JP2000096186A - Paper feeding shaft having excellent straightness and surface characteristic - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper feeding shaft having excellent straightness and surface characteristic by using graphite steel having excellent machinability. SOLUTION: The graphite steel which consists of graphite at >=60% of the total carbon content in a base metal, consists of the balance ferrite and carbide and contains 0.0003 to 0.015% Ca and 0.005 to 0.20% Zr is used for the paper feeding shaft which is formed with a rust preventive substrate treated layer on the surface of a cylindrical arbor and further, has a coating layer formed by heating and burning-in. In addition, the component composition of the graphite steel is recommended to contain 0.3 to 1.5% C, 0.5 to 2.0% Si, 0.10 to 1.2% Mn, <=0.2% (not inclusive of 0%) P, 0.05 to 0.2% S, 0.0003 to 0.05% B, 0.0003 to 0.015% Ca, 0.005 to 0.20% Zr and 0.0015 to 0.02% N and to consist of the balance Fe and inevitable impurities. Ceramic particles are preferably dispersed in the coating layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feed shaft having excellent straightness and surface properties.

[0002]

2. Description of the Related Art In recent years, paper feed shafts (paper feed rollers) provided in printers and copiers have tended to become longer due to the increase in paper size. Improvement is essential.

[0003] Therefore, the paper feed shaft is required to have better surface properties than ever, and straightness is an important characteristic. This is because if the straightness and surface roughness of the paper feed shaft are not good, the paper will be biased in the way it is fed, and the paper will be distorted with respect to the shaft, or the paper feed amount per rotation will be reduced. This is because problems such as variations and broken characters occur. Specifically, as the straightness, the deflection amount is 0.010 / 400.
mm or less is required, and the surface roughness is 20 μm in Rz.
It is requested that:

[0004] These characteristics are affected by the characteristics of the raw material itself and various conditions in the manufacturing process. As a material of the paper feed shaft, a rolled material of SUM-based free-cutting steel (sulfur / lead composite free-cutting steel) is generally used. In a manufacturing process, pickled rolled material and then lime Processing and drawing, then cutting,
A method of performing a coating process after performing a plating process (underlayer process) is usually employed.

[0005] The reason why the sulfur-lead composite free-cutting steel is used as a material for the paper feed shaft is that the surface quality after cutting is good. If a rolled material with insufficient machinability is used, the end face shape after parting off is
When the "pickling" shape becomes remarkable, the unevenness of the surface becomes remarkable, the adhesion strength of the plating is reduced, and the plating is easily peeled off. In addition, if the shape of the chips discharged in the grooving or drilling is bad, the chips are wound around the cutting edge of the tool, and the chips are rubbed and scratched, resulting in deterioration of the surface properties. Therefore, in order to prevent these problems related to the surface properties after cutting, a sulfur-lead composite free-cutting steel is currently used.

Further, depending on the type of steel material, a damaged layer is formed on the surface after cutting at a depth of several tens μm from the outermost surface. A large strain is applied to the affected layer, and as a result, a large residual stress is generated. For this reason, when a heating process is performed in the subsequent coating process, the internal stress is redistributed, and the residual stress adversely affects the straightness. It is difficult to cope with the adverse effect of the work-affected layer on straightness only by optimizing the cutting conditions, and sulfur-lead composite free-cutting steel is also used from the viewpoint of straightness.

However, the use of sulfur / lead composite free-cutting steel as a material for the paper feed shaft has the following problems. First, oxidized scale on the surface of a rolled material is removed by pickling, but this pickling is performed while corroding the surface of the base material, thereby affecting the properties of the surface. At this time, in the sulfur-lead composite free-cutting steel, since there are many substances such as inclusions in the material that cause a potential difference with the base material, the vicinity thereof is easily corroded, and the surface is likely to have irregularities after pickling. . If the surface has irregularities, the adhesion strength between the base treatment layer (plating layer, etc.) and the core metal material is reduced, the plating is liable to peel off, leading to rust generation and causing a significant deterioration in surface properties. I have.

[0008] Further, inside the free-sulfur / lead composite cutting steel, there is a structure called a striped structure generated by the addition of a large amount of sulfur, and the heterogeneity of the structure adversely affects the straightness. . Note that this striped structure can be reduced by performing heat treatment at a high temperature exceeding 1200 ° C. for a long time, but this is undesirable because it increases manufacturing costs.

Therefore, graphite steel (for example, JP-A-7-316732, JP-A-7-188848 and JP-A-7-18) is used in place of the sulfur-lead composite free-cutting steel.
No. 8848) as a free-cutting steel.
In these graphite steels, carbon present as a cementite phase in ordinary steel is converted into a graphite phase having lubricity,
It is intended to improve the machinability of a homogeneous carbon steel with few inclusions and the like. However, conventional graphite steel has not obtained machinability comparable to that of sulfur-lead composite free-cutting steel, and straightness and surface properties of paper feed shafts using it have not been satisfactory. .

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a paper feed shaft having excellent straightness and surface properties by using graphite steel having excellent machinability. It is intended to do so.

[0011]

According to the present invention which solves the above-mentioned problems, the present invention relates to a paper feeder having a rust-preventive base treatment layer formed on the surface of a cylindrical cored bar, and further having a coating layer formed by heating and baking. A shaft, 6% of the total carbon content in the body
% Or more is graphite, the balance consisting of ferrite and carbide, Ca is 0.0003 to 0.015%, and Zr is 0.0
The gist of the invention is to use graphite steel containing 0.05 to 0.20%.

The composition of the graphite steel is as follows: C: 0.3 to 1.5% Si: 0.5 to 2.0% Mn: 0.10 to 1.2% P: 0.2% The following (not including 0%) S: 0.005 to 0.2% B: 0.0003 to 0.015% Ca: 0.0003 to 0.015% Zr: 0.005 to 0.20% N: It is recommended to contain 0.0015 to 0.02%, with the balance being Fe and unavoidable impurities.

It is preferable that ceramic particles are dispersed in the coating layer. According to the present invention,
When the length of the shaft is L and the diameter of the shaft is D, excellent straightness can be obtained even when L / D is 20 or more.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors can significantly improve the machinability of graphite steel by making graphite grains fine by adding Ca and Zr to graphite steel in a complex manner. And that a paper feed shaft with excellent surface properties can be obtained,
The present invention has been made. The reason why the machinability of graphite steel can be greatly improved by adding Ca and Zr in a complex manner has not been fully elucidated. However, it is known that BN and the like in graphite steel become nuclei during graphite formation. In the graphite steel of the present invention, C
a and Zr promote nucleation such as BN for some reason,
It is considered that the machinability is greatly improved as a result of the large and fine generation of graphite particles.

In the graphite steel used in the present invention, by adding Ca and Zr in combination, the graphite grains can be made finer and the machinability of the graphite steel can be greatly improved. Is not obtained, so Ca is 0.0003%
It is necessary to add the above, more preferably 0.0005% or more, and more preferably 0.0010% or more. Further, it is necessary to add Zr in an amount of 0.005% or more, and desirably 0.010% or more.
More preferably, it is 5% or more.

On the other hand, if Ca is added excessively, inclusions increase, so that it is necessary to set the content to 0.015% or less.
0.010% or less is desirable, and 0.005% or less is more desirable. On the other hand, if Zr is excessively added, N decreases, and the graphitization promoting effect of BN is lost.
The upper limit must be 0%, preferably 0.10% or less, and more preferably 0.05% or less.

The amount of graphite varies depending on the composition of the raw material and the conditions for graphitization. If the amount of graphite is less than 60% of the total carbon content, sufficient machinability (cutting property, depth of the deteriorated layer of the processed layer) is obtained. Well,
Therefore, it is necessary to make the amount of graphite 60% or more of the total amount of carbon. On the other hand, if it is attempted to secure an amount of graphite exceeding 90%, the time required for the graphitization treatment needs to be 20 hours or more, which is not economical.

The graphite steel used in the present invention is characterized in that Ca and Zr are added in a complex manner.
It is desirable to control the component composition of the other elements (other than Fe and unavoidable impurities) as follows.

* C: 0.3-1.5% Necessary for producing graphite for improving machinability. If the amount is too small, sufficient machinability cannot be obtained. Desirably, 0.4% or more is more desirable. On the other hand, if the amount is too large, the remaining cementite hardens the steel so that sufficient machinability cannot be obtained. Therefore, the content is preferably 1.5% or less, and more preferably 1.2% or less.

* Si: 0.5 to 2.0% An element added to promote graphitization. If the content is too small, a sufficient effect cannot be obtained. % Is more desirable. On the other hand, if the content is too large, the steel becomes hard and the machinability deteriorates. Therefore, the content is preferably 2.0% or less, and more preferably 1.5% or less.

* Mn: 0.10 to 1.2% An element added to suppress the precipitation of FeS and to positively generate MnS. If the amount is too small, a sufficient effect cannot be obtained. % Or more, more preferably 0.30% or more. On the other hand, if it is too large, graphitization is inhibited, so that it is preferably 1.2% or less, and more preferably 0.9% or less.

* P: 0.2% or less (excluding 0%) This element is contained to reduce the roughness of the cut surface. However, if it is too much, it inhibits graphitization. It is desirable that the content be 0.07% or less.

* S: 0.005 to 0.2% An element added to form MnS and improve machinability. If the amount is too small, sufficient machinability cannot be obtained.
0.005% or more is preferable, and 0.010% or more is more preferable. On the other hand, if it is too large, hot cracking occurs. Therefore, the content is preferably 0.2% or less, and more preferably 0.15% or less.

* B: 0.0003 to 0.015% An element added to promote graphitization. If the content is too small, the effect is small. Therefore, the content is preferably 0.0003% or more, and 0.0015% or more. The above is more desirable. On the other hand, if it is too large, the effect of promoting graphitization is reduced, so that it is preferably 0.015% or less, and more preferably 0.005% or less.

* N: 0.0015 to 0.02% N is an element added to generate BN and promote graphitization. If the amount is too small, a sufficient effect cannot be obtained.
0.0015% or more is desirable, and 0.0040% or more is more desirable. On the other hand, if the content is too large, the steel material becomes hard and the machinability deteriorates. Therefore, the content is preferably set to 0.02% or less, and more preferably 0.015% or less.

In the paper feed shaft according to the present invention, when the length of the shaft is L and the diameter of the shaft is D, L / L
Even if D is 20 or more (more preferably 30 or more), straightness with a deflection of 0.010 / 400 mm or less can be obtained.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following Examples are not intended to limit the present invention, and any design change based on the gist of the preceding and following aspects will be described. Are included within the technical scope of

[0028]

EXAMPLES Thirteen types of steels A to M having the component compositions shown in Table 1 were melted, heated at 1200 ° C., rolled at a temperature of 900 ° C. or more (15 mm), and then cooled by air to room temperature. . The structure of each of the steel materials was ferrite and pearlite.

[0029]

[Table 1]

The steel type M is a conventional sulfur / lead composite free-cutting steel.
For the other steel types A to L, graphitization treatment (heating at 650 to 700 ° C. for 5 to 20 hours and then furnace cooling) was performed under various conditions, and the graphite ratios shown in Table 2 were obtained.

The test material after the graphitization treatment was drawn to a size of 14 mm (13% area reduction) by drawing, and straightness was examined by the method described later. Next, after cutting under the following conditions,
The surface roughness (Rz: 10-point average roughness) was investigated. Further N
Various types of paper feed shafts were produced by performing i-plating or Cr-plating and applying a ceramic coating.

[Cutting test (grooving) conditions] Tool: P10 Cutting speed: 150 m / min Feed: 0.06 mm / rev Total cutting depth: 1.0 mm Cutting width: 2 mm

[Straightness evaluation method] After the drawing, straightening, and straightening, the test piece cut to a predetermined length was set on a V block (with a knife edge), and the bending amount of a 400 mm span was measured using an electronic micrometer. It measured and judged as follows. ：: Deflection amount of less than 10 μm ×: Deflection amount of 10 μm or more The plating properties were visually inspected for the presence or absence of peeling of plating. The results are summarized in Table 2.

[0034]

[Table 2]

No. 1 to 6, No. 14, No. 17 ~
19 are all examples of the present invention, and since they have excellent machinability after graphite treatment, they have good surface properties, excellent straightness, and good plating properties.

No. No. 7 is an example in which the amount of C is too large, and although the graphitization ratio and the surface roughness are good, the straightness is insufficient because the number of graphite particles is small and the degree of dispersion is inferior. No. No. 8 is an example in which the amount of Si is too small. Graphitization was delayed and remained at a graphitization rate of 45%. As a result, the surface roughness was slightly poor and slight tearing occurred. No. No. 9 is an example in which a large amount of S was added. Although the surface roughness and the graphitization ratio were good, the straightness was inferior because a striped structure was formed and the internal quality varied. The result was. No. 10 to 12 are Ca and / or
Or, it is a comparative example to which Zr is not added, in which graphite particles are insufficiently refined, have poor machinability, and are inferior in finished surface roughness.

No. No. 13 is a conventional example using a sulfur / lead composite free-cutting steel, and the straightness could not satisfy the target value because the L / D was 35 and a long shaft. Furthermore, the generation of a large amount of MnS caused the surface to peel off after plating.

No. Nos. 14 to 16 were obtained by examining the difference in characteristics due to the difference in graphite ratio using the same steel type A as a material. No. 14 has excellent machinability after graphite treatment, and thus has good surface properties, excellent straightness, and good plating properties. On the other hand, no. Nos. 15 and 16 have a graphite ratio of less than 60%, have poor surface properties after cutting, and particularly have a graphite ratio of 20%.
o. In No. 15, the straightness was poor and the plating was peeled off. In addition, No. The reason why the straightness deteriorated in No. 15 was that the machinability was reduced due to the low graphite ratio, and a high residual stress was generated due to the deep formation of the work-affected layer. It is considered that redistribution occurred and straightness deteriorated.

No. Nos. 20 to 22 are conventional examples using a sulfur / lead composite free-cutting steel in which the L / D of the shaft is changed. 13, in the conventional example, L
Although the straightness of a short shaft with a small / D is good, L /
It can be seen that straightness deteriorates with a long shaft having a large D.

[0040]

As described above, according to the present invention, a paper feed shaft having excellent straightness and surface properties can be provided.

Continued on the front page (72) Inventor Toyofumi Hasegawa 2nd Nadahama-Higashi-cho, Nada-ku, Kobe Inside Kobe Steel, Ltd.Kobe Works (72) Inventor Yasuhiro Oki 2nd Nadahama-Higashi-cho, Nada-ku, Kobe Kobe Steel Works, Kobe Steel Works (72) Inventor Ryo Fukuoka 14 Sun Umezu Nishiura-cho, Ukyo-ku, Kyoto City (72) Inventor Isao Kawauchi 14 Umezu Nishiura-cho, Ukyo-ku, Kyoto Suncall Corporation F-term (reference) 2C059 CC24 3F049 AA10 LA02 LA07 LB03 4K044 AA02 AB04 BA11 BA12 BA18 BB03 BB11 BC09 CA02 CA18 CA21 CA62

Claims (4)

[Claims] 1. A paper feed shaft comprising a cylindrical cored bar having a rust-preventive undercoat layer formed on the surface thereof, and further having a coating layer formed by heating and baking, wherein the paper feed shaft comprises 60% of the total carbon content in the substrate. The above is graphite, with the balance consisting of ferrite and carbide and Ca in the range of 0.0003 to 0.0.
A paper feed shaft excellent in straightness and surface properties, characterized by using graphite steel containing 15% and 0.005 to 0.20% of Zr. 2. A paper feed shaft having a rust-preventive base treatment layer formed on the surface of a cylindrical cored bar and further having a coating layer formed by heating and baking, wherein 60% of the total carbon content in the substrate is provided. The above is graphite, the balance being ferrite and carbide, and C: 0.3 to 1.5% Si: 0.5 to 2.0% Mn: 0.10 to 1.2% P: 0.2% or less (Excluding 0%) S: 0.005 to 0.2% B: 0.0003 to 0.015% Ca: 0.0003 to 0.015% Zr: 0.005 to 0.20% N: 0 A paper feed shaft having excellent straightness and surface properties, characterized by containing 0.0015 to 0.02% and the balance being Fe and graphite steel which is an unavoidable impurity. 3. The paper feed shaft according to claim 1, wherein ceramic particles are dispersed in the coating layer. 4. When the length of the shaft is L and the diameter of the shaft is D, L / D is 20 or more.
3. The paper feed shaft according to any one of 3.