JPS60133951A - Molding method of core for cylinder block of engine - Google Patents

Abstract

PURPOSE:To improve the dimensional accuracy of a casting with respect to molding of the cylinder block which is cocast with a liner and is integrated with a head by forming a core for a crank case and a core for a port core print constituting cores into integral construction. CONSTITUTION:A liner 3 is preheated by the preheating molten metal poured through a sprue 6 into a chamber 5 for the preheating molten metal and is securely welded to a cylinder block, by which the alloy cylinder block integrated with a head is cast. This invention relates to a process for producing the core to be used for such casting in which a paper bobbin 4 is disposed on the inside of the liner 3 set to a pattern for the crank case to form the chamber 5 and an oil sand is molded to unite a core 1 for the crank case and a core 2 for a port core print into one body. A core print 9 of a core 7 for suction and exhaust ports is set in the core 2, by which the cores 1, 2, 7 are united to one body. The accuracy of the port position of the cylinder block to be mass-produced and the dimensional accuracy such as thickness deviation of the liner are thus improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for casting a cylinder block for an engine with an integrated head, and more particularly to a method for molding a core for the cylinder block.

Conventionally, the cylinder block and head have been integrated, eliminating the risk of gas leaking from the joint where the cylinder block and head are separated, and preventing obstruction of the flow of cooling air by head mounting bolts and nuts, or water leakage. Cylinder block engines with an integrated head have been used for a long time because there is no obstruction to the flow of cooling water within the jacket. Since such an engine is constructed of a light alloy cylinder with good heat conduction, it employs a structure in which an iron liner is co-cast.

[Prior art and its problems]

The conventional method of casting a cylinder block with an integrated head by co-casting a liner is to anneal a liner with one plating layer, as already filed by one of the inventors of the present invention, and to preheat the liner on the inner periphery of the liner. After pouring molten metal and preheating the liner, a cylinder block is formed by integrating the cylinder block and the head, and a cast-in liner is welded by pouring molten metal so as to cover the liner. A method is proposed.

The core used in this casting method is one in which molten metal for preheating is poured into the inside of the liner 3, although FIG. 1 shows one embodiment of the present invention. from,
In order to form the preheating molten metal chamber 5, it is necessary to remove the wedge shape for the chamber 5, so the crankcase core 1 and the boat Ogi core 2 are C.
It was separated at the part and molded into a separate core. Therefore, it is difficult to obtain dimensional accuracy such as the position and height of the intake boat relative to the center of the crank chamber. For example, in the case of a direct injection type cylinder head, even if the swirl ratio deviates slightly from the optimum value, it will affect the engine performance, so this dimensional accuracy cannot be compromised.

[Structure of the invention]

Therefore, the present invention was created in order to eliminate the disadvantages of the prior art.It is a molding method for a head-integrated cylinder block in which a liner is co-cast.In other words, a sand mold necessary for making a casting by pouring molten metal is created. It is an object of the present invention to provide a method for forming a crankcase core and a boat core into an integral structure.

Hereinafter, the configuration of the present invention will be explained in detail with reference to examples.

Figure 1 shows a cylinder block with an integrated head.
This is a cross-sectional view of the core for a cylinder water-cooled small diesel engine.
The figure shows a perspective view of a bobbin used for the core. After setting the liner 3 in the crankcase model (wooden mold or mold) and setting the bobbin 4 inside it, oil sand (self-hardening sand in this example, shell or mard box is also acceptable)
Put in. At this point, you can perform 2 manual loading or mechanical loading. The shape of the bobbin 4 is such that flanges 12.13 are fixed to the top and bottom of the cylindrical body ttX, and a space formed by the outer periphery of the cylindrical body 11 and the upper and lower surfaces of the upper and lower flanges 12.13 is the inner preheating molten metal chamber 5 of the liner 3.

The function of the preheating molten metal chamber 5 is as follows.

In other words, if the third lie is cast in aluminum alloy as it is, the temperature will drop the moment the molten metal contacts the liner 3 due to the heat capacity of the molten metal.
Since the amount of heat required for the diffusion reaction of the aluminum alloy is insufficient, the preheating formed inside the liner 3 and the melting temperature of the cast-in molten metal of the aluminum alloy, or the melting temperature of the cast-in molten metal, is transferred to the molten metal chamber 5. Preheating molten metal of another metal is poured from the sprue 6 to preheat the liner 3 from inside.

As a result, the cast-in aluminum alloy constituting the cylinder block takes longer to solidify, and is firmly welded to the liner 3 through a diffusion reaction.

Now, after setting bobbin 4, crankcase core 1
Oil sand is added to unite the boat and Ogi Nakako 2. However, the core 9 of the intake and exhaust boat core 7, which is separately molded, is inserted and set into the boat core 2. As a result, the crankcase core 1, the port core 2, and the intake and exhaust boat cores 7 can be integrated. Therefore, variations in the positions of the crankcase axis a and the intake and exhaust boat axes can be reduced during mass production.

The bobbin 4 is made of paper and is burnt out during pouring. Also, the first part in Figure 2 is the intake boat Nakamoto.

15 indicates the exhaust port core.

In summary, the present invention is a cylinder block with an integrated head made of aluminum alloy into which a liner is co-cast.A preheated molten metal chamber is formed inside the liner, and the liner is firmly welded to the cylinder block by the preheated molten metal. In the method for molding the core used in the method, since the core is made by integrating the crankcase core and the boat Ogi core, the following effects are achieved.

〔Effect of the invention〕

■When a cylinder block with an integrated head is mass-produced, the accuracy of the position of the boat that constitutes the direct injection combustion chamber and the dimensional accuracy of liner thickness deviation will be improved.

- As a result, variations in the positions of the crankshaft, liner, intake and exhaust points are made concentric, so all that remains is a matter of model accuracy, and when mass-produced, the variations are reduced overall.

■Therefore, the swirl ratio etc. do not deviate from the optimum value and the performance of one engine does not deteriorate.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is a plan view of FIG. 1, and FIG. 3 is a perspective view of the main parts. l:...Crankcase core, 2...Boat Ogi core. 3...Liner, 5...Preheating molten metal chamber, 7...Intake or exhaust boat core

Claims (1)

[Claims] A method for forming a core used in casting, in which a cylinder block with an integrated head made of aluminum alloy is co-cast with a liner, a preheated molten metal chamber is formed inside the liner, and the liner is firmly welded to the cylinder block by the preheated molten metal. , a method for molding a core for an engine cylinder block that integrates a crankcase core and a port core that constitute the core.