JPS5829565A - Production of small sized cylinder liner - Google Patents

Abstract

PURPOSE:To obtain products of pearlite base in an as-cast state in the stage of casting small-sized cylinder liners by the use of a sand mold core and an outside diameter die by specifying the wall thickness of the outside diameter die. CONSTITUTION:An outside diameter die 12 having the wall thickness equal to that of a cylinder liner 10 for small-sized engines is manufactured. Said die is preheated and held, and a sand mold core 14 is set at the center thereof. Molten metal for commonly used green sand molds is charged between the die 12 and the core 14. The molten metal begins to solidify by releasing the heat of solidification to the mold 12 and the core 14. Since the molten metal in contact with the core releases the heat very slowly on account of the heat insulation of the core, the greater part of the heat possessed by the molten metal flows to the die 12, then the die heats up quickly. Thus the quick cooling of the molten metal is prevented, and pearlite base is produced approximately 100%. The die 12 is opened in about 5-10sec after the charging of the molten metal is completed, and the solidified cylinder liner is removed together with the core 14.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fJl iQ method for small cylinder liners, and more particularly, to
The present invention relates to a method for manufacturing a small cylinder liner that can produce a cylinder liner for a small engine with a diameter of 1.5 ft.

BACKGROUND ART A method of manufacturing a VJ item such as a large cylinder liner using a mold on the outside diameter is widely known. This outer diameter mold is made using expensive alloy steel in order to increase the mold life, and the mold wall thickness is also increased in order to improve precision and mold life in times of danger1. . This results in the mold temperature rising excessively during repeated cycles.
In order to cool this, conditions such as water cooling are added and used, and it is possible to achieve a →noicle of about 1,000 watts of culm.

However, in the case of a small cylinder liner, the contact surface between the first diameter mold and the molten metal requires thick gold IX+! Rapid f and T heat conduction occurs, causing rapid cooling and causing chills at curved corners of the vI product, making post-processing impossible fi1. \/, v1
Houjinokyu 'l'fv + thing L7) J, (11uKIImt
Because it is easy to form ferrite, it becomes a ferrite material, and the formation of ferrite disrupts the so-called compatibility and balance with the piston ring, promoting wear. For this reason, castings in their 13M condition are used for manhole covers, water pipe joints, etc. where chilling is not a problem. Furthermore, it has been attempted to further heat-treat the chilled cylinder liner as cast to form pearlite, but this method is disadvantageous in terms of the heat treatment cost of 1~ and the number of man-hours.

For this reason, an outer diameter mold is used for the thin and small cylinder liner vJa, which is more likely to cause rapid cooling.
! J construction method is used. In this case, both the outer diameter sand mold and the sand mold core must be disintegrated each time, resulting in low productivity and an increase in total cost of 1. In addition, centrifugal ν1 construction is difficult to manufacture because thin castings tend to have uneven wall thickness, and when manufacturing small-diameter cylinder liners, sufficient uniformity cannot be obtained unless ultra-high speed rotation is used. There's a problem.

By using an outer diameter mold like this! Unlike sand molds, etc., ＋i molds have the characteristic that νJ a can be continuously repeated many times, but conventional outer diameter molds require rapid cooling, and for this reason, Jj W L/ castings cannot generate pearlite ground.

It was thought that making the wall thickness of the outer mold even thinner would not only affect the life of the mold, but also have a negative effect on dimensional accuracy. , while satisfying the mold life and dimensional accuracy using pearlite Jlu high-grade νf iron in the as-cast state? It had never even been considered that something like this could be done.

Therefore, the present inventors researched a method of casting small cylinder liners using an outer diameter mold, which had been considered a priority in the past.
Yuto explored the possible conditions and range of the use of outer diameter molds by changing the conditions of It was possible to obtain a small-sized cylinder liner that had a grain size of 1 and had a finer lead (3) than that for the sand mold (SJ).

In other words, to date, outer diameter molds have been used that have a wall thickness that is at least five times the product wall thickness in order to increase the mold life, the strength of the surface that comes into contact with the molten metal, and to withstand rough handling. Furthermore, it has become common technical knowledge to perform water cooling to avoid heat accumulation in order to extend the life of the mold, and we have never seen an example in which the conditions for the sand mold core core and outer mold wall thickness were considered. However, through experiments in which the outer diameter mold wall thickness for this sand mold core core was varied over a wide range, the inventors succeeded in determining the outer diameter mold wall thickness, which is completely different from conventional outer diameter molds. By setting the wall thickness to be approximately the same as that of a small cylinder liner, that is, in the range of 0 to 30% of the wall thickness of a small cylinder liner, and using it in combination with a sand mold core core, rapid cooling of the molten metal can be prevented. I was able to obtain VJ free casting made of pearlite.

That is, the object of the present invention is to use a sand mold core core and an outer diameter mold, and to make the wall thickness of the outer diameter mold approximately the same as the thickness of the inner diameter liner. To provide a method for manufacturing a small cylinder liner, which is characterized in that it generates dirt.

Embodiments of the present invention will be described in detail below with reference to the drawings.

An outer diameter mold 12 consisting of a frame having a wall thickness equivalent to that of a cylinder liner 10 for a small engine is produced, and the temperature of this outer diameter mold 12 is preheated to /30-300°C and maintained.

Next, the sand mold core core 14 is set in the outer diameter mold 12 core,
A commonly used molten metal for a green mold is poured between the outer diameter mold 12 and the sand mold core core 14. The molten metal poured into the mold releases solidification heat to the outer diameter mold 12 and the sand mold core core 14, and solidification begins. However, the heat release of the molten metal in contact with the sand mold core core 14 is extremely slow due to the insulation properties of the sand mold core core, and for this reason, most of the heat released from the molten metal is transferred to the outside, which has excellent heat conduction. The heat flows into the diameter mold, and the temperature of the outer diameter mold 12, which has been preheated, rapidly rises accordingly.

This temperature rise prevents the molten metal from cooling rapidly, and when 10 seconds have elapsed since the end of pouring the molten metal, the diameter mold 12 is opened and the solidified cylinder liner is taken out together with the sand mold core core. Insert a new sand mold core again, close the outer diameter mold, and then pour the molten metal → No cycle can be repeated. The outer mold temperature has increased to approximately 400°C in this case. Since rapid cooling of the molten metal is prevented, there is a risk that chill may occur due to rapid cooling.Also, even in the structure of νj'ML/, almost 100% pearlite is generated without the base becoming ferrite.

In addition, according to the results of various experiments in which the wall thickness of the outer diameter mold 12 was further reduced, cooling was made slower, resulting in a more raw material.
Although a structure close to WJR can be obtained, there is a technical limit in this respect because thermal deformation of the outer diameter mold is likely to occur and the mold life is shortened.

For this reason, the cylinder liner wall thickness for /l) type engines is 5.
It is practically difficult to use an outer diameter mold with a wall thickness of 0% or less. Furthermore, backing up the thin outer diameter mold with a heat insulating material is useful for preventing rapid cooling, but heat accumulates in the outer diameter mold, making it unusable in a short period of time. On the other hand, by increasing the wall thickness of the outer mold, it is possible to increase the mold life and prevent thermal deformation of the outer mold, but as in the past, it is possible to make as-cast products made of ferrite material, and furthermore, Therefore, it is not practical for an outer diameter mold having a wall thickness that is 100% or more of the wall thickness of a small cylinder liner.

Note that the cylinder liner for small engines here refers to the cylinder liner of engines used in passenger cars, motorcycles, motorcycles, etc. equipped with a 2000cc class gasoline engine or a 3000cc class diesel engine with a total displacement m. For example, diameter 0 on the left
~/30mm, height SO~2! ;Omm, wall thickness is 5-1
The upper and lower limits of the thickness of the product part were mainly 2 to 1/Smm. The lower limit is mainly due to the problem of uniformity, which makes the hot water area inappropriate, and because Sennari becomes ferrite.

Regarding the experimental example conducted using the experimental apparatus shown in Fig. 2 on the change in the metallographic structure of a cylinder liner for a small engine due to the change in the wall thickness of the outer diameter mold, in (7) in the drawing (A>' C02H type ( II): 17 product parts. Wall thickness 6m/+n(t)
(C); Outer diameter mold (D): Mold wall thickness 3 m/rn (E): Mold wall thickness 6 m/m (F): Mold wall thickness 9 m/m (G): Mold wall thickness 18 m/rn Mold temperature 2! ; 0 'C Molten metal component C2 3.25% S1 = 2-796 Todoroki In
=QJ, %P =0.3% 3% vicral etch.

Parts D, F, and F, which range from 50 to 750% of the cylinder liner wall thickness, are as-cast and made of pearlite, but the outer mold tooth thickness is 300% of the cylinder liner wall thickness. The G section contains ferrite and is unsuitable for use as a cylinder liner.

(8) Figure 4 A1B shows a comparison of the structures of cylinder liners for small engines manufactured using other conventional methods and cylinder liners for small engines manufactured using the method of the present invention.
, C.

A: Cylinder liner obtained by conventionally used sand mold core core and outer sand mold B: Cylinder liner obtained by using a sand mold core core and a sand mold core core having a wall thickness five times that of a cylinder liner for small engines. Cylinder liner C obtained by using this method: A cylinder liner obtained by using the thin outer diameter mold and sand core core according to this method. The outer diameter mold used here was made of cast iron, which is extremely inexpensive, and could be used repeatedly for about 3000 cycles.

Examining the respective mm, the cylinder liner jljl obtained using only the sand mold A is pearlite, but the grain size of its crystals is large. It can also be seen that the graphite molecule +7 is inferior, as the graphite has grown into a thick shape. In other words, in order to improve the durability of
It is desirable that Ni-Fly 1~ and graphite be dispersed and precipitated uniformly in this manner, but the sand mold vT
In M, the cooling was too slow, resulting in too much growth of barley 1 and graphite. The structure of the cylinder liner made by using the thick outer diameter mold of B is that the graphite type sample is fine flaky and the distribution is uneven, but since it is made of Feline 1~2, it is too soft and has poor durability. It is not compatible with conventional piston rings due to its abrasiveness.

The i and ua of the cylinder liner made using the thin-walled outer diameter mold according to the present invention shown in C are made of only pearlite, in which graphite is finely and evenly precipitated, and has high wear resistance. Since the precipitation is finer and more average than when using a sand mold, the two conditions that determine wear resistance are met. In the 400x magnified photograph, what appears white and amoeboid-like is phosphorus ferrite, not ferrite.

As described above, the method for manufacturing cylinder liners for small engines according to the present invention is extremely remarkable in that it combines the advantages of using a sand mold and an external mold. The diameter mold can also be made of extremely inexpensive material such as cast iron, and Flint'f 41 can be used, and the molten metal used for pouring has a special composition.1. X < 11M It is possible to use the commonly used molten metal for raw molds as is, making it a high-quality product in an easy way! The fJT steel cylinder liner for small engines has a remarkable moving bed that can be made into 71 pieces.

Note that in this application, the sand mold core core refers to a core core made of an inorganic material with high heat insulation properties, such as a mold for concrete 1, but as mentioned above, there is a heat insulation layer on the outer diameter mold surface. Backing up with stones is not recommended. This means that the method of the present invention can improve the thermal conductivity and heat capacity of the first diameter mold, the heat conductivity of the outside diameter mold surface, in other words, the heat insulation property, and the heat capacity of the molten lagoon, between A, 3, and F. This is due to the balance between This is because face-to-face problems arise.

Although various explanations (11) regarding the present invention have been explained above with reference to preferred embodiments, the present invention is not limited to these embodiments, and can be modified in many ways without departing from the spirit of the invention. Of course.

[Brief explanation of drawings]

The drawings show an embodiment of the invention, and FIG. 1 is a cross-sectional view of the mold;
Figure 2 is a vertical cross-sectional view of the mold, Figure 3 (r)), (E), (
F), (G) is that - E'%h%, (E), (F), (
G) Structure photograph of the casting product part, Fig. 4 (A), (A
'), (B), (TI'), (C), and (C') are all-sand casting metal structure, conventional thick-walled outer diameter mold casting metal structure, Kinoi 10... cylinder lye. , 12...
Outer diameter mold. 14...Sand mold core body core. 332 (] 2) Figure 1 Figure 2 Figure 3 (D) Figure 3 (F) Figure 4 Figure 4 Figure 4 C Procedural Amendment February 1982 251''5ru' Commissioner of the Patent Office Shimada's strange disease, 1゛1, Display of the case Showa leap year patent application number] 26+33 υ3, Relationship between the person making the amendment and the case Patent applicant 4, agent 6, number of inventions increased by amendment. 7. Specification and drawings to be amended 8. Contents of amendment 1) Page 13 of the specification, lines 8 to 12 “Figure 4 (A
),...It is a photograph. ” and insert the following sentence. "Figure 4A is a 100x enlarged micrograph of the entire sand mold casting metal structure, a is a 400x enlarged micrograph of the same, and Figure 4B is a 100x enlarged micrograph of the conventional thick outer diameter mold casting metal structure, b is a 400 times enlarged micrograph of the same, FIG. Correct as follows. 8 Contents of the amendment As shown in the attached sheet Figure 4 Figure 4 B Figure 4 [

Claims (1)

[Claims] 1. By using a sand mold core core and an outer diameter mold, and making the wall thickness of the outer diameter mold approximately the same as the thickness of a small cylinder liner, pearlite material can be produced in an as-cast state. A method for manufacturing a small cylinder liner characterized by generating. 2. The method for manufacturing a small cylinder liner according to claim 1, wherein the small cylinder liner has a wall thickness of 2 to 3 mm. 3. The wall thickness of the outer diameter mold is 50 ~ 50cm thick for small cylinder liners
A method for manufacturing a small cylinder liner according to claim 1 or 2, in which the cylinder liner is produced in a range of 130%. 4. A method for manufacturing a small cylinder liner according to claim 1, which uses a sand core core for the cylinder bore core.