JP2005014036A - Method for casting cylinder block and bore core - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To remove a rust preventive compound from the back surface of a cylinder liner without setting a special preheating process. <P>SOLUTION: As the cylinder liner 5, the one with the rust preventive compound pre-coated on the back surface, is used as it is, and after fitting this cylinder liner 5 to a bore core 6 disposed in a water jacket core 4, cooling for the bore core 6 is stopped by closing a valve 19, and the rust preventive compound on the back surface of the cylinder liner 5 is vaporized and removed by raising the temperature of the bore core 6 and the cylinder liner 5 with the heat received from a movable die body 13, surrounding fixed die 1, a slide core 3, and the water jacket core 4, etc. Then, at the suitable timing after ejecting molten metal in a cavity 9, the cooling for the bore core 6 is restarted and the shrinkage of the bore core 6 is promoted and sure separation from the die after opening the dies, is secured. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of casting a cylinder block of an internal combustion engine, and more particularly to a method of casting a cylinder block in which a separate cylinder liner is cast, and a bore core suitable for use in carrying out the casting method.
[0002]
[Prior art]
In recent years, as aluminum parts of automobile parts have been made aluminum, cast products of aluminum alloy have been used for cylinder blocks. In such an aluminum alloy cylinder block, in order to ensure desired wear resistance and sliding characteristics in the bore portion, generally, a cast iron or steel cylinder liner is separately prepared, and this cylinder liner is provided. The aluminum alloy (cast metal) is cast and integrated.
[0003]
However, in order to cast a cylinder block by casting a separate cylinder liner, it is necessary to closely fit the cylinder liner to the bore core in the mold. This is because if the fitting between the bore core and the cylinder liner is loose, the cylinder liner may be deformed by the pressure at the time of casting, or there is a risk that the molten metal may enter the fitting gap between the two. However, since the cylinder liner is closely fitted to the bore core in this way, it becomes difficult to release after casting, and if it is released forcibly, the inner surface of the cylinder liner is damaged, and in some cases the cylinder block Will cause deformation. Therefore, conventionally, consideration has been given to cooling the bore core from the inside through a casting cycle and facilitating mold release by thermal contraction of the bore core (see, for example, Patent Document 1).
[0004]
On the other hand, in the cylinder block formed by casting the cylinder liner, the adhesion between the back surface of the cylinder liner and the casting block is important. If the adhesion between the two is poor, the cylinder liner is deformed during use and the bore is completely round. As a result, the consumption of oil (lubricating oil) increases. As a countermeasure, a piston ring with high tension is used to cope with the deterioration of the roundness. However, with such a countermeasure, the friction between the bore inner surface (cylinder liner inner surface) and the piston ring can be reduced. A new problem arises that resistance increases and fuel consumption deteriorates.
[0005]
Therefore, conventionally, for the cylinder liner used in the above-mentioned cast-in, for example, as described in Patent Document 2, a countermeasure has been taken to increase the adhesion to the casting block by providing irregularities on the back surface by shot peening. It was. In addition to the above, measures to leave the casting surface on the back of the cylinder liner, measures to provide needle-like protrusions on the back of the cylinder liner when casting, or machining, water jet injection, chemical etching, etc. on the back of the cylinder liner Some measures have been taken to make it uneven.
[0006]
By the way, the cylinder liner used for casting is provided with various measures for improving the above-mentioned adhesion, and has a considerable time margin from its completion to actual casting. During this time, the surface of the cylinder liner The chance of rusting increases. In particular, when rust is generated on the back of the cylinder liner, this rust is a major cause of lowering the joint strength with the casting block. Therefore, conventionally, after the cylinder liner is completed, rust preventive oil is applied to the back of the cylinder liner. I was trying to apply.
[0007]
[Patent Document 1]
JP-A-6-71405 [Patent Document 2]
Japanese Patent Laid-Open No. 2002-221078
[Problems to be solved by the invention]
However, when the cylinder liner is cast with the rust preventive oil applied to the back surface, the rust preventive oil rapidly evaporates due to contact with the molten metal, resulting in insufficient adhesion between the cylinder liner and the cast block. For this reason, in the past, the cylinder liner was preheated in a heating furnace in advance to evaporate and remove the rust-preventing oil, and the extra heating time and energy consumption increased by setting the preheating process separately. There was a problem that an increase in the size was inevitable.
The present invention has been made in view of the above-described problems, and the problem is that the rust preventive agent can be removed from the back surface of the cylinder liner without setting a special preheating step, and the man-hours are reduced. An object of the present invention is to provide a casting method of a cylinder block that greatly contributes to reduction and reduction of energy consumption, and to provide a bore core suitable for use in carrying out this casting method.
[0009]
[Means for Solving the Problems]
In order to solve the above-described problems, the cylinder block casting method according to the present invention uses a cylinder liner that has been coated with a rust preventive agent on the back as it is, and fits the cylinder liner into a bore core in a mold. After the set, the cooling of the bore core is stopped, and this cooling stop is continued until at least the rust preventive agent evaporates.
In the cylinder block casting method performed in this manner, the cooling of the bore core is stopped, so that the temperature of the bore core rises due to heat input from the surrounding mold, and the bore core is fitted and set. The temperature of the cylinder liner also rises, and in response, the rust preventive agent applied to the back surface of the cylinder liner evaporates. In addition, by restarting the cooling of the cylinder liner at an appropriate timing from injection to mold opening, thermal contraction of the bore core proceeds, and as a result, mold release after mold opening becomes easy.
In the present casting method, the coolant may be circulated in the vicinity of the outer peripheral surface of the bore core to cool the bore core. However, the temperature rises or falls with high sensitivity, and the rust inhibitor can be removed and released more smoothly.
In the present casting method, not only the back surface of the cylinder liner may be uneven, but in this case, the adhesion between the cylinder liner and the casting block is further increased.
The type of cast metal and the type of cylinder liner used in the present casting method are arbitrary, but an aluminum alloy can be selected as the cast metal and an iron-based material can be selected as the cylinder liner.
[0010]
A bore core according to the present invention includes a bottomed cylindrical main body and a core member fitted in the main body, and a cooling liquid flows through a fitting surface between the main body and the core member. A passage is formed.
In the bore core configured in this way, the inner surface of the bottomed cylindrical main body is in contact with the coolant, so the bore core reacts with high sensitivity to cooling stop and restart, and evaporative removal of the rust inhibitor and Mold release can be performed more smoothly.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 shows one embodiment of the present invention. In the present embodiment, a cylinder block made of an aluminum alloy is obtained by a die casting method, and a casting mold used for this die casting is arranged so as to be movable with respect to the fixed mold 1 and the fixed mold 1. And a plurality of slide cores 3 arranged on the front surface of the movable mold 2 so as to be movable in a direction crossing the moving direction.
[0012]
The movable mold 2 includes a water jacket core 4 forming a water jacket and a bore core 6 for fitting and holding a cylinder liner 5 described later. Both the cores 4 and 6 are movable main bodies. 7 is fixed to the front surface of the unit 7 by using a fixing plate 8. The water jacket core 4 has a shape in which a number of cylindrical portions 4a corresponding to the required number of cylinders are connected in the direction perpendicular to the paper surface, and the bore core 6 is formed in each cylindrical shape of the water jacket core 4. It arrange | positions in the part 4a.
[0013]
The movable mold 2 moves forward and backward with respect to the fixed mold 1 by mold clamping means (not shown) in the die casting machine, while the slide cores 3 are mutually connected by drive means (not shown) attached to the movable mold 2. It moves in the direction of approaching and separating. In such a casting mold, after positioning the slide core 3 with respect to the movable mold 2, the movable mold 2 is advanced with respect to the fixed mold 1, so that the fixed mold 1, the movable mold 2, and the slide core 3. The person is closed. Then, in this mold closed state, a cavity 9 is formed as a casting space between the three parties, and the cylindrical portion 4 a of the water jacket core 4 is positioned in the cavity 9. The cylinder liner 5 is fitted and set to the bore core 6 in a mold open state in which the movable mold 2 is moved backward with respect to the fixed mold 1 and the slide core 3 is moved backward with respect to the movable mold 2. Accordingly, it is positioned in the cavity 9. In the movable mold 2, an extrusion pin that is inserted through the proximal end portion of the water jacket core 4 and extends into the cavity 9 is disposed.
[0014]
A cooling chamber (cooling passage) 10 is formed inside the bore core 6. A pipe joint 13 having a liquid supply nozzle 11 and a liquid discharge nozzle 12 is attached to an opening of the bore core 6 that communicates with the cooling chamber 10. The pipe joint 13 has a movable die 2 (movable main body). 7) A pipe joint 16 connecting the supply pipe 14 and the drain pipe 15 extending in the interior is detachably connected. Cooling liquid is pumped from the cooling liquid tank 17 to the liquid supply pipe 14 by a pump 18, and this cooling liquid is supplied from the liquid supply nozzle 11 to the cooling chamber 10. On the other hand, the cooling liquid in the cooling chamber 10 is returned to the cooling liquid tank 17 through the drain nozzle 12 and the drain pipe 15 and is re-cooled by a cooling means (not shown) during this return. Accordingly, an opening / closing valve 19 is interposed in the middle of the liquid supply pipe 14, and cooling of the bore core 6 is stopped and released in accordance with the opening / closing thereof. The opening / closing valve 19 is controlled by a control means of a die casting machine.
[0015]
Here, the cylinder liner 5 is made of general-purpose cast iron (for example, FC230), and a rust preventive agent is applied to the back surface of the cylinder liner 5 in advance. The cylinder liner 5 may leave the casting surface as it is on the back surface, but may also be subjected to shot peening or machining on the back surface so as to be uneven. The inner diameter of the cylinder liner 5 is set to be slightly larger than the outer diameter of the bore core 6. Therefore, the cylinder liner 5 can be set in a state of being closely fitted to the bore core 6.
[0016]
The cylinder block casting method according to the present embodiment will be described below with reference to FIG. In FIG. 2, L-5 represents a temperature curve of the cylinder liner 5, and L-6 represents a temperature curve of the bore core 6.
At the time of die casting, the cylinder liner 5 is fitted and set to the bore core 6 in the mold open state. At this time, the bore core 6 is cooled by the supply of the coolant to the cooling chamber 10 and is in a thermally contracted state. Therefore, the cylinder liner 5 can be fitted into the bore core 6 without difficulty.
[0017]
When the fitting of the cylinder liner 5 to the bore core 6 is completed, the slide core 3 is first moved forward and positioned with respect to the movable mold 2, and then the movable mold 2 is integrated with the slide core 3 into the fixed mold 1. Accordingly, the movable mold 2 and the slide core 3 are clamped (closed) with respect to the fixed mold 1. On the other hand, before and after the mold clamping, the on-off valve 19 is closed and the supply of the coolant to the bore core 5 is stopped. At this time, heat from the previous casting cycle is stored in the mold elements such as the fixed mold 1, the movable mold body 7, the slide core 3, and the water jacket core 4, and the bore core 6 receives heat from these. And the temperature of the cylinder liner 5 rises. When the temperature of the cylinder liner 5 is raised above the boiling point T ₁ of the rust inhibitor, corrosion inhibitor that has been applied to the back of the cylinder liner 5 begins to evaporate, the rust inhibitor is the injection starting point into the cavity 9 Almost all of it evaporates. In FIG. 2, the hatched range of L-5 represents the evaporation range of this rust inhibitor.
[0018]
Thereafter, the molten metal is injected into the cavity 9 at a high speed and a high pressure, so that the temperatures of the bore core 6 and the cylinder liner 5 rapidly increase. The on-off valve 19 is opened almost simultaneously with the completion of the filling of the molten metal into the cavity 9, whereby the coolant is supplied to the cooling chamber 10 of the bore core 6 and the bore core 6 is rapidly cooled. On the other hand, after the filling of the molten metal into the cavity 9 is completed, the solidification is completed with a slight time lapse, and the mold opening is performed at this timing.
[0019]
When the mold opening is completed, an unillustrated extrusion pin is operated, and the cast product is released from the movable mold 2. At this time, the bore core 6 is in a state of being thermally contracted by restarting the cooling, so that the mold release is performed smoothly, whereby the cylinder made of aluminum alloy formed by casting the cylinder liner 5 made of cast iron. The block is complete. When the cylinder block is cast, as described above, since the rust preventive agent is removed by evaporation from the back surface of the cylinder liner 5 before the start of the injection of the molten metal, the solidification is stably solidified on the back side of the cylinder liner 5. As a result, the joining strength between the cylinder liner and the casting block becomes sufficient.
[0020]
In the above embodiment, the die casting method is adopted as the casting method, but the casting method employed in the present invention is arbitrary, and the low pressure casting method as well as the gravity casting method can be adopted. Moreover, in the said embodiment, although the aluminum alloy was selected as a cast metal, the kind of this cast metal is also arbitrary, Magnesium or its alloy, copper or its alloy, an iron-type alloy, etc. can be selected.
[0021]
Here, the bore core 6 may have a structure as shown in FIG. In FIG. 3, the same parts as those shown in FIG. The bore core 6 </ b> A includes a bottomed cylindrical main body 21 and a core member 22 fitted in the main body 21. A through hole 23 is formed at the center of the core member 22, while a spiral groove 24 is formed on the outer peripheral surface thereof. The spiral groove 24 is provided as a cooling passage 25 in a state in which the core member 22 is fitted to the main body 21, and a core member is provided between the cooling passage 25 and the through hole 23. 22 is communicated by a radial groove 26 formed at the tip of 22. The liquid supply pipe 14 extending from the pump 18 is connected to the through hole 23, while the drainage pipe 15 is connected to the spiral groove 24, and the cooling liquid fed from the cooling liquid tank 17 is The fitting portion between the main body 21 and the core member 22 flows spirally and is discharged to the drainage pipe 15.
[0022]
In the bore core 6A configured as described above, the coolant flows in a spiral manner through the fitting portion between the main body 21 and the core member 22, that is, the portion close to the outer peripheral surface of the bore core 6A. When 19 is opened and the coolant is supplied to the bore core 6A, the main body 21 is quickly cooled, and therefore, the mold release after the mold opening can be performed without delay. On the other hand, when the on-off valve 19 is closed and the supply of the coolant to the bore core 6A is stopped, the temperature of the main body 21 rises rapidly due to the heat received from the surroundings. As a result, the rust preventive agent on the back surface of the cylinder liner 5 is rapidly applied. By evaporation, the rust inhibitor is completely removed by the start of injection. Further, since the main body 21 and the core member 22 have a double structure, the main body 21 can be removed and maintenance can be easily performed, and only the main body 21 can be replaced for easy setup. .
In the bore core 6A, the cooling passage 25 is formed by the spiral groove 24 provided in the core member 22, but an annular groove is provided in the core member 22 instead of the spiral groove 24. The annular groove may be connected to each other through a vertical groove to form a cooling passage. Further, these cooling passage grooves may be provided on the main body 21 side instead of the core member 22.
[0023]
【The invention's effect】
As described above, according to the method for manufacturing a cylinder block according to the present invention, the rust preventive agent can be removed by evaporation from the back surface of the cylinder liner in the casting cycle. As a result, it is possible to greatly contribute to cost reduction by reducing energy consumption and energy consumption.
Further, according to the bore core according to the present invention, since it reacts with high sensitivity to cooling stop and restart, it is possible to more smoothly carry out evaporation removal and mold release of the rust preventive agent, and to perform maintenance and steps. The replacement is easy and the utility value is great.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a structure of a casting mold for carrying out a first embodiment of the present invention.
FIG. 2 is a cycle diagram showing temporal changes in bore core temperature and cylinder liner temperature in the first embodiment.
FIG. 3 is a cross-sectional view showing a structure of a bore core and a cooling system used in the implementation of the second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fixed type 2 Movable type 3 Slide core 4 Water jacket core 5 Cylinder liner 6, 6A Bore core 9 Cavity 10 Cooling chamber 21 Main body 22 Core member 25 Cooling passage

Claims (5)

In a cylinder block casting method, after a cylinder liner is fitted and set to a bore core of a mold, the mold is clamped and a molten metal of a cast metal is injected into a cavity in the mold, and the cylinder liner is cast with the cast metal. The cylinder liner having a rust preventive agent applied to the back surface is used as it is. After the cylinder liner is fitted and set to the bore core, the internal cooling of the bore core is stopped, and this cooling is performed. The cylinder block casting method is characterized in that the stop is continued at least until the rust inhibitor evaporates. 2. The method for casting a cylinder block according to claim 1, wherein the bore core is cooled by circulating a coolant in the vicinity of the outer peripheral surface of the bore core. 3. The method of casting a cylinder block according to claim 1, wherein the back surface of the cylinder liner is uneven. 4. The method for casting a cylinder block according to claim 1, wherein the cast metal is an aluminum alloy and the cylinder liner is made of an iron-based material. A bore core for fitting and holding a cylinder liner to be cast in a cylinder block, comprising a bottomed cylindrical main body and a core member fitted in the main body, and the fitting between the main body and the core member A bore core characterized in that a cooling passage through which a coolant flows is formed in the joint part.

Images