JPH01309737A - Blanking punch - Google Patents

Abstract

PURPOSE:To enhance wear resistance by compounding atomized powder which is regulated in equiv. carbon content Ceq by the specific formula for the content of Cr, etc., and contains specific ratios of C, C-Ceq, Cr, etc., and the nitride, etc., of Ti, etc., at specific ratios, then molding and sintering the mixture, thereby forming a cemented carbide high speed tool steel. CONSTITUTION:The atomized powder of the high speed tool steel consisting of 3-10% Cr, 1-20% W, 1-11% Mo (where 18<=W+2Mo<=24), 5.6-15% V, <=15% Co, <=2% Si, <=1% Mn, <=2% Ni, <=0.1% N, and the balance Fe and unavoidable impurities and 1 or >=2 kinds of the nitride, carbide and carbonitride of Ti, Zr, V, Nb, Hf, and Ta are uniformly mixed at the ratios of 88-90% the former and 2-12% the latter in total. The blanking punch is formed by using the steel formed by molding and sintering said powder. In addition, 0.1<=C-Ceq<=0.6 is satisfied in the range of 2.0-3.5% C when Ceq=0.06Cr+0.033 W+0.063Mo+0.2V. The life of the punch is improved by using the blanking punch made by using such cemented carbide high speed tool steel.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a punch made of high-speed tool steel manufactured by powder metallurgy.

[Conventional technology]

In the automobile industry, processing punches for press-stamping steel plates for automobile bodies, and papers and plastics such as telephone cards and orange cards used in the communication and transportation fields, or special magnetic coatings or other coatings on the surface of these paper or plastics. Conventionally, punches for punching materials that have undergone surface treatment have been manufactured using high-speed tool steel, die steel, carbon tool steel, and punches that have undergone surface treatment such as nitriding or carburizing on the surface of these steel materials. has been used.

For the above-mentioned punches, an important issue is to improve the life of the punches in order to eliminate the time required to replace the punches.

The most common causes of the lifespan of punches are chipping due to galling with the workpiece and wear due to friction with the workpiece.

[Problem to be solved by the invention]

As mentioned above, punches manufactured using conventional high-speed tool steel, die steel, carbon tool steel, etc., suffer from chipping and wear due to friction with the workpiece, leading to the end of their lifespan.

When a punch reaches the end of its service life, time is required to replace the punch, and during that time, lost time occurs due to work stoppages. Furthermore, in card punches, the lifespan of the punch is the same as the lifespan of the punch unit, so improving the lifespan of the punch is an important issue.

In addition, the manufacturing method for these products involves cutting an annealed round bar into the approximate shape, quenching and tempering, then grinding to obtain one-dimensional accuracy, and then A common step is to perform surface treatment if necessary.

However, many of these materials, particularly high-speed tool steel and die steel, have high hardness even in annealed states, and therefore tend to result in expensive punches.

Therefore, the present invention has superior wear resistance than conventional materials.

The purpose of this punch is to extend the life of the punch by manufacturing it from a material that also has a certain degree of toughness.

Furthermore, in the manufacturing process, the present invention uses powder metallurgy to mold the powder state before sintering into approximate dimensions by press working, or kneads the powder with various binders,
After forming a round bar or square bar, it is formed into an approximate punch shape by cutting or grinding. After that, sintering, annealing, hardening, and tempering are performed, and finally, a polishing finish is applied.
The objective is to provide a punch that can reduce manufacturing costs by achieving dimensional accuracy.

[Means to solve the problem]

In the present invention, the equilibrium carbon content Ceq is Ceq=0.0 in weight ratio.
6Cr+ 0.033W+0.063Mo+0.2V, 0.1≦C− in the range of C2.0 to 3.5%
Satisfies Ceq≦0.6, and further contains 3 to 10% Cr, W
1-20%, Mo 1-11% (however, 18≦W
+2 Mo≦24), V 5.6-15%, Co
15% or less, Si 2% or less, Mn 1% or less, Ni 2
% or less, N 0.1% or less, balance Fe and unavoidable impurities.
90% and a total of 2 to 2 or more of Ti, Zr, V-Nb, Hf, Ta nitrides, carbides, and carbonitrides.
This punch is characterized by using ultra-hard high-speed tool steel that is formed by uniformly mixing 12% of the above ingredients, then molding and sintering. In addition, the ultra-hard high-speed tool steel is characterized by having a hardness of HRC72 or higher by quenching and tempering, and the ultra-hard high-speed tool steel is further characterized by a bending test at a hardness of HRC72 (test piece: 5 mmφ x 70 IQ, between fulcrums). Distance: 50
mm, absorption energy when using center-point loading method) is 130
The punch is characterized in that it has a punch of kgf-mm or more.

[Effect]

Next, the effects of each additive element in the ultrahard high-speed tool steel, which is the raw material for the punch of the present invention, and the reason for limiting the range of addition thereof will be described.

Among the compositions of the ultrahard high-speed tool steel that is the raw material for the punch of the present invention, the content of C is the most important component. C is
Cr, W, and Mo contained simultaneously.

■The effect of combining with M, C, MC, etc. to form carbides and imparting wear resistance, as well as the effect of increasing the hardness of the martensite base through quench hardening heat treatment and further increasing the amount of secondary hardening through tempering. There is. C, which is the carbide-forming element mentioned above
It is theoretically known that the equilibrium carbon amount Ceq at which r, W, Mo, V and C combine in just the right amount to form a carbide is expressed by the following equation.

Ceq=0.06(%Cr)+0.033(%W)+0
．． 063 (%Mo) + 0.2 (%V) In conventional high-speed tool steel, the difference between the C content and the equilibrium carbon content Ceq, C-Ceq, is adjusted to be negative (for example, JIS 5KH59 is , habo-0,3
, 10 for AISIM42, OS).

In the present invention, even if the amount of W, Mo, V or the amount of dispersed particles such as TiN is relatively small, a large number of alloy systems are used for the purpose of obtaining a highly practical punching material that has a superhardness of HRC 72 or higher. After experimenting and considering, Ceq=0.0
When 6Cr+0.033W +0.063Mo+0.2■, in the range of 18≦W+2Mo≦24,
0.1≦ without making C-Ceq negative like before
It has been newly discovered that C may be contained so as to satisfy C-Ceq≦0.6. If C-Ceq is less than 0.1, a superhardness of HRC 72 or higher cannot be obtained unless large amounts of W, Mo, V, and TiN are contained as described above. On the other hand, when C-Ceq exceeds 0.6, stable retained austenite increases significantly during quench hardening heat treatment, and the decomposition temperature of retained austenite shifts to a high temperature side, so secondary hardening is performed by tempering. However, it becomes impossible to obtain a superhardness of HRC72 or higher. That is, 18≦W +
2 Mo≦24, 0.1≦C-Ceq≦0
．． The purpose of the present application can be achieved only under condition 6.

As mentioned above, C should be appropriately changed depending on the amounts of Cr, W, Mo, and (2) contained at the same time.

Cr is the raw material for the punch of the present invention, which will be described later.

Within the content range of W, Mo, and V, Katsuo, l≦C-Ce
At least 2.0% of C is required to satisfy q≦0.6. On the other hand, even if the above conditions are met, if the C content exceeds 3.5%, the decrease in toughness will be significant.
The content is in the range of 2.0-3.5%, and.

It was limited to 0.1≦C-Ceq≦0.6.

Cr has the effect of increasing quench hardenability, but if it is less than 3%, this effect is small, and on the other hand, if it exceeds 1 part, the amount of retained austenite increases and reduces the hardness after quenching and tempering.
The content of r was limited to 3 to 10%.

In particular, in order to obtain a superhardness of HRC 72 or higher even when heat treated in a quenching furnace with a slow cooling rate such as vacuum quenching, the Cr content is desirably more than 6% and 10% or less.

W and Mo combine with the above-mentioned Totoku C to form M6C type carbide, which has the effect of increasing wear resistance and solid solution in the matrix during quenching and hardening heat treatment, which precipitates as fine carbide during tempering heat treatment. It has the effect of increasing the degree of secondary hardening. In order to achieve the purpose of stably obtaining superhardness of HRC72 or higher according to the present invention, W 1-20%, Mo 1-20%,
It is necessary to contain W + 2 Mo in an amount of 18% or more within a range of 11%. However, the amount of W+2Mo is 24%
If it exceeds this, the material will not only become expensive but also have lower toughness, so the W and Mo content should be 18 to 24% (W+2Mo amount).
limited to. Note that in the present invention, equal amounts (atomic percent) of W and MO have approximately equivalent effects.

V+JW, like Mo, combines with C to form MC type carbide. The hardness of this MC type carbide is HV2500-
3000 and MsC type carbide) IV1500-18
It has significantly higher hardness than 00. Therefore, in tools where wear resistance is particularly important, use of high-speed tool steel with a high V content improves tool life.

However, even if the ■ content is increased more than necessary, it will only worsen the grindability, induce a short life due to grinding burns, and reduce the toughness. Therefore, in the present invention, the upper limit of the ■ content is 15%. And so. On the other hand, if the V content is less than 5.6%, the wear resistance effect is insufficient, so the V content is limited to 5.6 to 15%.

CO dissolves in the matrix and has the effect of increasing tempering hardness and high-temperature hardness. However, if it is contained in a large amount, the toughness will be significantly reduced, so the content of +Co was limited to 15% or less.

Si is contained in an amount of 2% or less for the purpose of deoxidation, but especially in the range of 0.8 to 2% Si, in addition to the deoxidation effect, it has the effect of increasing the hardness of the base and the effect of increasing oxidation resistance and corrosion resistance. Furthermore, it has the effect of improving atomization workability. If it exceeds 2%, the toughness will be significantly reduced.

Mn also has a deoxidizing effect and also has the effect of improving hardenability, so it is contained in an amount of 1% or less. In particular, when the above-mentioned Si content is high, Mn can stabilize the ferrite and alleviate the adverse effects of SL, which increases the A4 transformation point.
It is preferable to contain Mn in an amount of 0.25 to 1.0%.

Ni has the effect of increasing the toughness of the matrix, but if it exceeds 2%, the amount of retained austenite increases extremely and the tempering hardness decreases, so the present invention allows the content to be 2% or less. Note that high-speed tool steel usually contains a trace amount of Ni, and a range of 0.25% or less Ni is treated as an impurity amount in JIS.

N has the effect of increasing the hardness of the matrix and the effect of forming a solid solution in the MC type carbide to form an MCN type carbonitride to improve the welding resistance. However, since the upper limit of the amount that can be contained industrially is 0.1%, it was limited to 0.1% or less. Note that high-speed steel usually contains about 0.05% or less of N as an impurity.

Nitride, carbide of Ti, Zr, V, Nb, Hf, Ta,
Dispersing carbonitride has the effect of increasing hardness.

-6 As in the present invention, the C content is the equilibrium carbon amount (Ceq)
It is conventional wisdom that if the value is higher than 0.1 to 0.6, the austenite I-crystal grains will become coarse during the quench hardening process, the martensitic structure will become rough, and the toughness will be extremely reduced. Ta.

However, according to the present invention, Ti, Zr, V, Nb, Hf,
This drawback can be overcome by uniformly dispersing one or more Ta nitrides, carbides, and carbonitrides in a total amount of 2 to 12%, resulting in high austenitization just below the melting start temperature. It was discovered that even if quench hardening treatment is performed in a temperature range, a significantly finer structure can be obtained.

That is, dispersing the nitrides, carbides, and carbonitrides effectively compensates for the drawbacks caused by the C content being higher than the Ceq amount, thereby achieving the object of the present invention. However, if it is less than 2%, the above effect is small, and on the other hand,
If it exceeds 12%, not only the effect will be saturated, but also the grindability and toughness will be significantly reduced, so the total amount of dispersion of the nitrides, carbides, and carbonitrides was limited to 2 to 12%.

A method for uniformly dispersing nitrides, carbides, and carbonitrides in a matrix is to produce powder of ultrahard high-speed tool steel with the above chemical composition by atomizing water, gas, oil, etc. The most suitable method is to mix the powder with nitride, carbide, or carbonitride powder, and then mold and sinter the mixture.

In addition, upon mixing, it is preferable to add and mix carbon powder such as graphite powder and black carbon at the same time for the purpose of adjusting the final carbon content after sintering and improving sinterability. Furthermore, Cr, Ni, Mo, W,
A total of 5 types of one or more of Cu, Co, and Fe powders
% or less, it has the effect of improving sinterability.

〔Example〕

Next, the present invention will be explained in more detail based on one embodiment.

In order to manufacture a punch for card punching having the shape shown in FIG. 3, a raw material for a punch of the present invention having a composition shown in Table 1 was first prepared.

A punch for card hole making was manufactured from this material, and at the same time, test pieces for a bending test and two types of abrasion tests were manufactured and tested in order to understand the characteristics of the material. This test piece and punch were subjected to a predetermined standard heat treatment to obtain the hardness shown in Table 1.

After heat treatment, six materials were subjected to a bending test and two types of abrasion tests, and the results are shown in FIGS. 2 to 4, respectively.

As shown in Fig. 1, the absorbed energy in the bending test of the ultra-hard high-speed tool steel, which is the material of the punch of the present invention, is higher than that of the conventional melt-sawn material 5K) 151.5KDII and the conventional powdered high-speed tool steel material. Although it shows a slightly low value, HRC
72 high hardness absorbs energy of 130kg? It was found that the diameter was more than mm.

Furthermore, Fig. 2 shows the results of the abrasive wear test. Second
The figure shows that in terms of wear resistance, the ultrahard high-speed tool steel, which is the material for the punch of the present invention, has approximately three times the performance of conventional materials.

Furthermore, Figure 3 shows the results of the matchlock abrasion test.

It can also be seen in FIG. 3 that the superhard high-speed tool steel, which is the material for the punch of the present invention, has superior wear resistance compared to conventional materials.

Next, a punch is made from the six materials mentioned above, the punch is actuated by a solenoid as shown in Figure 3, the punch is punched, and the return spring moves it to the original position, and the magnetic coating is applied. Thickness 0.211II+
The life of the punch was tested by punching out a card with a load of 5 kgf.

The standard for determining the lifespan of a punch is the point at which an appropriate hole shape is no longer formed on the surface of the card when the card is punched, or the point at which the card cannot be removed from the punch and cannot move normally when the punch returns. And so.

The test results are also listed in Table 1.

There are approximately 10 punches made from 5KD11 and 5KH51.
,000 times, the punch made from powdered high speed steel is 30
,000 times, the punch made of ultra-hard high-speed tool steel (punch material No. A, B, C) of the present invention continues to break even after 200,000 times, and the life is shortened. It was found that the lifespan was improved by about 10 times or more compared to powdered high-speed steel.

〔Effect of the invention〕

As described above, the punch according to the present invention has 1
It has a high hardness of 1Rc72 or higher and has excellent wear resistance.
It also has a suitable degree of toughness, and the life of the punch can be improved, making it an extremely effective invention industrially.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the results of the bending test of the punch material according to the present invention, FIG. 2 is a graph showing the results of the abrasive wear test, FIG. 3 is a graph showing the results of the matchlock wear test, and FIG. The figure is a schematic diagram of a unit used in a punching test of the punch of the present invention. 1: Punch punch, 2: Telephone card, 3: Punch die, 4: Punch guide, 5: Punch holder, 6: Return spring. 0 2.5 3.6 3
．． 5th morning'tJl (m/sec) Figure 4

Claims (1)

[Claims] 1. Equilibrium carbon content Ceq is Ceq=0.06Cr in weight ratio
+0.033W+0.063Mo+0.2V, in the range of C2.0 to 3.5%, 0.1≦C-Ceq≦
0.6 and further Cr3~10%, W1~20%
, Mo1-11% (however, 18≦W+2Mo≦24)
, V5.6-15%, Co15% or less, Si2% or less,
Mn 1% or less, Ni 2% or less, N 0.1% or less, balance F
Atomized powder of high speed tool steel consisting of e and inevitable impurities is 88-90%, Ti, Zr, V, Nb, H
After uniformly mixing a total of 2 to 12% of one or more of Ta nitrides, carbides, and carbonitrides, molding,
A punch characterized by using sintered ultra-hard high-speed tool steel. 2. HRC of superhard high speed tool steel is improved by quenching and tempering.
The punch according to claim 1, having a hardness of 72 or more. 3 Bending test of superhard high speed tool steel at hardness HRC72 (test piece: 5 mmφ x 70 mml, distance between fulcrums: 5
Absorbed energy at 0 mm (center single point loading method) is 13
The punch according to claim 1 or 2, characterized in that the punch is 0 kgf·mm or more.