JPH0144278B2 - - Google Patents

Description

[Detailed description of the invention]

Industrial Application Fields These inventions are used in hot forging to provide lubricity between the die and the workpiece to reduce friction between the two, release properties to shorten the contact time, and heat resistance. This relates to a die lubricant for hot forging to ensure the following. Conventional technology As is well known, in hot forging, mold lubricants are used to shorten the contact time between the mold and the workpiece, reduce heat transfer from the workpiece to the mold, and prevent damage to the mold. It is being As mentioned above, such mold lubricants are required to have excellent lubricity and mold release properties. Conventionally, graphite-containing lubricants prepared by diluting colloidal graphite in water or oil have been known as mold lubricants with excellent lubricity and mold release properties, and are widely used. This graphite-containing lubricant is used by applying it to a forging die by spraying (for example, 120 c.c. per forging die). By the way, although this graphite-containing lubricant has excellent lubricity and mold release properties, when it is applied, fine particles of graphite powder scatter or adhere to surrounding machinery, worsening the working environment. There is a problem. In addition, as the lubricant is used over and over again, graphite clogs the pipes and nozzles used to apply the lubricant, which hinders work and requires extra work to clean, which worsens work efficiency. Moreover, there is also the problem that they can invade the inside of mechanical equipment, such as electric motors, and adhere to rotors, often causing short-circuit accidents. In order to solve these problems caused by graphite-containing lubricants, lubricants that do not contain graphite, that is, graphite-free lubricants, are required, and some of them are in use. This type of lubricant is listed in "Plasticity and Processing", Volume 25, published by the Japan Society for Plastic Processing.
On pages 893 to 898, organic substances such as mineral oils, animal fats and oils, and polymers, and inorganic substances such as molybdenum disulfide and molybdates are disclosed.
-Adipic acid is disclosed in the specification of No. 13498. Problems to be Solved by the Invention However, the graphite-free lubricants described above have insufficient lubricity due to a rapid increase in the coefficient of friction as the temperature rises, and also have poor mold release properties. The problem is that it is inferior. Therefore, it is difficult to apply it to hot forging with a large deformation rate or hot forging of workpieces with complicated shapes. By the way, the speed of forged parts used in automobiles and other products is increasing as the precision and weight reduction is promoted.For example, shafted flange parts, which are the mainstream of automobile parts, have traditionally been produced using vertical extrusion presses. Previously, molds were stamped manually, but recently it has become possible to produce them fully automatically using hot multi-stage molding machines.
According to this, the productivity is 7 to 10 times higher than that using a conventional vertical extrusion press, and about 60 molds can be punched per minute. As described above, recent hot forging processes are performed at high speeds and high reductions, and demands for die lubricants are becoming more intense. That is, a mold lubricant for hot forging is required to have high lubricity and mold releasability, and conventional graphite-free mold lubricants cannot withstand use. On the other hand, graphite-containing lubricants are difficult to use due to the work environment and mechanical failure caused by scattered graphite. In view of the above points, these inventions do not have the above-mentioned drawbacks of graphite-containing lubricants, have excellent lubricity and mold release properties, and are suitable for hot forging at high deformation rates and hot forging of workpieces with complex shapes. The purpose is to provide a mold lubricant that can also be applied to molds. Means for Solving the Problems In order to achieve the above object, the present inventors
As a result of extensive research, we discovered a graphite-free lubricant with excellent lubricity and mold release properties, leading to the present invention. That is, the first invention among these inventions is characterized in that one or more types of alkali metal salts or alkaline earth metal salts of ligninsulfonic acid are dissolved or dispersed in a diluent. The second invention is characterized in that one or more alkali metal salts or alkaline earth metal salts of ligninsulfonic acid and an amine are dissolved or dispersed in a diluent. Effect According to the first invention among these inventions, by applying to the mold one or more types of alkali metal salts or alkaline earth metal salts of ligninsulfonic acid dissolved or dispersed in a diluted solution, the mold and the coating are coated. A film is formed between the workpiece and the workpiece, which reduces the coefficient of friction between the two and improves lubricity, and prevents contact and ensures mold releasability. According to the second invention,
The coating formed between the mold and the workpiece becomes strong, ensuring the above-mentioned mold releasability and further improving lubricity. Specific description for carrying out the invention Examples of the alkali metal salts of these ligninsulfonic acids include sodium salts or potassium salts,
As the alkaline earth metal salt, for example, a calcium salt, a magnesium salt, or a barium salt can be used. Some commercially available lignin sulfonate products contain by-products such as reducing sugars and sugar sulfonates, but these sub-components have no negative effect on the lubricant's performance. A commercially available lignin sulfonate containing subcomponents such as those obtained by treating sulfite pulp can be used as is as a raw material for the mold lubricant of the present invention. Furthermore, water or oil can be used as the diluent. However, dilution with water is preferable because it serves as mold cooling, is inexpensive, and does not degrade the environment. Furthermore, the amine in the second invention includes ethanolamine (mono, di, or tri), isopropanolamine (mono, di, or tri),
If alkanolamines such as secondary butanolamine (mono, di, or tri), dimethylethanolamine, diethylethanolamine, aminoethylethanolamine, and N-cyclohexyldiethanolamine are used, the effect of improving lubricity through a strong film is significant. . In addition to the above-mentioned essential components, the hot forging die lubricant in these inventions also contains surfactants, non-ferrous metal corrosion inhibitors, and auxiliary components conventionally used in hot forging lubricants. Foaming agents and the like can be appropriately contained as needed. In the present invention, the content of the essential components in the mold lubricant diluted solution is desirably 1% by weight or more. This is because if the amount is less than 1% by weight, a sufficient lubricating film will not be formed and the desired lubricating effect will not be obtained. However, it is also possible to prepare a concentrated dispersion or solution in advance and dilute it to an appropriate concentration before use. Further, it is desirable that the mold lubricant according to the present invention has a pH of 8 or more. This is because if the pH is less than 8, workability may be reduced due to putrefaction or pipes in the supply system may be clogged due to slime generation. This pH can be adjusted by adjusting the neutralization rate of lignin sulfonic acid by using alkali metal hydroxides, alkali metal carbonates, alkaline earth metal hydroxides, amines, etc. . It is advantageous to use an amine in this case because it has the effect of controlling the pH of the lubricant and at the same time strengthening the lubricating film to further improve lubricity. The hot forging die lubricant thus obtained is applied to the die by, for example, spraying or brushing. By the way, in hot forging, the workpiece material is usually
It is heated to 1000-1200°C, and due to heat transfer from this material, the mold is also heated to 80-350°C, raising its temperature. In the lubricant applied to the mold, low-boiling components such as water evaporate, and the remaining components form a film on the mold surface. This film then comes into contact with the workpiece material that has been heated to 1000-1200°C and undergoes thermal changes such as thermal decomposition. The mold lubricant according to the present invention has excellent lubricity and mold release properties under such usage environments.
This is because a thick lubricating film is formed on the mold surface that has been heated to 350°C, and the adhesion of this film is uniform and strong. This is because it is difficult to thermally decompose at high temperatures even if it comes into contact with it, and even if it is thermally decomposed, there is a large residual carbon component, which contributes to lubrication. Examples Examples of the present invention will be described below in comparison with a conventional hot forging die lubricant. Examples of the present invention and conventional mold lubricants are shown in Table 1. The mold lubricants are numbered No. 1 to 13, and No. 1 to No.
9 is an example of the present invention, Nos. 1 to 4 are examples of the first invention, and Nos. 5 to 9 are examples of the second invention. On the other hand, Nos. 10 to 13 are conventional mold lubricants;
No. 10 to 12 are graphite-free lubricants, and No. 13 is a graphite-containing lubricant. Various tests were conducted using these mold lubricants to evaluate the performance of the examples and conventional examples. First, a friction test (test method) was conducted under the test conditions shown in Table 2-1. This friction test was conducted using a friction testing machine shown in FIG.
This friction tester 1 coats a rotary body 2 with mold lubricant to a constant thickness, and presses a heating body 3 heated to a predetermined temperature while rotating the rotary body 2.
The friction performance is evaluated by measuring the time during which seizure occurs between the heating element 3 and the heating element 3. A transformer 4 is connected to the heating body 3, and by changing the output of the transformer 4, the temperature of the heating body 3 can be changed. Note that the lubricant is stored in an oil tank 5, and the lubricant in this oil tank 5 is supplied to the rotating body 2 by a pump 6. As shown in Table 2-2, the results of this friction test show that all of the examples of the present invention have excellent friction performance, but the conventional examples have poor friction performance except for lubricant No. 13. This frictional performance is based on the friction coefficient of each lubricant, and FIG. 2 shows the relationship between the friction coefficient and the dilution ratio in Examples of the present invention. The friction coefficient at a dilution rate of 10 is μ=0.14, which is equivalent to or better than the friction coefficient μ=0.15 of a graphite-containing lubricant at this dilution rate. Next, heat these mold lubricants to a predetermined temperature and apply them to a steel plate (50 x 100 x 70 mm) with a hand sprayer to form a film, and immediately rub it with a spa chiller.
The adhesion strength of the film was evaluated based on the sense of resistance at that time (test method). As shown in Table 3, the lubricants of the examples provide satisfactory performance, but the adhesive strength of the conventional lubricants is insufficient. Furthermore, a heat resistance test was conducted using these lubricants (test method). This test tested lubricant 105
After drying in a constant temperature bath at 110°C to 110°C, the weight loss rate was measured under the test conditions shown in Table 4-1. As shown in Table 4-2, the conventional example No. 13 is the best. Although the weight of the lubricant in the example gradually decreases as the temperature rises, there is no practical problem in the weight reduction rate in the temperature range where the lubricating film is heated during hot forging (around 250°C). . on the other hand,
In the conventional lubricants No. 10 to 12, the rate of weight loss in the practical temperature range is large, leading to deterioration of lubrication performance. Changes in the weight loss rate of this lubricant at various temperatures are shown in the graph of FIG. Furthermore, the residual carbon content: C (mass%) of each lubricant was measured according to the regulations of JIS2270, and the ash content: A (mass%) according to the regulations of 3.1 of JIS2272.
The residual carbon content contributing to the lubricating effect was measured using C ₀ =C-A (test method). The results are shown in Table 5. From this, the conventional example No.
As the weight reduction rate increases in the range of 10 to 12, the residual carbon content rapidly decreases and the lubricating performance deteriorates. A comprehensive evaluation of each lubricant was conducted based on these test results. The results of this comprehensive evaluation are shown in Table 6. The mold lubricant of the present invention obtained satisfactory results in all tests, indicating that it has performance equivalent to or better than graphite-containing lubricants. has been done.
On the other hand, conventional graphite-free lubricants did not give satisfactory results in all tests.

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[Table] Effects of the Invention As explained above, the first of these inventions dissolves or disperses one or more types of alkali metal salts or alkaline earth metal salts of ligninsulfonic acid in a diluted liquid, thereby providing a lubricating effect. It has excellent hardness and mold release properties, and can be used for high-speed, high-reduction hot forging. Moreover, unlike graphite-containing lubricants, it does not cause problems such as deterioration of the working environment or damage to peripheral equipment. In addition, in the second invention, a strong lubricating film can be obtained because one or more types of alkali metal salts or alkaline earth metal salts of ligninsulfonic acid or alkaline earth metal salts and an amine are dissolved or dispersed in a diluted liquid. can be further improved.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a testing machine for measuring the friction performance of one embodiment of these inventions, Fig. 2 is a graph showing the relationship between dilution ratio and friction coefficient of one embodiment, and Fig. 3 is a graph showing the relationship between dilution ratio and friction coefficient of one embodiment. It is also a graph showing the relationship between temperature and weight reduction rate in one example.

Claims (1)

[Claims] 1. A die lubricant for hot forging, which is prepared by dissolving or dispersing one or more types of alkali metal salts or alkaline earth metal salts of ligninsulfonic acid in a diluent. 2. A mold lubricant for hot forging, which is prepared by dissolving or dispersing one or more alkali metal salts or alkaline earth metal salts of ligninsulfonic acid and an amine in a diluent.