JPH0866715A - Method for manufacturing wire / bar material having highly smooth outer surface - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a method for manufacturing a wire / bar having a highly smooth outer surface as cold drawn. [Structure] (1) In a method for manufacturing a wire / bar material by a cold drawing method using a die, a ring-shaped recess 13 is provided at a contact portion of the die taper surface with the wire / bar material, and the recess is a wire.・ Apply ironing to the outer surface of the bar to reduce the surface roughness. (2) In a method of manufacturing a wire / bar material by a cold drawing method using a die, a ring-shaped step portion for reducing a die diameter is provided in a bearing portion of the die, and the step portion is provided on an outer surface of the wire rod material. Add ironing to reduce surface roughness. [Effect] Small outer surface roughness (Rmax 1.0 μm or less)
It can be obtained by cold drawing the wire / bar.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a wire / bar having a highly smooth outer surface. More specifically, the present invention relates to a method for producing a wire / bar material having a surface roughness Rmax of 1.0 μm or less.

[0002]

2. Description of the Related Art Conventionally, a relatively smooth surface (having a surface roughness of Rmax
The cold drawing method has been used as a processing method for wires and rods having an outer surface of 1.0 to 3.0 μm. This is a processing method in which, as shown in FIG. 7, the outer surface of the wire / bar material 72 that is the material to be processed is constrained by a die 71, and one end of the wire / bar material is chucked (not shown) and cold drawn out. Is. The lubrication method between the die and the wire / bar material mainly includes chemical conversion treatment lubrication and oil lubrication, but in order to obtain a relatively smooth outer surface, oil lubrication with a thin lubricating coating is used. In the case of this oil lubrication, the oil accumulates in the fine recesses on the outer surface of the work material, and during processing, the lubricating oil is gradually discharged from this oil reservoir (oil pit) and the recesses become smaller, but they do not disappear completely. No matter how much you use a die with a small surface roughness,
Since the dents exceeding 1.0 μm remain, the outer surface roughness should be Rm.
It was not possible to reduce the ax to less than 1.0 μm.

Accordingly, the surface roughness Rmax is higher and smoother.
In order to obtain a wire / bar having an outer surface of 1.0 μm or less (hereinafter, such wire / bar is referred to as “highly smooth wire / bar”), it is subjected to polishing. This is a method of removing the convex parts of the work material with fine abrasive particles and finishing the surface smooth, flowing fine abrasive particles at the interface between the work material and the tool, sliding the tool on the work material surface, This is a method in which the projections of the material to be processed are scraped off by the abrasive particles present at the interface.

There are two types of typical cold drawing dies for wire / bar materials as shown in FIG. Fig. 8 (a) is a cross-sectional view of the taper die cut in half, and the part that actually reduces the diameter of the workpiece (approaching portion) has a linear shape with a constant surface angle 2α, and the material of the wire / bar It is often used when is hard.

FIG. 8B is a cross-sectional view of a die with R, which has a constant curvature R when the shape of the approach portion is halved and is often used for a relatively soft wire / bar material.

The above-mentioned polishing method is often used to finish the wire / bar material manufactured by the cold drawing method. That is, the polishing method can obtain a highly smooth outer surface with Rmax of 1.0 μm or less, but it takes much longer to drop the same amount of outer diameter as compared with a processing method such as cold drawing. Since the efficiency is poor, in the processing of "high smooth wire / bar material",
In order to obtain a desired size, cold drawing, cutting, or the like is performed to an outer diameter slightly larger than the desired size, and then polishing is performed to finish.

Therefore, "high-smooth wire / bar material" is more expensive and more expensive than a wire / bar material having a Rmax of more than 1.0 μm, which is finished by cold drawing, because the number of processes is increased. It was.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a "high smooth wire / bar material" which is as cold as it is during polishing.
It is to provide a method of manufacturing at low cost.

[0009]

The gist of the present invention resides in the following methods (1) and (2) for producing a wire / rod.

(1) In a method of manufacturing a wire / bar material by a cold drawing method using a die, cold drawing is performed using a die having a ring-shaped recess at a contact portion of the tapered surface with the wire / bar material. A method of manufacturing a wire / bar material having a highly smooth outer surface, which is characterized in that

(2) In a method of manufacturing a wire / bar material by a cold drawing method using a die, a die having a ring-shaped step portion for reducing the die diameter in a bearing portion (finish parallel portion) is used for cold drawing. A method for producing a wire / bar material having a highly smooth outer surface, characterized by being drawn out.

As a method of reducing the outer surface roughness of a wire / bar material (hereinafter referred to as a work material) by drawing, reducing the roughness of the tool surface and a lubricating coating between the tool and the work material. It is well known to thin the. In addition to the above-mentioned well-known techniques, the present inventors further provided a concave portion or a stepped portion in the die, performed ironing on the outer surface of the work material, and concentrated shear plastic deformation there, whereby the outer surface roughness was increased. The present invention has been made based on the new finding that

[0013]

Now, the manufacturing method of the present invention will be described in detail together with its function and effect.

The object of the present invention is to reduce the outer surface roughness of a work material only by cold drawing. In order to reduce the surface roughness of the work material by plastic working, the above-mentioned well-known techniques alone are not sufficient, and it is necessary to add "ironing" that concentrates shear plastic deformation near the surface layer of the material. .

The first manufacturing method of the present invention and its effects will be described with reference to FIGS.

FIG. 1 (a) is a sectional view showing a state of cold drawing by a die having a recess, and FIG. 1 (b) shows (a).
FIG. FIG. 2 is a cross-sectional view of the vicinity of the recess showing a state in which the workpiece is in contact with the die between the recesses, and FIG. 3 is a cross-sectional view of the vicinity of the recess showing the definition of the ironing amount Δh. ) Indicates a taper die, and (b) indicates a case with a radius die.

In the first manufacturing method of the present invention, in order to concentrate the shear plastic deformation on the outer surface of the work piece 14 by cold drawing, it exists in the approach portion 12 of the die 11 in a ring shape along the inner circumference. The concave portion 13 is formed, and the workpiece is ironed (working amount Δh) at the point a on the outlet side edge of the concave portion. As a result, the outer surface roughness of the material to be processed can be made Rmax 1.0 μm or less.

Here, the position of the concave portion must be in a portion where the material to be processed comes into contact with the die because ironing is performed at the point a on the edge of the concave portion side. That is, it is necessary to arrange the point a so as to be on the outgoing side of the point b (see FIG. 1A) where the taper surface of the die and the workpiece are in contact. This is because the work piece begins to contact the die between the recesses.
In such a state, the outer surface of the workpiece undergoes extreme bending deformation in the axial direction at the contact start point b, and the roughness of the outer surface increases, canceling out the effect of improving the roughness by ironing. . Further, the ironing amount Δh fluctuates due to the variation in the outer diameter of the work material, and the outer surface roughness after drawing is not constant. Therefore, as shown in FIG. 1, it is necessary to set the position such that the entire concave portion is located on the outgoing side from the contact start point b between the workpiece and the die.

As shown in FIG. 3, the ironing amount Δh in the concave portion is a point c where the material to be processed is most distant from the broken line ae connecting the both ends of the concave side to the concave side. Expressed in the distance to. The larger this Δh, the greater the effect of improving the outer surface roughness of the workpiece. However, if Δh becomes too large, the surface layer processing becomes severe and seizure occurs. As shown in the examples below, Δh is preferably in the range of 0.01 to 0.08 mm. By the way, Δh is geometrically determined by the depth and axial length of the concave portion of the die and is not affected by the drawing speed or the lubrication method. That is, in the concave portion, the material to be processed progresses along the inner surface of the die when the outer diameter is constant at the portion where the outer surface is not in contact with the die and is constrained by the die.
h is uniquely determined from the axial length L of the recess, the shape of the recess, and the die surface angle near the recess.

If the angle β with respect to the die taper surface near the concave side is too small, the machining becomes gradual, and the ironing effect is lost, and the effect of improving the roughness cannot be seen. Conversely, if β is too large, the machining becomes sharp. And it causes burn-in.
The desirable range of β is 10 to 45 degrees.

Next, the second method of the present invention using a die provided with a step and its function and effect will be described with reference to FIG.

FIG. 4A is a sectional view showing a state of cold drawing by a die having a step portion, and FIG.
It is the A section enlarged view of (a). As shown, dice 41
The bearing portion (finishing parallel portion) 42 is provided with a step 43 such that the die diameter is rapidly reduced. At the point a _{1 of} this step, the outer surface of the workpiece 44 undergoes ironing (working amount Δh), and the roughness decreases. As a result, the outer surface roughness Rmax of 1.0 μm or less can be achieved.

Since the ironing process can be performed regardless of the position of the step portion on any part of the bearing portion and therefore the same improvement effect can be obtained, there is no difference in the roughness after processing depending on the position of the step portion. However, if the entire length of the bearing portion including the step becomes too long, seizure will occur. Therefore, it is desirable to set this length to the die hole diameter d or less. If the total length of the bearing portions satisfies the above condition, the outer surface roughness can be reduced regardless of the position of the step portion provided therebetween.

Ironing amount Δh at step (FIG. 4 (b))
As in the case of the die with recess, if it becomes too large, seizure with the work material occurs, so Δh is 0.
The range of 01 to 0.08 mm is desirable. Δh in a die having a step is uniquely determined from the height of the step provided in the bearing.

The angle between the contour of the die near the ironing point of the step and the taper surface of the die on the entry side (hereinafter referred to as the step angle) β ₁ is the same as in the case of the die with recesses, if the angle is too small Becomes less gradual and the ironing effect disappears, and the effect of improving the roughness cannot be seen. On the contrary, if it is too large, the processing becomes rapid and seizure occurs. Therefore, β ₁ is preferably set to ₁₀ to 45 degrees.

As for the material of the die, regardless of whether it is a die with a recess or a die with a step, a material having a high hardness such as cemented carbide is suitable. Further, when the material to be processed is a material that is easily seized, it is desirable to coat the die surface with a material having excellent seizure resistance such as TiCN.
If the material to be processed is a material that is difficult to seize, by coating, it may be possible to perform processing without seizure even if it is outside the above recommended range for the processing amount and die shape.

In the present invention, the shear plastic deformation is concentrated on the surface layer of the work material by ironing, and the lubricating film at the interface between the die and the work material is thinned to form fine irregularities on the outer surface of the work material. Since the material is deformed along the surface of the die, it is impossible to make the surface roughness of the workpiece after drawing smaller than that of the surface of the die. Therefore, it is necessary to finish the surface roughness of the die to be equal to or lower than the surface roughness desired for the work material.

[0028]

【Example】

[Example 1] Example using [die having recess] Work material: SUS304, outer diameter: 20 mm, outer surface roughness: R
A 5.0 μm round bar at max was cold drawn.

The shape and dimensions of the die used are shown in FIG.
The die is the taper die shown in FIG. 5 (a) and the taper die shown in FIG. 5 (b).
There are two types of dies with R shown in.

The die material is cemented carbide (JIS V20 equivalent)
The surface roughness of Rmax was 0.3 μm or less.

Lubrication was oil lubrication, and a lubricating oil (a mixed oil of sulfurized oil and paraffin) was applied to the outer surface of the material to be processed and cold drawn under the following conditions.

First, die hole diameter (d): 17.0, 18.0, 19.0
For each of the 3 mm types, the ironing amount Δh is 0 to
A die was prepared in the range of 0.10 mm, cold drawn, and the outer surface roughness was measured by Rmax. At this time, the angle β of the edge of the concave side is 30 degrees, and the concave position L ₁ (El 1) in FIG.
Unified to 2.0 mm. The position of the recess was set so that the entire recess was located on the exit side of the point b at which the workpiece and the die started to contact each other under all conditions. The above conditions and measurement results for the taper die and the die with R are shown in Table 1 and Table 2, respectively.

[0033]

[Table 1]

[0034]

[Table 2]

As shown in Tables 1 and 2, seizure occurred when Δh exceeded 0.08 mm in all the die hole diameters, and when Rh was less than 0.01 mm, Rmax was 1.0 μm or less. It is impossible to get. Therefore, it is understood that Δh is preferably in the range of 0.01 to 0.08 mm.

Then, the die hole diameter (d) is 1 as in the above.
For three types of 7.0, 18.0, and 19.0 mm, the recess position L ₁ (El 1) was changed in the range of 0 to 12.0 mm, cold drawing was performed, and the outer surface roughness was measured by Rmax. Here,
The ironing amount Δh has been unified to 0.06 mm, and the recess side edge angle β has been unified to 30 degrees. The axial length L (L) of the recess was 0.4 mm for the taper die. By the way, in the case of a die with R, the face angle of the approach part becomes smaller as it approaches the finishing parallel part, and even with the recess of the same size, Δh becomes geometrically smaller as it approaches the parallel part, so the same 0.06 mm Δh In order to obtain, it is necessary to lengthen the axial length L (L) of the recess. Therefore, when the value of the recess position L ₁ (L 1) becomes small (the recess approaches the parallel finish part), the recess axial length L
I made (Ell) bigger. The above conditions and results for the taper die and the die with R are shown in Table 3 and Table 4, respectively. Note that these tables were described also combined (C _L in Figure 5) the distance from the die bearing section entry side end to the point b die and the workpiece starts to contact with the pore size.

[0037]

[Table 3]

[0038]

[Table 4]

As shown in Tables 3 and 4, when the recess position L ₁ (L1) exceeds the value of C _{L and} the whole recess is not in contact with the die, the surface roughness is the same as that obtained by normal cold drawing. Is the same as On the other hand, as shown in FIG. 2, (if that is between L ₁ (El 1) of C _L and C _L -L (El)) If die and workpiece between the recess starts contacting Although the surface roughness is slightly improved as compared with the above, the improvement effect is small compared to the case where the entire concave portion is located on the output side from the contact point b,
Rmax of 1.0 μm or less cannot be achieved. Therefore, as for the recess position, the position where the entire recess is closer to the exit side than the point b where the workpiece and the die start contact (L
_It can be seen that it is preferable to set ₁ ( _L1 ) to a position smaller than CL-L (L).

Further, a test for investigating the influence of the concave side edge angle β was conducted.

The die used had the dimensions shown in FIG. 5, the hole diameter d was 18.0 mm, the recess position L ₁ (L1) was 2.0 mm, the ironing amount Δh was 0.06 mm, and the angle β was 5 ~ 50
Cold drawing was performed while changing the temperature range, and the occurrence of seizure and the outer surface roughness were measured. The above conditions and results are shown in Table 5.

[0042]

[Table 5]

As shown in Table 5, when the angle β is 50 degrees, seizure occurs in both the taper die and the R die. On the other hand, when the value is 5 degrees, the improvement effect does not appear.

Therefore, the range of the edge angle β of the recess side is 10 to 45.
Degrees are preferred, and even more preferred are 15 to 45 degrees.

[Example 2] Example using [die having step] Same as the test when a die having a recess was used as a work material, outer diameter: 20 mm, outer surface roughness: 5.0 μm in Rmax
Cold drawing was performed using a SUS304 round bar.

The basic shape and dimensions of the die used are shown in FIG.

The die material is cemented carbide (JIS V20 equivalent)
The surface roughness of Rmax was 0.3 μm or less.

Lubrication was oil lubrication, and a lubricating oil (a mixed oil of sulfurized oil and paraffin) was applied to the outer surface of the material to be processed and cold drawn under the following conditions.

First, die hole diameter (d): 17.0, 18.0, 1
For three types of 9.0 mm, the ironing amount Δh is
Prepare a die in the range of 0 to 0.10 mm, cold draw,
The outer surface roughness was measured by Rmax. At this time, the test was conducted with the length E ₁ before the stepped portion of the bearing portion, the length E ₂ after the stepped portion, and the angle β ₁ of the stepped portion being kept constant at 2.0 mm, 3.0 mm, and 30 degrees, respectively. The above conditions and results are shown in Table 6.

[0050]

[Table 6]

As shown in Table 6, seizure occurs when Δh exceeds 0.08 mm, while it is impossible to obtain Rmax of 1.0 μm when Δh falls below 0.01 mm.
Therefore, it is understood that Δh is preferably in the range of 0.01 to 0.08.

Next, in order to investigate the length and the position of the bearing portion, E ₁ and E ₂ before and after the step portion in FIG. 6 are changed between 0 to 20 mm and ₂ to 19 mm, respectively, and the step (ironing amount) is changed. Cold drawing was performed with Δh being 0.06 mm, the step angle β ₁ being 30 degrees, and the die diameter being 18 mm. The above conditions and results are shown in Table 7.

[0053]

[Table 7]

As shown in Table 7, seizure occurs when the total of E ₁ and E ₂ exceeds the diameter of the die hole. Therefore, the length of the bearing portion (total of E ₁ and E ₂ ) is preferably equal to or smaller than the diameter of the die hole. The position of the stepped portion in the bearing portion does not affect the outer surface roughness itself.

Next, the influence of the step angle β ₁ was investigated. That is, the die hole diameter is 18 mm, the step (ironing amount) Δh is 0.06 mm, and the bearing lengths E ₁ and E ₂ are
Under constant conditions of 2.0 and 3.0 mm, β ₁ was changed in the range of 5 to 50 degrees and cold drawn, and the presence or absence of seizure and the outer surface roughness were measured. The results are shown in Table 8.

[0056]

[Table 8]

As shown in Table 8, image sticking occurs when β ₁ is 50 degrees. On the other hand, when the value is 5 degrees, the improvement effect does not appear. Therefore, the range of the step angle β ₁ is
10 to 45 degrees is preferable, and 15 to 45 degrees is even more preferable.

[0058]

According to the present invention, a wire / bar material having an outer surface roughness Rmax of 1.0 μm or less, which is suitable for a piston of a hydraulic cylinder, a roll for processing a decorative steel plate, or the like, is manufactured by cold drawing. can do. As a result, it is possible to omit processing such as polishing for further improving the outer surface roughness, and it is possible to significantly reduce the manufacturing cost.

[0059]

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a state of cold drawing using a die having a recess. (A) is a general view, (b) is (a)
FIG.

FIG. 2 is a cross-sectional view of the vicinity of a recess showing a state in which a workpiece is in contact with a die in the recess.

FIG. 3 is a cross-sectional view near a recess showing the definition of an ironing amount Δh. (A) is a taper die, (b) is a die with R.

FIG. 4 is a cross-sectional view showing a state of cold drawing using a die having a step portion. (A) is a general view, (b) is an enlarged view of part A of (a).

FIG. 5 is a cross-sectional view of a die having a recess used in an example. (A) is a taper die, (b) is a die with R.

FIG. 6 is a cross-sectional view of a die having a step portion used in an example.

FIG. 7 is a cross-sectional view showing a state of cold drawing of a conventional wire / bar material.

FIG. 8 is a cross-sectional view of a conventional wire / bar cold drawing die. (A) is a taper die, (b) is a die with R.

[Explanation of symbols]

11: Die having concave portion, 12: Approach portion, 13: Recessed portion, 14: Workpiece material, 41: Die having step portion, 42: Bearing portion, 43: Step portion, 44: Workpiece material, 71: Conventional Die, 72: Workpiece material, d: Die hole diameter, 2α: Die surface angle, β: Recessed part outlet side edge angle (angle between the die contour line and the die tapered surface near the recessed part outlet side ironing point), β
₁ : Step angle (angle between the die contour line near the ironing point of the step and the die taper surface on the entry side), Δh: Ironing amount (step), L ₁ (El 1): Recessed position (die bearing Distance from the entry side end of the section to the recess exit side position), L
(L): axial length of recess, C _L : distance from the end on the die bearing section entry side to the point where the die contacts the workpiece, E ₁ : length before the step section of the die bearing section, E ₂ :
Length after step of die bearing

Claims (2)

[Claims] 1. A wire drawn by a cold drawing method using a die.
In the method for producing a bar material, the wire / bar material having a highly smooth outer surface is characterized by cold drawing using a die having a ring-shaped recess at a contact portion of the taper surface with the wire / bar material. Manufacturing method. 2. A wire drawn by a cold drawing method using a die.
In the method for manufacturing a bar material, a method for manufacturing a wire / bar material having a highly smooth outer surface, characterized by cold drawing using a die having a ring-shaped step portion for reducing a die diameter in a bearing portion .