JPH0762379A - Lubricants for warm forming of aluminum materials - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a lubricant for warm forming of aluminum material, which has excellent formability and galling property particularly on the high temperature side in the warm forming temperature range. [Composition] The temperature at which the solubility in water reaches 20% is 5
2.5 to 20% of saturated fatty acid soap consisting of an alkyl group having a carbon number of 12 to 18 at a temperature lower than 0 ° C, and one or two of aluminum stearate, zinc stearate, calcium stearate, and magnesium stearate.
Lubricant consisting of 1 to 20% of seeds or more and balance of water.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricant used during warm forming of aluminum material. In addition,
In the present specification, the aluminum material includes not only industrial pure aluminum material but also various aluminum alloy materials. Further, in the present specification, the warm forming is a process of forming into a predetermined shape while contacting with a mold, a tool, and a roll, and is at least room temperature or higher and a recrystallization temperature or lower at the time when the material is subjected to molding. I say processing. However, a temperature of 150 ° C. or higher and 300 ° C. or lower is preferable in order to obtain a remarkable effect of warm forming.

2. Description of the Related Art If an aluminum material can be used in place of the mild steel currently widely used, it is possible to significantly reduce the weight. However, among the aluminum materials, those having a formability equivalent to mild steel lack strength, while those having a strength comparable to mild steel have poor ductility and are less formable than ordinary mild steel in normal room temperature forming. Inferior Therefore, various molding methods for improving the formability of aluminum materials have been developed and studied, and various methods have been studied as warm forming of aluminum as one of them. Warm formation involves heating the workpiece to room temperature or higher to perform the forming process. At that time, the issue is how to improve the formability and prevent seizure and galling due to it. . Therefore, the lubricant becomes a problem, but as the conventionally known lubricant, soybean oil, a sheet made of tetrafluoroethylene (commonly called Teflon: trade name), a polymer mixed with graphite, or a grease or a mineral oil is used. There is a mixture of graphite, molybdenum disulfide and mica.

However, in the warm forming of aluminum material, it has not been possible to obtain a product having sufficient formability and satisfactory seizure and galling. It is far from the situation. The present invention has been made in view of the above circumstances, and provides a lubricant having excellent lubricity, which is used for warm forming of an aluminum material and particularly realizes good formability without causing seizure or galling. It is intended.

[Means for Solving the Problems] The present inventors have completed the present invention as a result of various studies and repeated studies for solving this problem. That is, the present invention is

2.5 to 20% of a saturated fatty acid soap having an alkyl group having a carbon number of 12 to 18 and having a solubility of 20% in water of less than 50 ° C., aluminum stearate / zinc stearate / calcium stearate A lubricant for warm forming of an aluminum material, which comprises 1 to 20% of magnesium stearate and 1 to 20% and the balance water.

The base material of the present invention is an aqueous solution of soap (sodium salt or potassium salt) of saturated fatty acid having an alkyl group. Among the so-called soaps, there are also unsaturated fatty acid soaps, which have excellent solubility in water, but have the drawback that seizure easily occurs during warm forming and the quality of the formed product deteriorates. It decomposes during warm molding and produces smoke, and the odor of paraffin is strong and the working environment deteriorates. Besides this,
Lubricating oils based on mineral oils or synthetic oils (polybutene) decompose at a temperature of 200 ° C. or higher to generate smoke, deteriorating the working environment, and lowering lubricity and galling. Two
May ignite above 50 ° C. 180 grease
At a temperature of up to 300 ° C, it reacts with the aluminum material, and degreasing after molding becomes difficult. If the carbon number C of the alkyl group is less than 12, lubricity is poor and galling is likely to occur. When the carbon number C exceeds 18, the adhesion to the aluminum material is deteriorated, coating unevenness is apt to occur, and the scuffing property is apt to vary, and the seizure property is deteriorated, which is not suitable for practical use. Also, the solubility of soap in water is 20.
When the temperature reaching 50% is 50 ° C. or higher, it is necessary to heat the aluminum material or the lubricant at the time of application for uniform application. However, when an aluminum material is brought into contact with an aqueous solution containing soap at a high temperature, corrosive stains are generated and the commercial value of the surface of the molded product is reduced. Also, the addition of an extra heating step increases the processing cost. If the concentration of the aqueous soap solution is less than 2.5%, the lubricity is poor and galling is likely to occur. On the other hand, if it exceeds 20%, the seizure property is deteriorated and the commercial value of the product surface is reduced. Therefore, the base of the present invention is a saturated fatty acid soap consisting of an alkyl group having a carbon number of 12 to 18 and a solubility in water of 2
2.5-20% if the temperature reaching 0% is less than 50 ° C
The aqueous solution to be contained. The above-mentioned aqueous soap solution has good performance as a lubricant for warm forming of aluminum materials without adding anything. However, when the above-mentioned aqueous solution of soap is used alone, continuous processing is difficult because galling is likely to occur during processing on the high temperature side where the temperature of the aluminum material, the mold, the tool and the roll is 150 to 300 ° C even in the warm molding temperature range. Therefore, as a result of further earnest research, aluminum stearate, which is almost insoluble at room temperature in the aqueous solution of the soap,
The total amount of one or more of zinc stearate, calcium stearate, and magnesium stearate is 1.0.
It was found that the continuous gallability on the high temperature side can be significantly improved and the continuous processing can be performed by containing ˜20% by dispersion. If the total content of aluminum stearate, zinc stearate, calcium stearate, and magnesium stearate to be dispersed is less than 1.0%, there is no effect on galling due to addition, while if it exceeds 20%, not only the economic efficiency deteriorates. There is a drawback that the effect is not stable due to easy peeling after coating and drying. Therefore, 1.0 to 20% of aluminum stearate, zinc stearate, calcium stearate, and magnesium stearate are dispersed and contained in the above aqueous solution of soap.
The particle size of aluminum stearate, zinc stearate, calcium stearate, and magnesium stearate to be dispersed is 0.01 to 2 which is inexpensive and easily available.
The range of 0 μm is preferable. The aluminum stearate, zinc stearate, calcium stearate, magnesium stearate together with graphite, mica,
It is also effective to coexist powders of tetrafluoroethylene resin, boron nitride, talc and the like. Furthermore, extreme pressure additives such as sulfur-based, phosphorus-based, and chlorine-based, which are resistant to high temperatures, such as diphenyl disulfide.
e), trilauryl phosphonate (trilaur)
yl phosphite), monochlorobenzene (m
It is preferable to add non-chlorobenzene to improve the load resistance. When the lubricant according to the present invention is used, it is desirable to sufficiently stir it so that it can be applied in a uniform state. The warm forming may include a method of indirectly heating an aluminum material in contact with a molding die, a tool, or a roll to heat the material, a method of preheating the aluminum material itself, or both. In any case, the lubricant of the present invention is applied to an aluminum material in advance at room temperature,
After drying, it is subjected to warm molding. Also, molds and tools,
If the surface of the roll is coated and dried in advance, the effect is further stabilized. Further, as a method of applying the lubricant of the present invention, a commonly used method is the form of an aluminum material,
It may be selected appropriately depending on the amount. Further, it is possible to obtain further effects by applying the lubricant according to the present invention after performing various surface treatments on the surface of the aluminum material.

EXAMPLES The effects of the present invention will be described in detail below based on examples. Using a JIS 5182-O material having an aluminum thickness of 0.8 mm, warm forming was performed under the following conditions. Mold punch 60 mm × 60 mm × two double sinks Distance between punches 60 mm Blank holder force 1000 kg Hold at 250 ° C. for 1 minute Molding depth 60 mm The results of warm molding were evaluated according to the following criteria. Here, “+” is preferable and “−” is not preferable, and the middle is ±. Working environment: The situation of odor and smoke during actual use. -: Strong odor, much smoke and poor visibility. ±: Smell odor, slightly smoked. +: Weak odor, very little smoke. Galling property: The galliness limit number in the Bowden friction test (at 250 ° C.). -: 5 times or less. ±: 6 times or more and 10 times or less +: Over 10 times. Formability: The height that can be formed without cracking. (However, due to device limitations, the maximum is 60 mm). -: 20 mm or less. ±: 21 mm or more and 59 mm or less. +: 60 mm. Burn-in: Strength of stain generated on an aluminum material at 250 ° C. in the atmosphere. -: Strong. ±: Medium. +: Weak. Adhesion: Adhesion and drop-off of lubricant before drying after pressing. -: Adhesion was poor and there was dropout. ±: Adhering state. +: Good adhesion and no falling off. Degreasing property: After being immersed in running tap water for 5 minutes, the water wetting rate after 30 seconds of pulling up was evaluated. -: Water wetting rate 79% or less (defective). ±: 80% to 99% wettability (somewhat poor). +: 100% wettability (good). [Preliminary Experiment] Performance Evaluation of Base Materials Warm moldability was investigated with various base materials. The results are shown in Table 1. In the "lubricant" column of Nos. 4 to 8 in Table 1, the C number of the alkyl group, the type of soap, and the concentration of the aqueous soap solution are described.

[Table 1] As can be seen from Table 1, an aqueous solution of unsaturated fatty acid soap (N
o1), synthetic oil (No3), an aqueous solution (No2) of a soap of a fatty acid consisting of an alkyl group but having a low solubility in water (a temperature reaching 20% is 72 ° C), a soap of a fatty acid consisting of an alkyl group, and a solubility in water Although the C number and the concentration are out of the range of the base material of the present invention even if the value is high, the aqueous solution (No. 4 to 7) is "-" in any of work environment, galling property, moldability, seizure property, and degreasing property. Received an evaluation of (Poor). On the other hand, a fatty acid soap aqueous solution (No8) satisfying the conditions of the base described in the claims of the present invention is
All of them are “+” (good) except that they are evaluated as “±” in gnawing property.
It has excellent performance as a lubricant for warm forming of aluminum materials except for galling property. [Examples] Performance comparison when metal stearate was added Next, the influence of the content was investigated when aluminum stearate, zinc stearate, calcium stearate, and magnesium stearate were further added to the No. 8 base of the preliminary experiment. . Incidentally, aluminum stearate, zinc stearate, calcium stearate, and magnesium stearate are generally powdery, and the particle size is 0.
A powder of 01 to 25 μm was used. In this range particle size does not affect performance. The results are shown in Table 2. Also,
All work environments were evaluated as “+”, so they are not listed in Table 2.

[Table 2] As shown in Table 2, when aluminum stearate, zinc stearate, calcium stearate, and magnesium stearate powder having a content satisfying the scope of the claims of the present invention are added (No 10 to 17), the high temperature side is 250 ° C. Even at the warm molding temperature of 1, the workability, adhesiveness, moldability, seizure, and degreasing properties of the base were not impaired, and in addition to this, further improvement in galling was observed.

[Effect] As described above in detail and as shown in the examples,
The lubricant according to the present invention has the following effects. (1) The aluminum material has good galling resistance even at a high temperature of not less than room temperature and not more than the recrystallization temperature, and galling does not occur in continuous production. (2) Good product surface quality can be obtained because no galling occurs and the surface does not become rough. (3) The image sticking property is good and no stain is generated. (4) A good working environment can be obtained without producing offensive odors or smoke. (5) The molding limit is high and good moldability is obtained. (6) Good adhesion and no peeling or powdering of the lubricant after coating and drying. (7) Good degreasing property after pressing. Therefore, it has excellent performance as a lubricant for warm forming of an aluminum material which has not been industrialized because the performance of the lubricant has been confirmed, but the performance of the lubricant is insufficient. Therefore, by using the lubricant according to the present invention, the galling property in the warm forming is remarkably improved, so that the continuous warm forming process can be performed for a long time. Especially 15
The galling property on the high temperature side of 0 to 300 ° C. is greatly improved, and therefore the continuity of warm forming in this temperature range can be significantly improved.

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Claims (1)

[Claims] 1. A saturated fatty acid soap comprising an alkyl group having a carbon number C of 12 to 18 and a temperature of less than 50 ° C. at which the solubility in water reaches 20%, 2.5 to 20%, aluminum stearate, zinc stearate, and A lubricant for warm forming of an aluminum material, which comprises 1 to 20% of calcium stearate or magnesium stearate, and 1 to 20% and the balance water.