JPS5830358B2 - Lubricant for cold to warm processing of metal pipes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lubricant for cold to warm processing of metal pipes, and more specifically, the present invention relates to a lubricant for cold to warm processing of metal pipes, and more specifically, a lubricant containing hydrogen carbonate as a main component and an appropriate amount of a dispersant and a surfactant, or further containing a metal soap or a surfactant. This relates to an aqueous dispersion containing a solid lubricant such as graphite.

When various types of metal pipes, including steel pipes, are subjected to processing such as cold or warm rolling, forging, extrusion, drawing, etc., various methods are used to improve the quality of processed products and suppress tool wear (prevention of seizure). lubricants are used.

However, the known lubricants cannot be said to satisfy all of the requirements such as lubrication performance, ease of removal after processing, and low pollution of waste fluid.

For example, metal soap, animal/vegetable oil, mineral oil, plastic working oil (containing extreme pressure additives), etc. are used as lubricants for relatively light machining, but as the degree of machining increases, the The metal contact area with the tool increases and damage to the tool and product becomes significant.

In order to prevent such troubles, it has been conventional practice to form a chemical conversion film on the surface of the pipe material in advance and to improve lubricity with a chemical metal soap coating agent.

The above chemical conversion coating is a phosphate coating (ordinary steel or low alloy steel)
, aluminum aluminum coating (AI), oxalate coating (stainless steel), etc. are known.

With this method, a chemical conversion coating is interposed between the pipe to be processed and the chemical metal soap coating, and since these are chemically integrated, the lubricating coating exhibits extremely strong adhesion and increases the processing rate. Demonstrates sufficient lubrication function even when the temperature is high.

However, this method has the problem that the lubricating effect decreases as the processing temperature increases.

For example, a chemical metal soap coating applied to a phosphate coating loses most of its lubricating effect at around 350°C.

Moreover, since it is a chemically reactive lubricant, managing the treatment liquid is troublesome, and its short lifespan requires frequent treatment of waste liquid, which poses economic problems and causes pollution. There is also.

In addition, since the above-mentioned lubricating coating has too good adhesion, there is also the problem that it is difficult to remove the coating from the processed product.

Therefore, a lubricant that has a high machining rate and exhibits excellent lubrication in both cold and warm machining, is easy to handle, can be easily removed after machining, and does not cause waste fluid pollution. development is desired.

The present inventors have focused on the above-mentioned circumstances and have conducted research with the aim of developing a lubricant that can satisfy all of the above-mentioned requirements.

As a result, this type of lubricant has hydrogen carbonate as its main ingredient, which has never been used before, and a small amount of dispersant and surfactant, or an appropriate amount of solid lubricant is mixed with these. Having learned that an aqueous dispersion is an excellent lubricant that meets the above objectives, the present invention was successfully completed.

That is, the composition of the lubricant for cold to warm working of metal pipes according to the present invention is hydrogen carbonate: 5 to 55% (weight %: the same hereinafter), dispersant: 0.1 to 1.0%, and Surfactant: 1~
The gist is that the aqueous dispersion contains 2% of metal soap and/or graphite, or 12% or less of metal soap and/or graphite.

As mentioned above, conventional lubricants for metal tube machining generally do not exhibit sufficient lubrication at high machining rates, even at low machining rates, and furthermore, as the machining temperature increases, the lubricating effect is extremely reduced.

However, when the present inventors investigated the lubricating performance of a number of substances under high pressure, it was confirmed that bicarbonates such as sodium bicarbonate and potassium bicarbonate form an extremely good lubricating film even under high pressure. Moreover, it has been found that this lubricating film is stable not only during cold working but also under warm working conditions in which temperatures of about 400° C. are applied, and maintains a high lubricating function.

As a result, it is possible to prevent seizure during machining, improve the surface quality of the product, and extend the life of the tool.

Moreover, it has been confirmed that the above-mentioned lubricating film can be easily removed from the surface of the processed product and hardly causes problems such as waste liquid pollution.

However, since hydrogen carbonate is a solid substance, it is difficult to use it as it is as a lubricant in terms of workability and the like, so it is necessary to find an appropriate form of use as a lubricant.

This point was easily addressed by dispersing the bicarbonate with small amounts of dispersants and surfactants.

That is, although the preferred content of hydrogen carbonate will be clarified later, its blending ratio with respect to the total amount of the lubricant is quite high, and it is often used in a state exceeding its solubility in water.

Therefore, unless special measures are taken, the lubricant will be used in a suspended state, resulting in poor stability and practical problems.

However, when a small amount of a dispersant and a surfactant are coexisting in this suspension system, the mixing and dispersibility during the preparation of the dispersion are improved, the stability of the prepared dispersion is also improved, and furthermore, during processing. The formation of a lubricating film and the lubricity itself are also promoted.

In particular, surfactants act on the interface between water and solid components (bicarbonate) to lower the interfacial tension and have the effect of uniformly and rapidly dispersing the solid components.

However, surfactants promote foaming of the dispersion, which causes various problems during processing (poor adhesion of lubricant, uneven adhesion, etc.), and should therefore be kept to a necessary minimum.

There are various surfactants that exhibit this effect, but the most preferred surfactants confirmed through preliminary experiments are fatty acid amine soaps such as η fatty acid monoethanolamide and fatty acid jetanolamide. Ta.

Further, the dispersant has the effect of increasing the stability of the dispersion liquid, and is an essential component as an anti-settling agent for bicarbonate.

However, if the amount is too large, the fluidity of the dispersion will decrease and it will be difficult to apply it uniformly to the lubricated surface, so it should be kept to the minimum necessary level.

Although various dispersants that exhibit such an effect can be considered, the optimal dispersants confirmed in preliminary experiments are linear polysaccharides, silicates, fatty acid metal salts, and the like.

The purpose of the lubricant of the present invention can be achieved by making the above three components into four essential components and appropriately adjusting the proportions of each component. This increases the protection effect of the new tool surface.
The tool life can be further extended.

The reason why the content range for the four essential constituents in the present invention was determined will be explained below by following the experimental progress.

First, an aqueous dispersion with various contents of hydrogen carbonate (NaHCO3 and KHCO3) was prepared, with 0.2% linear polysaccharide as a dispersant and 1.0% fatty acid monoethanol as a surfactant. The lubrication performance of each was examined.

The processing conditions were as shown in Table 1.

The results are shown in Table 2. ×: Significant seizure of pipe material and tools* ○: Good ◎: Very good As is clear from these results, the water dispersion contains hydrogen carbonate along with a small amount of dispersant and surfactant. The liquid exhibits very good lubrication performance.

In order to effectively exhibit the lubricating effect of hydrogen carbonate, it is necessary to contain it in the dispersion at least 5% or more, preferably 20% or more.

However, within the content range conducted in this experiment, there was no upper limit as far as lubricating performance was concerned.

However, among those used in the above experiments, a tendency for the aqueous dispersion to separate was observed in those with a hydrogen carbonate content of over 60%, so the relationship between the stability of the aqueous dispersion and the hydrogen carbonate content was clarified. We conducted an experiment to find out.

That is, an aqueous dispersion (lubricant) was prepared by using the same dispersant and surfactant as above, and adding 5 to 70% hydrogen carbonate (NaHCO3) thereto, and after leaving it for 200 hours. The stability of the liquid was investigated.

The results are shown in Table 3.

As is clear from the above results, the separation stability of the lubricant is better when the hydrogen carbonate concentration is lower;
Up to about 5%, it is excellent, but when it exceeds 50%, it tends to decrease, and when it exceeds 55%, separation becomes significant and the separated solid components become solidified, making it impractical.

However, if it is less than 55%, there will be a slight tendency toward separation, but it will be sufficient to redisperse it by natural stirring during use.
There is no practical problem.

From these experiments, it is understood that in order to satisfy both lubrication performance and separation stability, the content of hydrogen carbonate should be set in the range of 5 to 55%, more preferably 20 to 45%.

Next, based on the above experimental results, we set the amount of hydrogen carbonate at 30%, which is considered to be the optimum amount, and created a lubricant with various surfactant contents while keeping the dispersant content constant at 0.5%. The relationship between the amount of surfactant and the dispersibility of solid components was investigated.

The hydrogen carbonate used was hydrogen carbonate, and the dispersant used was linear polysaccharide. The surfactant used was fatty acid monoethanolamide.

As a result, the solid components could not be uniformly dispersed without the addition of a surfactant, but when 1% or more was added, the solid components were easily separated with short stirring, making it possible to obtain a uniform lubricant. Ta.

However, if it exceeds 2%, foaming of the lubricant becomes significant, which tends to cause poor adhesion of the lubricant and uneven lubrication during use.

From these results, the amount of surfactant is 1 to 2 in the total lubricant.
% is optimal.

Next, we set hydrogen carbonate (NaHCOs) at 30% and surfactant (fatty acid monoethanolamide) at 1.0%, and investigated the relationship between the amount of dispersant (linear polysaccharide) added and the stability of the lubricant. Examined.

As a result, if no dispersant is added, hydrogen carbonate cannot be uniformly dispersed and a uniform and stable lubricant cannot be obtained, but if 0.1% or more of a dispersant is added, extremely stable and uniform dispersion can be obtained. It was found that a liquid was obtained.

However, as the amount of dispersant added increases, the fluidity of the dispersion decreases, and if it exceeds 1.0%, the dispersion solidifies into a gel-like state and cannot be used as a lubricant.

From these results, the content of dispersant in the total amount of lubricant is 0.
It was concluded that it should be set in the range of 1 to 1.0%.

Through the above experiments, the preferred content ranges of hydrogen carbonate, dispersant, and surfactant, which are the four essential constituents of the lubricant of the present invention, have been clarified.

However, the present inventors conducted the following experiment in order to clarify the more preferable content range of hydrogen carbonate, which is the main component, among the above-mentioned essential components.

That is, as shown in Table 4, a large number of lubricants with different hydrogen carbonate contents were prepared, and each lubricant was tested using the lubrication performance test method developed by the applicant (Japanese Patent Laid-Open No. 52-68493).
The lubrication performance was measured according to the following.

In this test method, for example, as shown in Fig. 2A-C, a short steel tube 1 coated with lubricant on the inner surface is inserted into a die 2 with a gap, and a steel ball 3 placed above is placed on a ram 4. The short tube 1 is rolled by forcibly pushing it in.

The performance of the lubricant is judged from the inner surface properties of the rolled short tube 1 and the surface properties of the steel balls 3. Since the conditions are more severe than the actual rolling conditions, the performance of the lubricant is strictly judged. be able to.

The performance of each lubricant obtained in the above tests (inner surface flaws on steel pipe 1 and surface flaws on steel ball 3), together with the amount and stability of lubricant adhesion and the actual rolling experiment results (conditions in Table 1 above), is shown below. All are shown in Table 4.

The performance evaluation criteria in the table are as follows.

◎・・・Excellent ○・・・Good △・・・Problems (slightly many surface scratches)×・・・
...Poor (severe surface scratches make it unusable) From the results in Table 4, the following can be considered.

■ In the above-mentioned severe rolling test, even when the amount of hydrogen carbonate was added above the specified amount, there were almost no scratches on the inner surface of the short tube, and this tendency is the same as the results of the actual rolling test. There is a tendency for surface scratches to become more severe when the hydrogen carbonate content exceeds 40%.

The presence or absence of surface scratches on the steel ball has a correlation with the wear of the die in actual rolling tests, and from this experiment it is thought that the more preferable upper limit of the hydrogen carbonate content is around 40%.

In addition, when observing the occurrence of short tube inner surface scratches, it changes from "good" to "excellent" when the content of hydrogen carbonate increases from 15% to 20%, and the preferable lower limit of the amount of hydrogen carbonate is It is thought to be around 20%.

■ The above tendency can also be seen from the amount of lubricant deposited.

In other words, in the lubricant of the present invention, it has been confirmed in preliminary experiments that the seizure of the die tends to become more pronounced as the amount of lubricant applied increases, but when the amount of hydrogen carbonate exceeds 40%, the amount of adhesion increases rapidly. From this point of view, it is considered that the most preferable amount of hydrogen carbonate is 40% or less.

(2) The lubricant AIII group is an example of using a carbonate together with a hydrogen carbonate, and even in this case, a lubricant with excellent performance can be obtained.

However, it has been confirmed that when all of the hydrogen carbonate is replaced with carbonate, the separation stability and lubricating function of the lubricant are far inferior.

In addition, according to preliminary experiments conducted separately, it was found that adding a small amount of solid lubricant made of metal soap and/or graphite to the above-mentioned lubricant further improved the lubrication performance, and in particular, there was a tendency to reduce die seizure. Therefore, an experiment was conducted to clarify the preferred content of the solid lubricant.

That is, as shown in Table 5, lubricants were prepared in which the contents of NaHCO3, dispersant, and surfactant were kept constant, and only the amount of solid lubricant (calcium stearate or graphite) was changed,
Separation stability and lubrication performance were examined using the same test methods as in Table 4.

The results are summarized in Table 5.

As is clear from Table 5, an appropriate amount of metal soap and/or
Or, when graphite is used in combination, the lubrication performance is further improved.

The allowable addition amount of these solid lubricants is 12% or less from the viewpoint of stability of the lubricant, but in order to effectively exhibit the effect of improving lubrication performance, the range of 2 to 8% is optimal.

By the way, it is desired that the lubricant not only have good separation stability and lubrication performance as described above, but also not impair the corrosion resistance of the pipe to be processed.

Therefore, we conducted an experiment to clearly confirm this point.

[Corrosiveness to metal materials]

The following three types of lubricants were prepared, and each lubricant was dip-coated onto an iron, copper, or AI plate (6 ohm x 80 mm) polished with #240 emery paper.

After this was left at 110° C. for 2 hours, the state of corrosion on the surface was observed.

The results are shown in Table 6. Lubricant A...-NaHCO3:
30%, dispersant 20, 2%, surfactant: 1% Lubricant B-"NaHCO3: 30%, dispersant 20.2
%, surfactant: 1%, Ca stearate: 4%, lubricant C...NaHCO3: 30%, dispersant: 0.
2%, surfactant: 1%, graphite: 4% There is no fear that the agent will corrode the pipe material to be treated.

The outline of the present invention is constructed as described above, but the key point is that hydrogen carbonate is used as the main component, and this is uniformly dispersed in water with an appropriate amount of a dispersant and a surfactant, or an appropriate amount of solid is added to this. By adding a lubricant, it has become possible to provide a lubricant having excellent mechanical properties as listed below.

■ It forms a lubricating film with excellent performance even under severe machining conditions, so it can be used effectively over a wide range of machining rates.

In addition, seizure during processing is drastically reduced, the quality of processed products is improved, and the life of processing tools is greatly extended.

■ It is stable against heat and exhibits excellent lubrication even under processing conditions of around 400°C, so it can be used not only for cold working but also for warm working.

(2) Since no adhesive is used and the main component, hydrogen carbonate, is easily soluble in water, it is extremely easy to remove after processing.

- Hydrogen carbonate is economical because it is cheaper than general lubricants, and it is also harmless, so there is no risk of causing waste liquid pollution.

■ The lubricant is stable, has little deterioration, and has a long life, making it highly suitable for continuous processing.

■ This lubricant is most effective when used for processing (especially rolling) metal tubes, but it is also used as a lubricant for rolling and wire drawing of metal plates, bars, wires, etc. also exhibits excellent functionality.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a separation state observed in a lubricant separation stability test, and FIG. 2 is a schematic cross-sectional explanatory diagram showing a lubricant performance test method. 1...Metal short tube, 2...Dice, 3.
...Steel ball, 4...Ram.

Claims (1)

[Claims] 1. Hydrogen carbonate: 5 to 55% by weight, Dispersant: 0.1 to 1
．． A lubricant for cold to warm working of metal pipes, characterized by comprising an aqueous dispersion containing 0% by weight and 1 to 2% by weight of a surfactant. 2 Hydrogen carbonate: 5-55% by weight, dispersant 20, 1-1
．． A lubricant for cold to warm working of metal pipes, characterized by comprising an aqueous dispersion containing 0% by weight, 1 to 2% by weight of surfactant, and 12% by weight or less of metal soap and/or graphite. .