JPH0341845Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Application Field] The present invention relates to a cylindrical guide member for guiding hot rolled steel materials in a steel hot rolling line. [Prior art] In addition to non-friction type guide rollers, a friction type tube is installed in a steel hot rolling line to control the running direction and running posture of the steel material conveyed along the line. A shaped guide member is installed. The shape of the cylindrical guide member varies, but basically it has a tapered part that has a conical passage whose hole diameter gradually decreases in the direction of movement of the steel material passing through, and a small diameter part that is continuous with the conical passage of the tapered part. It is a cylindrical body with a body having a passage. Examples are shown in FIGS. 5 and 6. The example shown in FIG. 5 has a tapered part 20 at the front as a steel material inlet, and a body part 30 having a small diameter passage r3 at the rear side of the tapered part 20. In the example shown in FIG. 6, there is a cylindrical part 10 forming a large diameter passage r1 which is an attachment part at the front part, a tapered part 20 having a conical passage r2 at the rear thereof, and a small diameter passage r3 following the cylindrical part 10.
A body portion 30 having a body portion 30 is provided. Steel bars, wire rods,
The hot rolled steel material S, such as a bar-in-coil, advances in the direction of the arrow from the right side of the figure, and passes through the path r2 of the tapered portion 20.
is introduced into the passage r3 of the body 30 through the passage r
It is derived to the left from the tail end of 3. The steel material S introduced from the passage r2 of the tapered part 20 into the narrow passage r3 of the body part 30 travels in the passage r3 at high speed while making irregular movements such as dancing and springing. Therefore, in the passage r3 of the cylindrical guide member during the continuous conveyance process of the steel material, collisions and strong rubbing (sliding contact) of the steel material S are repeatedly applied to the wall surface here and there. In order to alleviate collisions and sliding contact due to dancing, splashing, etc. of the steel material S in the passage r3, the passage r3 is designed to have a shape that widens at the end so that the diameter gradually increases toward the tail end, as shown in Fig. 5. Although this has been done, since enlarging the diameter of the passageway is accompanied by a decrease in the guiding effect of the cylindrical guide member, there are naturally restrictions on the shape design of the cylindrical guide member, and it cannot be expected to be very effective. In the passage r2 of the tapered portion 20, the steel material S collides or slides against the wall surface only when the tip of the steel material is taken in and passes therethrough.
If a steady state is established in which the tip is introduced into the passage r3, frequent collisions and collisions such as in the narrow passage r3 will be avoided.
Although it should not receive sliding contact, in some rolling lines, even after the steady state is reached, the steel material S is subject to irregular movement as described above, so the area adjacent to the passage r3 In some cases, the steel material S repeatedly collides and slides against the surface (portion indicated by reference numeral 22 in FIG. 2). Note that in a cylindrical guide member in which a cylindrical portion 10 is formed as an attachment in front of the tapered portion 20 as shown in FIG. In addition, the passage r1 is given a sufficiently large diameter. [Problems to be Solved by the Invention] Ductile cast iron has traditionally been used as the cylindrical guide member due to its resistance to impact and abrasion caused by rolled steel. However, although the cylindrical guide member has excellent resistance to mechanical shock,
Wear resistance is not sufficient, and the problem is that
Due to the collision and sliding contact of red-hot rolled steel, the body 3
Seizure of the steel material and resulting roughness are likely to occur here and there on the wall surface of passage r3.
Depending on the usage conditions, it is not uncommon for seizure to occur on the rear wall surface of the passage r2 of the tapered portion 20 as well. If a cylindrical guide member with seizing on the inner surface of the passage is used as is, the surface of the rolled steel material passing through it will be scratched. When the steel material has passed through the final rolling roller, the flaws become surface defects on the product, which inevitably reduces quality and yield. As a countermeasure to this problem, it may be possible to apply carbide materials such as WC-based materials, which have recently attracted attention as wear-resistant materials for rolling lines, to the cylindrical guide member. Although it has properties such as heat resistance and heat resistance, it is not much different from conventional materials such as ductile cast iron in terms of seizure resistance, so it cannot be expected to have much effect. Note that if we focus only on measures to prevent seizure, it is effective to line the inner surface of the guide member with a carbon layer, and its good lubrication effect makes it possible to almost completely prevent seizure. However, since the carbon layer has poor abrasion resistance, abrasion thinning due to collision with steel materials and sliding contact and surface roughness progress rapidly, resulting in problems in maintenance, durability, etc. The present invention provides an improved cylindrical guide member for guiding hot rolled steel materials in order to cope with the above-mentioned circumstances. [Means and effects for solving the problem] The present invention includes a tapered portion having a conical passage whose inner diameter gradually decreases in the direction of movement of the passing steel material;
A cylindrical guide member for a hot-rolled steel material guide having a body part having a passage continuous with a conical passage of the tapered part, wherein at least a front part of the tapered part is a metal member, and from the metal member to the body part. The portion up to the rear end has a two-layer structure including an outer layer made of metal and an inner layer made of ceramic sintered body laminated on the inner surface of the outer layer, and the metal member of the tapered portion and the two It is characterized in that the inner diameter of the inner layer is larger than the inner diameter of the metal member at the joint between the layered structure and the inner layer, which is a ceramic sintered body, so that a step is formed at the joint. The present invention will be described with reference to drawings showing embodiments. In FIGS. 1 and 2, a is an outer layer made of a metal material (metal outer layer), and b is a ceramic sintered body laminated on the metal outer layer a. The inner layer (ceramic inner layer) consists of In the example shown in FIG.
The inlet portion 31 is made of a metal material, and the portion behind it up to the tail end of the body has a two-layer structure consisting of a metal outer layer a and a ceramic inner layer b.
In addition, FIG. 2 shows a countermeasure against repeated collisions and sliding contact with the rear part 22 of the tapered part 20.
The region from the inlet 31 of the body 30 to the tail end, including the rear part 22 of the tapered part 20, has a two-layer structure of a metal outer layer a and a ceramic inner layer b, so that collisions and sliding contact of steel materials are virtually no problem. Front part 21 of tapered part 20
The cylindrical portion 10 in front of the cylindrical portion 10 is shown as an example in which ceramic is omitted and only metal is used. The cylindrical guide member of the present invention uses a ceramic sintered body to form the steel passageway in the portion where seizure is likely to occur, so even under severe conditions where red-hot steel passes through at high speed, Shows stable and high seizure resistance. It also has sufficient abrasion resistance, and even after long-term use, there is very little wall thinning or roughening caused by abrasion. Although ceramic sintered bodies have excellent seizure resistance, they have lower fracture toughness values than metal materials. In view of this, in the present invention, at least the front part 21 of the tapered part 20, which is directly subjected to the mechanical impact of the passing steel material, is made of metal, which is a high-toughness material. Ensures resistance and prevents cracks and damage. In addition, for the parts where the steel passages are made of ceramic sintered bodies, the ceramic sintered body is used as the inner layer (b), and this is reinforced with the metal outer layer (a) to prevent cracks and damage caused by the load and impact of the steel. are doing. Furthermore, due to the difference in abrasion resistance between the metal member and the ceramic sintered body, the metal member wears out quickly, so the metal member may wear unevenly near the joint (boundary area) between the metal member and the ceramic sintered body. Therefore, the inner surface of the ceramic sintered body tends to protrude from the inner surface of the metal member. When the steel material passes through in this state, a large mechanical shock is applied to the ceramic sintered body. As a countermeasure against this problem, the present invention, as shown in FIGS. 3 and 4, makes the inner diameter of the ceramic sintered body at the joint part larger than the inner diameter of the metal member to provide a step G. It is designed to avoid or reduce mechanical shock to the body. The size of the step G depends on the difference in abrasion resistance between the ceramic sintered body and the metal member, but it is approximately
It is desirable to set it to 0.5mm or more. In FIG. 1, the tapered part 20 and the inlet part 311 of the body part 30 are formed of metal, but depending on the usage conditions of the guide member, the inlet part 31 of the body part 30 may also be made of a ceramic inner layer b and a metal outer layer a. It may have a two-layer structure, and the rear part of the tapered portion 20 may also have a two-layer structure, as in the example shown in FIG. In addition, in FIG. 2, the tapered part 20 has a two-layer structure over its entire length including the rear part 22, but the tapered part 20
0, the ceramic inner layer b of the rear part 22 may be omitted and the body part 30 may be formed of metal in the same way as the front part 21.
The ceramic inner layer b of the inlet portion 31 may be omitted in some cases. The material of the ceramic forming the inner layer b in the two-layer structure portion of the cylindrical guide member of the present invention is not particularly limited, and may be silicon nitride, silicon carbide, alumina, zirconia, etc. Silicon nitride ceramics are preferably used because they have superior seizure resistance and thermal shock resistance compared to other ceramics. In particular, a dense silicon nitride sintered body with a relative density of 90% or more and a bending strength of 60 kgf/mm ^{2 or more} has a high degree of toughness that can withstand mechanical loads and impacts, so it can be used in the present invention. It is particularly suitable as a ceramic inner layer b. On the other hand, the material of the metal outer layer a of the two-layer structure and the other metal members is not particularly limited, but
It is sufficient to use a material that has not only strength and toughness but also wear resistance, such as ductile cast iron that has been commonly used. The ceramic sintered body and the metal member can be integrated by mechanical methods such as fitting, fitting, screwing, etc., and the joint surfaces can be bonded by brazing, epoxy resin adhesive, etc. as necessary. Laws are used together. [Example] As shown in Fig. 2, the entire length of the rear part 22 and body part 30 of the tapered part 20 is a two-layer structure consisting of a metal outer layer a and a ceramic inner layer b, and the front part 21 of the taper part is a single metal layer. A cylindrical guide member (however, it does not have the cylindrical portion 10 in front of the tapered portion) was manufactured. The ceramic inner layer b is a hot isostatic pressure sintered product, and the metal outer layer a and the ceramic inner layer b are integrated by fitting, and the interface is bonded with an epoxy resin adhesive. The dimensions are as follows. Body: Outer diameter of tapered part: 60mm Body part 30 Axial length: 500mm Thickness of outer layer a: 10mm Thickness of inner layer b: 10mm Inner diameter of passage r3: 20mm (straight) Tapered part 20 Axial length: 50mm Length of the rear part 22: 25mm Slope opening angle: 30° Difference in level between the front part 21 and the rear part 22 of the tapered part: 0.8mm Also, for comparison, instead of ceramic, cemented carbide (WC-C ₀ ) or carbon A cylindrical guide member of the same type as above (the dimensions are the same as above) having a two-layer structure with inner layer material, and a conventional cylindrical guide member made of a single material of ductile cast iron were prepared. Each of the above cylindrical guide members is made of special steel bar material (φ8~
It was installed at the final roll stand of a 12 mm) continuous hot rolling line and subjected to actual machine use tests. Table 1 shows the measurement results of the maximum wear depth (mm) and the roughness of the sliding surface (Rmax, μm), as well as the presence or absence of seizure on the inner surface of the guide member after the test. The amount of steel rolled in each case is 1000 tons. In the same table, invention example No. 1 (using silicon nitride ceramic) and No. 2 (using alumina ceramic)
When compared with the conventional ductile cast iron cylindrical guide member (No. 11), the conventional example suffers from seizing, has a significantly roughened surface, and has a large depth of wear. Note that the significant deterioration of the surface roughness is due to
It is observed that this is mainly due to roughness of the structure due to seizure. In contrast, invention example (No.
1, No. 2) could not handle rolling 1000 tons of steel material,
There is no seizure, the surface roughness is good, the depth of wear and thinning is extremely small, and there is no damage such as cracks or chips due to impact, making it sound enough to continue to be used for a long time. In addition, the invention examples (No. 1, No. 2) were compared to other comparative examples No. 12.
and No. 13, No. 12 (using cemented carbide)
Although No. 13 has the same wear resistance as the invention example, it suffers from seizure similar to that of the ductile cast iron example, and the surface roughness deteriorates significantly due to seizure. (using carbon),
Although it has good seizure resistance, there is large wear loss and a decrease in surface roughness (this surface roughening is observed to be due to the progression of wear).
cannot be avoided, and both are inferior to the invention examples (No. 1 and No. 2).

[Effect of idea]

The cylindrical guide member of the present invention, due to the combined effect of the material properties of ceramic material and metal material, can withstand high-speed sliding contact with red-hot steel without losing the mechanical impact resistance necessary for a friction-type cylindrical guide member. It has a high degree of seizure resistance. It also has excellent wear resistance. Therefore, roughness on the inner surface of the steel passage and the occurrence of surface flaws on the steel material due to the roughness are effectively prevented, and the surface quality and yield of the steel material are significantly improved. Furthermore, by improving the useful life of the cylindrical guide member, various effects such as reduced replacement frequency, reduced maintenance, and improved efficiency of rolling line operation can be obtained.

[Brief explanation of the drawing]

Figure 1 [] is an axial sectional view showing an embodiment of the present invention, the same figure [] is a - sectional view, and Figure 2 []
is an axial cross-sectional view showing another embodiment of the present invention, the figure [ ] is a - cross-sectional view, Fig. 3 is an enlarged view of section A in Fig. 1, and Fig. 4 is an enlarged view of section B in Fig. 2. Figure, 5th
6 are axial sectional views showing a conventional example. 20: Tapered part, 30: Body part, a: Metal outer layer,
b: Ceramic inner layer, G: Step, S: Steel material.

Claims (1)

[Claims for Utility Model Registration] A heating system comprising a tapered part having a conical passage whose inner diameter gradually decreases in the direction of movement of the passing steel material, and a body part having a passage continuous to the conical passage of the tapered part. In the cylindrical guide member for guiding inter-rolled steel materials, at least the front part of the tapered part is a metal member, and the part from the metal member to the rear end of the body includes an outer layer made of metal and an inner surface of the outer layer. It has a two-layer structure with an inner layer made of a ceramic sintered body laminated on the inner layer, and the inner diameter of the inner layer at the joint between the metal member of the tapered part and the inner layer of the ceramic sintered body of the two-layer structure part. A cylindrical guide for a hot-rolled steel material guide having excellent seizure resistance, wear resistance, and impact resistance, characterized in that a step is formed at the joint part by having a diameter larger than the inner diameter of the metal member. Element.