JPH0699216A - Hot extruding die - Google Patents

Abstract

PURPOSE:To reduce deformation and wear by building up a composite material wherein heat and wear resisting compound grains having an average grain diameter each of a special range in a substrate metal made from heat resisting alloy are dispersed at a rate of a special range on the inner surface containing at least a bearing part of a die body. CONSTITUTION:A die body 10 is constituted of alloy tool steel and on the inner surface containing at least the bearing part is built up the composite material 20 wherein heat and wear resisting compound grains having an average grain diameter each 50-100mum are dispersed at a rate of 10-50wt.%. The base metal of the composite material 20 is made Ni base heat resisting alloy and the compound grain is made NbC. In this way, the bearing part of a hot extruding die is poor in deformation and wear and since the die itself is free from deformation, many repeated uses can be made. Since composite material is used partially to refrain deformation and wear, the die itself can be reduced in cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot extrusion die used for producing a seamless pipe or the like by hot extrusion.

[0002]

2. Description of the Related Art As shown in FIG. 1, a seamless hollow tube is manufactured by hot extrusion.
It is manufactured by inserting the mandrel 4 into the die 3 after passing through the material 1 and pressing the material 1 forward in this state. That is, the pressed material 1 is extruded in a tubular shape forward through an annular gap formed between the die 3 and the mandrel 4. Here, the die 3 is housed in the die holder 5, and is supported by the die backer 6 from the front in the extrusion direction.

As a material of a die used for such a hot extrusion pipe, SKD6 is less likely to be deformed and worn.
Alloy tool steels such as No. 1 are common, and recently, an integral die made of a Mo-based or Ni-based heat-resistant alloy that is more excellent in strength and wear resistance at high temperatures is also used.

[0004]

However, the so-called bearing portion of the die, in which the die and the material come into contact with each other, has a high temperature of 900 to 1100 ° C. due to abrasion with the material and heat transfer from the material, and a large compressive force and shearing force. Receive power.

Therefore, in the case of a die made of alloy tool steel, if the extrusion conditions such as a small-diameter thin-walled pipe are severe, or if the material is a difficult-to-process material, it is possible to perform 0.5-2.0 mm in one processing.
Some degree of wear and deformation occurs in the bearing. as a result,
The dimensional accuracy of the product pipe deteriorates. Further, the die life is shortened and the pipe manufacturing cost is increased.

On the other hand, the integral die made of the heat-resistant alloy has less wear and deformation of the bearing portion. But M
O-based heat-resistant alloys are expensive, and it is difficult to suppress an increase in pipe manufacturing cost even if abrasion and deformation are suppressed. In that respect, the Ni-based heat-resistant alloy is relatively inexpensive, and this integral die is usually used.

However, Ni-base heat-resistant alloys are inferior in strength at room temperature to alloy tool steels. As shown in FIG. 1, the die is supported in the die holder 5 by the die backer 6 and the like, and its supporting portion does not become as hot as the inner surface during processing. Therefore, the die itself may be deformed depending on the pushing force. When the die itself deforms,
The size of the product pipe is extremely reduced, and it becomes difficult to reuse the die. Further, the deformation and wear of the bearing portion are becoming insufficient under the recent severe extrusion conditions.

An object of the present invention is to provide a hot extrusion die in which the deformation and wear of the bearing portion are small even under the recent severe extrusion conditions, and the die itself is not likely to be deformed.

[0009]

In the hot extrusion die of the present invention, the die main body is made of alloy tool steel, and the inner surface including at least the bearing portion has an average grain size in the base metal made of a heat-resistant alloy. It is characterized in that a composite material in which heat resistant and abrasion resistant compound particles of 50 to 100 μm are dispersed at a ratio of 10 to 50% by mass is built up.

[0010]

In the hot extrusion die of the present invention, since the composite material in which the heat resistant and wear resistant compound particles are dispersed in the base metal made of the heat resistant alloy is built up on the inner surface including the bearing portion, The deformation and wear of the bearing part are even less than those of the heat resistant alloy integrated die.

Further, since the die body is made of alloy tool steel having excellent strength at room temperature, deformation of the die itself, which is a problem with the integrated die of heat resistant alloy, does not occur.

Further, since the composite material is integrated with the die body by padding, there is no possibility that this portion will come off from the die body. Since the mandrel is pulled out rearward after the extrusion is completed in the hot-extrusion pipe making, the bearing part receives a strong force in both the front and rear directions, and there is a possibility that it will come off when the composite material ring is fitted.

The base metal used in the composite material is Mo-based, N-based.
As a heat-resistant alloy such as i-based, a Ni-based heat-resistant alloy such as Hastelloy C276 and Inconel 718 (both are trade names) is more economical and desirable.

As the compound particles dispersed in the base metal, for example, NbC, WC or the like can be used. These not only have high hardness and high wear resistance at high temperatures, but also have a specific gravity equivalent to that of the base metal and are advantageous in promoting dispersion of the compound particles during buildup.

The content of the compound particles is 10-5 by mass ratio.
0% If it is less than 10%, the effect of improving the strength and wear resistance at high temperature is small, and if it exceeds 50%, the toughness of the composite material decreases, and there is a risk of cracking during padding or extrusion.

The average particle size of the compound particles is 50-100 μm.
m. If it is less than 50 μm, it is difficult to disperse the particles, and 10
If it exceeds 0 μm, the toughness of the composite material is significantly reduced.

The build-up can be carried out regardless of the kind, for example, by plasma-buildup thermal spraying of a mixture of the powder of the base metal and the compound powder. It can also be carried out by gas shielded arc welding using a wire in which a compound powder is filled in a metal tube made of a base metal.

The range of build-up requires the bearing portion on the inner surface of the die body. The front and rear approach parts and the relief part of the bearing part may be padded if necessary.

The surplus allowance is preferably set to 2 mm or more.
That is, if it is less than 2 mm, the component ratio of the alloy tool steel that dissolves in the composite material becomes large, and there is a concern that the original high temperature strength of the composite material may not be obtained. The upper limit does not need to be particularly limited, but as the build-up allowance increases, there is a risk that the heat-affected zone of the alloy tool steel will have a decreased strength due to an increase in the build-up frequency, so that no decrease in strength occurs. It is desirable to set the degree to a certain degree, which varies depending on the composition of the alloy tool steel to be used. Therefore, it is preferable to determine the limit by an experiment appropriately so as not to exceed the limit.

[0020]

EXAMPLES Examples of the present invention will be described below.

In producing the extruded tube shown in Table 1 under the same conditions shown in Table 1, three kinds of dies were used.

The first die is an integrated die made of alloy tool steel SKD61 (JIS G4404) whose composition is shown in Table 2. The second die is an integral die made of a Ni-base heat-resistant alloy (Hastelloy C276) whose composition is shown in Table 2. As shown in FIG. 2, the third die has a composite material 2 over the entire inner surface including the bearing portion of the die body 10.
0 is built up and the inner surface is finished by cutting. The die body 10 is made of the above alloy tool steel,
The composite material 10 was coated by plasma overlaying spraying. The basic metal of the composite material 10 was the above Ni-based heat-resistant alloy, and the compound particles were NbC. The diameter of the NbC particles was 100 μm on average, and the content was variously changed in the range of 0 to 60 mass%.
The build-up allowance of the composite material in the bearing part is 3 mm,
1 mm was removed by cutting.

Table 3 shows the results of using each die. The inner diameter variation is the inner diameter variation of the bearing part by one extrusion, and the number of repetitions is 1.0 m of this inner diameter variation.
This is the number of times extrusion is repeated until m or more.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

The tool steel integrated die has an inner diameter variation of 0.5 m.
m is large and the number of repetitions is only two. The heat-resistant alloy integrated die has a small variation in inner diameter per machining,
Since the die itself was deformed by the single processing, it could not be used repeatedly. On the other hand, the die having the composite of the heat-resistant alloy and the compound powder has a smaller inner diameter variation than the heat-resistant alloy integrated die as long as the amount of the compound powder is appropriate. Moreover, since the die itself is not deformed and the composite material is not peeled off, the number of repetitions is significantly increased. Further, since the composite material is locally used and the main body is made of inexpensive tool steel, the cost of the die itself is low. Therefore,
Along with the improvement of the dimensional accuracy of the product, the reduction of the pipe manufacturing cost is achieved.

[0028]

As is apparent from the above description, the hot extrusion die of the present invention has little deformation and wear of the bearing portion, and since the die itself is not deformed, it can be repeatedly used many times. Is. Furthermore, since the composite material that suppresses deformation and wear is locally used, the cost of the die itself is low. Therefore, the ratio of the die cost to the product manufacturing cost is reduced, and the manufacturing cost is significantly reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an outline of a hot extrusion pipe manufacturing method.

FIG. 2 is a cross-sectional view schematically showing a configuration example of a die of the present invention.

[Explanation of symbols]

 10 Dice body 20 Composite material

Claims (1)

[Claims] 1. A die body is made of an alloy tool steel, and 10 to 50 heat resistant and abrasion resistant compound particles having an average particle size of 50 to 100 μm are contained in a base metal made of a heat resistant alloy on an inner surface including at least a bearing portion thereof. A die for hot extrusion, characterized in that a composite material dispersed in a mass% ratio is piled up.