JP3288590B2 - Cast-in method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of assembling, and more particularly to a method of assembling a steel material as an assembling material with a cast iron as a base material so as to complete the welding of the two. The present invention relates to a method of assembling.

[0002]

2. Description of the Related Art FIG. 3 is a sectional view showing a mold used in a conventional casting for manufacturing a mold clamping cylinder of an injection molding machine. In the figure, reference numeral 1 denotes an upper die, and reference numeral 2 denotes a lower die. The upper die 1 is provided with a sprue part 3 and a feeder part 4, respectively. Cavities 6 corresponding to the shapes of cylinders, which are products into which molten metal is poured from the runner 5, are provided. A core 7 is provided at the center of the cavity 6, and its outer peripheral surface 7A forms a sliding surface of the piston.

[0003] In the above configuration, at the time of casting,
A molten metal (not shown) is injected into the cavity 6 through the gate 3 and the runner 5, and the cavity 6 is filled with the molten metal.

FIG. 4 shows a mold used in a conventional casting for manufacturing a piston or a plunger. In the figure, reference numeral 1 denotes an upper die, and reference numeral 2 denotes a lower die. 3
The lower mold 2 is provided with a runner 5 and a cavity 8, respectively. The surface 8A forming the cavity 8 forms the sliding surface of the cylinder.

[0005]

When a mechanical structural member having a sliding surface, such as a piston (plunger) or a cylinder (barrel), is manufactured by casting, a particularly problematic point is that the sliding surface has a problem. This may cause defects peculiar to castings such as pinholes, blowholes and sand bits. If pinholes or blowholes occur on the sliding surface, fluid leakage of oil, air, etc. will occur, and if sand on the sliding surface causes abnormal wear of the mating sliding member, etc. There is.

Therefore, conventionally, the portions in contact with the surfaces 7A and 7B for forming the sliding surfaces have been formed of a cast-in material, but the most important thing in this casting is that the cast-in material is The point is that the molten metal is more completely welded, that is, the interface between the cast-in material and the casting base material is more completely welded.

However, in the case where a steel material is used as a cast material and cast iron is used as a base material, since the melting point of the steel material may be high, it is difficult to completely weld the cast material to the base material. Met.

The inventors of the present invention have conducted various studies on the cast-in-place insert made of the steel material and cast iron as a base material. As a result, the welding between the cast-in-place material and the base material is affected by the temperature and the carbon content of the cast-in material. Has a significant effect.

The present invention has been made on the basis of the above knowledge, and it is intended that welding of a steel material to a base material of cast iron as a cast-in material is performed.
It is an object to provide a method of assembling which can be more complete.

Another object of the present invention is to prevent fluid leakage of oil, air, etc. from a sliding surface, abnormal wear of a mating sliding member, and the like, and furthermore, an interface between a cast-in material and a base material. Is to be able to obtain a completely inserted member such as a plunger or a cylinder.

[0011]

In order to achieve the above-mentioned object, the present invention provides a cast-in-place material made of steel having a carbon content of 0.5% by weight or less, and the cast-in-place material is placed in a mold. And pouring the molten cast iron into the mold. While monitoring the temperature of the cast-in material, pouring is continued until the temperature of the cast-in material reaches at least 1050 ° C or higher. The above-mentioned cast-in material and base metal cast iron are welded under the above temperature conditions.

[0012] The carbon content of the steel material as a cast-in material is appropriately selected according to the required function.
In the range of 0.5% by weight or less, carbon in the molten cast iron easily diffuses into the cast-in material, and sufficient welding can be expected. On the other hand, if it exceeds 0.5% by weight, it becomes difficult to diffuse, and it diffuses into supersaturation to form cementite and becomes brittle.
For this reason, it is preferable that the carbon content of the steel material which is a cast-in material is 0.5% by weight or less.

[0013] The temperature of the cast-in material is 1050
If the temperature is lower than 1 ° C., the welding will be incomplete.
050 ° C. or higher is preferred.

[0014]

As a method for increasing the temperature of the cast-in material to a temperature equal to or higher than the set temperature, for example, a method of using a heating source other than the molten metal is conceivable.
It is possible to more easily raise the temperature of the as-cast material to the set value.

According to the present invention, a plurality of thermocouples are attached in advance to required portions of the cast-in material, and while the temperature of the cast-in material is directly detected by the thermocouples, the temperature is kept within the above temperature range. It is characterized in that the casting is stopped after reaching.

The upper limit of the temperature of the cast-in material is regulated by the temperature of the molten metal of the cast iron to be cast, and it is desirable that the temperature be higher in order to make the welding more complete. Casting is stopped when the temperature exceeds 1050 ° C. because it is necessary to discharge. This makes it possible to further reduce the amount of molten metal discharged from the mold.

[0018]

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional view showing a mold used in a method of casting a mold clamping cylinder of an injection molding machine as a method of casting according to the first embodiment of the present invention. In the figure, reference numeral 11 denotes an upper die, reference numeral 12 denotes a lower die, and the upper die 11 is provided with a gate 13 and a feeder 14, respectively.
The lower mold 12 has a runner 15 and a cavity 1.
6 are provided. And the cavity 16
A core 17 is provided at the center of the
7 so that the carbon content is 0.5% by weight
A cast-in material 18 formed of the following steel material (in this embodiment, S20C material) into a bottomed cylindrical shape is disposed.

A thermocouple 19 is set at three points inside the cast-in material 18. The temperature detected by the thermocouple 19 is displayed on a thermometer 20 and the detected temperature is displayed. When the temperature reaches 1050 ° C, alarm 2
1 sounds.

A molten metal 23 in which ductile cast iron is melted is poured into the gate 13 by means of a tribe 22, and the molten metal 23 has a cavity through a runner 15. 16 are filled. When the alarm 21 does not sound even when the molten metal 23 rises to the feeder portion 14 of the upper mold 11, the pouring of the molten metal 23 is further continued, and the extra molten metal 23 is set at another position. The ingot case 24 is discharged via a ceramic tube 25.

At the time of casting, the molten metal 23 is taken out by the trivet 22 with the cast-in material 18 set on the outside of the core 17 and when the temperature reaches 1320 ° C.
Pour into 3 Then, the poured molten metal 23 is filled into the cavity 16 through the runner 15.

While the molten metal 23 rises to the feeder section 14 of the upper die 11, the temperature of the cast-in material 18 is increased by the heat of the molten metal 23. The temperature of the cast-in material 18 is detected by thermocouples 19 set at three places, and the detected value is
Displayed as 0. When all of the three thermocouples 19 reach 1050 ° C., the alarm 21 sounds. Therefore, pouring is stopped.

In some cases, even if the filled molten metal 23 rises to the riser 14, the cast-in
In some cases, the temperature of 8 does not reach 1050 ° C., and the alarm 21 does not sound. In such a case, pouring is further continued until the alarm 21 sounds, and the excess molten metal 23 is discharged to the ingot case 24 via the ceramic tube 25.

However, the cast-in material 18 is 1050 ° C.
Since the molten metal 23 is welded at the above temperature, the interface between the cast-in material 18 and the base material can be almost completely welded.

In general, when a cast iron casting is manufactured, the casting temperature is set in the range of 1300 to 1350 ° C. This is due to the difficulty of forming shrinkage cavities of cast iron castings, the difficulty of baking with sand molds, the difficulty of generating gas and the like from the molten metal, and the state of running around the molten metal.

Here, assuming that the casting temperature is 1350 ° C., the relationship between the weight of the base cast iron and the temperature of the cast-in material is given by the following equation. γ '+ x · α ₁ (1350−T ₁ ) =
y · α ₂ (1350-1050) where x: weight of base material cast iron y: weight of cast material T ₁ : room temperature α ₁ : specific heat of base material cast iron α ₂ : specific heat of cast material γ ′: sand mold From the above formula, when the weight of the cast-in material is determined, the weight of the base metal cast iron is determined. However, the weight of the base metal cast iron is determined by design and not by a calculation formula. In the case of a complicated structure, the calculated value of the temperature rise obtained from the calculation formula and the actual value often do not match. Therefore, in the present embodiment, the thermocouples 19 are set at three positions, and all the thermocouples 19 are 105
The alarm 21 is sounded when 0 ° C. is detected. As a result, it becomes possible to perform actual casting. If the casting and the casting conditions are constant, once the casting conditions are set, it is not necessary to detect the temperature each time.

Next, FIG. 2 shows a mold used in a method of casting a piston as a method of assembling according to a second embodiment of the present invention.
Reference numeral 2 denotes a lower mold. The upper mold 11 is provided with a gate 13 and a feeder 14, respectively. The lower mold 12 has a runner 15 and a cavity 26 corresponding to the shape of a piston. Is provided. A cast-in material 27 made of S20C having a carbon content of 0.5% by weight or less is provided on an inner peripheral portion of the lower mold 12 forming the cavity 26.

Thermocouples 19 are set at three places on the outside of the cast-in material 27. The temperature detected by the thermocouples 19 is displayed on a thermometer 20, and all thermocouples 19 are set. Is detected, the alarm 21 sounds.

As shown in FIG. 2, the gate 13 has
The molten metal 28 equivalent to FC300 taken into the tribe 22 is poured, and the molten metal 28 is filled into the cavity 26 through the runner 15. If the alarm 21 does not sound even when the molten metal 28 rises to the feeder portion 14 of the upper mold 11, the molten metal 2
8 is further continued, and the excess molten metal 28 is discharged to the ingot case 24 set at another position via the ceramic tube 25.

At the time of casting, while the casting material 27 is set in the cavity 26, the molten metal 28 is taken out by the tribe 22 and poured into the gate 13 at a casting temperature of 1320 ° C. Then, the poured molten metal 28 flows into the runner 15
Through the cavity 26.

As in the first embodiment, each of the three thermocouples 19 has a temperature 1050 of the cast-in material 27.
C. is detected, and pouring is stopped when the alarm 21 sounds.

When the alarm 21 does not sound even when the molten metal 28 filled in the cavity 26 rises to the feeder section 14, pouring is further continued until the alarm 21 sounds, and the excess molten metal 28 is removed. It is discharged to the ingot case 24 via the ceramic tube 25.

In this manner, the cast-in material 27 is removed from the
Since the molten metal 28 is welded at a temperature of 0 ° C. or more, the interface between the cast-in material 27 and the base material can be almost completely welded.

[0036]

EXAMPLE According to the embodiment shown in FIG. 1, 20 mold clamping cylinders of an injection molding machine having a base material cast iron weight of about 5000 kg and a cast-in material weight of 30 kg were cast, and the embodiment shown in FIG. As a result, 30 pistons having a base material cast iron weight of 2000 kg and a cast-in material weight of 15 kg were cast. Then, the presence or absence of casting defects such as pinholes and blowholes was examined.

As a result, in both the case of the mold-clamping cylinder and the case of the piston, all of them are good products,
It was confirmed that there was no individual.

Further, experiments were conducted on the relationship between the carbon content and the welding rate by changing the carbon content of the steel material used for each of the inserts 18 and 27 variously. And the result shown in Table 1 was obtained.

[0039]

[Table 1] As is clear from Table 1, if the amount of carbon in the as-cast material increases, the deposition rate gradually decreases, and if the amount of carbon exceeds 0.5% by weight, diffusion of carbon in the molten metal becomes insufficient. It was found that unwelded portions occurred.

Here, the welding rate was determined as follows.

That is, for example, the cast-in material 2 shown in FIG.
Taking Example 7 as an example, the welding condition of the entire inner peripheral surface of the cast-in material 27 was investigated, and the circumferential length of the unwelded portion was measured. Then, the welding rate was determined using the following equation.

[0042]

(Equation 1) Here, m: the circumferential length of the as-cast material n: the circumferential length of the unwelded portion Further, in the casting method shown in FIGS. 1 and 2, the temperature at which pouring is stopped for each of the as-cast materials 18 and 27 is varied. An experiment was conducted with the change in the relationship with the deposition rate. And the result shown in Table 2 was obtained.

[0043]

[Table 2] As is clear from Table 2, the temperature of the as-cast material was 105
When the temperature is 0 ° C. or higher, the welding rate becomes 100%,
When the temperature was lower than 0 ° C., it was found that unwelded portions were generated. This is because if the temperature of the cast-in material is low, the carbon in the molten metal does not sufficiently diffuse into the cast-in material, so that an unwelded portion occurs,
At 1050 ° C. or higher, it is considered that the molten metal around the cast-in material is maintained in a semi-molten state, and the diffusion of carbon is so fast that no unwelded portion is generated.

[0044]

As described above, according to the present invention, in a state in which a cast-in material made of a steel material having 0.5% by weight or less of carbon is installed in a mold, a molten cast iron is cast into the mold, Since the temperature of the material is maintained at least at 1050 ° C. or more, the cast-in material and the molten metal are welded to each other, so that the welding of both can be more complete.

The present invention also provides for a temperature of the
As a method of raising the temperature to a preset temperature range around 0 ° C., even after the inside of the mold is filled with the molten metal, the casting is continued while the molten metal in the mold is discharged,
The temperature of the cast-in material can be easily raised to the set value, and no special heating source is required.

[0046]

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a method of forming a cast according to a first embodiment of the present invention.

FIG. 2 is an explanatory view showing a method of forming according to a second embodiment of the present invention.

FIG. 3 is an explanatory view showing a method for casting a mold clamping cylinder of a conventional injection molding machine.

FIG. 4 is an explanatory view showing a conventional piston casting method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Upper mold 12 Lower mold 13 Sluice section 14 Filler section 15 Runner section 16, 26 Cavity 17 Core 18, 27 Cast-in material 19 Thermocouple 20 Thermometer 21 Alarm 23, 28 Molten metal 24 Ingot case 25 Ceramic tube

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B22D 19/00

Claims (2)

(57) [Claims] 1. A cast-in material is formed from a steel material having a carbon content of 0.5% by weight or less, the cast-in material is disposed in a mold, and a molten cast iron is poured into the mold. Said pouring
While monitoring the temperature of the filler material, continue pouring until the temperature of the cast-in material reaches at least 1050 ° C,
A stuffing method comprising welding the stuffed material and the base material cast iron under the temperature condition of 1050 ° C. or more . 2. A thermoelectric device according to claim 1, wherein a plurality of thermoelectric
A pair is attached in advance, and while the temperature of the as-cast material is directly detected by the thermocouple , casting is stopped after the temperature reaches the temperature range. The method of assembling according to the above.