JPH041798B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a lubricant for cold working of metals, and in particular to a lubricant that is easy to handle when plugging stainless steel pipes and the like and can significantly improve the surface roughness of processed materials. [Prior art] When performing cold working (rolling, extrusion, drawing, etc.) on various metal pipes such as steel pipes, various lubricants are used to improve the quality of processed products and suppress tool wear (prevent seizure). It is used. However, known lubricants cannot be said to satisfy all required properties such as lubrication performance, ease of removal after processing, and low pollution of waste fluid. As a relatively new lubrication method, a method has also been developed in which a chemical conversion film is formed on the surface of a metal material in advance and a secondary lubricant (for example, chemical metal soap) is further applied to improve the lubrication performance. As such chemical conversion coatings, phosphate coatings (applied to ordinary steel, low alloy steel, etc.), aluminum fluoride coatings (applied to Al or Al-based alloys), oxalate coatings (applied to stainless steel, etc.) are known. In this method, a chemical conversion film is interposed between the metal to be machined and the chemical metal soap film, and these are chemically integrated, so the lubricating film exhibits extremely strong adhesion and increases the processing rate. It exhibits sufficient lubrication function even when the temperature is increased. [Problems to be Solved by the Invention] However, while it is possible to obtain a high processing rate with the above method, the formation of a chemical conversion film may be very unstable if the cost is higher than that of oil-based lubricants. This is raised as a problem. Furthermore, after machining, the secondary lubricant remaining on the workpiece must be removed with an alkaline solution (for example, an aqueous sodium orthosilicate solution), and the chemical conversion film must also be removed. Since the chemical conversion film chemically reacts with the workpiece and has very good adhesion to the workpiece, pickling is essential when removing the chemical conversion film after processing is completed. Furthermore, if the chemical conversion coating is removed by pickling, the surface of the workpiece will be etched, making it impossible to obtain a smooth metal surface. On the other hand, oil-based lubricants are currently used only in cases where the machining rate is extremely low, such as during dry drawing or mandrel drawing. In particular, the processing pressure generated during processing of stainless steel is much higher than that of other metals, so there is no oil-based lubricant that can withstand that high pressure, and chemical conversion treatment is superior in terms of pressure resistance during lubrication. There is. In view of the above circumstances, the present inventors have conducted research to provide an oil-based lubricant that can provide a smooth metal surface and that can be used even when processing rates are high, and have completed the present invention. It came to this. [Means for Solving the Problems] The present invention comprises: () A: A mixture of chlorinated paraffin and phosphoric acid ester in a weight ratio of 4:1: 40 to 50 parts by weight; B: A combination of isobutylene and n-butene. A mixture of a polymer with an average molecular weight of 1,200 to 2,400 and an animal or vegetable oil with a kinematic viscosity of 30 cst at 50°C: 50 to 60 parts by weight, and has a viscosity of 200 ± 50 cst at 50°C. The gist is that 20 to 30 parts by weight of a solid lubricant, which is a metal soap and/or an inorganic solid lubricant powder, is blended with 100 parts by weight of oil. [Function] In order to solve the above problem, the present inventors have particularly improved the surface roughness of stainless steel pipes, so that the boundary lubrication state is good and there is no seizure (streaky defects).
Focusing on the need to develop a lubricant that does not cause
In order to achieve this, we determined that the effect of extreme pressure additives was important and conducted various research. In addition, the purpose can be achieved by selecting a base oil and a substance that will be a carrier for extreme pressure additives that have strong adsorption power to metal surfaces, good ability to maintain oil film thickness, and a high viscosity index, and blending both in the appropriate ratio. It was recognized that For example, when drawing a plug from a stainless steel pipe, the tool temperature (plug, die, etc.) is around room temperature at the start of drawing, but as the drawing progresses, the tool temperature rises rapidly (estimated to be around 200°C), and then the drawing starts. Due to the wall thickness of the metal tube and the temperature of the tool, a large load is applied at the time, which can lead to seizure accidents. In order to prevent such seizure accidents, it is desirable that the extreme pressure additive exhibit excellent extreme pressure effects from room temperature to about 200°C. The extreme pressure effect here refers to the thermal decomposition of extreme pressure additives due to heat such as frictional heat, which interacts with the metal surface to produce a certain type of compound, which reduces friction or the amount of damage to the surface. describe a phenomenon. Substances that exhibit extreme pressure effects are called extreme pressure additives, and chlorine compounds, sulfur compounds, phosphorus compounds, and the like are known as such extreme pressure additives. (FP Bowden and D. Tabor,
“The Friction and Lubrication of solids”
(See "Friction and Lubrication of Solids" translated by Norimune Soyo, translated by Oxford 1974). The present inventors investigated extreme pressure additives that exhibit excellent extreme pressure effects in the temperature range from room temperature to about 200°C. As extreme pressure additives satisfying the above conditions, chlorinated paraffins, phosphoric esters, sulfurized oils and fats, etc. were obtained. Chlorinated paraffin exhibits excellent extreme pressure effects in the temperature range of 150 to 250°C, and its action is thermal decomposition in boundary lubrication conditions, breaking C-Cl bonds and producing Cl ₂ or HCl, which makes it difficult to bond with steel. The reaction produces a film of ferrous chloride or ferric chloride on the metal surface. Since these chlorides have a layered structure with low shearing force, they are easily sheared by external forces, thereby reducing friction and preventing seizure. Phosphate ester also reacts with steel in the same way as the chlorinated paraffin, producing iron phosphate (FePO ₄ .2H ₂ O), which has a low melting point and good slipperiness. This reaction proceeds in a temperature range from room temperature to about 180°C. As mentioned above, sulfurized oils and fats are extreme pressure additives other than chlorinated paraffins and phosphoric esters, but in the case of sulfurized oils, the extreme pressure reaction temperature range is
The temperature is high, 250°C or higher, and is not suitable for the purpose of the present invention. Although there is no extreme pressure additive that effectively exhibits extreme pressure effects in the temperature range from room temperature to about 200 degrees Celsius by itself, it is possible to achieve the objective of the present invention by blending the above-mentioned chlorinated paraffin and phosphoric acid ester in a predetermined amount. I got the idea that it would be possible to create a suitable extreme pressure additive. In order to assist the adsorption of the extreme pressure additive selected in this way onto the metal surface and to maintain the oil film thickness, it is necessary to select a base oil with a high viscosity index that functions as a carrier. Isobutylene and n-
A copolymer of butene is chosen. The copolymer is a substance commonly called polybutene, which is effective in maintaining the lubricant film thickness, shows little change in viscosity with temperature, is chemically stable, and has good stability against heat and ultraviolet rays. However, the above-mentioned copolymers have a drawback in adsorption to metal surfaces, and although the adsorption is better than that of mineral oil, the adsorption is not very good. Therefore, the present inventors thought that addition of an oiliness improver would be effective in supplementing the adsorption properties of the copolymer. The oiliness improver refers to animal/vegetable oils and fats, fatty acids, or fatty acid esters, and is composed of a long hydrocarbon group and a polar group. In oiliness improvers, the hydrocarbon group is similar to the lubricating oil molecule and dissolves it, while the polar group is different from the oil molecule, so it acts as an additive and improves the properties of the lubricating oil. . Furthermore, since metals and water have polar surfaces, molecules with polar groups are adsorbed to the surfaces of metals and water. For the reasons stated above, in the present invention, a mixture of the above-mentioned copolymer and an oiliness improver was used as the base oil. The base oil prepared in this manner exhibited a far superior lubricating effect compared to mineral oil alone. The viscosity of lubricant is one of the important items in drawing processing. The higher the viscosity, the higher the oil film retention effect and the better the lubrication performance.However, the purpose of the present invention is to improve the surface roughness due to the boundary lubrication state, and from this point of view, the viscosity of the lubricant becomes too high. This increase in the fluid lubrication area is not a desirable matter, and also causes problems in terms of workability. On the other hand, if the viscosity of the lubricant is too low, seizure accidents are likely to occur, which not only causes damage to the tool but also makes it difficult to improve the desired metal surface roughness. [Examples] Example 1 The present inventors conducted an experiment to investigate the optimal blending ratio of chlorinated paraffin and phosphoric acid ester.
The chlorinated paraffin with 12 carbon atoms and 70% chlorine content was used, and the phosphoric acid ester was dialkyl phosphite with 13 carbon atoms. A mixture of chlorinated paraffin and phosphoric acid ester has a viscosity of 30cst at 50℃.
Prototype oil No.a-1 ~ diluted with paraffinic mineral oil
A-6 was prepared. The reason for diluting with mineral oil is that the seizure load would be too high if only the extreme pressure additive was used. However, the seizure load test is based on the Defense Agency provisional standard.
The test was conducted at a rotation speed of 750 rpm in accordance with NDS/XXK2740 (Soda four-ball test method), and the wear marks after the test indicate the size of the marks in the "rotational direction x axial direction", and the friction coefficient is the Soda four-ball test method. This is a value determined using a pendulum type oil tester. The results are shown in Table 1.

【table】

[Table] As is clear from Table 1, the weight ratio of chlorinated paraffin and phosphate ester is 4:1 (prototype oil
No. a-2) was optimal. Therefore, in the present invention,
The weight mixing ratio of chlorinated paraffin and phosphoric acid ester was determined to be 4:1. The viscosity of the prototype oil with this formulation at 50°C was 200 cst. Example 2 Next, the present inventors conducted a steel ball passage test to investigate the appropriate blending ratio of the extreme pressure additive (prototype oil No. a-2) to the base oil, for which the blending ratio had been determined. . The steel ball through test is a performance test method proposed by the applicant (see Japanese Patent Application Laid-open No. 52-68493), in which a die as shown in Fig. 1 is made of SKD11 tempered material, and SUS304 is used. Size made of stainless steel
After applying lubricant to a 22 × 19 × 1.5 ^t × 40 ^l (mm) test piece (tube), insert it into the hole of the die, and 13/16
(20.64〓mm) steel balls for bearings, size
Deform the test piece by sequentially pushing it into the inner hole of the test piece with a push rod of 19.1 × 60 ^l × (tip) 10.3R (mm),
The load required for deformation and the surface condition of the test piece and steel ball were investigated. This test method judges the performance of the lubricant from the inner surface properties of the rolled test piece and the surface properties of the steel balls, and because it is conducted under conditions that are harsher than actual processing conditions, the performance of the lubricant cannot be evaluated. It can be judged strictly. Additionally, as the base oil, a mineral oil with approximately the same viscosity as the extreme pressure additive (a paraffinic mineral oil with a viscosity of 240cst at 50°C) was used, and adjustments were made so that the viscosity would not change due to the blending ratio. In this way, the prototype oil No.
Samples b-1 to b-6 were prepared, and the amount of extreme pressure additive required for the base oil was determined. The results are shown in Table 2. The evaluation criteria for the surface condition in Table 2 are as follows. (Surface condition) ×...Poor (deep linear scratches) △...Problem (slight linear scratches) ○...Good (no linear scratches but poor gloss) ◎...Excellent (no linear scratches) Good gloss)

【table】

[Table] As a result, the combination of extreme pressure additives was 40% of the total.
Weight% or more is preferable (prototype oil No. b-3 to b-
6). Example 3 Based on the results of Example 2, the average molecular weight (W)
is 1200, 2400 polybutene and the viscosity at 50℃ is
The base oil is a mixed oil of 30 cst animal/vegetable oils and fats, and the extreme pressure additives whose optimal blending ratio was selected in Example 1 are blended in various proportions to achieve a viscosity judged to be preferable (200 cst at 50°C). lubricating oil No.T1 so that
-a~T1-j, T2-a~T2-j, T3-a~T3
-j various lubricating oils were prepared. In this way, we investigated the optimal blending ratio of polybutene and animal/vegetable oils. The viscosity of polybutene with an average molecular weight of 1200 at 50°C was 12,000 cst, and the viscosity of polybutene with an average molecular weight of 2400 at 50°C was 24,000 cst.
Further, the determination was made by the same steel ball passing test as in Example 2. The results are shown in Tables 3 (1) to (3).

【table】

【table】

[Table] As is clear from Table 3 (1) to (3), lubricating oils with a viscosity of about 200±50 at 50°C gave good results in the steel ball penetration test. There was also a tendency for the treated surface to lose its gloss as the proportion of the extreme pressure additive increased, but no difference was observed due to the difference in the average molecular weight of polybutene. Therefore, polybutene has an average molecular weight (W) of 1200,
2400, or a mixture of the two, or one having an average molecular weight intermediate between the two. Example 4 In order to investigate in more detail the optimal blending ratio of extreme pressure additives and base oil, lubricating oils that were better than the results of Example 3 (lubricating oil No. T1-c, T1-h; T2-c, T2- h;
A pullout test was conducted on T3-c and T3-h). However, the pull-out test was conducted using SUS304 seamless pipe [22〓×
2.2 ^t (mm)] using an FSP type plug, 19〓×1.7 ^t
(mm) (section reduction rate of 26.5%), the state of the plug and the state of the pipe were investigated. The results are shown in Table 4, and an extremely good metal surface with good surface gloss and no linear scratches was obtained when the compounding ratio of the extreme pressure additive was in the range of 40 to 50% by weight. A chatter phenomenon occurred during drawing, leaving chatter marks on the metal surface. The evaluation criteria for the pull-out test are as follows. (Condition of plug) △... Seizure (not shown in Table 4, but shown in Table 5 below) ○... Light clouding is observed ◎... No abnormality (condition of pipe) △ ...There are light linear scratches (not shown in Table 4, but
(Represented in Table 5 below) ○...No linear scratches but poor gloss ◎...No linear scratches and good gloss (excellent)

[Table] Example 5 The present inventors determined that the chatter phenomenon was caused by the drawing speed and lubrication performance not being compatible, that is, the lubrication performance of the lubricating oil was too good. Therefore, we came up with the idea of adding a solid lubricant as a method to suppress the lubrication performance and prevent the chatter phenomenon without causing seizure or reducing the metal surface roughness. Among the lubricating oils shown in Table 4, good ones (lubrication No. T1-c, T1-h, T2-c, T2-h,) are mixed with solid lubricants in various proportions to create various lubricants. was prepared and subjected to the same pull-out test as in Example 4 to investigate the chatter phenomenon. The solid lubricant is a metal soap (such as Ca stearate) or an inorganic solid lubricant powder (talc, mica, etc.), and is mixed and dispersed in the above lubricating oil. The results are shown in Tables 5 (1) to (4). The evaluation criteria for the pull-out test were the same as in Example 4.

【table】

【table】

【table】

【table】

[Table] As is clear from Table 5 (1) to (4), stearic acid
20 to 30 when combined with either Ca or talc
The chatter phenomenon stopped at a blending ratio of % by weight, and the surface roughness of the workpiece was as good as in Example 4.
However, if the blending ratio exceeds 40% by weight, linear scratches will increase and the prepared lubricant will become paste-like, making workability extremely difficult. Therefore, the optimum blending ratio of the solid lubricant is based on 100 parts by weight of the lubricating oil.
A range of 20 to 30 parts by weight is preferred. The solid lubricant may also be a mixture of Ca stearate and talc. [Effects of the Invention] The present invention is configured as described above, but the key point is to determine the blending ratio of the selected extreme pressure additive and base oil, specify the viscosity, and eliminate the chattering phenomenon during drawing. By using a one-component lubricant with a solid lubricant dispersed therein, the following benefits can be enjoyed. (1) Since it is a one-liquid type, lubrication is easy (simply immerse the workpiece in this lubricant and dry it). (2) Metal workpieces with good surface roughness can be manufactured without surface grinding or other maintenance. (3) Since it does not use a chemical reaction like chemical conversion treatment, it is easy to remove after processing. (4) It can be used not only for processing metals, but also for processing metal wires, metal plates, etc.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a die used in the steel ball passing test.

Claims (1)

[Claims] 1 () A: A mixture of chlorinated paraffin and phosphoric acid ester in a weight ratio of 4:1: 40 to 50 parts by weight, B: A copolymer of isobutylene and n-butene whose average molecular weight is those that are 1200-2400 and those that are 50
50 to 60 parts by weight of a mixture with animal/vegetable oils and fats with a kinematic viscosity of 30 cst at °C, and 100 parts by weight of a lubricating oil with a viscosity of 200 ± 50 cst at 50 °C, () metallic soap and/or A lubricant for cold working of metals, characterized in that it contains 20 to 30 parts by weight of a solid lubricant, which is an inorganic solid lubricant powder.