KR100265250B1 - Valve and manufacturing method thereof - Google Patents

Abstract

PURPOSE: A valve and a manufacturing method thereof are provided to lengthen the life span of a valve by optimizing the mechanical and physical properties of the valve and to reduce the production cost by making mass production possible. CONSTITUTION: A manufacturing method of a valve comprises the steps of preparing a stainless steel sheet constituted of 1.0-3.0wt.% of Mn, 6.0-9.0wt.% of Ni, 15-18wt.% of Cr, 1.0-3.0wt.% of Cu, 0.04-0.08wt.% of C, 0.5-1.7wt.% of Si, 0.01-0.04wt.% of P, 0.001-0.03wt.% of S, and Fe, forming a valve body blanking the stainless steel sheet, spreading a drawing oil on the blanked stainless steel sheet, placing a PVC(Poly Vinyl Chloride) film on thereon, and drawing via a die in a specific pressure, forming an inlet and an outlet in the valve body and welding an inlet and an outlet pipes to the inlet and the outlet, forming a spring cap, and integrating the valve body with the spring cap. During drawing, the pressure ratio of a punch to a die is 5:1 to reduce percent defective and to prevent cracks.

Description

Valve and its manufacturing method

The present invention relates to a valve and a method for manufacturing the same, and more particularly, to a method of deep drawing using a stainless steel sheet containing Mn, Ni, Cr, Cu and C, Si, P, S, which are inevitably contained. By forming the valve body and the spring cap (or Bonnet: "spring cap") and integrating them together to manufacture the valve, the surface of the valve is beautiful and the manufacturing process is simple. It would be.

In general, a valve is a group of mechanisms, which are installed as a part of a machine, through which a fluid can flow, and functions as a pressure, a flow rate, or a temperature control when gas or liquid enters or exits. It is divided into control valve, flow control valve and directional valve, and this valve is composed of trim (TRIM), which is a kinematic element that directly controls the physical quantity of spring and fluid, and they are divided into body and spring cap. do.

Here, the body and the spring cap should be operated smoothly by mutually mechanically combining the metallic characteristics of the valve material, the strength characteristics of the material itself, and the valves according to the use environment of the valve material. Sufficient structural strength should be maintained.

Conventional valve manufacturing method is manufactured using the method of forging or casting and the material is shown in Table 1 (KS regulations).

The valve manufactured by the conventional casting or forging has the following problems.

First, the casting process is accomplished by dissolving the material as it is well known, injecting it into a mold prepared in advance, solidifying it, and then taking it out. However, even though it is important to obtain a uniform and coaxial microstructure, injecting molten metal into a mold has the risk of bringing uneven structure due to the difference in cooling rate between the outside and inside of the metal.

In addition, bubble defects are generated by the gas absorbed in the molten metal. Shrinkage cayity caused by shrinkage during solidification, deformation due to difference in cooling rate, high temperature cracking, surface defects, etc. are defects in casting, and a casting method for fundamentally completely removing these defects has not been developed yet.

Therefore, when manufacturing the valve body by the casting process, in order to prevent casting defects and stress concentration at the structural discontinuity, the teeth should be specially thickened and the valve should be reduced to reduce the structural discontinuity as much as possible from other wall thicknesses. The overall thickness should be made.

In consideration of the importance of high internal pressure valves, the products produced by the casting process have problems with their reliability due to the defects mentioned above.

Secondly, it is fundamentally impossible for the forged valve to manufacture the flow passage of the body by the forging process. All forged valves are swaged after cutting the inside of the valve body. However, there is a drawback of excessive design due to the lack of elasticity due to thermal load due to more severe structural discontinuity than the valve by the casting process, but the biggest problem is very disadvantageous in terms of productivity and cost competitiveness due to the high production time and cutting processing volume. There is this.

Therefore, considering that the shape of the valve body is generally cylindrical, the manufacturing method by deep drawing has a uniform stress distribution on the internal pressure surface of the valve, and can withstand high pressures even on a thin wall thickness and has a long service life. It would be advantageous for manufacturing process shortening or cost reduction.

The present invention has been invented to solve the problems of the prior art as described above, the purpose of which is deep using Mn, Ni, Cr, Cu and inevitably contained C, Si, P, S, containing stainless steel sheet By forming the valve body and the spring cap by the drawing method and integrating them together to manufacture the valve, it is possible to extend the service life of the valve by making the mechanical and physical properties of the valve optimally.

In addition, another object of the present invention is that the valve manufacturing process is simple and easy, so that mass production can be carried out, so that the unit cost of the valve can be reduced, and by using the deep drawing method, the pressure distribution surface of the valve has a uniform stress distribution. It can withstand high pressure even with thin wall thickness, has a long service life, shortens manufacturing process, reduces cost, and provides beautiful valve surface.

1 is a process chart showing a process of manufacturing the valve of the present invention.

2 is a block diagram showing a mold for manufacturing the valve of the present invention.

3 (a) to 3 (b) are cross-sectional views of the valve body and the spring cap of the present invention completed.

4 (a) to 4 (b) are cross-sectional views showing a process of drawing the valve body of the present invention.

5 (a) to 5 (d) is a cross-sectional view showing a process of drawing a spring cap of the present invention.

6 (a) to 6 (e) are perspective views of different forms of valves produced by the present invention.

7 is a graph of true stress-strain comparison between the present invention and a comparative example.

8 is a comparative graph of hardness change according to the cold working of the present invention and the comparative example.

9 is a graph comparing the molding limit of the present invention and comparative examples.

10 is a graph of shape freezing of the present invention and a comparative example.

11 is a graph of comparison of corrosion resistance between the present invention and a comparative example.

* Explanation of symbols for main parts of the drawings

10: Punch 20: Die

30: valve body 31,32: inlet and outlet

33,34: Entrance and exit 40: Spring cap

Referring to the technical features of the present invention for achieving the above object in detail as follows.

The valve manufacturing method of the present invention is Mn: 1.0 to 3.0wt%, Ni: 6.0 to 9.0wt%, Cr: 15 to 18wt%, Cu: 1.0 to 3.0wt%, C: 0.04 to 0.08wt%, Si: 0.5 to 1st process of providing the stainless steel plate which is 1.7 wt%, P: 0.01-0.04 wt%, S: 0.001-0.03 wt%, and remainder is Fe; A second step of blanking the stainless steel sheet and injecting the drawing oil into the blanked stainless steel sheet, and then laying a PVC film thereon and drawing the valve body by drawing with a predetermined pressure using a die provided with a die and a punch; A third step of drilling the inlet / outlet of the valve on the molded valve body and welding the inlet / outlet pipe separately manufactured through the list-recreating and trimming process to the perforated inlet / outlet; A fourth step of forming a spring cap by working the stainless steel sheet of the first step in the same manner as the second step and the third step; And a step of integrating and integrating the valve body and the spring cap formed by the first step, the second step, the third step, and the fourth step with each other.

The number of drawing of the valve body is made at least two times and the drawing oil is oiled every drawing process, the drawing cap of the spring cap is made at least three times and the drawing oil is oiled every drawing process. The pressure for forming the used valve body and spring cap is a ratio of punch 5: die 1.

In addition, the valve of the present invention is produced by the first step, the second step, the third step, the fourth step, the fifth step of the valve manufacturing method.

The valve of the present invention having such a feature and a method of manufacturing the same will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, Mn: 1.0-3.0 wt%, Ni: 6.0-9.0 wt%, Cr: 15-8 wt%, Cu: 1.0-3.0 wt%, C: 0.04-0.08 wt%, A stainless steel sheet is prepared by cutting two sheets with a predetermined cree from a coil in which strips of Si: 0.5 to 1.7 wt%, P: 0.01 to 0.04 wt%, S: 0.001 to 0.03 wt% and the rest are Fe are wound.

The Mn (manganese), Ni (nickel), Cr (chromium), Cu (copper) are the main components of the material to make the valve body 30 and the spring cap 40 of the present invention and the remaining C (carbon), Si (silicon) ), P (phosphorus) and S (sulfur) are inevitably contained components.

The Mn is to give strength to the stainless steel sheet to make the valve body 30 and the spring cap 40 of the present invention, Ni gives ductility to the stainless steel sheet, Cr forms an oxide film on the surface of the stainless steel sheet, Cu gives the corrosion resistance of a stainless steel plate.

One of the two stainless steel sheets prepared in this way is blanked to a size for forming the valve body 30 using a blanking machine (blanking: sheet metal is punched out using punches and dies) and the blanked stainless steel After drawing oil on the steel sheet, a PVC film is placed thereon, and a required shape is drawn at a predetermined pressure using a mold provided with a punch 10 and a die 20 as shown in FIG. And the valve body 30 as shown in Fig. 3 (a).

However, the drawing work of the stainless steel sheet for making the valve body 30 is divided into two times, and before drawing, the oil must be oiled on the surface of the stainless steel sheet, and then a PVC film having a thickness of 0.02 mm is laid thereon. do.

Select the selected place of the valve body 30 made as described above, that is, the place where the inlet / outlet 31, 32 of the valve is to be formed and perforated therein and restriking the shape of the product made in the previous step. After correcting the dimension and finishing the trimming process, trimming (cutting or removing unnecessary edges or pins of the pressed product) and shaping the product cleanly.

The mouth of the valve when the above operation is completed. Inlet and outlet pipes 33 and 34, which have already been manufactured in the perforated holes to form the outlets 31 and 32, are brought into close contact with the holes and welded to provide the inlet and outlet ports 31 and 32 of the valve. do.

Thereafter, the valve body 30 is formed, and another stainless steel sheet is blanked, drawn, rolled, and trimmed to form a spring cap 40 as shown in FIG. 3 (b).

However, the molding process of the valve body 30 and the spring cap 40 may be made by each mold, or may be made by exchanging the punch 10 and the die 20 using one mold. .

When all the above operations are completed, the valve body 30 and the upper portion of the spring cap 40 are in close contact with each other to be fastened, thereby completing the manufacturing work of the valves as shown in FIGS. 6 (a) to 6 (e).

And the drawing work at the time of shaping | molding the said valve body 30 is divided into primary and secondary as shown to FIG. 4 (a) and FIG. 4 (b), and the punch 10 and die during the said drawing work are carried out. The pressure of 20 is 5: 1 because the depth of the valve body 30 is so deep that molding in one operation increases not only the defects in shape but also the probability of occurrence of unfinished products, cracks, etc. There is a problem that occurs.

Therefore, it is desirable to make an unfinished product by drawing first and to make a final product by drawing the second drawing.

In addition, the drawing work at the time of forming the spring cap 40 is divided into several times (four times) as shown in FIGS. 5 (a) to 5 (d), and the punch 10 and The pressure of the die 20 is 5: 1, because the spring cap 40 has a deeper depth than the valve body 30, so it is necessary to divide the work several times so that the shape of the product, as well as the occurrence of an unfinished product, can be achieved. Probability is low and crack does not occur.

Hereinafter will be described the characteristics of the material for forming the valve body and the spring cap of the present invention.

Among the components of the present invention, Ni-Cr-Mn steel, in which Cu is not added, can be compared with STS304 (KS), but STS304 is the same austenitic stainless steel as in the present invention, and Mn, Ni, and Cr are each 2.00wt. % Or less, it contains 8.00-10.50wt%, 18.00-20.00wt%. However, experiments with this material have shown that fracture could not be used when deep drawing a valve body longer than its diameter.

In the following, various characteristics of STS304 and the steel adopted by the present invention (hereinafter referred to as STS304Jl) will be compared.

FIG. 7 is a true stress-strain curve of STS374 and STS304Jl, wherein the material has a low work hardening index in the low strain region and a high work hardening index in the high strain region. Therefore, it is easy to mold by small stress at the beginning of molding, and delays necking at the end of molding, so it is relatively small in variation of thickness and is advantageous for deep drawing.

8 shows the change in hardness according to the cold working amount, and this material exhibits advantageous forming characteristics even if the cold working amount is increased because the work hardening due to the increase in the cold working amount is low.

9 compares STS430, STS304 and STS304Jl of the present invention with respect to forming limits. The lower part of each line in Fig. 9 shows a region that is stably formed without breaking the material. Therefore, it can be seen that the STS304Jl of the invention has a low risk of fracture during molding.

FIG. 10 shows the extent to which the material is spring back (reduced from the shape of the die 20 when pressed and released from the die 20) after molding, and maintains the shape without causing the phenomenon to exhibit precise dimensions. It is understood that STS304Jl of the present invention is excellent in shape freezing by comparing the shape freezing shown with STS304.

FIG. 11 compares the corrosion resistance. The corrosion resistance of stainless steel is due to the formation of a thin and dense oxide film on the surface of the steel sheet.

STS304Jl is slightly lower in Cr than STS304, but the added Cu shows the same level of corrosion resistance as compared to STS304.

As described above, even in the Cr-Ni-Mn steel, it can be seen that STS304Jl containing 0.1-3.0 wt% of Cu is a suitable material for applying deep drawing.

Hereinafter, the valve manufacturing method of the present invention will be described with reference to Examples.

Example 1

Mn: 1.35wt%, Ni: 7.71wt%, Cr: 17.l6wt%, Cu: 2.11wt%, C: 0.04wt%, Si: 0.61wt%, P: 0.024wt%, S: 0.004wt%, Rest Prepares and blanks the stainless steel sheet which is Fe, and then injects the drawing oil on the blanked stainless steel sheet, and then spreads it twice using a mold provided with a punch 10 and a die 20 thereon. The valve body 30 was molded by drawing at a pressure ratio of 5: 1, and another stainless steel sheet was worked in the same manner as the above method, but divided only four times in the number of drawings.

As a result, the mechanical properties and physical properties of the valve body 30 and the spring cap 40 were as shown in Table 2 and Table 3 below.

Example 2

In the second embodiment of the present invention, each component ratio of the steel material for forming the valve body and the spring cap is Mn: 1.0wt%, Ni: 6.0wt%, Cr: l5wt%, Cu: 1.0wt%, and the remaining C, Si, P, S, Fe and molding conditions were the same as in the first embodiment. As a result, the mechanical properties and physical properties were similar to those of Tables 2 and 3.

Example 3

In the third embodiment of the present invention, Mn: 3.0wt%, Ni: 9.0wt%, Cr: 18wt%, Cu: 3.0wt%, different from the first and second embodiments, and the remaining C, Si, P, S, Fe and molding conditions were the same as in the first embodiment. As a result, the mechanical and physical properties were similar to those of Tables 2 and 3.

Since the mold used in the present invention is the same as a conventionally used mold, only one representative mold is shown in FIG.

This mold is a mold for the third drawing of the spring cap 40, and consists of two punches 10 and a die 20 as a basis. In the drawings, reference numeral 11 denotes a packing plate, 12 a stripper, 13 a punch, and 10 holders, respectively.

FIG. 6 (a) is a continuous venting valve acting as a vent, FIG. 6 (b) is a pressure reducing valve, FIG. 6 (c) is another pressure reducing valve, and FIG. 6 (d) is an overflow valve. 6 (e) is a breathing / venting valve.

In addition, a valve having a small diameter deep body or a spring cap 40 can be applied to all, for example, an air release valve (air release valve). It can also be applied to float actuated steam traps.

The present invention as described above is a valve body and spring in the order of blanking, deep drawing, list-lining, trimming using stainless steel sheet containing Mn, Ni, Cr, Cu and C, Si, P, S, inevitably contained By forming the caps and integrating them together to manufacture the valves, the manufacturing process is simple and easy to reduce the mass production and valve cost, and improve the mechanical and physical properties of the valves, thereby improving the service life of the valves. There is a unique effect that can be extended.

Claims (5)

Mn: 1.0 to 3.0 wt%, Ni: 6.0 to 9.0 wt%, Cr: 15 to 8 wt%, Cu :. 1st which provides the stainless steel plate whose 1.0-3.0 wt%, C: 0.04-0.08 wt%, Si: 0.7-1.7 wt%, P: 0.01-0.04.wt%, S: 0.001-0.03 wt%, and remainder are Fe. fair; A second step of blanking the stainless steel sheet, injecting drawing oil into the blanked stainless steel sheet, and then laying a PVC film on the stainless steel sheet and drawing the valve body at a predetermined pressure using a mold provided with a punch and a die; A third step of drilling the inlet / outlet of the valve on the molded valve body and welding the inlet / outlet pipe separately manufactured through the list-writing and trimming process to the perforated inlet / outlet; A fourth step of forming a spring cap by working the stainless steel plate of the first step as the second step and the third step; And a fifth step of integrating and integrating the valve body and the spring cap formed by the first step, the second step, the third step, and the fourth step. The method of claim 1, wherein the number of drawing of the valve body is made at least twice, and the drawing oil is oiled every time the drawing process is performed. The method of claim 4, wherein the number of drawing of the spring cap is made at least three times, and the drawing oil is oiled every time the drawing process is performed. The method of claim 1, wherein the molding pressure of the valve body and the spring cap using the mold is a ratio of punch 5: die 1. A valve, characterized in that manufactured by the manufacturing method of claim 1.

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