KR101221707B1 - Method for treatmenting heat of Concrete-Convey Pipe - Google Patents

Abstract

The present invention relates to a heat treatment method for a concrete transfer pipe and a transfer pipe heat treated by the heat treatment method. In the heat treatment method for the concrete conveying pipe, it is slower than the existing line speed, and the hardening temperature is set lower than the existing temperature so that no crack is generated without performing the tempering process, and the internal hardness of the concrete conveying pipe is improved. It relates to an improved heat treatment method. More specifically, the step of injecting the raw tube into the heat treatment line with a line speed of 92mm / s; Hardening by heating the raw tube to a 770 ~ 780 ℃ hardening temperature; And quenching the hardened tube at a quenching temperature of 35 ° C. to 40 ° C ..

Description

Heat treatment method for concrete conveying pipe {Method for treatmenting heat of Concrete-Convey Pipe}

The present invention relates to a heat treatment method for a concrete transfer pipe and a transfer pipe heat treated by the heat treatment method. More specifically, in the heat treatment method for the concrete conveying pipe, it is slower than the existing line speed, the hardening temperature is set to a temperature lower than the existing temperature, hardening cracks are not generated without performing a tempering process The present invention relates to a heat treatment method for improving the inner hardness of a concrete conveying pipe.

In the case of metal pipes, the heat treatment process is essential, especially for concrete delivery pipes requiring strength and hardness. This heat treatment technology is a technology that gives specially useful properties (e.g., wear resistance, extended service life, etc.) by repeating heating and cooling to change the mechanical properties of metal materials, machine parts and mold tools. Is done in

Examples of general heat treatment techniques include annealing, normalizing, quenching, tempering, martempering, austempering, and aging. Annealing mainly has the effect of softening the part, improving workability and removing residual stress. And, normalizing has the effect of homogenization of the abnormal tissue generated during processing and improvement of processability. In addition, the quenching is performed for the hardening of the part, the tempering is performed to stabilize the residual stress relief structure and mechanical properties after the quenching treatment.

In particular, in the case of concrete conveying pipes, a quenching and tempering process for increasing hardness is essential. In particular, the hardness condition should be a high hardness of the inner surface of the transfer pipe. Specifically, it requires a condition that the Rockwell (HRC) hardness value will be at least 55. With increasing hardness, there should be no cracks after quenching.

A common quenching process is to increase the hardness and to heat the tube to hardening temperature and to cool the tube to quenching temperature. In order to increase the hardness and to prevent cracking, it is necessary to control the hardening temperature, the quenching temperature, and the heating and cooling rates. Typically, cooling according to the quenching temperature is to use a water cooling method. Tempering is carried out to remove the quench residual stress and to prevent cracking with increasing hardness.

The usual tampering process is performed again by heating to a tempering temperature lower than the hardening temperature, heating to a slightly higher soaking temperature than the tempering temperature, and then air-cooled. However, through such a tempering process, residual stress can be removed to prevent the occurrence of cracks in the transfer pipe, but a problem arises in that hardness and strength are lowered.

Therefore, there is a need for an improved heat treatment process that satisfies the hardness conditions required in such quenching and tempering heat treatment processes and does not generate cracks.

Accordingly, the present invention has been made to solve the above problems, and provides a heat treatment method in which hardening cracks do not occur without performing a tempering process.

According to one embodiment of the present invention, in a typical quenching and tumpering process, tempering is performed by slowing the heat treatment line moving speed by about half, slightly lowering the hardening temperature, and performing heat treatment at a temperature slightly higher at the quenching temperature. Without this, it provides a heat treatment method for the inner surface Rockwell (HRC) hardness required for the concrete delivery pipe to be 55 or more.

Other objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments in conjunction with the accompanying drawings.

An object of the present invention, in the tube heat treatment method, the step of injecting the raw tube into the heat treatment process line having a heat treatment line speed of 80 ~ 100mm / s; Heating and hardening the tube at 750-820 ° C. hardening temperature; And quenching the hardened raw tube at a quenching temperature of 20 to 40 ° C ..

The line speed may be characterized by being 90 to 95 mm / s.

Hardening temperature may be characterized in that the 790 ~ 810 ℃.

The quenching temperature may be characterized in that 34.2 ℃.

The line speed may be characterized as being 92 mm / s.

Hardening temperature may be characterized in that the 770 ~ 780 ℃.

Quenching temperature may be characterized in that 35 ~ 40 ℃.

The raw tube may be characterized in that the concrete transfer pipe.

As another category, an object of the present invention can be achieved by a concrete conveying pipe, characterized in that the heat treatment by the heat treatment method.

The HRC hardness of the tube can be characterized in that 62 to 67.

Therefore, as described above, according to one embodiment of the present invention, there is an effect of obtaining the required inner hardness without causing hard ring cracks without performing the tempering process.

In addition, the heat treatment method according to an embodiment of the present invention by using the existing quenching equipment as it is, to obtain the desired value for the heat treatment line speed, hardening temperature and quenching temperature, to satisfy the internal hardness required for the concrete conveying pipe Has the effect.

In addition, the heat treatment method of the present invention has the advantage that it can be realized while maintaining the existing heat treatment system as it is, rather than using new equipment has a wide range of applications. Since the heat treatment method according to an embodiment of the present invention does not perform a tempering process, there is an advantage of realizing a simplification of the process and speeding up of the process, and since the tempering equipment is not required separately, it has economic advantages. .

In addition, the present invention is a numerical limited invention in which the numerical values of the existing processes and methods are limited, and these numerical values described in the claims have a significant effect in quantity compared to the known art, and thus the technical significance is satisfied, and the numerical value is critical. Significance is satisfied.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, it will be appreciated by those skilled in the art that various other modifications and variations can be made without departing from the spirit and scope of the invention, All fall within the scope of the appended claims.

1 is a process flow diagram of a conventional heat treatment process including a quenching and tempering process,
2 is a flow chart of a heat treatment method according to an embodiment of the present invention,
3 is a partial cross-sectional view of the concrete conveying pipe for measuring the internal hardness using a Rockwell hardness (HRC) measuring device,
Figure 4 shows a microstructure photograph of the inner surface of the concrete transfer pipe heat-treated by the seventh round in the experimental data of Table 1.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, in describing in detail the operating principle of the preferred embodiment of the present invention, if it is determined that the detailed description of the related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

The same reference numerals are used for portions having similar functions and functions throughout the drawings. Throughout the specification, when a part is 'connected' to another part, this includes not only 'directly connected' but also 'indirectly connected' with another element in between. do. In addition, "including" a certain component does not exclude other components unless specifically stated otherwise, it means that may further include other components.

<Of the present invention Example  Heat treatment method according to

Hereinafter will be described a heat treatment method according to an embodiment of the present invention. First, FIG. 1 shows a flowchart of a quenching and tempering process according to a conventional heat treatment process. As shown in FIG. 1, the raw tube 10 is injected into the heat treatment line 30, and the quenching process is performed by the quenching equipment 40. As shown in Fig. 1, the quenching process is performed by heating the raw tube to a hardening temperature which is a high temperature and then cooling it by water cooling. Then, the quenched tube is moved to the tempering equipment 50 line, heated again to a tempering temperature lower than the hardening temperature, maintained at a soaking temperature slightly higher than the tempering temperature, and cooled by air cooling.

After the quenching and tempering heat treatment are completed, the pressure is applied to the raw tube heat-treated with the hydraulic press 60 to perform the washing and the like. Then, if necessary, EMI (70 electromagnetic shielding agent) treatment and inspection marking 80 to produce a product.

2 shows a flowchart of a heat treatment method according to an embodiment of the present invention. The heat treatment method of the present invention is characterized in that the heat treatment line speed, hardening temperature, and quenching temperature are appropriately performed in the conventional conventional quenching step, and do not undergo a tempering process. In the present invention, the crack is not generated on the inner surface of the concrete conveying pipe 11 even without performing the tempering process, and the heat treatment is performed such that the HRC hardness is 55 or more. This is achieved by a suitable combination of hardening temperature, quenching temperature, and heat treatment line travel speed. That is, this invention corresponds to the numerical limited invention which has a technical significance to a numerical value in the existing process.

First, the manufactured concrete transport pipe 10 corresponding to the original pipe is put into the heat treatment line. The line transfer speed of the heat treatment line is about 80 to 100 mm / s, preferably 92 mm / s. Then, the concrete transport pipe 10 is transferred along the heat treatment line, and the quenching process is performed. In the quenching process, the concrete delivery pipe 10 is heated to the hardening temperature. Hardening temperature is about 750-820 degreeC, Preferably it is 770-780 degreeC. Then, the concrete transfer pipe 10 is cooled by the water cooling method. Quenching temperature which is cooling temperature is about 20-40 degreeC, Preferably it is 35-40 degreeC. Hardness and crack generation according to the temperature will be described in detail in the following examples. In addition, the present invention is characterized by not performing a tempering process.

< Example >

Hereinafter will be described the experimental data results according to an embodiment of the present invention. First, Table 1 shows the working conditions and experimental data according to an embodiment of the present invention.

The concrete transfer pipe 10 put into the work used a transfer pipe 10 manufactured by HUSTEEL CO. LDT. The size of the cone transfer pipe 10 is 120-140 mm in diameter, and 3.0-5.0 mm in thickness. In addition, the quenching and tempering process equipment used equipment manufactured by SMS Elotherm.

And, Figure 3 shows a partial cross-sectional view of the concrete conveying pipe 10 for measuring the hardness using a Rockwell hardness (HRC) measuring device. As shown in FIG. 3, after the heat treatment, the hardness of the inner surface 11 of the concrete delivery pipe 10 was measured by the Rockwell hardness tester 20. Alternatively, the inner surface 11 of the concrete transport pipe 10 may be measured with a Vickers hardness tester, and then converted into Rockwell hardness to extract data. The condition is that there are no cracks or residual stresses.

division Working condition Hardness (HRC) Hardening temperature
(℃) Quenching temperature
(℃) Tempering temperature
(℃) Soaking temperature
(℃) Line speed
(mm / s) Internal measuring range 1st round 760-790 23 160-170 180-200 95-100 57-58 Second round 800-820 27.5 170-190 200 ~ 220 95-100 58-59 Three times 760-790 23 No tempering 80 ~ 90 59-61 Four times 760-790 27.5 No tempering 80 ~ 90 62 5 times 780-820 28-32 No tempering 90-95 60 to 63 6th round 790-810 34.2 No tempering 90-95 62 ~ 65 7 times 770-780 35 to 40 No tempering 92 62-67

<The first round>

In the first experiment, as shown in Table 1, the heat treatment line feed speed (line speed) was set to 95 to 100 mm / s. The hardening temperature was 760 to 790 ° C, the quenching temperature was 23 ° C, the tempering temperature was 160 to 170 ° C, and the soaking temperature was 180 to 200 ° C. The measured inner surface 11 Rockwell hardness (HRC) is about 57-58.

<The second round>

In the second experiment, as shown in Table 1, the heat treatment line moving speed was set to 95 to 100 mm / s, the hardening temperature was set to 800 to 820 캜, and the quenching temperature was set to 27.5 캜. Then, the process was performed with a tempering temperature of 170 to 190 ° C and a soaking temperature of 200 to 220 ° C. As a result, Rockwell hardness was 58 to 59.

<The third round>

In the third experiment, as shown in Table 1, the heat treatment line movement speed was 80 to 90 mm / s, the hardening temperature was 760 to 790 ° C, the quenching temperature was 23 ° C, and no tempering was performed. As a result, Rockwell hardness was 59 to 61. By reducing the line speed and not tempering, it can be confirmed that the hardness is increased compared to the same condition for the first round.

<4th>

In the fourth experiment, as shown in Table 1, the heat treatment line moving speed was the same as 80 to 90 mm / s, the hardening temperature was 760 to 790 ° C, and the quenching temperature was 27.5 ° C. No tempering was performed. Experimental results showed that the Rockwell hardness was 62. It can be seen that the hardness value is increased by increasing the quenching temperature as compared with the third round.

<5th>

In the fifth experiment, as shown in Table 1, the heat treatment line moving speed was increased to 90 to 95 mm / s, the hardening temperature was set to 780 to 820 캜, the quenching temperature was set to 28 to 32 캜, and no tempering was performed. Did. As a result, Rockwell hardness was 60-63.

<Sixth>

In the sixth experiment, as shown in Table 1, the heat treatment line moving speed was 90 to 95 mm / s, the hardening temperature was slightly lowered to 790 to 810 ° C., and the quenching temperature was slightly increased to 34.2 ° C. And no tempering was performed. Experimental results show that Rockwell hardness is 62 ~ 65. That is, it can be seen that the hardness value is increased by slightly increasing the quenching temperature in a state in which the line speed is slower than the normal process and the hardening temperature is slightly lowered without tempering.

<Seventh>

In the seventh experiment, as shown in Table 1, the heat treatment line moving speed was 92 mm / s, the hardening temperature was 770 to 780 ° C, and the quenching temperature was 35 to 40 ° C. And no tempering was performed. Experimental results show that the Rockwell hardness is 62 to 67, which satisfies the most requirements. It can be seen that this effect can be obtained by lowering the hardening temperature by 10-20 ° C. and increasing the quenching temperature by 2-5 ° C. more than the sixth round.

Figure 4 shows a high magnification microstructure of the inner surface 11 of the concrete transport pipe 10 subjected to the heat treatment according to the seventh temperature condition. As shown in FIG. 4, tissues such as pearlite are observed in some dark areas, but it can be seen that most regions are transformed into martensite.

10: concrete conveying pipe
11: Inside
20: hardness measuring instrument
30: thermal processing line
40: quenching equipment
50: tempering equipment
60: Hydraulic press
70: EMI
80: inspection marking part

Claims (10)

In the tube heat treatment method,
Injecting a raw tube into a heat treatment process line having a heat treatment line speed of 80 to 100 mm / s;
Heating and hardening the tube at 750-820 ° C. hardening temperature; And
And quenching the hardened raw tube at a quenching temperature of 20 to 40 ° C. The method of claim 1,
The line speed is a heat treatment method, characterized in that 90 ~ 95mm / s. The method of claim 2,
The hardening temperature is 790 ~ 810 ℃ heat treatment method, characterized in that. The method of claim 3, wherein
The quenching temperature is a heat treatment method, characterized in that 34.2 ℃. The method of claim 1,
The line speed is 92mm / s heat treatment method characterized in that. The method of claim 5, wherein
The hardening temperature is 770 ~ 780 ℃ heat treatment method, characterized in that. The method according to claim 6,
The quenching temperature is a heat treatment method, characterized in that 35 ~ 40 ℃. The method according to any one of claims 1 to 7,
The raw tube is a heat treatment method, characterized in that the concrete transfer pipe. delete delete

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