JP2003211249A - Grasping holder for material to be forged - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grasping holder for a material to be forged, which can suppress a temperature drop of the material to be forged, and has satisfactory durability. <P>SOLUTION: In the grasping holder 6' for the material to be forged 1 consisting of a Ti-based alloy, the heat permeability of the Ti-based alloy is preferably 4,300 W.s<SP>0.5</SP>/(m<SP>2</SP>.K) or less at a temperature of 20°C, and 7,500 W.s<SP>0.5</SP>/(m<SP>2</SP>.K) or less at a temperature of 500°C. The tensile strength of the Ti-based alloy is preferably 800 N/mm<SP>2</SP>or more at a temperature of 20°C, and 400 N/mm<SP>2</SP>or more at a temperature of 500°C. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a jig for holding a material to be forged, and more particularly to a jig for holding a material to be forged which can suppress a temperature decrease of the material to be forged and has good durability. Regarding

[0002]

2. Description of the Related Art A forged product, for example, a bar material, as shown in FIG. 1, holds both ends of a material 1 to be forged, which is heated to a predetermined temperature or more by a heating furnace, by a chuck portion 4 of a manipulator device 3, It is manufactured by reciprocating inside the forging machine 2 and forging with an anvil 5. At the time of forging described above, the gripping jig 6 mounted on the chuck portion 4 and in direct contact with the material 1 to be forged
The temperature depends on the forging temperature, but is, for example, 500 to 600.
Rises to ℃. Therefore, as a material for the gripping jig, a medium carbon steel or nickel-based alloy having high hot strength and good durability has been conventionally used.

[0003]

By the way, when forging a material to be forged such as a heat-resistant alloy such as Inconel or Waspaloy, high temperature forging is carried out at a forging temperature of around 1000 ° C. In that case, medium carbon is used. The use of a holding jig made of steel or a nickel-based alloy causes a problem that the temperature of the material to be forged markedly decreases.

When the temperature of the forged material is excessively lowered, the deformation resistance and the deformability of the forged material are increased, the workability of the forged material is deteriorated, and defective molding or forging crack occurs in the forged product. In the worst case, the pressure required to process the forged material exceeds the capacity of the forging machine, which makes it impossible to forge the forged material.

Such a phenomenon is considered to be caused by the following. First, since medium carbon steel and Ni-based alloys have a large density ρ, they have a large heat capacity per unit volume, and when a holding jig made of these materials comes into contact with a forged material having a higher temperature than that, The amount of heat required to raise the temperature of the contact surface with the material to be forged to a certain temperature is large. Also,
Since medium carbon steel and Ni-based alloys have large thermal conductivity λ,
Since the amount of heat of the forged material is easily transferred within the holding jig, it is considered that the holding jig continues to take heat from the forged material even after the temperature of the contact surface of the holding jig reaches a constant temperature. Therefore, when performing forging using a holding jig made of medium carbon steel and a Ni-based alloy, the amount of heat taken by the holding jig from the holding jig while it is in contact with the material to be forged is large. It is considered that the temperature drop of the forged material progresses remarkably.

In order to suppress the temperature drop of the material to be forged during forging, a ceramic holding jig is rarely used. However, since ceramics are weak against impact and easily cracked, the holding jig made of ceramics has poor durability and requires frequent repair and replacement, which causes a problem that the manufacturing cost of the forged product increases. An object of the present invention is to provide a gripping jig for a forged material that solves the above-mentioned problems, can suppress the temperature decrease of the forged material, and has good durability.

[0007]

In order to achieve the above object, the present invention provides a jig for holding a forged material, which is made of a Ti-based alloy. And
The Ti-based alloy has a thermal effusivity of 43 at a temperature of 20 ° C.
^{00W · s 0. 5 / (m} 2 · K) or less, and the temperature 50
Thermal effusivity at 0 ℃ 7500W · s ^0.5 / (m ² ·
It is preferably K) or less.

Further, the Ti-based alloy is a tensile strength at a temperature 20 ° C. is 800 N / mm ² or more, and a tensile strength at a temperature 500 ° C. is preferably at 400 N / mm ² or more.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors prototyped gripping jigs made of various steel types and, while conducting repeated performance evaluations as gripping jigs, the gripping jigs made of Ti-based alloys were not covered during forging. It has been found that the temperature drop of the forged material can be suppressed and that the forged material has good durability. Then, the present inventors also examined the relationship between various physical property values of the Ti-based alloy and the characteristics required for the holding jig of the material to be forged. As a result, when the specific heat of the Ti-based alloy is c, the density is ρ, and the thermal conductivity is λ, the smaller the thermal effusivity defined by the following formula: (c × ρ × λ) ^0.5 , the more We have found that the temperature drop of the forged material can be suppressed.

Here, the thermal effusivity is an index showing the ability of a certain material to absorb heat or to rapidly accept heat. Specifically, the small thermal permeability means that the heat capacity per unit volume, which is the product of the specific heat c and the value of the density ρ, is small, and / or the thermal conductivity λ is small. Therefore, for example, when a gripping jig is made of a material having a low thermal effusivity, the amount of heat required to raise the temperature of the contact surface with the material to be forged is reduced in the gripping jig, and / or this contact surface is covered. It becomes difficult for the heat received from the forged material to be transmitted through the holding jig. Therefore, the amount of heat taken by the holding jig from the material to be forged during the forging becomes small, and the temperature decrease of the material to be forged can be suppressed.

By the way, as is apparent from the above equation, the thermal effusivity is a function of temperature. In the forging method described above, since the manipulator device 3 reciprocates to reciprocate the material 1 to be forged in the forging machine 2, the temperature of the gripping jig 6 may change according to the elapsed forging time. Becomes More specifically, at the earliest stage of forging, the holding jig 6 has the lowest temperature, and then the forging material 1 is held by the holding jig 6 so as to reciprocate in the forging machine 2, and the manipulator is operated. The forging is repeated by reciprocating the device 3. Then, when the forging is completed, the holding jig 6 has the highest temperature.

[0012] Therefore, the inventors of the present invention set the representative value of the maximum temperature reached by the holding jig and the representative value of the minimum temperature exhibited by the holding jig to use the thermal effusivity of the Ti-based alloy as an index of the present invention. Therefore, it is necessary to quantify the thermal effusivity. Therefore, in the present invention, the thermal permeability of the Ti-based alloy is specified at a temperature of 20 ° C. as a typical value of the minimum temperature exhibited by the holding jig and at a temperature of 500 ° C. as a typical value of the maximum temperature reached by the holding jig 6. To be done. Thus T
Since the thermal effusivity of the i-based alloy is specified at two representative temperatures, the holding jig for a forged material of the present invention can be effective even when the temperature of the forged material is low or high. It is possible to suppress the temperature decrease of the material to be forged.

The holding jig for a forged material of the present invention is no different from the conventional holding jig for a forged material except that it is made of a Ti-based alloy. Therefore, for example, as shown in FIG. 1, the gripping jig 6 ′ of the material to be forged according to the present invention can be attached to the chuck portion 4 of the manipulator device 3.
The holding jig for the forged material of the present invention is made of a Ti-based alloy.
The Ti-based alloy has the same specific heat c as the medium-carbon steel and the Ni-based alloy, but has a smaller density ρ. Therefore, since the heat capacity per unit volume is smaller than that of the conventional material described above, when the gripping jig made of the Ti-based alloy is in direct contact with the high-temperature forged material, it is more than in the case of the medium carbon steel and the Ni-based alloy. The amount of heat required to raise the temperature of the contact surface of the holding jig with the material to be forged to a constant temperature becomes small. Also, T
Since the i-based alloy has a smaller thermal conductivity λ than the medium carbon steel and the Ni-based alloy, after the temperature at the contact surface of the holding jig of the Ti-based alloy with the forging material becomes constant, The amount of heat transmitted from the forged material through the holding jig, that is, the amount of heat that escapes from the forged material to the environment through the holding jig is smaller than in the case of medium carbon steel and Ni-based alloy. Therefore, T
If a holding jig made of an i-based alloy is used, medium carbon steel and N
The temperature drop of the forged material during forging is suppressed more than in the case of the i-based alloy. As a result, the workability of the material to be forged can be ensured, and the occurrence of molding defects and forging cracks in the forged product can be prevented.

In the present invention, the Ti-based alloy has a temperature of 2
Thermal effusivity at 0 ℃ is 4300W ・ s ^0.5 / (m ²・
K) or less, and the thermal permeability at a temperature of 500 ° C. is preferably 7500 W · s ^0.5 / (m ² · K) or less. Thermal permeability of Ti-based alloy is 4300W at 20 ℃
・ When s ^0.5 / (m ² · K) is exceeded or temperature is 500
If the temperature exceeds 7500 W · s ^0.5 / (m ² · K) at ℃, the amount of heat taken by the gripping jig from the forged material during forging becomes large, and the temperature of the forged material decreases, resulting in deterioration of the workability. Invite.

In the present invention, the Ti-based alloy has a tensile strength of 800 N / mm ² or more at a temperature of 20 ° C. and a tensile strength of 400 N / m at a temperature of 500 ° C.
It is preferably m ² or more. The tensile strength of the Ti-based alloy is less than 800 N / mm ² at a temperature of 20 ° C, or a temperature of 500
If it is less than 400 N / mm ² at 0 ° C., the gripping jig will be deformed or worn during repeated forging, requiring frequent repair or replacement of the gripping jig.

In the present invention, since it is easily available, the following Ti-based alloy is more preferable.
Base alloys are given. First, as an α-type Ti alloy, Ti
-5Al-2.5Sn, Ti-5.5Al-3.5Sn
-3Zr-1Nb-0.3Mo-0.3Si, then as a near α-type Ti alloy, Ti-8Al-1Mo-1V,
Ti-2.25Al-11Sn-5Zr-1Mo-0.
2Si, Ti-6Al-2Sn-4Zr-2Mo, Ti
-5Al-5Sn-2Zr-2Mo-0.25Si, T
i-6Al-2Nb-1Ta-0.8Mo, Ti-6A
1-2Sn-1.5Zr-1Mo-0.35Bi-0.
1Si, Ti-6Al-5Zr-0.5Mo-0.2S
i, Ti-5Al-6Sn-2Zr-1Mo-0.25
Si, and as an α + β type Ti alloy, Ti-8Mn, T
i-3Al-2.5V, Ti-6Al-4V, Ti-6
Al-6V-2Sn, Ti-7Al-4Mo, Ti-6
Al-2Sn-4Zr-6Mo, Ti-6Al-2Sn
-2Zr-2Mo-2Cr-0.25Si, Ti-10
V-2Fe-3Al, Ti-4Al-2Sn-4Mo-
0.5Si, Ti-4Al-4Sn-4Mo-0.5S
i, Ti-2.25Al-11Sn-4Mo-0.2S
i, Ti-5Al-2Zr-2Sn-4Mo-4Cr,
Ti-6Al-5Zr-4Mo-1Cu-0.2Si,
Ti-5Al-2Cr-1Fe, Ti-5.5Al-4
Sn-4Zr-0.3Mo-0.5Si-0.06C-
1Nb, Ti-6Al-7Nb, and as a β-type Ti alloy, Ti-13V-11Cr-3Al, Ti-8Mo.
-8V-2Fe-3Al, Ti-3Al-8V-6Cr
-4Mo-4Zr, Ti-11.5Mo-6Zr-4.
5Sn Ti-15Mo-5Zr, Ti-15Mo-5Zr-3
Al, Ti-15V-3Cr-3Al-3Sn, Ti-
6Al-4V-10Cr-1.3C, and Ti-22
V-4Al can be mentioned.

Therefore, the Ti-based alloy usable in the holding jig of the present invention is Al: 8 mass% or less, V: 23 mass% or less, Mn: 8 mass% or less, Mo: 15 mass% or less, Sn: 11 mass% or less, Zr: 6 mass% or less, Si: 0.5 mass% or less, C
r: 11 mass% or less, Fe: 2 mass% or less, Nb: 8 mass% or less, Ta: 1 mass% or less, Bi: 0.35 mass%
Hereinafter, it can be generalized as a Ti-based alloy containing at least one selected from the group consisting of Cu: 1 mass% or less and C: 1.3 mass% or less, with the balance being Ti and inevitable impurities.

[0018]

EXAMPLES Examples 1-4, Comparative Examples 1-4 1. Creation of gripping jig The dimensions of the contact surface with the material to be forged are 100 mm in length and 50 m in width
A gripping jig having a thickness of 50 mm and a thickness of 50 mm was manufactured from the steel seed materials shown in Table 1. On the other hand, when manufacturing these gripping jigs, test pieces for measuring density ρ, specific heat c, thermal conductivity λ, and tensile strength were made of the same material as the gripping jigs.

2. Evaluation of gripping jig 1) Thermal permeability and tensile strength The density ρ, the specific heat c, and the thermal conductivity λ of the prepared test piece were measured at respective temperatures of 20 ° C. and 500 ° C., and based on these values. The heat capacity and thermal effusivity per unit volume were calculated. Similarly, 20 ℃ and 500 ℃
The tensile strength was measured at each temperature.

Of the above results, the results of tensile strength are shown in Table 2.
Table 1 shows the other results. 2) Temperature change of the material to be forged (square rod) due to contact with the holding jig. As the material to be forged, the external dimensions are 1000 mm in length and 100 in width.
A square rod (made of SUS304) having a thickness of 100 mm and a thickness of 100 mm was prepared and heated so that the temperature of the square rod was 1000 ° C. Then, on the side surface of this heated square bar, a temperature of 20 ° C.
The gripping jig was contacted with a force of 30 kN for 10 seconds and then separated. Immediately after that, the temperature of the portion of the square rod that was in contact with the gripping jig was measured, and the temperature change of the portion of the square rod was obtained.

Further, the temperature change of the portion of the square bar which was in contact with the gripping jig was obtained in the same manner as above except that the gripping jig was preheated to 500 ° C. The above results are shown in Table 1. 3) Useful life of the gripping jig The outer dimensions of the material to be forged are 500 mm in length and 100 in diameter.
A mm round bar (made of SUS304) was prepared. Then, while heating this round bar to a temperature of 1000 ° C,
Hold a gripping jig at a temperature of 500 ° C on its side surface with a force of 30 kN.
Touch for 0 seconds and then pull for 10 seconds 1
This operation was repeated as times, and the number of times was counted until the contact surface of the gripping jig with the round bar was worn by 1 mm, and this was taken as the useful life.

[0022]

[Table 1]

[0023]

[Table 2]

As is clear from Table 1, the Ti-based alloys constituting the holding jigs of Examples 1 to 4 have a smaller heat capacity per unit volume than the steel types of Comparative Examples 1 to 3. For this reason, according to the holding jigs of Examples 1 to 4, the temperature decrease at the portion in contact with the holding jig of the rectangular bar is suppressed more than in the cases of Comparative Examples 1 to 3. Further, as is clear from Table 2, Examples 1 to 4
The Ti-based alloy that constitutes the holding jig of Comparative Example 4 is pure Ti of Comparative Example 4.
Greater tensile strength. Therefore, the holding jigs of Examples 1 to 4 are superior in durability to the holding jigs of Comparative Example 4, and have good durability comparable to that of Comparative Examples 1 to 3.

[0025]

As is apparent from the above description, according to the holding jig for a forged material of the present invention, the temperature drop of the forged material at the time of forging can be suppressed, so that the forging material is machined. It is possible to manufacture a forged product without deteriorating the moldability and causing molding defects and forging cracks.

Further, the holding jig for the material to be forged according to the present invention has an appropriate strength and therefore has a good durability.

[Brief description of drawings]

FIG. 1 is a structural example of an apparatus used for hot forging.

[Explanation of symbols]

1 Forged material 6'Holding jig for forged material

Claims (3)

[Claims] 1. A holding jig for a material to be forged, which is made of a Ti-based alloy. 2. The Ti-based alloy has a thermal permeability of 4300 W · s ^0.5 / (m ² · K) or less at a temperature of 20 ° C. and a thermal permeability of 7500 W · s at a temperature of 500 ° C.
The holding jig for a forged material according to claim 1, having a s ^0.5 / (m ² · K) or less. 3. The Ti-based alloy has a tensile strength of 800 N / mm ² or more at a temperature of 20 ° C. and a temperature of 50 N / mm ^2.
The holding jig for a forged material according to claim 1 or 2, which has a tensile strength at 0 ° C of 400 N / mm ² or more.