JP2650561B2 - Manufacturing method of steel metal head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a golf club head such as a wood or iron head, and more particularly, to a plastic working such as drawing with an iron-based material, followed by quenching to increase the strength. And a method for manufacturing a steel metal head.

[0002]

2. Description of the Related Art When a metal head is manufactured from an iron-based material, the head shape is conventionally formed by a precision casting method. However, when a golf club head is formed by this precision casting method, the occurrence of casting defects cannot be avoided, and the crystal grains are large compared to a work material such as forging or rolling. There is a disadvantage that it is inferior to the material.

[0003] On the other hand, high-strength steel sheets produced by rolling or forging are used in various fields. However, when these high-strength steel sheets are formed, for example, after heat treatment such as steel sheets for automobiles. Is formed into a predetermined shape by drawing or the like using the heat-treated material described above.

[0004]

However, this conventional high-strength steel sheet does not have the large deformability required for a golf club head for wood because the strength is increased at the expense of workability by heat treatment. There is a disadvantage. For this reason, it is difficult to manufacture a golf club head using a high-strength steel plate conventionally manufactured by rolling or forging.

On the other hand, in the case of the precision casting method, a golf club head for a wood having a large shape cannot be manufactured, and the size of the wood shape is necessarily limited. For this reason, the golf club head for wood manufactured by the precision casting method has a drawback that the sweet spot area is narrow.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to achieve a high level of balance between workability and strength of an iron-based material, and to improve a directional stability by expanding a sweet spot area. It is an object of the present invention to provide a method of manufacturing a steel metal head capable of stably and easily manufacturing a large-sized steel metal head.

[0007]

The method for manufacturing a steel metal head according to the present invention is a method for manufacturing a steel metal head made of a steel plate having a yield stress of 1000 MPa or more. This method of manufacturing a steel metal head uses an iron-based material having the following composition. That is, C contains 0.05 to 0.35%, Si 0.40% or less Mn 2.20% or less Ni 4.00% or less Cr 3.0% or less Mo 1.00% or less Nb 0.10% Al 0.10% or less P 0.02% or less S 0.01% or less Cu 1.50% or less B 0.001% or less N Restricted to 0.01% or less, balance Fe and inevitable impurities Carbon equivalent 0 .80 to 1.30. In this iron-based material, the composition of each component of Si to N is an upper limit value, and in the present invention, these components are optional components. The composition of these components contains 0%.

[0008]

However, this carbon equivalent is for the case where the iron-based material is air-cooled in the subsequent quenching treatment step.
05 to 1.30 or less.

The method of the present invention comprises annealing a ferrous material having this composition at 650 to 750 ° C. to reduce the yield stress to 400 MPa or less and elongation to 20% or more, and the ferrous material after the annealing. Forming a metal head into a shape or a predetermined shape of a component constituting the metal head, and after this process, the iron-based material is quenched to have a yield stress of 1000 MPa or more and a tensile strength of 120 MPa.
And setting the pressure to 0 MPa or more.

[0011]

According to the present invention, the iron-based material is easily processed by annealing, and the material is formed into a golf club head shape with a large deformability, and then quenched to increase the strength. Improve. In this case,
In order to secure the strength of the material by cooling in the heat treatment process,
As the iron-based material to be used, C: 0.05% or more and 0.3
5% or less, Si: 0.40% or less, Mn: 2.20% or less, Ni: 4.00% or less, Cr: 3.0% or less, M
o: 1.00% or less, Nb: 0.10% or less, Al:
0.10% or less, P: 0.02% or less, S: 0.01%
Hereinafter, Cu: 1.50% or less, B: 0.001% or less,
N: 0.01% or less, Fe: The composition of the balance and unavoidable impurities is used. In particular, when the cooling in the quenching process for increasing the strength is air cooling, the carbon equivalent Ceq is used.
Is determined such that satisfies Equation 1 below, and when the cooling is water cooling, the composition is determined such that the carbon equivalent Ceq satisfies Equation 2 below. However, the carbon equivalent Ceq satisfies Equation 3 below.

[0012]

0.80 ≦ Ceq ≦ 1.30

[0013]

## EQU2 ## 0.05 ≦ Ceq ≦ 1.30

[0014]

Ceq = (% C) + (% Mn) / 6 + (% Si)
/ 24 + (% Ni) / 40 + (% Cr) / 5 + (% M
o) / 4 + (% V) / 14 As a result, when molding into a golf club head, sufficient deformability can be obtained, and in the subsequent heat treatment and cooling steps, the strength required for the golf club head is secured. can do. For this reason, a golf club head can be manufactured by using a processed steel plate such as a forged material or a rolled material instead of the conventional precision casting method, and the size of the head can be easily increased. Thereby, the sweet spot of the head is enlarged, and a steel metal head having excellent directivity can be manufactured.

The yield stress and elongation before the quenching treatment are preferably 400 MPa or less and 20% or more, respectively. If the yield stress before the quenching treatment is 500 MPa, the formability is inferior, but if the yield stress is 400 MPa, the formability becomes possible.
Moldability becomes good at 0 MPa or 200 MPa. Further, if the elongation before the quenching treatment is 10%, the formability is inferior, the elongation is 20%, the formability is possible, and if the elongation is 30% and 40%, the formability is good. For this reason, the yield stress before the quenching treatment is 400 MPa or less, and the elongation is 20 MPa.
% Or more.

On the other hand, the yield stress after quenching is 100
Make it 0 MPa or more. When heads were made of steel plates of various strength levels and tested to see if dents occurred in the heads, the yield stress after quenching was 100%.
When the pressure is 0 MPa or more, dents do not occur and 800 MPa
A dent occurred below a. For this reason, the yield stress after the quenching treatment is set to 1000 MPa or more.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the accompanying drawings.

FIG. 1 is a flow chart showing the method of the embodiment of the present invention in the order of steps. First, as shown in FIG. 1A, a cold-rolled material, a forged material, a solution-treated material, or the like is used.
This is annealed. This annealing temperature is 65
0 to 750 ° C. Thereby, the cold-rolled material or the like made of the iron-based material having the above composition is softened and easily processed.
If the annealing temperature is lower than 650 ° C., the material or the like after cold rolling cannot be softened to such an extent that it can be used in a subsequent step of forming a head shape. On the other hand, if the annealing temperature exceeds 750 ° C., coarse carbides precipitate during cooling, which adversely affects hardenability.

Next, the reasons for adding the components of the iron-based material having the above composition and the reasons for limiting the composition will be described.

C (carbon): C has the effect of increasing the strength of the iron-based material used as the material of the metal head. C is 0.
If it is less than 05%, the strength does not satisfy the required strength as a golf club head. On the other hand, C is 0.35%
If it exceeds 300, the toughness and weldability of the base material deteriorate. For this reason, C is set to 0.05 to 0.35%.

Si (silicon): Si has a deoxidizing action. However, if the Si content exceeds 0.40%, the weldability deteriorates and the toughness of the weld heat affected zone (hereinafter, referred to as HA)
Z toughness) is deteriorated. For this reason, the Si content is set to 0.40% or less.

Mn (manganese): Mn improves strength and hardenability. However, when the Mn content exceeds 2.20%, weldability and HAZ toughness deteriorate. For this reason,
The Mn content is set to 2.20% or less.

Ni (nickel): Ni improves the strength and toughness of the base material. However, if the Ni content exceeds 4.00%, the weldability deteriorates. Therefore, the Ni content is set to 4.00% or less.

Cr (chromium): Cr has an effect of increasing the strength of the base material and the welded portion. However, when the Cr content is 3.
If it exceeds 0%, the weldability and the HAZ toughness deteriorate. For this reason, the Cr content is set to 3.0% or less.

Mo (Molybdenum): Mo has an effect of increasing the strength of the base material and the welded portion. However, when the Mo content exceeds 1.0%, the weldability and the HAZ toughness deteriorate. For this reason, the Mo content is set to 1.0% or less.

Nb (niobium): Nb has the effect of bringing the microstructure of austenite to the normal temperature range. But N
If the b content exceeds 0.10%, the effect of Nb addition saturates. Therefore, the Nb content is set to 0.10% or less.

Al (aluminum): Al is deoxidized and A
1N has the effect of bringing the microstructure of austenite to the normal temperature range. However, when the Al content exceeds 0.10%, the effect of adding AlN saturates. For this reason,
The Al content is set to 0.10% or less. P (phosphorus): P is an unavoidable impurity, but if its amount is large, it deteriorates the low-temperature toughness. Therefore, the P content is 0.0
Restrict to 2% or less.

S (sulfur): S is an unavoidable impurity, but deteriorates low-temperature toughness like P. For this reason, the S content is restricted to 0.01% in order to ensure low-temperature toughness.

Cu (copper): Cu is an element for improving strength. However, when the Cu content exceeds 1.50%,
Hot workability deteriorates. Therefore, the Cu content is 1.5
0% or less.

B (boron): B has an effect of improving hardenability. However, if the B content exceeds 0.001%, the toughness of the base material deteriorates. For this reason, the B content is set to 0.001% or less.

N (nitrogen): N is an unavoidable impurity.
However, if the N content exceeds 0.01%, the toughness deteriorates, so the N content is set to 0.01% or less.

Carbon equivalent Ceq When the iron-based material having the above composition is air-cooled at the time of cooling in the subsequent heat treatment step, the carbon equivalent Ceq
Set eq to 0.80 or more. When water-cooling is performed during the cooling, the carbon equivalent Ceq is set to 0.05 or more. In this way, by defining the lower limit of the carbon equivalent, the strength of the iron-based material can be increased as in the case of adding C. The cooling step after the heat treatment is preferably air-cooled in order to suppress the quenching distortion of the molded article. Thus, in order to obtain sufficient strength at a relatively slow cooling rate of air cooling, it is necessary to make the carbon equivalent larger in the case of air cooling than in the case of water cooling. On the other hand, if the carbon equivalent exceeds 1.30, the HAZ toughness deteriorates. For this reason, the upper limit of the carbon equivalent is 1.30.

Next, as shown in FIG. 1 (b), an iron-based material having the above-mentioned composition and softened by annealing is formed into a predetermined head shape or a part of the head by plastic working such as press working. It is formed into a head split part shape. Thereafter, the head is cut into a predetermined shape and further welded by MAG welding or the like to assemble the head as shown in FIG. Next, after the heat treatment, the head is cooled under the cooling conditions described above to increase the strength of the head.

FIG. 2 is a graph showing the mechanical properties of an iron-based material heat-treated and cooled under the above conditions. As shown in this figure, the yield stress of the iron-based material before forming is 50%.
0 MPa or less, and the elongation is 10% or more. However, by performing a heat treatment after molding, although the elongation is reduced, the yield stress becomes 1000 MPa or more. Thereby, the required strength as a golf club head can be secured.

Then, the head after the heat treatment and cooling is polished and subjected to a surface treatment such as plating or painting to complete a golf club head. Thereafter, a shaft is assembled to the head to form a golf club.

In this embodiment, after annealing under a predetermined condition, the head is formed into a head shape or a divided part thereof by plastic working such as press forming, and then assembled into a head shape, and then subjected to a quenching process to obtain the strength. To be sufficient as a golf club head. For this reason, a golf club head can be manufactured not by precision casting but by using a rolled or forged material of an iron-based material, so that a large head having a wide sweet spot can be obtained. Therefore, a head having excellent directional stability can be manufactured by the method of this embodiment.

[0037]

According to the present invention, an iron-based material having a predetermined composition such as a rolled material or a forged material is used, normalized under predetermined conditions, formed into a predetermined shape of a head, and thereafter, Since the strength is increased by quenching, a head having a large shape can be manufactured at low cost, and a gluf club head having a wide sweet spot can be obtained.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a method according to an embodiment of the present invention in the order of steps.

FIG. 2 is a graph showing the effect of the present invention.

Claims (2)

(57) [Claims] 1. A method for manufacturing a steel metal head comprising a steel plate having a yield stress of 1000 MPa or more, comprising 0.05 to 0.35% (% by weight, the same applies hereinafter) of C, and 0.40% or less of Si. 2.20% or less Ni 4.00% or less Cr 3.0% or less Mo 1.00% or less Nb 0.10% or less Al 0.10% or less P 0.02% or less S 0.01% or less Cu 1. 50% or less B 0.001% or less N 0.01% or less, and annealed at 650 to 750 ° C. an iron-based material having a balance of Fe and unavoidable impurities and a carbon equivalent of 0.80 to 1.30. A step of forming the iron-based material after the annealing treatment into a metal head shape or a predetermined shape of a component constituting the metal head; and, after this processing, quenching the iron-based material by air cooling. Method for producing a steel metal head characterized by having a step. 2. A method for manufacturing a steel metal head comprising a steel plate having a yield stress of 1000 MPa or more, comprising 0.05 to 0.35% of C, 0.40% or less of Si, 2.20% or less of Mn, and Ni4. 0.000% or less Cr 3.0% or less Mo 1.00% or less Nb 0.10% or less Al 0.10% or less P 0.02% or less S 0.01% or less Cu 1.50% or less B 0.001 % Or less N: 0.01% or less, the balance being Fe and unavoidable impurities, a step of annealing an iron-based material having a composition with a carbon equivalent of 0.05 to 1.30 at 650 to 750 ° C., and after this annealing A step of forming the iron-based material into a metal head shape or a predetermined shape of an article constituting the metal head; and, after this processing, a step of quenching the iron-based material by water cooling. A method for manufacturing a steel metal head.