JPH059657A - Steel material for piston rod of stamping hammer - Google Patents

Abstract

PURPOSE:To offer a piston rod for a stamping hammer having a long service life. CONSTITUTION:A steel material for the piston rod of a stamping hammer consisting of, by weight, 0.22-0.32% C, <=0.15% Si, <=0.60% Mn, <=0.020% P, <=0.020% S, 3.25-4.20% Ni, 1.25-2.00% Cr, 0.20-0.6O% Mo, <=0.17% V and the balance of essentially Fe is prepd. This steel material has remarkably improved shock resistance and improved other mechanical characteristics and the service life is made much longer than that of SNCM439 or SCM440 as a conventional piston rod material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel material for a piston rod of a stamping hammer.

[0002]

2. Description of the Related Art A stamping hammer for stamping a steel material into a desired shape is a piston in which a piston rod and a stamping part are integrally connected by a piston rod having a diameter smaller than those of the piston rod is set in a cylinder. The piston is moved up and down by compressed air. Conventionally, SCM440 (JIS) is mainly used for this piston rod.
Steel grades such as and SNCM439 (JIS) are used.

[0003]

By the way, when the above-mentioned punching hammer is operated, a shock load is violently applied to the piston rod which moves up and down. As the punching hammer becomes larger, the impact load is further increased, and bending and twisting are also added to a nonnegligible level. Since these piston rods have a smaller diameter than the cylinder head and the stamping section, these external forces are mainly concentrated on the connecting portion between the piston rod and the cylinder head and the stamping section.

Therefore, when the stamping hammer is operated for a long period of time, impact fatigue accumulates in the joint portion of the piston rod, and when it exceeds the strength limit, the piston rod is removed from the joint portion. It may break. For example, it has been pointed out that when a steel type such as the above-mentioned SCM440 or SNCM439 is used as the piston rod of a two-ton type hammer, it will break after about one month of operation.

The present invention solves the above-mentioned problems and provides an SCM4
40 and SNCM439 have superior shock resistance, and when used as a material for the piston rod of a stamping hammer, the piston rod of the stamping hammer can remarkably extend the service life of the piston rod. The purpose is to provide steel materials for use.

[0006]

To achieve the above object, in the present invention, C: 0.22 to 0.32% by weight, Si: 0.15% by weight or less, Mn: 0.60% by weight. % Or less, P: 0.020% by weight or less, S: 0.020% by weight or less, Ni: 3.25 to 4.20% by weight, Cr: 1.25 to 2.0
Provided is a steel material for a piston rod of a stamping hammer, characterized in that 0% by weight, Mo: 0.20 to 0.60% by weight, V: 0.17% by weight or less, and the balance substantially consisting of Fe. ..

In the composition of the steel material of the present invention, C is a component necessary to secure the quenching hardness on the surface of the steel material at the time of quenching treatment and improve the wear resistance and the fatigue resistance property. .22 wt% or more is contained. However, if the content is too large, the toughness and machinability are deteriorated, so the content is set to 0.32% by weight or less. Si is a component that acts as a deoxidizing agent during melting, and at the same time contributes to the improvement of toughness. However, if the content is too large, an abnormal layer will be formed on the surface during quenching. The amount is limited to 0.15% by weight or less.

[0008] Mn is a component that is effective as a deoxidizing agent during melting and at the same time contributes to the improvement of hardenability and strength, but if it is contained in too much, it causes a decrease in toughness, so its content is 0. Limit to less than .60% by weight. P, S
Is a component that is included as an impurity,
For example, when the content of P is large, the strength is remarkably reduced, and when the content of S is large, inclusions are generated in the steel material, which is a starting point and easily breaks. All the contents are limited to 0.020% by weight or less.

Ni is a component that contributes to the improvement of hardenability and toughness, and for that purpose, it is contained in an amount of 3.25% by weight or more.
However, if the content is too large, the above-mentioned effect only reaches saturation and not only the cost is increased, but also the machinability is deteriorated, so the content is 4.20% by weight.
Limited to: Cr is a component that improves corrosion resistance and enables deep quenching. For that purpose, 1.25 wt% or more is contained. However, if contained too much, the machinability will be deteriorated, so the content is
Limit to 2.00% by weight or less.

Mo improves not only hardenability but also
It is an effective component for increasing the tempering resistance by forming double carbide together with Cr, and for that purpose, 0.2
It is contained in an amount of 0% by weight or more. However, if the content is too large, the above-mentioned effects reach saturation and the machinability and toughness decrease, so the content is limited to not more than 0.60% by weight.

V is a component necessary for enhancing the toughness and especially for improving the impact resistance, but if it is contained in too much, it causes deterioration of the hardenability, so its content is 0.
It should be 17% by weight or less. The steel material of the present invention is obtained by forging and annealing a predetermined amount of each of the above components, for example, by vacuum refining, then forging and annealing, and then cutting to a predetermined shape as a piston rod, normalizing, quenching, It can be manufactured by sequentially performing tempering.

[0012]

EXAMPLES Examples 1 to 3 Steels having the compositions shown in Table 1 were melted and a piston rod of a stamping hammer for 2 tons was manufactured under the following conditions. That is, after ingoting and forging molten steel, annealing in furnace cooling at 830 ° C., roughing, then oil cooling at 850 ° C., air cooling at 580 ° C., quenching, tempering, finishing, The rod portion was induction hardened and finally polished.

The mechanical properties of each steel material were measured, and the values are shown in Table 1. In addition, the working hammer was operated for 8 hours a day, and the service life until the piston rod was broken and became inoperable was measured. The results are also shown in Table 1.

[0014]

[Table 1]

[0015]

As is apparent from the results shown in Table 1, the steel material of the present invention has superior mechanical properties to the conventional SCM440 material used as the piston rod material of the stamping hammer. There is. Above all, the shock resistance is remarkably excellent. As a result, the life of the piston rod is extended about 12 times, and its industrial value is extremely large.

Claims (1)

Claims: C: 0.22 to 0.32% by weight, Si: 0.1
5% by weight or less, Mn: 0.60% by weight or less, P: 0.020
% By weight, S: 0.020% by weight or less, Ni: 3.25 ~
4.20% by weight, Cr: 1.25 to 2.00% by weight, Mo: 0.0.
A steel material for a piston rod of a punching hammer, which is characterized by 20 to 0.60% by weight, V: 0.17% by weight or less, and the balance being substantially Fe.