JPS61269927A - Dies for hot punching tubes - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a hot-punching die for use in the punching step of the Erhardt pipe-making method.

In the conventional Erhardt pipe manufacturing method, a rectangular steel piece is generally heated, and then a vertical press is used to punch the steel piece into a pressed blank pipe with a steel plate, followed by a heating process for reheating. It is sent to the punching process where it is punched out. WE3
The figure is an explanatory view of the punching process. In the punching process, the mandrel ■ of the Bush Bench is inserted into the hollow cylindrical pipe (1) with a garden, which is an intermediate product that has been perforated in the drilling process and reheated in the heating process, and the rear end of the mandrel is Push it strongly and punch it through the punching die (3) of the bushing bench to reduce the diameter and thickness of the entire length of the tube to obtain a product tube. The number of punching dies (3) is determined depending on the degree of diameter reduction and thickness reduction.

The punching die (3) has a diameter of 1000~
Garden pipe reheated to 1250℃ (1) K500~
It is punched out using a hydraulic press of about 2000T. Therefore, the punching die C) is required to have a high degree of wear resistance, heat cracking resistance, and fracture resistance at high temperatures. Therefore, the chemical composition is (I) C: 1.0-1.2%, Ni: 3-5%, C
r: 23-28%, or (II) C: 1, o
~1.2%, Ni: 30-35%, Cr: 30-35%
An integrally cast die is used.

Fig. 2 is a partially enlarged sectional view of the vicinity of the hole of such a die (3), and as shown in Fig. 3, the raw pipe (1) with the mandrel (2) inserted therein is shown in the middle of the mandrel (2). Due to the pressing force applied to the rear end, the diameter and thickness of the tube are reduced while the tube is pushed through the hole of the die opening from the right side to the left side in FIG. 2 to become a product tube. The hole of the die (3) has a bearing part (B) which is the part with the minimum hole diameter approximately equal to the outer diameter of the product tube, and a bottom element IF.
While performing diameter reduction processing on (1), the bearing portion (
It consists of an approach part (A) which is a part that leads to B), and a relief part (C) which is a part which leads the product tube subjected to diameter reduction processing to the outside of the die (3). When punching bare pipes (1) of various materials and dimensions, and therefore of various deformation resistances, with one die, insert multiple pieces into the approach part (A) of the hole of the die (3). (two in the figure) angle of inclination (
When the deformation resistance of the garden-equipped pipe (1) is large, the garden-equipped pipe (1) is provided at the part with a small inclination angle (in the figure, the part with the inclination angle α). When the deformation resistance of There is.

Problems to be Solved by the Invention However, even with the die (3) as described above, the high-temperature abrasion, which is a characteristic required of the die, is small, and the die is prone to thermal cracking and breakage. It is difficult to satisfy all the characteristics at the same time, and the chemical composition is the first!i!(I)
The die had to be replaced when about 50 pieces were punched out using a die having a chemical composition of (II), and about 100 pieces were punched out using a die having a chemical composition (II).

Means for Solving the Problems The present invention is intended to solve such problems, and the present invention has the chemical components on the surface of the hole of the die body made of carbon steel or low alloy steel, C: α8 to 20%, Si : 20% or less, Mn: α3
~&0%, Cr: 15-35%, Mo: 15% or less, the balance is Ni and impurities to form an overlay weld metal layer, and the cross-sectional shape of the approach part of the hole is adjusted to an inclination angle of 12 to 0%.
This relates to a die for hot extrusion making pipes whose gist is to form a straight line with an angle of 18 degrees.

FIG. 1 is a partially enlarged sectional view of the vicinity of the hole of the die (3) of the present invention, and shows a die body (31) made of carbon steel or low alloy steel.
Overlay welding is performed on the hole, and the chemical composition of the overlay weld metal layer in the hole is as follows: C: α8~zO%, Si: ZO or less, Mn:
α3-3.0%, Cr”.

15 to 35%, Mo: 15% or less, the remainder consisting of Ni and impurities, and the approach part of the hole (A
) with a linear inclination angle (α) of 12 to 18 degrees. In order to obtain the chemical composition of the overlay weld metal layer in the hole, it is necessary to perform overlay welding using a welding rod that has a higher content of alloy components than the chemical composition.

In addition, MAG welding, which is easy to weld, is suitable for the overlay welding, and the approach part (A)-13 of the hole and the bearing part (B) are welded in three or more layers to obtain a stable weld metal component. For the relief part (C) of the hole, which is desirable, wear is relatively small, so two-layer welding is sufficient.

Next, the reason why the chemical composition of the overlay weld metal layer in the hole of the die (3) is limited as described above will be explained.

C has the effect of imparting high-temperature wear resistance to the overlay weld metal layer and preventing seizure, but if its content is less than α6%, high-temperature wear increases (or The amount of C precipitated, which affects lubrication, decreases, making seizure more likely.

In addition, if C exceeds 20%, weld cracking during overlay welding becomes noticeable, so the C content should be α6~'
It was set at 2.0%.

St has a negative effect on ts weldability during overlay welding, and inclusion of 20% or more promotes cracking, so 2.
It was set to 0% or less.

Mn is an element that is effective as a deoxidizing agent, but 0.3%
If it is less than aO%, there will be insufficient deoxidation, and if it is more than aO%, it will have little effect as a deoxidizer and will promote cracking.
%.

Cr has the effect of ensuring high-temperature strength and high-temperature wear resistance in the overlay weld RWA, but if its content is less than 15%, the desired effects cannot be obtained, and particularly the high-temperature resistance is Abrasion properties deteriorate significantly. Furthermore, if Cr is added in an amount exceeding 35%, precipitation of spheroidal carbides within crystal grains at high temperatures will be reduced and lubricity will be significantly deteriorated, resulting in seizure and cracking during welding. In order to encourage this, the rate has been set at 15-35%.

Mo improves wear resistance at high temperatures, but if it exceeds 15%, weld cracking will occur, so
It was set to 5% or less.

Ni is a basic component.

The reason why the inclination angle (α) of the cross section of the approach part (A) of the hole of the die (3) is limited to 12 to 18 degrees is because if it is 18 degrees or more, there will be a large push when punching out the eaves-equipped tube (violet). Overlay weld metal II which is the surface layer for removing force! Peeling of I (32) occurs, and if the force is less than 12ff, the punching force when punching out the eave-equipped tube (1) is relatively small, but the outer surface of the eave-equipped tube (1) and the die (3) This is because the contact area with the approach portion (A) of the hole is large and the shear component is large, so that the overlay weld metal layer (32), which is the surface layer, is likely to peel off.

In addition, the cross section of the approach part (A) is not shaped like a broken line with multiple portions of inclination angle (α and β) as in the conventional die shown in FIG. The reason why the weld metal layer (32) is formed in a straight line is that if a plurality of inclined angle portions are provided, the overlay weld metal layer (32) is likely to separate from the portion where the inclination angle changes, that is, the corner of the broken line.

Function The die (3) of the present invention has a die body (31) made of carbon steel or low alloy steel that is not likely to break, and has small high-temperature wear, excellent high-temperature lubricity, and no thermal cracks. Since the overlay metal II (32) was formed by overlay welding, it has high heat resistance, abrasion resistance, heat resistance,
Combines breakage resistance.

In addition, since the cross-sectional shape of the approach portion (A) of the hole is made into a straight line consisting of a single inclined angle portion with an optimal inclination angle, it is possible for the overlay weld metal layer (32) to separate from the die body (31). Nor.

[Example] When the eaves-equipped raw tube shown in Table 1 was punched out using the die shown in Table 2, and the chemical composition of the surface layer of the hole and the angle of inclination of the approach part were varied, it was found that the die was Table 3 shows the number of blank tubes with eaves that were punched out before they needed to be replaced, and the results of replacing the die.

Table 1 Table 2 Birds Listed in Table 3 ■ Listed in Table 3 Table 3 Table 3 Nal~Taka 7, IklB, Blood 17, Hiro 19.1
m20. The dies of &23 to N&26 of the present invention can punch out more than 760 bare pipes before the die is replaced, whereas the chemical composition of the overlay weld metal W4!m is different from that of the present invention. Yang 10 to Arashi 15, which is outside the range of the dice.
Na18. Na22. The inclination angle of the ridge 21 and the approach portion is outside the range of the die of the present invention. All of the Na27 dies can be punched with 490 or less raw tubes. However, even if these dies are not the dies of the present invention, they are different from the conventional integrally cast dies. A comparison shows that there has been significant progress.Also, there were no broken dice.

Effects of the Invention As mentioned above, the punching pipe-making die of the present invention has a high degree of abrasion resistance, heat cracking resistance, and splitting resistance in high ink, so it has an extremely long life, and the die cannot be used for wear or other reasons. It is possible to punch out a large number of raw pipes until they need to be replaced, which has extremely large industrial effects such as improving production efficiency and reducing production costs.

[Brief explanation of drawings]

FIG. 1 is a partially enlarged sectional view of the vicinity of the hole of the die of the present invention;
Figure t42 is a partially enlarged view of the vicinity of the hole of the conventional die.
The figure is an explanatory diagram of the punching process.

Claims (1)

[Claims] The chemical components on the surface of the hole of the die body made of carbon steel or low alloy steel are C: 0.8 to 2.0%, Si: 2.0% or less, and Mn.
:0.3~3.0%, Cr:15~35%, Mo:15
% or less, the remainder is Ni and impurities to form an overlay weld metal layer, and the cross-sectional shape of the approach part of the hole has a linear inclination angle of 12 to 18 degrees. dice.