JPS6167771A - Production of product for cold forging - Google Patents

Abstract

PURPOSE:To produce inexpensively a product for cold forging by subjecting a specifically composed steel having an excellent strain aging resistance to a surface treatment by zinc phosphate, etc., then to a lubricating treatment, drawing and preforming the treated steel and subjecting the same to normal forming after another surface treatment and lubricating treatment. CONSTITUTION:The steel bar or wire consists of <=0.45% C, <=0.35% Si, 0.20-2.00% Mn, <=0.040% P, <=0.025% S, 0.030-0.090% SolAl and <=45ppm N has >=20 SolAl/N, and consists of the balance Fe and unavoidable impurities. This steel wire has <=5% the age hardening rate calculated by the equation; the age hardening rate =(T.S'-T.S)/T.SX100% (T.S': the tensile strength of the age treated material after the drawing, kg/mm<2>, T.S; the tensile strength of the as-drawn wire, kg/mm<2>) and has the excellent strain aging resistance. Such wire is subjected to the lubricating treatment by the lubricating agent consisting essentially of sodium stearate after the surface treatment for lubrication by zinc phosphate or calcium zinc phosphate (0.1-1.0Ca/Zn) and is then drawn and preformed; thereafter, the preformed wire is again treated in the same manner as mentioned above and is then subjected to the normal forming, by which the product for cold forging is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method for manufacturing screws and various other products for cold forging from steel wire rods.

Conventional technology and its problems Manufactured using wire rods. As the steel bar wire rod for cold forging, rimmed steel and low-medium carbon aluminum killed W4 bar wire rod have been practically used.

1. In the cold forging of carbon steel, general rift steel, and general low-medium steel, the temperature is lowered to about 100 to 200℃ during processing, and cold forging is performed in the blue brittle temperature range. Therefore, age hardening occurs during cold forging, significantly reducing tool life. Therefore, conventionally, intermediate annealing was performed after preforming, and then main forming was performed.

Further, the base treatment in conventional lubrication treatment was zinc phosphate treatment. That is, in the case of a zinc phosphate film, since the heat resistance is poor, there is a drawback that the film cracks due to wire drawing and seizures occur.

Purpose of the Invention This invention has been made in view of the above-mentioned conventional circumstances.
The purpose of the present invention is to propose a method for producing cold forged products using steel wire rods with excellent lubricity and which can omit intermediate annealing.

Structure of the Invention The method for manufacturing a cold forging product according to the present invention is as follows: C: 0
．． 45% or less, Si: 0.35% or less, Mn:
0.20-2.00%, P: 0.040% or less, S
: 0.025% or less, Sof, Al: 0.0
30-0.090%, N: 45T)T)m or less,
And Sol, Aj'/N = 20 or more and the remainder F
Using a steel wire rod with excellent strain aging resistance, which consists of unavoidable impurities such as e, Th, and has an age hardening rate of 5% or less calculated by the following formula, zinc phosphate or zinc phosphate force yv is used after descaling. Si (Ca/Zn=0.1~1
．． 0) Postscript 1 in which the wire rod obtained by pre-forming the wire rod after lubrication treatment with VC and subsequent lubrication treatment with a lubricant (reactive soap) mainly consisting of sodium stearate
1M, descaling followed by zinc phosphate iv
V-C A (Ca/Zn=0.1-1.0) is used for lubricating the base and lubricating with a lubricant (reactive soap) mainly consisting of sodium stearate, followed by main molding. In addition, after preforming the wire obtained by drawing the wire after pre-treating it with zinc calcium phosphate and lubricating it with a lubricant (reactive soap) mainly consisting of sodium stearate, it was not subjected to any lubrication treatment. This is characterized by the fact that the final molding is carried out in the following manner.

r, S': Tensile strength of aged material after wire drawing KP/-)
T, S: Tensile strength as drawn (M/+d) In other words, this invention uses non-aging low and medium carbon aluminum guild steel (
Sof, Al 0.03-0.09 for non-aging
%, N45T) 1) Contains less than m, So/,
lkJ/N=20 or more -E), calcium phosphoric acid skin with excellent heat resistance as a lubricating base treatment before preforming and main forming; vague treatment (Ca/Zn = 0.10-1
．． 0), and is a method in which the zinc phosphate film treatment is performed only before preforming, and the lubrication treatment before the main molding is omitted and the main molding is performed.

This invention will be explained in detail below.

First, the reason for limiting the components of the target steel of this invention will be explained.

As for the composition system of the target steel of this invention, the tensile strength of the wire rod, which can be practically cold-forged as rolled, is 90.
C, St.

Mn, Sof, AI! , The reason why the composition range of N was determined as described above is as follows.

When C is 0.45% or more in this invention steel, the compression ratio is 7.
Since processing cracks occur at 5%, the -F limit was set at 0.45%. Moreover, the lower limit is not particularly limited, since the smaller the amount of C, the better the aging properties.

Although Si does not affect aging properties, it is only added for deoxidation or strength adjustment, so the upper limit was set at 0.35%.

If the content exceeds 0.35%, cold forging workability deteriorates, which is not preferable.

Mn, which is used to prevent cracking during hot rolling due to Si and to adjust the strength of steel bars, does not need to exceed 2.0%, and the lower limit is 0.2% to prevent cracking due to S. %is necessary.

SO1! , AJ is set in the range of 0.03 to 0.09% because if it is less than 0.03%, it is insufficient to fix N, and if it exceeds 0.09%, there will be many inclusions.

NokeSat, -L limit of A/no value 75E0.09% terror (7) TeSo/.

At/N'>20 and the N limit was set to 45 ppm.

That is, this invention steel has a Sat, A/content of 0.
03 to 0.09%, Sat, At/N >
By setting it to 20, N is fixed as AtN and 1-. This is clear from the relationship between Soe, Al/N and age hardening rate shown in FIG.

■After hot rolling 17 and pickling/lubrication treatment on φ17.
The wire was drawn to 6 φ, and the resulting wire was aged (80°C
xlhr)l, is the result. As is clear from this figure, Sat. When the Al/N ratio is 20 or more, the age hardening rate is 5% (range shown by diagonal lines).

Next, the lubrication treatment conditions will be explained.

The present invention is characterized in that a zinc calcium phosphate solution having excellent heat resistance is used as a lubricating base treatment agent. This is because in the case of a zinc-calcium phosphate coating, cracks in the coating due to wire drawing are less likely to occur. Further, the Ca/Zn ratio of this zinc calcium phosphate film was set to 0.1 to 1.
The reason why the Ca/Zn ratio was set to 0 was because the Ca/Zn
When the ratio of () is less than 1, the Ca ratio is low and C
The effect of adding a is small and the heat resistance is insufficient. Still Ca
When the ratio of Ca /Zn is 1.0 or more, the chemical conversion properties and reactivity with reactive soaps are poor. Calcium adhesion amount (≧5)/I), reaction rate (≧1)
f/d) is difficult to obtain.

The total acidity (processing rate), temperature, and time are not particularly limited, but may be changed as appropriate depending on the difficulty of the target processed product (usually a total acidity of 30 ~4() points, temperature 70-80℃, time 5
~20 minutes). In addition, the reactive soap treatment after the lead calcium phosphate treatment may be the same as the conventional zinc phosphate treatment (
Usually concentration 1-2 points, temperature 7o-900C, time 3-7 minutes).

Fig. 4 and Fig. 5 show the manufacturing process of the cold forged product of this invention, and Fig. 41 shows the descaling process after hot rolling this invention steel into a bar steel wire rod (age hardening rate of 5% or less). For example, after pickling in the process, zinc calcium phosphate treatment or zinc phosphate treatment is performed in the lubrication base treatment step, followed by reactive soap treatment in the lubrication treatment step, and then wire drawing in the wire drawing step.

The obtained wire drawing material is then preformed in a cold forging process, followed by a degreasing process, a descaling process, and then a zinc calcium phosphate treatment in a lubrication base treatment process, followed by a reactive soap treatment in a lubrication treatment process. In this method, main forming is performed in a cold forging process.

Figure 5 shows that the first lubrication base treatment step is zinc calcium phosphate treatment, then the lubrication treatment step is reactive soap treatment, the wire drawing step is drawing, and the resulting wire is cooled. This is a method of manufacturing cold forged products by preforming in an inter-forging process, followed by main forming. That is, since a zinc calcium phosphate film treatment with excellent heat resistance is carried out before preforming, seizure etc. will hardly occur during main molding even if the lubrication treatment after preforming and before main forming is omitted.

Compensation Example Using the test materials shown in Table 1, wire was drawn after being subjected to zinc calcium phosphate treatment as a base treatment for secondary lubrication, and forming processing was carried out at a total compression ratio of 80%. The results are shown in Table 2.

For comparison, Table 2 shows a case in which rimmed steel was used, subjected to lead phosphate treatment and intermediate annealing (conventional example), and a case in which steel according to the invention was subjected to phosphoric acid 11 annealing and intermediate annealing. The results for the case where sintering was omitted (comparative example) are also shown.

From the results in Table 2, using the non-ageable J14 of this invention,
And in the lubrication process before actual molding? It has been found that by performing zinc calcium phosphate treatment as the top smoothing treatment, it is possible to omit annealing before main molding, that is, intermediate annealing.

In addition, even if the non-aging steel of the present invention is used, if the primary lubrication and secondary lubrication are treated with conventional zinc phosphate (Test No.
For 2), it was possible to forge a small amount, but seizure occurred in the case of one production.

In addition, when zinc phosphate calcium treatment is performed as primary lubrication, intermediate annealing and secondary lubrication calcium phosphate treatment can be omitted, but as shown in test NIL4 (the load during main forming is Although it is more expensive, cold forging turned out to be an IT song.

Table 1 Test material (margin) Table 2 Cold forging results Primary lubrication: Type 2 of phosphate treatment for elongated tfAllJ+J
Next lubrication: Type of phosphate treatment before main forming (after preforming) Main forming = D/D0≧2 (D: 9 product diameter, Do: wire diameter) As described in detail, this invention is A7 ．． By controlling the amount of N and using non-aging low-medium carbon aluminum guild steel with an age hardening rate of 5% or less, and by performing zinc calcium phosphate treatment with excellent heat resistance as a lubricating base treatment, the intermediate after preforming Since annealing can be omitted, steps can be omitted and product manufacturing costs can be reduced.

[Brief explanation of drawings]

Fig. 1 is a chart showing the relationship between So/, Ae/N and age hardening rate in this invention, Fig. 2 is a chart showing the relation between Ca, N ratio and phosphate film deposition amount, and Fig. 3 is a chart showing the relationship between So/, Ae/N and age hardening rate. Similarly, a chart showing the relationship between the Ca/Zn ratio and the amount of reaction layer deposited, No. 4
5 and 5 are process diagrams showing the manufacturing method of the present invention. (?'/l) NJHJWiEtsiny Q(r/,g
)! Rooster

Claims (1)

[Claims] 1 C: 0.45% or less, Si: 0.35% or less, Mn
: 0.20-2.00%, P: 0.040% or less, S:
0.025% or less, Sol. Al: 0.030-0.0
90%, N: 45 ppm or less, and Sol. Al
/N = 20 or more, the balance consists of Fe and unavoidable impurities, and the age hardening rate calculated by the following formula is 5% or less. Using a steel wire rod with excellent strain aging resistance, after descaling, zinc phosphate or phosphoric acid is used. Zinc calcium (Ca/Zn
= 0.1 to 1.0), followed by a lubricant (reactive soap) based on sodium stearate.
After preforming the wire rod obtained by drawing the wire after lubrication treatment with A method for manufacturing a cold forging product, characterized in that main forming is performed after lubrication treatment with a lubricant (reactive soap) mainly consisting of sodium stearate. 2 C: 0.45% or less, Si: 0.35% or less, Mn
: 0.20-2.00%, P: 0.040% or less, S:
0.025% or less, Sol. Al: 0.030-0.0
90%, N: 45 ppm or less, and Sol. Al
/N = 20 or more, the balance consists of Fe and unavoidable impurities, and the age hardening rate calculated by the following formula is 5% or less. A steel wire rod with excellent strain aging resistance is used, and after descaling, zinc calcium phosphate (Ca /Zn=0.1~1.0)
The method is characterized in that the wire rod obtained by drawing after being lubricated with a lubricant (reactive soap) mainly containing sodium stearate is preformed and then subjected to final forming. A method of manufacturing products for cold forging. Age hardening rate=T. S'-T. S/T. S×100(%)
T. S': Tensile strength of aged material after wire drawing (Kg/mm^
3) T. S: Tensile strength as drawn (Kg/mm^3)