WO2014027599A1 - Method for quenching cylinder head, and flow contact prevention member - Google Patents

Abstract

The present invention is a method for quenching a cylinder head (A), for performing quenching by bringing a flow of cooling gas into contact with a cylinder head, wherein all or part of a portion (a) having a small heat capacity is covered by a flow contact prevention member (40) for preventing contact with the flow of cooling gas, and the cooling gas is brought into contact only with a portion (b) having a large heat capacity.

Description

Cylinder head quenching method and flow contact prevention member used therefor

The present invention relates to a quenching method for a cylinder head such as a reciprocating engine and a flow contact prevention member used therefor.

As this type of prior art, there is one disclosed in Patent Document 1 under the name of “metal casting manufacturing method”.
The method for producing a metal casting disclosed in Patent Document 1 is formed from a heat-treatable liquid aluminum copper alloy, and can enjoy the advantages of solution heat treatment. The mold is filled with the liquid alloy and the alloy solidified metal is obtained. The step of forming a casting and the step of removing from the mold are quenched directly from 350 ° C. or higher, and no heat treatment is performed between the removal of the casting from the mold and the quenching, and the quenched metal casting is aged. And a step of curing.

Japanese Patent No. 4035664

The one described in the above-mentioned Patent Document 1 is a type in which a mold is filled with a molten metal, cooled to 350 ° C. or higher, taken out from the mold, and quenched from 350 ° C. or higher to perform artificial aging. Due to the complicated shape, residual stress is generated depending on the cooling method during quenching.

In order to reduce the residual stress, it is necessary to cool uniformly or slowly, and it is also known that air quenching is more effective than water quenching.
However, if the cooling rate is low, the material characteristics will not improve, and in the actual part, the sprue part and the part connected to the spigot (bottom of the cylinder head) have a large heat volume, and due to differences in thickness distribution, etc. It is difficult to cool uniformly.

Accordingly, the present invention provides a quenching method for a cylinder head that can reduce the difference in cooling rate between the respective parts even if there is a difference in the thickness distribution and the like, and reduce the residual stress, and the inflow prevention member used therefor. The purpose is to provide.

The method of quenching a cylinder head according to the present invention for solving the above-described problem is to quench by flowing a cooling gas to the cylinder head and classify the cylinder head according to the heat capacity of the cylinder head. Cover all or part of the portion with a relatively small heat capacity with a flow prevention member for preventing the flow of cooling gas from flowing, and flow the cooling gas to the portion with a relatively large heat capacity. It is characterized by contact.

According to this configuration, all or a part of the portion having a relatively small heat capacity is covered with the flow contact prevention member for preventing the flow of the cooling gas from flowing, and the portion having the relatively large heat capacity is covered with the cooling gas. Therefore, even if there is a difference in thickness distribution, the difference in cooling rate between these parts can be reduced and the residual stress can be reduced.

An inflow prevention member used in a method for quenching a cylinder head according to the present invention for solving the same problem as described above has a covering member for covering all or a part of the portion having a relatively small heat capacity. Yes.
According to this configuration, it is possible to prevent the cooling gas from flowing in contact with all or a part of the portion having a relatively small heat capacity. The residual stress can be reduced while reducing the cooling rate difference between the parts.

According to the present invention, even if there is a difference in wall thickness distribution or the like, it is possible to reduce the difference in cooling rate between these parts and reduce the residual stress.

It is a perspective view of the cylinder head concerning an example. It is sectional drawing which follows the II line | wire shown in FIG. It is a perspective view which shows the core used for casting of a cylinder head same as the above. It is a schematic sectional drawing of the casting apparatus for casting a cylinder head same as the above. It is a perspective view which shows a mode that the flow contact prevention member was mounted | worn with the cylinder head same as the above. It is sectional drawing of the hardening apparatus which concerns on an example. (A) is a graph which shows the cooling rate of the representative site | part in the conventional hardening method, (B) is a graph which shows the cooling rate of the representative site | part in the quenching method which concerns on this invention. It is a graph which compares and shows the residual stress in the conventional hardening method, and the residual stress in the hardening method which concerns on this invention. (A) is an external perspective view of a flow contact prevention member according to another example, and (B) is an external perspective view showing a state in which the flow contact prevention member according to another example is mounted on a cylinder head.

Hereinafter, modes for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a cylinder head according to an example, and FIG. 2 is a cross-sectional view taken along the line II shown in FIG. FIG. 3 is a perspective view showing a core used for casting the cylinder head, and FIG. 4 is a schematic sectional view of the casting apparatus.

A cylinder head A according to an example of the present invention has an upper deck 11 formed in a cylinder head-shaped portion (head bolt) 10 and is provided with gates 12 and 12 at the lower portion. As a material, it is integrally cast into a substantially rectangular parallelepiped shape in a plan view by a low pressure casting method.

The cylinder head-shaped portion 10 is formed by both side walls 13 and 14, a front wall 15 and a rear wall 16, and on both side walls 13 and 14, an intake port (not shown) corresponding to the number of cylinders is provided. And the same number of exhaust ports 18 are formed to face each other. Reference numeral 19 denotes a cavity.

The upper deck 11, the front wall 15 and the rear wall 16 are relatively thin and have a relatively small heat capacity, while the gates 12 and 12 and the side walls 13 and 14 are formed thick. Therefore, the heat capacity is relatively large.
The lower surface having the combustion chamber is also a portion having a relatively large heat capacity because it is formed with a lower mold close to the holding furnace and is always supplied with heat from the gate although it is not thick.
In the present embodiment, a portion having a relatively small capacity is “a”, and a portion having a relatively large capacity is “b”.

As shown in FIG. 3, the core 20 used for casting the cylinder head A having the above-described configuration is formed by integrally arranging port cores 22 and 23 on both side edges of the water jacket core 21.

As shown in FIG. 4, the casting apparatus 30 has a mold 32 disposed in an upper opening of a holding furnace 31 that stores molten aluminum m.
The mold 32 is for simultaneously molding the two cylinder heads A and A, and includes a lower mold 33, an upper mold 34, and a center mold 35.
The lower mold 33 is formed with gates 33a, 33a at positions relative to the two cylinder heads A, A.

FIG. 5 is a perspective view showing a state in which the inflow preventing member is mounted on the cylinder head.
The quenching method of the cylinder head A according to the present invention is a content in which quenching is performed by flowing a cooling gas through the cylinder head A, and all or part of the portion a having a small heat capacity is cooled. It is characterized in that it is covered with a flow preventing member 40 for preventing the flow of the working gas, and the cooling gas is flowed into only the portion b having a large heat capacity.

The “cooling gas” shown in the present embodiment is air, but other argon or the like may be employed. Hereinafter, air will be described as an example of “cooling gas”.
In addition, “flow contact” in the present embodiment includes, for example, a mode in which air is blown to the entire cylinder head A by a single fan, in addition to those in which air is blown to each portion by cooling nozzles 60 to 62 described later.

The flow preventing member 40 shown in the present embodiment is for preventing air from flowing into all or part of the portion a having a small heat capacity, and is formed of a core material.
As shown in FIG. 5, the front covering member 41, the side covering members 42 and 43, the rear covering member 44, and the upper covering member 45, which are formed independently of each other, include the front covering member 41 and the rear covering member 44. Is formed integrally with the above-described core 20.

The front covering member 41 is a core formed in a shape and size that covers the entire front wall 15 described above.
The side covering members 42 and 43 are formed as horizontally long hollow bodies extending elongated between the front wall 15 and the rear wall 16, and are coupled between the port cores 22 and 23 that are formed to protrude in parallel. It has been made.

The rear covering member 44 is formed in a shape and size that covers the entire rear wall 16.
The upper covering member 45 is a plate-like body that is sized and shaped to cover the upper deck 11.

Next, the hardening apparatus B which concerns on an example is demonstrated with reference to FIG. 6 with FIG. 5 mentioned above. FIG. 6 is a cross-sectional view of a quenching apparatus according to an example.
As shown in FIG. 6, the quenching apparatus B according to an example has a plurality of cooling nozzles 60 to 62 and an exhaust fan 65 appropriately disposed in a cooling booth main body 50.

The cooling booth main body 50 is formed in a volume that accommodates the cylinder head A to which the anti-flow contact member 40 (41 to 45) shown in FIG. 5 is mounted, and is formed on the edge of the bottom wall 51 that is square in plan view. Side walls 52 to 55 are erected and an upper wall 56 is disposed on the side walls 52 to 55 (55 is not shown).

A cylindrical exhaust cylinder 57 projects from the central portion of the upper wall 56, and the exhaust fan 65 is disposed in the exhaust cylinder 57.
On the bottom wall 51, a mounting table 58 for mounting the cylinder head A, to which the anti-flow contact member 40 is mounted, spaced from the bottom wall 51 is disposed.

A cooling nozzle 62 for blowing air toward the gates 12 and 12 of the cylinder head A mounted thereon is disposed below the mounting table 58.
Cooling nozzles 60 and 61 for blowing air toward the side surface of the cylinder head A placed on the side of the mounting table 58 are arranged.

The cooling nozzles 60 to 62 are connected to an air feeding device 70 for feeding air through feeding pipes 70a to 70c, respectively. The exhaust fan 65 is connected to a power feeding device (not shown). It is connected and appropriately rotated.
Further, the air supply device 70 and the exhaust fan 65 are connected to the output side of a controller (not shown) and are appropriately controlled.

According to the quenching apparatus B having the above-described configuration, the air blown from the cooling nozzles 60 to 62 can be blown only to the portion b having a large heat capacity, while the portion a having a small heat capacity is covered by the inflow prevention member 40. As a result, air contact can be prevented.
The heated air that has flowed into the cylinder head A is discharged to the outside by the exhaust fan 65 to prevent the temperature of the air in the cooling booth main body B from rising.

7A is a graph showing the cooling rate of the representative part in the conventional quenching method, FIG. 7B is a graph showing the cooling rate of the representative part in the quenching method according to the present invention, and FIG. 8 is a conventional quenching method. It is a graph which compares and shows the residual stress in and the residual stress in the hardening method which concerns on this invention.
As is clear from FIGS. 7A and 7B, according to the quenching method according to the present invention, the cylinder head A is compared with the difference in the cooling rate of the representative portion in the conventional quenching method shown in FIG. The difference in the cooling rate of each part is small.
Further, as apparent from FIG. 8, it was confirmed that the residual stress was reduced according to the quenching method according to the present invention as compared with the residual stress in the conventional quenching method.

According to the quenching method of the cylinder head having the above configuration, the upper deck upper surface, the front surface, and the rear surface are molded with a sand mold, so that air does not flow directly to the thin portion, By causing air to flow through the portions, even if there is a difference in thickness distribution or the like, the difference in cooling rate between these portions can be reduced, and the residual stress can be reduced while maintaining the material characteristics.

When the core is not used as the cover material, the core sand is used by performing the quenching with the cover material shown in FIG. A similar residual stress reduction effect can be obtained while reducing the amount of use.

Next, a flow contact prevention member according to another example will be described with reference to FIGS. 9 (A) and 9 (B). FIG. 9A is an external perspective view of a flow contact prevention member according to another example, and FIG. 9B is an external perspective view illustrating a state in which the flow contact prevention member according to another example is mounted on a cylinder head.

The flow preventing member 80 according to another example is for preventing air from flowing to all or part of the thin portion, and includes an upper covering member 81 and a side covering member 83 (one is not shown). ), The front covering member 84 and the rear covering member 85 are integrally formed.

The upper covering member 81 has a rectangular shape in plan view with an area covering the entire upper deck 11 of the cylinder head A described above.
The front covering member 84 has a rectangular shape when viewed from the front and has an area facing the entire front wall 15 of the cylinder head A. The upper edge 84a is connected to the front edge 81a of the upper plate 81. Yes.

The rear covering member 85 has a rectangular shape when viewed from the front and has an area facing the entire rear wall 16 of the cylinder head A. The upper edge 85a is connected to the rear edge 81b of the upper plate 81. Yes.

The side covering member 83 has a lateral rectangular shape in a side view so as to face and cover the port of the cylinder head A, and the front and rear side edges 83a and 83b thereof are connected to the side edge 84b of the front plate 84 and the rear plate. It is constructed on 85 side edge 85b. In addition, the side plate which is not shown in figure is comprised similarly.

According to the flow preventing member 80 according to the other example described above, in addition to the effects obtained by the flow preventing member 40 according to the above-described example, after the sand is dropped, the parts are reworked, or the above-described quenching device. Due to the trouble of B, it can be used at the time of quenching when re-heat-treating.

The present invention is not limited to the above-described embodiments, and the following modifications can be made.
In the embodiment described above, an example in which all of the portion having a small heat capacity is covered with the inflow prevention member for preventing the inflow of the cooling gas has been described. Of course, it may be configured to cover.

40,80 Anti-flow contact member A Cylinder head a Part having a small heat capacity b Part having a large heat capacity

Claims (5)

1. In the quenching method of the cylinder head for quenching by flowing the cooling gas to the cylinder head,
   The cylinder head is divided according to the heat capacity of the cylinder head, and all or a part of the relatively small heat capacity is covered with a flow prevention member for preventing the flow of cooling gas. A method for quenching a cylinder head, characterized by causing a cooling gas to flow in contact with a relatively large portion.
2. The method for quenching a cylinder head according to claim 1, wherein the portions having a relatively small heat capacity are the upper deck, the front wall, and the rear wall.
3. The method for quenching a cylinder head according to claim 1 or 2, wherein the portion having a relatively large heat capacity is a gate, a combustion chamber, and a side wall.
4. The method for quenching a cylinder head according to any one of claims 1 to 3, wherein the quenching with the cooling gas is performed immediately after being released from the mold.
5. The inflow prevention member used in the method for quenching a cylinder head according to any one of claims 1 to 4, wherein all or a part of a part of the cylinder head having a relatively small heat capacity is partially or partially. An inflow prevention member for use in a method of quenching a cylinder head, comprising a covering member for covering.

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