JP2006110558A - Continuous casting mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a continuous casting mold with which even in the case of continuously casting molten metal for long time, a cast material having good surface characteristic can be produced at high productivity without causing any roughening and the rip on its surface. <P>SOLUTION: The continuous casting mold 1 is formed into an inversely tapered shape widened toward the casting direction at 0.1-1.3° inclining angle on the inner surface thereof and composed of a material having ≥0.7 cal/cm<SP>.</SP>sec<SP>.</SP>°C thermal conductivity and ≥250 MPa yield stress. Further, the mold 1 is made of a material of copper alloy. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a casting mold for continuous casting of aluminum or aluminum alloy (hereinafter referred to as aluminum alloy).

  Conventionally, there is continuous casting as a casting method that can be produced efficiently. In this continuous casting, molten aluminum alloy is introduced into a cylindrical mold, and while the aluminum alloy is cooled, the inner surface of the mold is slid and gradually discharged to the outside, thereby continuously casting a casting material having a predetermined diameter. Can be manufactured. As continuous casting, vertical (vertical) type continuous casting and horizontal (horizontal) type continuous casting are generally performed.

  In the vertical continuous casting, the molten metal is introduced from the upper part of the mold whose upper and lower sides are opened, and the cast material is discharged from the lower opening by its own weight or drawn downward, whereby the cast material is continuously produced. In horizontal continuous casting, a cast material is continuously produced by introducing molten metal from one opening of a mold opened in the horizontal direction and pulling out the cast material while supporting the cast material from the other opening side. In horizontal continuous casting, compared to vertical continuous casting, the aluminum alloy falls under its own weight in the mold, so the distribution of the lubricating film of the lubricating oil supplied to the inner surface of the mold tends to be non-uniform, and the casting material is pulled out. On the other hand, since it is necessary to strictly control the above, the facility is small in the vertical direction, so that the cost for the facility is small and it is easy to manufacture a long cast material.

  In addition, as a forging material before forging a forged part such as a suspension for automobiles, conventionally, an extruded material processed by extrusion has been generally used, but in recent years, as a forging material in order to further reduce the cost. Cast materials have come to be used instead of extruded materials. Therefore, it is necessary to manufacture a cast material having a diameter smaller than the conventional one having a diameter of about 50 to 100 (mm), which is the size of the extruded material, by continuous casting.

In the conventional continuous casting, if the diameter of the cast material is small, the cast material is likely to be broken due to non-uniform cooling during the casting, and the productivity and quality are significantly impaired. As a technique for solving such problems, a cooling structure in which the inner diameter of the mold is matched with the shrinkage at the time of casting of the cast material (see Patent Document 1), and the lubricant is uniformly distributed in the mold portion and cast. It has been disclosed to prevent deterioration of the material surface properties (see Patent Document 2).
JP-A-56-39152 (first page, lower right column, line 12 to page 2, lower right column, line 18; drawing) JP-A-11-170009 (paragraph numbers 0006 to 0009)

  However, even if the cooling structure as described in Patent Document 1 is provided in the mold, the aluminum alloy has a small shrinkage at the time of casting. Therefore, when the cast material is an aluminum alloy, there is a gap between the mold and the cast material. However, there is a problem that the contact resistance increases inside the mold, and the cast material is broken during casting.

  Further, even if the lubricating oil is supplied as described in Patent Document 2, there may be variations in the load when the aluminum alloy is drawn and the position of the cast material in the mold, which results in an uneven distribution of the lubricating oil. It became uniform, and cooling and heat removal might become uneven. At this time, if the casting is continued for several hours, there is a problem that the surface of the cast material is roughened and eventually torn off.

  The present invention was devised in view of the above-mentioned problems, and even when casting for a long time, the cast material does not cause surface roughening or tearing, and a cast material having good surface properties can be produced with high productivity. An object is to provide a continuous casting mold that can be produced.

  In order to solve the above-mentioned problem, the continuous casting mold according to claim 1 has an inner surface formed in a taper shape having a taper angle of 0.1 degrees or more and 1.3 degrees or less and extending toward the casting direction, and heat conduction. The structure is made of a material having a rate of 0.7 (cal / cm · sec · ° C.) or more and a yield stress of 250 (MPa) or more.

  A continuous casting mold according to claim 2 is the continuous casting mold according to claim 1, wherein the material is a copper alloy.

  If comprised in this way, while being able to reduce the contact resistance with the casting_mold | template at the time of extraction of a casting material, heat extraction and cooling are performed uniformly and the casting material which has favorable surface property can be produced continuously for a long time. A continuous casting mold can be provided.

  In the casting mold for continuous casting according to the present invention, since the taper angle and the material of the casting mold are set appropriately, a cast material having a good surface property can be obtained even if casting is performed for a long time. Therefore, the cast material can be produced with high productivity.

Embodiments of the present invention will be described below with reference to the drawings. Here, the case where the continuous casting mold according to the present invention is mounted on a continuous casting apparatus that performs horizontal continuous casting will be described.
[Configuration of continuous casting equipment]
First, with reference to FIG. 1, the structure of the continuous casting apparatus A provided with the casting mold 1 for continuous casting which concerns on this invention is demonstrated. FIG. 1 is a side sectional view schematically showing a configuration of a continuous casting apparatus including a continuous casting mold according to the present invention.

  The continuous casting apparatus A is for producing an aluminum alloy casting material B by horizontal continuous casting. The continuous casting apparatus A includes a continuous casting mold 1, a ceramic nozzle 2, a molten metal reservoir 3, a fixing means 4, and a drawing means 5. Further, the continuous casting apparatus A is connected to cooling water supply holes 12, 12,... (See FIG. 2) of the continuous casting mold 1 and lubricating oil supplied via a cooling water transport pipe and a lubricating oil transport pipe (not shown). Cooling water and lubricating oil are introduced from the outside into the holes 13, 13,.

  The casting mold 1 for continuous casting cools the molten aluminum M introduced from the ceramic nozzle 2 to produce a casting material B having a predetermined diameter. The continuous casting mold 1 has a cylindrical shape opened in the horizontal direction, and a ceramic nozzle 2 is connected to one opening.

  The ceramic nozzle 2 is a nozzle made of ceramic having heat resistance, and supplies the molten aluminum M of the aluminum alloy in the molten metal reservoir 3 to the continuous casting mold 1. The ceramic nozzle 2 is provided through the side surface of the molten metal reservoir 3.

  The molten metal reservoir 3 stores a molten metal M of an aluminum alloy. The fixing means 4 is attached to the outer side surface of the molten metal reservoir 3 and fixes the continuous casting mold 1 and the ceramic nozzle 2 to the molten metal reservoir 3.

  The drawing means 5 supports the casting material B and pulls it from the continuous casting mold 1. The drawing means 5 continuously casts the casting material B in order to draw the casting material B cooled in the continuous casting mold 1 and cast to a predetermined diameter in the horizontal direction at a constant speed.

[Construction of continuous casting mold]
Next, the configuration of the continuous casting mold 1 will be described with reference to FIG. 2 (refer to FIG. 1 as appropriate). FIG. 2 is a schematic view schematically showing a configuration of a continuous casting mold according to the present invention, (a) is a side sectional view schematically showing a continuous casting mold and a part of a ceramic nozzle, and (b) is a side view. It is a schematic diagram which expands and shows a part of inner surface of the casting mold for continuous casting shown by C in (a). The continuous casting mold 1 is provided between the cooling water supply holes 12, 12,... For supplying cooling water to the casting material B (see FIG. 1), and the inner surface 1a of the continuous casting mold 1 and the casting material B. Are provided with lubricating oil supply holes 13, 13,. The cooling water supply holes 12, 12,... And the lubricating oil supply holes 13, 13,.

  Here, the continuous casting mold 1 has a tapered inner surface 1a. As shown in FIG. 2B, the inner surface 1a is formed in a taper shape whose diameter increases in the casting progress direction, and the taper angle (gradient) θ is not less than 0.1 degrees and not more than 1.3 degrees. Set to Further, the continuous casting mold 1 is made of a material having a thermal conductivity of 0.7 (cal / cm · sec · ° C.) or more and a yield stress of 250 (MPa) or more. Here, the continuous casting mold 1 has an outlet-side opening formed in a tapered shape so as to spread at a taper angle larger than the inner surface 1a from the vicinity of the outlet of the cooling water supply holes 12, 12,... It has decided to have further part 1b.

  Next, the reason why the taper angle θ of the inner surface 1a of the continuous casting mold 1 according to the present invention and the thermal conductivity and yield stress of the material constituting the continuous casting mold 1 are limited numerically will be described.

(Taper angle θ: 0.1 to 1.3 degrees)
When the taper angle θ of the continuous casting mold 1 is less than 0.1 degree, the contact resistance between the continuous casting mold 1 and the casting material B when the casting material B is drawn increases, and the continuous casting mold 1 The distribution of the lubricating oil with the casting material B is biased. Therefore, a non-uniform lubricating film is formed on the cast material B, and tearing occurs several hours after the start of casting. On the other hand, if the taper angle θ is larger than 1.3 degrees, the gap between the surface of the casting material B and the inner surface 1a of the continuous casting mold 1 becomes wide, and the cooling supplied from the cooling water supply holes 12, 12,. Water flows into the continuous casting mold 1 and casting becomes impossible. Therefore, the taper angle θ needs to be 0.1 degrees or more and 1.3 degrees or less. In order to better achieve the object of the present invention, the taper angle θ is more preferably 0.1 degree or more and 1.0 degree or less, and 0.3 degree or more and 0.7 degree or less. More preferably.

(Thermal conductivity: 0.7 (cal / cm · sec · ° C) or more)
When the thermal conductivity of the material constituting the continuous casting mold 1 is lower than 0.7 (cal / cm · sec · ° C.), the heat removal at the time of solidification of the cast material B becomes insufficient, and the surface of the cast material B becomes If it is rough and casts for several hours, the cast material B is torn off. Therefore, the thermal conductivity of the continuous casting mold 1 needs to be 0.7 (cal / cm · sec · ° C.) or more. The thermal conductivity of the continuous casting mold 1 is more preferably 0.8 (cal / cm · sec · ° C.) or more in order to better achieve the object of the present invention.

(Yield stress: 250 (MPa) or more)
When a material having a yield stress lower than 250 (MPa) is used, the continuous casting mold 1 is deformed during casting, and the surface of the cast material B becomes rough as the casting time progresses, and finally, tearing occurs. Therefore, the yield stress of the continuous casting mold 1 needs to be 250 (MPa) or more. The yield stress is more preferably 300 (MPa) or more in order to better achieve the object of the present invention.

  As described above, by controlling the taper angle θ of the inner surface 1a of the continuous casting mold 1 and the thermal conductivity and yield stress of the material constituting the continuous casting mold 1, the cast material B can be cast even for a long time. (See FIG. 1) No tearing occurs, and it is possible to obtain a continuous casting mold 1 capable of obtaining a cast material B having a good surface property.

[Operation of continuous casting machine]
Next, with reference to FIG.1 and FIG.2, operation | movement of the continuous casting apparatus A provided with the casting_mold | template 1 for continuous casting which concerns on this invention is demonstrated.

  As shown in FIG. 1, in the continuous casting apparatus A, the molten aluminum M stored in the molten metal reservoir 3 is introduced from the molten metal reservoir 3 through the ceramic nozzle 2 into the continuous casting mold 1. Then, heat is removed through the inner surface 1a in the continuous casting mold 1, and the aluminum alloy solidifies from the surface (surface) in contact with the inner surface 1a.

  Here, a lubricating film is formed between the surface of the aluminum alloy and the inner surface 1a of the continuous casting mold 1 by the lubricating oil supplied from the lubricating oil supply holes 13, 13,. Further, since the cast material B is drawn at a predetermined speed by the drawing means 5, the solidified aluminum alloy moves at a predetermined speed along the inner surface 1 a of the continuous casting mold 1. Since the inner surface 1a is formed in a tapered shape, the contact resistance decreases as the aluminum alloy advances in the casting direction, and heat is removed from the inner surface 1a of the continuous casting mold 1 that is in contact with the aluminum alloy. It gradually solidifies towards. In the vicinity of the outlet of the cooling water supply holes 12, 12,..., The aluminum alloy is forcibly cooled by the cooling water supplied from the cooling water supply holes 12, 12,.

  With the above operation, the casting material B is continuously cast by the continuous casting apparatus A. Here, although the case where the continuous casting mold 1 according to the present invention is applied to the continuous casting apparatus A that performs horizontal continuous casting has been described, it is applied to a continuous casting apparatus (not shown) that performs vertical continuous casting. It is good to do.

  Examples according to the present invention will be specifically described below. First, a mold having a taper angle and a material as shown in Table 1 was prepared. Moreover, about each material, the thermal conductivity and the yield stress were measured according to JIS-Z-2241.

  Examples 1-4 use the copper alloy containing 0.1 weight% chromium (Example 1) or iron (Examples 2-4) as a material, and all satisfy the conditions regulated by this invention. is there. On the other hand, Comparative Example 1 uses 6061 aluminum alloy (6061-T651, specified in JIS-H-4000) whose material is tempered T651, and the thermal conductivity and yield stress are numerically limited in the present invention. In Comparative Example 2, pure copper is used as the material, and the yield stress is less than the lower limit value of the range numerically limited in the present invention. Comparative Example 3 has a taper angle that is less than the lower limit value of the range limited by the present invention, and Comparative Example 4 has a taper angle that exceeds the upper limit value of the range limited by the present invention. .

  The casting molds of Examples 1 to 4 according to the present invention and Comparative Examples 1 to 4 that do not satisfy the conditions regulated by the present invention were installed in a horizontal continuous casting apparatus and continuously cast with 6 strands. did. A 6000 series aluminum alloy (alloy number 6061) was used as a raw material for the cast material, and a round bar cast material having a diameter of 70 (mm) was produced. The casting speed is 300 to 400 (mm / min), the amount of lubricating oil is 5 to 20 (ml / min / line), and the amount of cooling water is 100 to 120 (l / min / line). I went there. Hereinafter, the evaluation method performed about each casting_mold | template and cast material is demonstrated.

(Continuous casting time)
For each mold, the continuous casting time during which casting was possible without tearing was measured. Then, the continuous casting time was measured up to 48 hours, and if it was 48 hours or longer, it was determined that there was no practical problem.

(Cast material surface properties)
Visually evaluate the surface properties (cast material surface properties) of the cast material produced by each mold. If the surface is not rough, it is “Good”. Depending on the degree, “△ (somewhat poor)” or “× (bad)” was set.

  As shown in Table 1, in Comparative Examples (Comparative Examples 1 to 4) that do not satisfy the conditions regulated by the present invention, those that satisfy all of the evaluation items were not obtained.

  That is, in Comparative Example 1, the heat removal efficiency during casting was poor, the mold was deformed during casting, the continuous casting time was as short as 5 hours, and the surface quality of the cast material was “x (defect)”. It was. Further, in Comparative Example 2, due to the deformation of the mold, the casting time was as short as 20 hours, and the cast material surface property was “Δ (somewhat poor)”. In Comparative Example 3, since the distribution of the lubricating oil was uneven, the continuous casting time was as short as 5 hours, and the surface quality of the cast material was “x (defect)”. In Comparative Example 4, the cooling water flowed into the mold and became impossible to cast.

  On the other hand, the examples (Examples 1 to 4) according to the present invention had no problems in any evaluation items of continuous casting time and cast material surface properties.

It is side surface sectional drawing which shows typically the structure of the continuous casting apparatus provided with the casting_mold | template for continuous casting which concerns on this invention. The schematic diagram which shows typically the structure of the continuous casting mold which concerns on this invention, (a) is side sectional drawing which shows typically a casting mold and a part of ceramic nozzle, (b) is (a). It is a schematic diagram which expands and shows a part of inner surface of the casting mold for continuous casting shown by C in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mold for continuous casting 1a Inner surface 1b Outlet side opening 12 Cooling water supply hole 13 Lubricating oil supply hole 2 Ceramic nozzle 3 Molten metal reservoir 4 Fixing means 5 Drawing means A Continuous casting apparatus B Cast material M Molten metal

Claims (2)

In a continuous casting mold used in a continuous casting apparatus for continuously casting a cast material,
The inner surface is formed in a taper shape having a taper angle of 0.1 degrees or more and 1.3 degrees or less and extending toward the casting direction,
A continuous casting mold made of a material having a thermal conductivity of 0.7 cal / cm · sec · ° C. or more and a yield stress of 250 MPa or more.   The continuous casting mold according to claim 1, wherein the material is a copper alloy.

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