JPH06234012A - Method for extrusion molding from zinc based alloy material - Google Patents

Abstract

PURPOSE: To enable extruding zinc-based alloys which are said to be difficult to extrude and to enable obtaining extrusion products with high dimensional precision. CONSTITUTION: In an extrusion molding process of the zinc-based alloy in which a material is preheated and is extruded at a speed within a range of 1 to 20 m/minute, then extruded shape is made to be straight and is cooled at atmospheric temperature, a temperature range of the material is restricted at and below an eutectoid temperature thereof, the extrusion product taken out of an extrusion die is supplied with forced air and/or water to be quenched. Further a mechanical conveyor for receiving the extrusion products taken out of the extrusion die is installed.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to an improved process for extrusion from zinc-based alloys.

[0002]

BACKGROUND OF THE INVENTION Zinc and zinc-based alloys have traditionally been considered unsuitable materials for extrusion. This is due to their mechanical properties. Many attempts have been made in the past to develop zinc-based alloys with improved mechanical properties to make them suitable for extrusion, rolling and other industrial processes for producing molded parts.

The present invention relates to an improvement in the extrusion process of superplastic zinc alloys having improved mechanical properties, which improvement prevents the material from exceeding the eutectoid temperature and thus the extrusion process. Control the superplastic behavior between
Extrusion is achieved in this way by avoiding the occurrence of the gamma phase transformation and ensuring the dimensional stability of the final product.

[0004]

BACKGROUND OF THE INVENTION Various improvements have been made to zinc-based alloys to make them suitable materials for producing molded parts.

Thus, Harle US Pat. No. 3,6
76,115, U.S. Pat. No. 3,743 to Collet et al.
U.S. Pat. No. 2,16 to Winter et al.
No. 9,441 Gerweis et al., U.S. Pat. No. 3,79
U.S. Pat. No. 3,850,6 to Wayne.
No. 22, and US Patent No. 3,966,50 to Drah.
Nos. 5 and 4,029,525 refer to zinc-based alloys with improved physical properties and various methods of making them. These alloys have proven suitable for different industrial processes such as die casting, rolling and extrusion.

[0006] In particular, Mexico Patent No. 61483 issued to Universidad National Autonoma de Mexico (National Autonomous University of Mexico) has improved mechanical properties to provide structural and architectural shapes. It mentions an inexpensive extrusion method of the zinc-aluminum-copper alloy that can be obtained.

The extrusion process covered by this Mexican patent No. 61483 is based on a zinc-based composition containing 69-77% by weight Zn, 20-30% by weight Al and 1-8% by weight Cu and trace amounts of impurities. Uses alloy. This method basically uses one alloy ingot.
Preheat within a temperature range of 50 ° C to 350 ° C, with a speed of 1 to 20 min / min.
It consists of extruding at a speed between the meters, immediately straightening the extruded shape and allowing it to cool at ambient temperature.

[0008]

It is an object of the present invention to further improve the method of extruding zinc based alloys. More particularly, the present invention provides an improvement in the method of extruding zinc alloys.

[0009]

The improvement according to the invention prevents, on the one hand, the material temperature from exceeding the eutectoid temperature both during the preheating of the alloy ingot and during the whole extrusion process, Preventing the material from undergoing a γ-phase transformation and, on the other hand, cooling the extruded product with forced air and / or water at the exit of the extrusion die,
This ensures that the extruded product is kept outside the superplastic γ phase, ie inside the α + β phase, and finally, is dimensionally stable before straightening the extruded product. Comprising receiving the extruded product on a conveyor table to ensure its integrity.

Through confirmatory (pilot) testing of the extrusion of zinc-based alloys using the extrusion method covered by Mexican Patent No. 61483, it was found that the resulting extruded product had problems with dimensional stability. It was This is due to the superplastic behavior of the material.

In such a test, a region of the material produced a gamma phase at the exit of the extrusion die that exhibited the superplastic behavior characteristic of Zn-Al eutectoid alloys, which was acted upon by the receiving table on the material. It was determined that the extruded product was deformed in combination with the friction force.

In order to overcome the drawbacks mentioned above, the inventor of the present invention has developed various improvements in the method of extrusion of zinc-based alloys, which have achieved optimum industrial results.

Such optimum industrial results have limited the temperature range throughout the entire extrusion process to below the eutectoid temperature of the zinc-based alloy, ie below 275 ° C (527 ° F). Also, the improved industrial results show that the extrusion temperature range is 176 ° C (350 ° F) to 275 ° C (527 ° F).
It was achieved by approaching within the range of °).

Further, such an alloy extrusion process is such that as the product leaves the extrusion die, the extruded product is cooled by forced air and / or water to prevent the material from reaching the eutectoid temperature. Improved by eggplant.

Finally, to avoid frictional forces acting on the extruded product at the receiving table, the inventor of the present invention comprises an improvement using a conveyor to hold the product shape constant, which Prevents any dimensional changes in the final product.

[0016]

The improvements covered by the present application will be better understood with reference to the accompanying Zn-Al phase diagram of FIG. FIG. 1 shows that the superplastic γ phase occurs at a temperature of 273 ° C. or higher for the chemical composition range of the eutectoid alloy referred to in Mexican Patent No. 161483. It has also been shown that the processing temperature must be kept below this eutectoid temperature in order to ensure that the extrusion process is carried out in the non-superplastic range corresponding to the α + β phase.

It should be noted that the binary phase diagram of FIG.
This is to mention only the Al alloy, which is the basis for the Zn-Al-Cu alloys mentioned herein. Addition of a small amount of copper does not significantly affect the phase transformation temperature.

Example 1 A Zn-Al-Cu alloy having a standard composition of 21% by weight of Al, 2% by weight of Cu and the balance of Zn was extruded in an aluminum extruder of 1800 tons. Mexico Patent No. 16148
Parameters were given with reference to No. 3.

The product obtained at the exit of the extrusion die exhibits great ductility, which results in poor shape control and the product exhibits dimensional irregularities including waviness and bulges. Shows.

Example 2 For comparison purposes, a similar test was carried out on the same extruder using the same zinc-based alloy as in Example 1 with the improvement of the present application. That is, prior to modification by maintaining a temperature below 273 ° C. through this method, rapidly cooling the extruded product by forced air at the exit of the extrusion die, and using a mechanical conveyor to straighten the product leaving the extrusion die. I received it. As a result of the improvements incorporated into this extrusion method, extruded products with optimum mechanical properties, including shapes and dimensions within tolerances, were achieved by this test.

Through the industrial tests of this comparative example described above, the eutectoid alloy is a zinc-based alloy exemplified here, but not limited to Zn-Al-Cu alloys, by the improvements covered by the present application. This extrusion process was carried out and produced optimum industrial results.

While the present invention has been described with reference to preferred embodiments, variations and modifications can be effected to those skilled in the art without departing from the spirit and scope of the application as set forth in the appended claims. It will be obvious that you will get it.

[Brief description of drawings]

FIG. 1 is a phase diagram of a Zn-Al alloy that is a zinc-based alloy.

[Explanation of symbols]

 None.

Continuation of the front page (72) Inventor Gabriel Tresbuy. Dee, Ittaparapa, Mexico. F. , Col. Sinatel, Larga Distantia Number 90

Claims (1)

[Claims] 1. For example, 69 to 79% by weight of Zn and Al20
-30% by weight and 1.0-8% by weight Cu, characterized in that a particular Zn-Al-Cu alloy is used, and alloy ingots and containers and extrusion dies up to 350. Preheat to a temperature of ℃, extruding the ingot in the temperature range of 150 ℃ ~ 350 ℃ at a speed of between 1 to 20 meters per minute and applying a corresponding pressure load, straightening the extruded shape. In a method for extrusion molding from a zinc-based alloy, which comprises the steps of cooling at ambient temperature, the temperature range during the extrusion step is kept below the eutectoid temperature of the Zn-Al-Cu alloy of 275 ° C (527 ° F). Limit and approach the extrusion temperature between 176 ° C. (350 ° F.) and 275 ° C. (527 ° F.) to force the extruded product leaving the extrusion die with forced air and / or
Or an extrusion process from zinc-based alloy material comprising the steps of supplying water to quench and using a mechanical conveyor to receive the extruded product leaving the extrusion die.