JP3124442B2 - Forging tool having tilt function and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tool for heating a material such as hot forging and warm forging, and particularly for processing a component having a complicated shape.

[0002]

2. Description of the Related Art Hot forging and warm forging are widely used as techniques for manufacturing a large number of parts used in automobiles, construction machines, aircrafts, and the like. In recent years, the weight of these parts has been reduced, and in order to use a high-strength material and compensate for the lack of rigidity, the shape of the parts has become thin but complicated. In such a case, a strong load is applied to the mold due to the deformation resistance of the material being forged, and the life of the mold is remarkably reduced.

[0003] To solve this problem, it is most effective to reduce the deformation resistance of the material. From this viewpoint, for example, in Japanese Patent Application Laid-Open No. H5-15935, the deformation resistance is minimized by heating to the vicinity of the material solidus. Techniques for lowering and forming complicated shapes have been proposed. However, when working in such a high temperature state, the heat of the raw material is taken away by the mold and the temperature is lowered, and a sudden increase in the deformation resistance is unavoidable. Therefore, in the present invention, rapid forming of 500 mm / s or more is essential. Unless these high-speed presses are nurtured, this technique is difficult to use, and even if it is molded at high speed, some heat escaping is inevitable, and the increase in deformation resistance due to it is not negligible.

[0004] A method of processing semi-molten metal using a non-metal die having low thermal conductivity in order to cope with this heat leakage is proposed in US Pat. No. 5,037,489. It has low strength and is very susceptible to thermal shock and impact load, and cannot withstand repeated use, especially with complex die forging dies. For the reasons described above, the production of a part having a complicated shape requires dividing into a plurality of relatively simple shapes, forging and assembling, or adding a large number of cutting steps, and following a long process. As a result, the manufacturing costs are very high.

[0005]

In the case of processing a complicated part by heating a material such as hot forging or warm forging, the strength is high, and it is strong against thermal shock and impact load.
Development of a hot and hot forging tool having a tilting function that can withstand repeated use and greatly suppresses the flow of material heat to the tool to lower the material temperature and increase the deformation resistance, and to develop a method of manufacturing the same. There is a need and the present invention has been made to meet that need. Above
The above-mentioned inclination function is the same as that of the forging tool of the present invention.
Insulation and strength toughness continuously change from the surface to a certain depth
Means to go.

[0006]

SUMMARY OF THE INVENTION The present invention has been devised to solve such a problem, and the gist of the invention is that the inside is made of steel or cast iron and at least comes into contact with a workpiece. Between 0.5 to 3 mm of the surface layer of the part,
The weight mixing ratio of the ceramic to the internal component is continuously changed so as to be 0 inside and 0.6 to 1.0 at the outermost surface, and it is necessary to have a cooling pipe inside the tool as necessary. A hot and hot forging tool having a characteristic tilting function, and a powder made of tool steel or cast iron component and a ceramic made of tool steel or cast iron. The powder mixture is supplied while continuously changing the mixing ratio, and low pressure plasma spraying is applied to the tool surface to form a coating layer having a thickness of 0.5 to 3 mm, and the weight mixing ratio of the ceramic to the internal components is 0 internally, and at the outermost surface, The present invention relates to a forging tool having a tilt function and a method of manufacturing the same, wherein a ceramic mixed layer having a thickness of 0.6 to 1.0 is formed.

[0007]

[Function] Normal hot and hot forging tools require heat resistance, but in forging complex parts of high-strength material, it is very important to insulate so that heat is not taken away by the mold. As described above, since ceramic alone cannot withstand impact or thermal shock, in the present invention, the toughness is imparted by gradually changing the mixing ratio of metal and ceramic according to the portion.

FIG. 1 shows an example of a process of forming a part by hot forging. Reference numeral 1 denotes a heated metal material, 2 denotes a lower die of a split die, 3 denotes a counter punch, and 4 denotes an upper part of the split die. Type,
5 is a punch. 2 is an enlarged view of a portion A in FIG. 1, and FIG. 3 is a perspective view of a processed product of the material 1 in FIG. As the punch 5 is pushed in, the material 1 fills the cavity of the mold, but the ribs 6, 6 ′, 7, 7 ′, 8, 8, 8, 8.
In 8 ', the heat transfer to the mold is large, the material temperature is reduced, the fluidity is lost, and the material is not easily filled.

In the present invention, for example, as shown by enlarging part A in FIG. 1 to FIG. 2, ceramic shown in black and steel or cast iron shown in white are mixed, and most of the surface is made of ceramic, In the interior, everything is steel or cast iron. During that time, the composition ratio of steel or cast iron increases as the steel enters from the surface to the inside, and becomes 100% steel or cast iron at a depth t. The change of the ceramic component ratio can be arbitrarily selected whether it is linear or curved in the depth direction.

As a material inside the mold, it is preferable to use tool steel having both strength and toughness, but in a mold having a small load, it is also possible to use cast iron. Then, 0.5 mm or more and 3 mm or less on the surface layer of the die or punch are mixed with the internal component and ceramic. The range of the depth is determined from a lower limit for exhibiting the effect of heat insulation and an upper limit for securing the strength toughness. The weight ratio of the ceramic at the outermost surface is in the range of 0.6 to 1.0 because the heat insulation effect is small when the ceramic mixing ratio of the outermost layer is less than 0.6. As the type of ceramic, ZrO ₂ , SiC, A
A material having a heat insulating effect and strength such as l ₂ O ₃ , TiC, and Y ₂ O ₂ is desirable.

The most effective method for producing the tool of the present invention is low pressure plasma spraying while mixing a powder composed of a mold component and a ceramic powder in a steel or cast iron mold finished to a substantially predetermined size and shape. Is the process of doing The reason for using the low-pressure plasma spraying method is that, because the spraying atmosphere is sprayed in a vacuum vessel replaced with an inert gas such as Ar gas,
In particular, since oxidation of the metal spray material can be prevented, a high-strength coating can be secured. According to this method, the ceramic exerts the heat insulating effect, while the steel and the cast iron share the strength. Therefore, it is possible to withstand the strong pressure applied through the material to be processed and greatly suppress the heat conduction.

Furthermore, since there is almost no metal component in the surface layer, adhesion of the material to be processed to the tool is suppressed, and the coefficient of friction is greatly reduced. In some cases, it is not necessary to add a lubricant. Even if such a surface layer is coated with a heat-insulating substance, if the production is continued for a long time, heat may propagate inside and the tool material may soften, so if necessary, place a pipe near the internal surface layer as necessary. It is also effective to arrange and circulate the coolant.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The tool shown in FIG.
Using SKD61, the inner diameter of the die was 70 mm, and the fin thickness of each part was 3 mm. In this shape, one is SK
D61 single tool, the other, the tool surface layer of the workpiece contact portion, SKD6 gradually from the outermost layer to the inside
By increasing the ratio of 1, a tool having a minimum depth of 0.5 mm and a maximum of 3 mm at which the ceramic content becomes zero was formed by thermal spraying using low-pressure plasma.

Table 1 shows the low pressure plasma spraying conditions. Table 2
2 shows the state of the surface ceramic layer of the prepared tool. Table 2
The ceramic weight mixing ratio of the outermost layer means the ratio of ceramic weight / steel component weight. Experiments were conducted for one type of ceramic and a case of mixing two types of ceramics, and the weight ratio in the case of mixing is also shown in Table 2.

[0015]

[Table 1]

[0016]

[Table 2]

[0017] These various tools are heated to 1350 ° C.
A material of IS-S55C having a diameter of 68 mm x 80 mm was pressed with various punches. 170m punching speed
m / s and a load of 40 tonf was applied. The dimensions of the parts formed after cooling after this processing were measured as the overhang lengths of the thin fin-like projections 6, 6 ', 7, 7', 8, 8 '(all corresponding to the reference numerals in FIG. 1). Table 2 shows the overhang lengths of the paired fins averaged.

According to the results, the fin length of Comparative Example 1 was 5 mm at 6, 6 ', 5 mm at 7, 7', and 9 at 8, 8 '.
Although the fin length is not so large in Comparative Example 2 in which the mixing ratio of the ceramic and the tool steel is gradient-distributed up to a depth of 0.3 mm in the surface layer, the fin length is not so large. As described above, the length of the fin according to the present invention of 3 mm or less significantly exceeds Comparative Examples 1 and 2, and it is clear that the present invention is excellent in mold filling of a narrow portion. This tendency is not significantly affected by the type of ceramic, the plurality of ceramics, and the ceramic weight mixing ratio in the outermost layer. As the depth of the ceramic mixing portion increases, the fin overhang length tends to gradually increase. However, if the mixing portion is small, the effect is sufficiently recognized.

However, the mixing ratio shown in Comparative Example 3 was 4.5.
In comparison with mm, the fin length was large, but it was damaged early during use and was not practical. When the ceramic weight ratio in the outermost layer was as low as 0.5 as in Comparative Example 4, the heat insulating effect was reduced, and the mold filling was insufficient. As described above, the present invention exerts extremely excellent power for molding a part having a complicated shape.

[0020]

According to the present invention, a complicated die forging can be performed, and the step of repeatedly performing heating and forging a plurality of times in the past can be greatly shortened, which makes a great contribution to the industry.

[Brief description of the drawings]

FIG. 1 illustrates an embodiment of the present invention.

FIG. 2 is an enlarged view of a part of FIG.

FIG. 3 is a perspective view of the material shown in FIG. 1;

[Description of Signs] 1 Material 2 Lower Die 3 Counter Punch 4 Upper Dice 5 Punch 6, 6 ', 7, 7', 8, 8 'Fin

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Saburo Kitaguchi 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Corporation Technology Development Division (56) References JP-A-61-110770 (JP, A) Kaihei 1-1127122 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B21J 13/02 C23C 4/04, 4/12

Claims (2)

(57) [Claims] The weight ratio of ceramic to said internal components is 0 internally at least in a surface layer portion of 0.5 to 3 mm at a portion in contact with a workpiece, and the inner surface is made of steel or cast iron. A forging tool having a tilt function, wherein the forging tool continuously changes so as to be 0.6 to 1.0. 2. A tool made of tool steel or cast iron is supplied to a surface of at least a portion in contact with a workpiece while continuously changing a mixing ratio of powder made of tool steel or cast iron and ceramic powder. Low-pressure plasma spraying is performed on the tool surface to form a ceramic mixed layer having a coating layer thickness of 0.5 to 3 mm and a weight mixing ratio of ceramic to the internal components of 0 internally and 0.6 to 1.0 at the outermost surface. The method for manufacturing a forging tool having a tilt function according to claim 1, wherein the forging tool is formed.