown on an enlarged scale 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 1.21, for example, and has an overall shape formed by a conical portion 16 projecting upward and a flange portion 17 around its lower end. 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 portion 16 is equal to the runner 1 in the upper mold 8 and the core assembly 1 (bore core 2'2').
The diameter of the opening 1 is approximately equal to that of the opening 1.
The diameter of 8 is smaller than the diameter of these runners 12°6.

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

First, as shown in FIG. 1, the cores 2 to 5 are assembled to form a core assembly 1, and this is 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 a flange part 17 is provided around the opening of the runner 6 on the upper surface of the bore cores 2', 2'. It is housed in the recess 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 a cavity 11 is formed from the sprue 13 on the upper surface of the upper mold 8 to the lower runner 12 in the upper mold 8, the intermediate runner 6 in the core assembly 1, and the lower runner 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 inserted between the joint surfaces of the core assembly 1 and the upper mold 8 in the runner 20. There will be an intervention. Note that the plate member 15 has an insertion blade portion 19 provided on the outer peripheral edge of the flange portion 17.
is inserted into the lower surface of the upper die 8, thereby being securely fixed between the bonding surfaces.

After the mold matching is completed in this way, the sprue 1
When molten metal is poured from step 3, step 1. This molten metal is poured into the runner 20 (
Top &! The molten metal is injected into the cavity 11 through the runner 12, middle runner 6, and lower runner 14, but at this time, the molten metal passes through the opening 18 of the plate member 15 interposed in the middle of the runner 20. It will flow 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. As a result, the casting sand of the bore cores 2', 2' and the lower mold 9, which constitute the surrounding areas, are not stripped off by the flow of the molten metal at the introduction part from the runner 20 to the cavity 11, etc. , casting sand is prevented from being brought into the cavity 11.

When the molten metal is subsequently injected from the sprue 13, the conical portion 16 of the plate member 15 is melted by the heat of the molten metal, the diameter of the opening 18 in the plate member 15 gradually increases, and finally the runner 12. It becomes approximately equal to the diameter of 6. Therefore, the flow rate 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 rate increases. Therefore, the casting sand is not stripped off and brought into the cavity 11,
Moreover, the pouring of the molten metal 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 cough runner 12 and the intermediate runner 6, it is stopped by the plate member 15, as shown in FIG. As shown by the chain line X, the particles are deposited on the surface 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 the plate member 15 melts and erodes without falling downward.

In this way, casting sand is prevented from being carried into the cavity 11 during pouring, thereby preventing the production of a product 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. .

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 drawings]

The drawings show an embodiment of the present invention, and 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 m--■ in FIG. 2, and FIG. 4 is an enlarged sectional view of the main part. 1.8.9... mold (1... core assembly, 8... upper mold, 9... lower mold), 20... runner (6... middle runner, 12 ... Upper runner, 14... Upper runner), 15
... Plate member, 18... Opening. Figure 3 Figure 4

Claims (1)

[Claims] (1) A casting method in which molten metal is poured into a cavity through a vertical runner in a mold, and the molten metal is poured into a cavity at a middle height and in the center between the joint surfaces of the mold forming the runner. Casting characterized by having an opening smaller than the diameter of the runner, interposing a plate member which is melted by the flow of molten metal passing through the opening, and then pouring the molten metal from above the runner. Method.