JP2002307127A - Cylindrical formed body manufacturing method, and cylindrical formed body manufactured by the manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of efficiently performing the cold forging of a cylindrical formed body represented by a cold forged product of high rigidity, in particular, a high nut, etc., and the cylindrical formed body formed by the method. SOLUTION: Stock steel materials 10A-10E are formed of stainless steel containing >=0.02 wt.% carbon, the stock steel materials 10A-10E are housed in dies 3a-3e, the stock steel materials 10A-10E are subjected to composite extrusion or upsetting by punches 5a-5e having a forming space between the dies 3a-3e and themselves to obtain the cylindrical formed body having the cylindrical length larger than the outside diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical molded product represented by, for example, a high nut and a method for producing the same.

[0002]

2. Description of the Related Art Generally, when a metal material is cold forged,
The punch is advanced in the die to press the metal raw material to obtain a molded body with an outer shape corresponding to the inner surface shape of the die. Pressing the metal material and plastically flowing through the gap in the direction opposite to the direction of the punch movement to obtain a cylindrical molded body by "backward extrusion" processing, or by compressing a long metal material to a thick and short molded product A known "swaging" process is known. These cold forging methods are intended for processing relatively soft metal raw materials.

On the other hand, among stainless steels, SUSXM7
Is known for its good cold forging formability. Still, when using SUSXM7 as a metal raw material and continuously trying to obtain a high nut or the like having a long cylinder length with respect to the outer diameter by cold forging such as forward extrusion or backward extrusion, the metal raw material hardens during cold forging. Since it is likely to cause breakage of punches and dies, annealing has to be performed for each step. For this reason, hollow working such as forward extrusion and backward extrusion of stainless steel by cold forging is considered to be extremely difficult and has been considered unsuitable for mass production.

[0004] For this reason, the fact is that high nuts and the like are manufactured by cutting a raw stainless steel into a predetermined outer shape, and further cutting with a drill to form a cylindrical hole. However, in the method of obtaining a stainless steel product by the above-described cutting process, there is a problem that cutting chips are generated, and it takes too much processing time to produce a large amount, so that the production cost is high. Realization of continuous mass production of cylindrical molded bodies has been strongly desired.

In order to meet such a demand, the applicant of the present application has changed the carbon content and the sulfur content based on the Japanese Industrial Standards (JIS) SUSXM7, thereby making it possible to cool stainless steel as a raw material by composite extrusion or the like. The one that enables cold forging has been previously proposed (Japanese Patent No. 2707232).

[0006]

However, in the prior proposal of the present applicant, since the carbon content and the sulfur content are extremely reduced, the hardness of the stainless steel is reduced, and the rigidity of the product is reduced. However, there was a problem that was reduced. Therefore, the present invention has been proposed in view of the above problems, and has a high rigidity, a cold forging product, particularly a method and a method capable of efficiently cold forging a cylindrical molded body represented by a high nut and the like. It is an object of the present invention to provide a molded cylindrical body.

[0007]

Means for Solving the Problems As a result of intensive studies, the present inventor has found that a method of manufacturing a completed cylindrical body by cold forging is at least a stainless steel having a carbon content of 0.02% by weight or more. Construct the raw steel material, house the raw steel material in a die, compound extrusion or swaging the raw steel material with a punch forming a molding space between the die,
What is claimed is: 1. A method for producing a cylindrical molded body, comprising: molding a cylindrical molded body having a cylinder length longer than an outer diameter, wherein at least two of the following items are combined. The surface of the alloy is coated with titanium nitride or titanium carbide nitride. The surface of the die is coated with titanium carbide nitride. The tip angle of the punch pin is set to 3 to 10 degrees. The cemented carbide is V30 (JIS). , The die diameter flying tolerance is 0.15 mm, the clearance between the stripper and the knockout is about 0.2 mm, the lubrication is directly applied to the work part of the work, the ram clearance is 0.08 mm or less. The pressure at the time of correcting the end face is set to about 17 t / cm ² .

In the above method, the carbon content is 0.02% by weight or more and the sulfur content is 0.03% by weight.
The present invention is also applicable to the case where the raw material steel is made of stainless steel of 0% by weight or less. In addition, the cylindrical molded body having a long cylinder length with respect to the outer diameter according to the present invention has a carbon content of at least 0.02% by weight of stainless steel or a carbon content of at least 0.02% by weight and a sulfur content of at least 0.02% by weight. 0.030% by weight or less of raw material steel is accommodated in a die, a punch pin is coated on a surface of a cemented carbide with titanium nitride or titanium carbide nitride, and a processed surface of the die is coated with titanium carbide nitride. The tip angle of the punch pin is set to 3 to 10 degrees. The cemented carbide is formed by V30 (JIS). The jump tolerance of the die diameter is 0.15 mm. The clearance between the stripper and the knockout is about 0.2 mm. , Directly lubricate the processed part of the work, Reduce the ram clearance to 0.08 mm or less, When correcting the end face By combining two or more of said items to be around 17t / cm ² pressure, and the composite extrusion or swaging the raw material steel punch which forms a molding space between the dies, molding the cylindrical molded body It is molded by a method for producing a cylindrical molded body. Here, "composite extrusion" refers to performing forward extrusion and rearward extrusion sequentially or simultaneously.

[0009]

Embodiments of the present invention will be described in detail below. First, the stainless steel used in the present invention belongs to, for example, SUSXM7 of Japanese Industrial Standard (JIS). SUSXM7 specified in JIS is Ni: 8.5 to 10.5% by weight relative to the whole composition,
Cr: 17.0 to 19.0%, Si: 1.0% or less,
Mn: 2.0% or less, P: 0.045% or less, C
u: 3.0 to 4.0%, C: 0.08% or less, S:
It is an austenitic type containing 1.0% or less of main components.

Next, an embodiment for manufacturing a high nut made of stainless steel will be described with reference to the drawings. The high nut is a nut having an axial dimension (cylinder length) longer than the diagonal dimension (outer diameter). Here, a rough product having a diagonal dimension of, for example, 17 mm and a height (cylinder length) of, for example, 30 mm is manufactured. An example is shown below.

FIG. 1 is a plan view showing a parts former, which is one type of a horizontal transfer press for forging high nuts according to the present invention. In the parts former machine shown in the figure, four-stage forging machines 1a, 1b, 1c, 1d and a piercing machine 1e are arranged in parallel, and a transfer chuck (not shown) is arranged between them. Each forging machine 1a, 1b, 1c, 1d and the piercing machine 1e are provided with a die 3a, 3b, 3c, 3d, 3e and a punch pin 5, respectively.
a, 5b, 5c, 5d, and 5e, and the punch pins 5a, 5b, 5c, 5d, and 5e are held by punch driving devices 4a, 4b, 4c, 4d, and 4e, respectively. The punch driving devices 4a, 4b, 4c, 4d, and 4e are connected to one motor (for example, having a maximum capacity of 160 t / cm ² ) via a crank mechanism, and are driven in synchronization with each other. The punch driving devices 4a, 4b,
4c, 4d, and 4e crank speeds are 80 rpm
m is set to 55 rpm. This results in a decrease of about 30% in the number of rotations. However, the interval thus provided prevents the temperature rise of the apparatus and promotes cooling, thereby preventing an increase in the defective rate of the product due to an increase in the hardness of the raw materials. Productivity could be improved.

FIG. 2 is a diagram exemplifying a die and a die holding portion provided in the third forging machine 1c. In the figure, a die 3c has a processed surface coated with titanium carbide nitride, and is held and fixed to a die holding portion 2c. The die hole 7c of the die 3c is formed as a long hole having a regular hexagonal opening, is larger than the outer diameter of the punch 5c, and has a shape and dimensions capable of forming a molding space with the outer peripheral surface of the punch 5c. Is set to Other dies 3a, 3b, 3d, 3e, 3f and punches 5a, 5a
The arrangement relations with b, 5d, 5e, and 5f are almost the same. In addition, the jump tolerance from the next step, that is, the difference in diameter of the dies is set to 0.15 mm. This jump tolerance is generally 0.05 mm to 0.1 mm, whereas the jump tolerance is 0.1 mm.
When the diameter is set to 15 mm, swelling to the outside occurs during molding, and seizure of the die occurs. In order to cope with the seizure, a swelling margin is provided to reduce friction.

[0013] Of the punch pins, at least the third punch pin 5c and the fourth punch pin 5d are the cores of cold forging, and therefore have a toughness greater than that of high-speed steel and a cemented carbide (tungsten) superior in strength. Carbide (WC) type DA30 (product code of Mitsubishi Materials Corporation, V30 in JIS) is used, and its surface is coated with titanium nitride or titanium carbide nitride.
It is configured at 0 degrees.

In addition, the length of the so-called relief portion from the tip of the punch pin to the base portion having a slightly smaller diameter is increased, for example, from 20 mm to 15 mm from the conventional 30 mm to increase the strength. On the other hand, the raw steel material has a weight ratio of Ni: 8.0 to 10.00% and Cr: 17.
00 to 19.00%, Si: 1.0% or less, Mn:
2.0% or less,% P: 0.45% or less, Cu:
00% to 4.00%, C: 0.10% or less, S:
It is made of austenitic XM7 stainless steel containing 0.03% or less of main components. In addition, the clearance between the knockout pins 6a, 6b, 6c and the strippers 6d, 6e of the corresponding portion and the members supporting these are reduced from the conventional 0.05 mm to 0.2 mm.
To prevent seizure due to high temperature during molding.

When a rough product with a high nut is manufactured using the parts former machine having the above configuration, as shown in FIGS.
First, using a cutting machine (not shown), a raw steel material 10 (see FIG.
(See (a)), and the raw steel material 10
a in the die 3a. The surface of the raw steel material 10 is previously coated with 7% MoS2 metal chloride soap (emulsified molybdenum) in order to suppress the occurrence of seizure between the die and the die during cold forging. Since this emulsified molybdenum is liable to cause unevenness in the coating state, each die 3a is used to more completely prevent seizure during cold forging.
-3e are also coated with titanium carbide nitride.

Further, a cold rolling oil containing a mineral oil as a base material and containing an oiliness improver and a chlorine-based extreme pressure agent is directly supplied to each raw material forging portion (working portion) of the part former machine.
The clearance between each punch pin 5a, 5b, 5d, 5e, 5f of the punch driving device 4a, 4b, 4c, 4d, 4e and the ram of the punch driving device 4a to which the punch pin 5a is mounted,
It is set to 0.08 mm or less. This is because when the clearance exceeds 0.08 mm, rattling increases, and when the punch pins 5a, 5b, 5d, 5e, and 5f of the punch driving devices 4a, 4b, 4c, 4d, and 4e are driven, the clearance becomes oblique. Not only does the hardness of each raw material contained cause defective products, but also each punch pin 5a, 5b, 5d, 5e, 5f
In addition, this is for reducing the durability of each of the dies 3a to 3e.

Further, by driving the punch driving device 4a,
The punch 5a advances toward the bottom surface in the die 3a to push the raw steel material 10 forward, and the raw steel material 10 is moved to the die 3a.
When forging into an outer shape of a chamfer corresponding to the inner surface shape, an intermediate product 10A having a centering hole on one end side is formed (see FIG. 3B). Although the pressure at the time of chamfering (pressure at the time of correcting the end face) is generally 23 ton / cm ² , which is relatively low at 17 ton / cm ² , work hardening is prevented. And increased productivity. By driving the knockout pin 6a, the intermediate product 10A is moved to the die 3
protruded from a. The intermediate product 10A is gripped by the claws of the transfer chuck, and after being turned over in the axial direction, is conveyed into the die 3b of the next forging machine 1b.

In the forging machine 1b, the punch pin 5b pushes the intermediate product 10A forward by the driving of the punch driving device 4b, and the intermediate product 10A is forged into a chamfered outer shape corresponding to the inner shape of the die 3b. Here, an intermediate product 10B having a centering hole on the other end side is molded.
(C)). By driving the knockout pin 6b and the transfer chuck, the intermediate product 10B is moved to the die 3
b for the next forging machine 1c
Is transported into the die 3c.

It is preferable that the amount of thrust by the first punch 5a and the second punch 5b be minimized. This is because, when the first punch 5a or the second punch 5b pushes the raw steel material too hard, the raw steel material is liable to work hardening, and the third punch 5c and the fourth punch 5d are made of cemented carbide. This is because, even in this case, breakage is likely to occur.

In the forging machine 1c, the punch 5c is advanced by driving the punch driving device 4c while pressing the intermediate product 10B, whereby the intermediate product 10B plastically flows in a direction opposite to the punch advancing direction and is extruded backward. You. Here, an intermediate product 10C in which a single hole corresponding to the forward trajectory of the punch 5c is formed (see FIG. 3D). By driving the knockout pin 6c and the transfer chuck, the intermediate product 10C is taken out of the die 3c, turned over in the axial direction, and then conveyed into the die 3d of the next forging machine 1d.

Further, in the forging machine 1d, the punch driving device 4
By driving d, the punch 5d moves forward while pressing the intermediate product 10C, whereby the intermediate product 10C plastically flows in the direction opposite to the punch advancing direction and is pushed backward. Here, an intermediate product 10D in which a single hole corresponding to the forward trajectory of the punch 5d is formed (see FIG. 3E). By driving the knockout pin 6d and the transfer chuck, the intermediate product 10D is taken out of the die 3d, and is conveyed in the same direction into the die 3e of the piercing machine 1e.

In the piercing machine 1e, the remaining portion between the single holes in the intermediate product 10D is made to penetrate with the punch 5e to form the cylindrical hole 11e.
Then, a crude product 10E having a high nut is obtained (see FIG. 3F). The crude product 10E is pushed out of the die 3e by the knockout pin 6e, and a series of cold forging steps is completed. The crude product 10E has a tube length L (about 30 mm) longer than the outer diameter D (about 17 mm). Further, a female screw portion is threaded into the cylindrical hole 11 of the crude product 10E, and a high nut final product is obtained.

Finally, in the present invention, various studies were conducted to cold forge stainless steel having high hardness. As a result, the main change in the apparatus was (1) the punch pin was replaced with titanium nitride on the surface of the cemented carbide. Alternatively, titanium carbide nitride is coated (2), the work surface of the die is coated with titanium carbide nitride (3), the punch pin tip angle is set to 3 to 10 degrees (4), and the cemented carbide is V30. (5), Die diameter jump tolerance is set to 1.5 (6), clearance between stripper and knockout is set to about 0.2mm (7), and lubrication is directly applied to the work part of the work (8) Reduce the clearance of the ram to 0.08 mm or less (9), adjust the pressure at the time of correcting the end face to around 17 tons (10), and set the relief part of the pin to 15 to 20 mm. Although one of them can be expected to have a considerable effect, it is not enough, and it is desirable to combine it with one or more other. As described above, in this embodiment, since stainless steel, which hardly causes work hardening even during continuous cold forging of 5 to 6 steps, was used as a raw material, it is possible to prevent damage to punches and dies during the forging. It is possible to efficiently manufacture a high nut.

In the above, an embodiment in which a high nut is manufactured as a cylindrical molded body has been described. However, the present invention is applicable to cold forging such as a cylindrical stainless steel sleeve shape or a solid shaft shape. Of course, it is also applicable.

In the above, the embodiment using the cold forging method has been described. However, it is needless to say that the forging method, which is easier to process, can be used.

[0026]

As described above, according to the cylindrical molded body and the method of manufacturing the same according to the present invention, the composition is hard because of its high carbon content, and hardly worked due to work hardening during cold forging. The punch, die and the like are not damaged even under the severe conditions of forward extruding, backward extruding, and upsetting of stainless steel, and there is no need to perform steps such as annealing. Therefore, a stainless steel cylindrical molded body can be continuously and efficiently mass-produced by cold forging. In addition, since the raw steel material is not wasted, the yield is much higher than that of the current cutting, so that it can be manufactured at lower cost.

[Brief description of the drawings]

FIG. 1 is a plan view showing a parts former for high nut forging according to the present invention.

FIGS. 2A and 2B show an example of a dice and a dice holding portion provided in a part former machine, wherein FIG. 2A is a front view and FIG.

FIG. 3 shows a process of manufacturing a high nut from a raw steel material.
It is a side view including a partial section shown in order from (a) to (f).

FIG. 4 is a side view of a punch portion.

[Explanation of symbols]

 1a-1d Forging machine 1e Piercing machine 3a-3e Dies 5a-5e Punch 10 Raw material steel 10E Crude product D Outer diameter L Tube length

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B21J 5/00 B21J 5/00 A 5/06 5/06 D 5/08 5/08 Z 13/14 13 / 14 A B21K 1/68 B21K 1/68 A F term (reference) 4E087 AA09 AA10 BA02 CA25 CA31 CB03 CB07 CB11 DA05 EC17 EC34 EC37 ED01 ED06 EE00 HA57 HB01

Claims (3)

[Claims] A raw steel material is made of stainless steel having a carbon content of at least 0.02% by weight. The raw steel material is housed in a die, and the raw material steel is formed by a punch forming a molding space between the raw steel material and the die. A composite extrusion or upsetting of a steel material, a method of manufacturing a cylindrical molded body characterized by molding a cylindrical molded body having a long cylindrical length with respect to the outer diameter, wherein at least two or more of the following items Manufacturing method of cylindrical molded body in combination, Coating titanium carbide or titanium carbide nitride on surface of cemented carbide forming punch pin, Coating titanium carbide nitride on die processing surface, Tip angle of punch pin Is set to 3 to 10 degrees, the cemented carbide is formed by V30 (JIS), the flying tolerance of the die diameter is 0.15 mm, The clearance between par and the knockout of about 0.2 mm, to refuel directly to the processing part of the work, to less than 0.08mm ram clearance, the pressure during the end surface correction to 17t / cm ² before and after 2. The method according to claim 1, wherein stainless steel having a carbon content of 0.02% by weight or more and a sulfur content of 0.030% by weight or less is used as a raw steel material. 3. A die containing at least a stainless steel having a carbon content of at least 0.02% by weight or a raw steel material having a carbon content of at least 0.02% by weight and a sulfur content of at most 0.030% by weight. , Coating titanium carbide or titanium carbide nitride on the surface of a cemented carbide forming a punch pin; coating titanium carbide nitride on the processing surface of a die; setting the tip angle of the punch pin to 3 to 10 degrees; Forming cemented carbide with V30 (JIS), Making die diameter flying tolerance 0.15mm, Making clearance between stripper and knockout about 0.2mm, Lubricating directly to work part of work, Ram clearance the to 0.08mm or less, the pressure during the end surface correction on the back and forth 17t / cm ² By combining two or more of the items, the above raw steel material is compositely extruded or swaged with a punch that forms a molding space between the die and a die, and molded by a method of producing a cylindrical molded body. A cylindrical molded body having a longer cylinder length than its outer diameter.