JPH0515361Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a cold tube rolling mill called a cold pilger mill.

[Conventional technology]

In this type of rolling mill, as shown in Fig. 9, the raw tube 1 that is sent by being fitted onto the mandrel enters the roll stand 3 from the left side of the figure, and is assembled into the roll stand 3. In addition, rolling is performed by the back and forth reciprocating motion of the lower pair of rolling rolls 2, 2. The rolled tube 16 slides inside the chucks 14 and 15 and moves a fixed length toward the exit side each time it completes one reciprocating process of rolling. In the figure, 4 is a roll stand housing.

Generally, in the above-mentioned rolling operations, when the degree of processing per hour is increased, the amount of heat generated by processing increases, and the material temperature rises. In this case, when the temperature exceeds a certain temperature, the rolling oil supplied generates carbide due to thermal decomposition, and this adheres to the product pipe, but this carbide is not completely removed even in the next process of degreasing with an organic solvent, resulting in a decrease in product quality. It causes. Therefore, it is necessary to suppress the rise in material temperature due to processing as much as possible.

In contrast, conventionally, ring nozzles c and d are installed before and after the movement stroke area of the rolling rolls 2, 2.
A system was adopted in which the rolling oil was sprayed in a concentrated manner toward the center of the rolling area from the ring nozzles c and d. Note that g indicates the oil pan.

[The problem that the idea aims to solve]

However, in this method, only the axially central portion of the material rolling zone is intensively cooled. It is true that the temperature of the rolling zone is highest in the axial center, but the material is heated over a wide range in the axial direction due to recuperation due to axial heat conduction. For this reason, in the conventional method of intensively injecting and supplying rolling oil to the center of the rolling zone, even if the amount of oil is increased, it is not possible to suppress the recuperation effect due to axial heat conduction, and as a result, due to the formation of carbides. The current situation is that we have no choice but to reduce the amount of processing per hour and work at low efficiency, which inevitably leads to a decline in product quality.

FIG. 5 shows the results of investigating the relationship between the local surface heat transfer coefficient and cooling rate of the cooling part and the amount of oil supplied in the conventional rolling oil supply system. As shown in this figure, the horizontal axis shows the oil amount (/min), and the vertical axis shows the heat transfer coefficient (KcaI/m ² h℃) and cooling rate (℃/sec). With this method, it can be seen that the cooling capacity cannot be expected to improve much beyond a certain range due to an increase in the amount of oil.

In view of the current situation, the present invention provides a cold tube rolling mill that can effectively cool the entire material rolling area and thereby significantly suppress the rise in material temperature.

[Means to solve the problem]

The cold tube rolling mill of the present invention is a cold tube rolling mill that rolls a tube that is externally inserted into a mandrel and sent by the forward and backward movement of a pair of upper and lower rolling rolls, and is provided directly above the moving stroke area of the rolling rolls. To,
The present invention is characterized in that a rolling oil flow down nozzle for supplying rolling oil is provided over the entire length of the upper surface of the pipe existing in the moving stroke region of the rolling rolls.

Note that the present invention does not preclude the use of a conventional ring header which intensively injects and supplies rolling oil toward the center of the rolling area.

[Effect]

In the cold tube rolling mill of the present invention, the material is cooled throughout the rolling stroke range, and the rolling roll itself is also cooled regardless of its moving position. The heat recuperation effect due to conduction is suppressed, the temperature level of the entire tube is reduced, and the formation of carbide is suppressed.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 3. FIG. 1 is a schematic diagram showing the entire cold tube rolling mill of the present invention.

In the figure, reference numeral 1 denotes a raw tube that is inserted into a mandrel and sent, and is rolled by the forward and backward movement of a pair of upper and lower rolling rolls 2, 2 built into a roll stand 3. 5 is a rolling oil supply header provided on the upper part of the housing 4 surrounding the roll stand 3.

As shown in FIGS. 1 and 2, the rolling oil supply header 5 is installed directly above the moving stroke area of the rolling roll 2, and has a number of shower-type rolling oil flow down nozzles 6 installed directly downward. It has been established since then.

The rolling oil supply header 5 is connected via a supply pipe 7 to a supply pump P installed outside the housing 4, and supplies the rolling oil supplied under pressure from the supply pump P to the many rolling oil flow down nozzles 6. From there, it is supplied to the entire length of the upper surface of the tube existing in the moving stroke area of the rolling rolls 2.

Note that the inside of the rolling oil supply header 5 is always maintained at a gauge pressure of 1 kg/cm ² or more.

Although not shown, a conventional concentrated injection supply type ring nozzle is also provided before and after the rolling stroke area.

3A and 3B show another embodiment of the rolling oil flow down nozzle 6, which is of the so-called slit laminar system.

According to this figure, the rolling oil supply header 5a is in communication with the primary header 8 below the primary header 8, and has a large number of outflow holes 12 in the circumferential direction.
a secondary header 9 having a
It consists of a tertiary header 10 that concentrically covers the header from the outside and has a discharge hole 13 below, and a tapered nozzle 11 that communicates with the discharge hole 13.

The rolling oil supplied to the primary header 8 is pressure-equalized and rectified by the secondary header 9, and falls from the tertiary header 10 through the taper nozzle 11, and the rolling oil at this time becomes a curtain-like laminar flow. As in the case of the above embodiment, the rolling roll 2
is supplied to the entire length of the upper surface of the tube that exists in the moving stroke area of the pipe.

FIG. 4 shows a comparison of the temperature distribution in the axial direction on the outer surface of the tube when the rolling mill of the present invention is used and when a conventional rolling mill is used. As shown in this figure, when the horizontal axis represents the position of the tube in the rolling direction and the vertical axis represents the temperature (°C), the heat generated by processing is conducted in the axial direction of the tube, so the center of the rolling area In a conventional rolling mill that cools only the rolling stock centrally, the temperature distribution is high over the whole as shown by the dotted line, and this tendency is not improved even if the amount of oil is increased. On the other hand, in the rolling mill of the present invention, in addition to the concentrated cooling in the center of the rolling zone, the entire processing area is cooled, so the recuperation effect of the material due to axial heat conduction is also suppressed, and the overall temperature level is maintained as shown by the solid line. significantly lower.

Moreover, FIG. 6 compares the difference in cooling effect depending on the rolling oil supply method with respect to the material temperature at the center of the rolling zone.

In other words, a conventional rolling mill with a ring header that centrally cools the rolling area, a rolling mill of the present invention that has both a ring header and a shower-type rolling oil flow down nozzle, and a rolling mill of the present invention that has both a ring header and a laminar-type rolling oil flow down nozzle. The relationship between the material feed amount and the material temperature is shown for the three types. The material temperature was measured at the center point of the rolling zone immediately after rolling.

In conventional rolling mills, the material temperature is high, and this cannot be improved by increasing the amount of oil.

In contrast, the rolling mill of the present invention uses a shower method,
When any of the slit laminar flow nozzles is used in combination with a ring header, the material temperature will drop significantly at the same material feed rate.

In addition, Figures 7 and 8 are measurements of the amount of carbide remaining on the tube surface after degreasing the rolled tube with an organic solvent. This is the case with the rolling mill of the present invention.

In Figures 7 and 8, the amount of ΔC (x10 ³ wt%) on the horizontal axis is the amount of carbide remaining on the tube surface, and the amount of carbide remaining on the tube surface and the sample chipping away from the center of the tube wall thickness. It is shown by the difference in the amount of C contained. Although the frequency is plotted on the vertical axis, it can be seen that Figure 8 shows that compared to Figure 7, the cold rolling mill of the present invention has a smaller overall ΔC amount and less adhered carbides than the conventional rolling mill. .

[Effect of idea]

As is clear from the above description, in the cold tube rolling mill of the present invention, the cooling effect improves as the amount of rolling oil increases. Therefore, it is possible to suppress the temperature rise of the material and suppress the generation of carbides due to thermal decomposition of the rolling oil, thereby improving the quality of the product.In addition, by suppressing the temperature rise, it is possible to increase the rolling speed, improving work efficiency. It has excellent effects, such as being able to significantly improve

[Brief explanation of the drawing]

1 to 3 show an embodiment of the cold tube rolling machine of the present invention, and FIG. 1 is a schematic diagram of the entire device;
Figure 2 A and B are front and side views of the shower type header, Figure 3 A and B are front and side views of the slit laminar type header, and Figure 4
Figure 5 is a diagram showing the temperature distribution in the axial direction of the rolled material, Figure 5 is a diagram showing the relationship between oil amount and heat transfer coefficient, Figure 6 is a diagram showing the relationship between material feed rate and material temperature, and Figure 7 is a diagram showing the relationship between material feed rate and material temperature. Figure 8 and Figure 8 are charts showing the amount of carbide remaining on the pipe surface after degreasing with an organic solvent after rolling, and Figure 9 is a schematic diagram showing the rolling oil supply system in a conventional cold pipe rolling mill. . In the figure, 1...Main pipe, 2...Rolling roll, 5...
Cooling header, 6... Downflow nozzle, 16... Rolled pipe.

Claims (1)

[Scope of utility model registration request] In a cold pipe rolling mill that rolls a tube that is externally inserted into a mandrel and sent by forward and backward movement of a pair of upper and lower rolling rolls, a pipe that is present in the moving stroke area of the rolling rolls is located directly above the moving stroke area of the rolling rolls. 1. A cold pipe rolling machine, characterized in that a rolling oil flow down nozzle is provided for supplying rolling oil to the entire length of the upper surface of a pipe.