JPS6029416A - Stepped extruding pin for plastic - Google Patents

Abstract

PURPOSE:To obtain a stepped extruding pin for plastics with superior toughness and wear resistance by working a steel rod having a specified composition subjected to soln. heat treatment to a prescribed shape and by carrying out aging at a specified temp. for a specified time. CONSTITUTION:The composition of a steel is composed of, by weight, <0.02% C, <0.2% Si, <0.2% Mn, <0.015% P, <0.015% S, 12-15% Ni, 9-11% Mo, 0.01-0.25% Al, 0.1-0.3% Ti, 13-15% Co and the balance Fe with impurities. The steel is subjected to soln. heat treatment at about 1,000 deg.C, and it is formed into a rod. This rod is worked to a prescribed shape and aged at about 480 deg.C for several hr to provide about 62 HRC hardness by precipitation hardening.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a stepped extrusion pin for a plastic mold.

Conventional. As an extrusion pin for plastic, generally 8KB
2/. Harden tool steel such as SKD// to a hardness of around 11069. Tempered ones have been used. However, SK8.2/. The extrusion pin is made by SKD//.

Although it has good wear resistance, it has low toughness and is prone to breakage, so it cannot be used for stepped pins with a small diameter of φ20 or less. Therefore, for such small-diameter stepped pins, extruded pins made of INi maraging steel and nitrided have recently been developed. came into use.

lg Chi Ni maraging steel is ToNr. j%M
A low carbon martensitic steel having chemical compositions of o, 9% Co, θA%T+, θ/%Afi, which is subjected to solution treatment, that is, g, 2θ° C. heating followed by air cooling treatment.

It is easy to process because it softens to HRO3θ~32.

After that, HIIC!
3, but this hardness lacks wear resistance, so the pin is subjected to gas nitriding treatment at θ°C x 3b to increase the surface hardness from Hv 0θ to θθ. It is used as a trumpet. However, the cost of gas nitriding treatment is high, which limits its applications.

The present invention was made in view of these problems, and
The purpose is to provide an ultra-fine stepped extruded pin that is precipitation hardened to 81060 or higher by aging treatment alone and does not require any gas nitriding treatment.

That is, 1 the present invention is 0002% or less in weight%.

Sio, λθ coefficient or less, Mnt), Koθchi or less, Pθθ/
S chi or less, SO, θ/j% or less, Ni /20 to 7.5
: θ%, M.

TS, θ～//θ俤, ALθθ/～θ2S%, Ti θ/
θ ~ 0.30%, Oo / 3θ ~ is, o = s Steel consisting of balance iron and impurities, which has been solution-treated from about / θ θ θ ° C. After processing into a predetermined shape, approx. <
(by aging treatment at tgθ℃ for several hours) lRO
A. This is a stepped extrusion bottle for plastics with excellent wear resistance and toughness, which is characterized by precipitation hardening to a hardness of around 2. The bottle of the present invention having the above structure has good toughness and wear resistance.

Heat treatment is easy as nitriding is not required.

It is characterized by a relatively low price.

Next, the reasons for limiting the composition of the extrusion bottle of the present invention will be described.

Because C impairs the toughness of low carbon martensite.

It is preferable that θθ is 2% or less. Si and Mn have a deoxidizing effect, but if θ exceeds 21t, the toughness decreases.

Since θ, 2%, P, and 8 are impurities and impair toughness, they were each set to θθ15 or less. N1 is necessary to form a martensitic structure.

Also, it is necessary to stabilize martensite up to the aging temperature, but below /2θ, the effect is small, and
If it exceeds sts+, residual austenite will be removed, so 7.2. θ~/S0chi. Mo is necessary to produce precipitation hardening with Fe and Ni and the intermetallic compound Fe2MO1Ni3Mot1 aging treatment, but 9.
The effect is small below θ.

7'c//: If it exceeds 0%, the toughness will decrease, so 2.
θ~//, θchi. A℃ is added as a deoxidizing agent and improves age hardenability, but if it is less than θθ/%, its effect is small, and if it exceeds 023%, the toughness decreases, so θ
θ/~θ, :zses. Oo4″1.Fe2M0
・It is effective in promoting precipitation hardening due to N13Mo, but less than /3 t is less effective, and /! Since the improvement in effect is small even if the value exceeds 4f, it is set to 73θ~/buθ. Ti improves age hardenability, but if it is less than θ/θ-, the effect is small, and even if it exceeds 630%, the effect is greatly improved, so it was set as θ/θ to θ3θ.

Steel with this composition can be softened to around HnOJj by solution treatment at 9jθ~/θjθ℃, so it can be cut to +nOJj by aging treatment at qgθ℃ for 3 hours.
It is precipitation hardened to o4.2, so it has high wear resistance. Hereinafter, the present invention will be explained in detail with reference to Examples.

Table 1 shows the chemical composition of the /ff% Ni maraging steel extrusion pin and the extrusion pin of the present invention.

Table 1 Chemical composition of extrusion pin The table also shows the φ made of steel with the chemical composition shown in Table 1.
The results of the durability test of the stepped extrusion bottle of θgmn are shown.

Table - Extrusion bottle durability test results The 7g% Ni maraging steel extrusion pin with symbol A is.

By gas nitriding treatment for 4t x θ°C x h (hours), the surface hardness Hv was 2θ, and the internal hardness HROj3. on the other hand.

The extruded pin of the present invention is subjected to aging treatment at θ℃ x Jh.
It showed high hardness of HraC1,2.

Table 2 shows the /θθθθ shot and jθθθθ when tested in a plastic precision mold for 10 packages.
This shows the presence or absence of breakage of the ejector pin after the shot, and the ejector pin of the present invention is marked B.

Same as /ff%Ni maraging steel extrusion pin with symbol A<, jθθθθ It did not break even after being shot, indicating excellent toughness. There were also no problems with wear.

As explained above, one extrusion pin of the present invention has 0θθ, 2
% or less, 8+0.2θ ratio or less, MnO2θ− or less.

26075% or less, Sθθ/j or less, Ni/, Zθ~
/j%, Mo ta, θ ~ l / θ%, Ajl
θ θ / ~ θ, 2j%.

Steel consisting of Tiθ/θ~θ3θchi, Oo/Jθ~/Sθchi, the remainder iron and impurities is subjected to solution treatment at approximately /θθθ℃, then machined to the desired shape, and then heated to 0℃ for several hours. It is precipitation hardened to 98RC6.2 by aging treatment, and has the characteristics of good wear resistance and high toughness even without gas nitriding treatment, and dimensional change due to aging treatment is extremely small. Therefore, it is suitable as a stepped extrusion pin for ultra-thin diameters of 20 mm or less.

Claims (1)

[Claims] Weight%: 0θθ2% or less, 8I02θchi or less, Mn9
20% or less, Pθθ/j ratio or less, Sθθ/S ratio or less, N
l/, Z θ ~ /3.0%, Mo ta, θ ~//
θ%, Anθθ/~0.2j%, Tiθ/θ~θ3
θ%, Oo/jθ ~ /ma θ A steel consisting of the remainder iron and impurities, which has been solution-treated from about /θθθ℃, is processed into a predetermined shape, and then heated to about 0℃. A stepped extruded pin for plastics with excellent wear resistance and toughness, which is precipitation hardened to a hardness of around 11062 (by aging for several hours).