JP5393963B2 - Rolling screw machining method - Google Patents

Description

  The present invention relates to a rolling screw machining method using a non-chlorine-based lubricating oil suitably blended for rolling screw machining.

  Examples of methods for processing a metal material include rolling, cutting, grinding, forging, pressing, drawing, and rolling. At that time, lubricating oil is used for preventing wear and chipping of the tool and improving the processing accuracy and quality of the metal material. Therefore, such lubricating oil is mainly required to have high lubricity. This is the same even when the thread is formed by rolling. Conventionally, chlorine-based lubricating oils that are excellent in lubricity and seizure resistance are often used as lubricating oils used in processing metal materials. However, when using chlorinated lubricants, the chlorinated additive components contained in the lubricant decompose during processing or over time, rusting metal materials and tools, and dioxins and other harmful substances are generated during incineration. The problem is pointed out that the life of the incinerator is shortened due to corrosion and damage to the incinerator. Therefore, there is a demand for a lubricating oil for processing a metal material that does not contain a chlorine-based additive and has a lubricity equivalent to or higher than that of a chlorine-based lubricating oil. Here, Patent Documents 1 to 4 have been proposed as non-chlorine lubricants having high lubricity and the like in rolling.

JP 57-42797 A JP-A-11-181458 JP 2001-348588 A JP 2006-249369 A

  By the way, when manufacturing a screw by rolling, a thread and a groove are formed by rotating a rolling tool and plastically deforming a material to be processed. For example, in order to manufacture a female screw, the rolling tap is rotated to plastically deform the inner peripheral surface of the screw pilot hole, and the thread 1 as shown in FIG. 1 is raised. At this time, the thread 1 is raised by the bending action so that surrounding materials gather together along the shape of the rolling tool, so that it does not gather together at the top 2 of the thread 1 as shown in FIG. A depression-like recess 3 is often formed. If it does so, the mechanical strength of the top part 2 will become weak, and there exists a possibility that the top part 2 may be missing at the time of fastening with a male screw. In addition, if a piece with a missing top portion 2 is engaged with a screw fitting portion (between the male screw flank and the female screw flank 4), the balance between the tightening torque and the axial force is lost and the shaft is broken. There is also a problem that the force (fastening force) is reduced and the removal work due to seizure becomes difficult. In addition, the flank angle of the female screw and the male screw is designed to be the same in order to ensure smooth sliding at the time of fastening and a reliable fastening force (60 ° for a general metric coarse screw specified in JIS B0205). However, if the recess 3 of the screw thread top 2 is large, there is a risk that an error may occur in the flank angle and the height of the screw thread. Such a problem becomes more serious as the recess 3 is larger, and the rolling speed is greatly affected along with the lubricity of the lubricating oil.

  On the other hand, Patent Documents 1 to 4 propose lubricating oils that can be suitably used for rolling, but these are not developed for rolling when forming threads. Therefore, although these lubricating oils have high lubricity, the thread formed by rolling is raised by the bending action, so if the lubricity is too high, the bending action is difficult to occur and the recess size at the top of the screw thread is difficult. Tend to be larger. Moreover, although the screw thread bulge (height) dimension and the dent dimension also affect the rotational speed at the time of rolling, Patent Documents 1 to 4 do not pay particular attention to the rolling rotational speed, and are formed thereby. No particular consideration has been given to the size of the recess at the top of the screw thread.

  However, in order to reduce the dent at the top of the screw thread, it is not practical to perform rolling at a special rotational speed that is generally not carried out so much. That is, if the rotational speed at the time of rolling is too low, the productivity is poor, and if the rotational speed is too high, there is a concern that the cost will increase and the loss of tools and processed materials will increase, leading to a deterioration in yield. Therefore, there is a need for a rolling method that can reduce the recess at the top of the screw thread as much as possible while ensuring lubricity suitable for thread formation without using a special rotation speed.

  Therefore, the present invention solves the above-described problem, and uses a non-chlorine lubricant having good lubricity, and manufactures a screw having a small recess at the top of the screw thread regardless of a special rotation speed. It is an object of the present invention to provide a rolled screw machining method capable of

  The rolling screw processing method of the present invention comprises (A) a base oil and (B) a basic calcium sulfonate, and contains the above component (B) in an amount of more than 0% by weight and 1.5% by weight or less. Processing can be performed at a rotational speed of 100 to 300 rpm using a system lubricant.

  Moreover, another rolling thread processing method of this invention has (A) base oil and (B) basic calcium sulfonate, and contains the said (B) component 2.0 to 2.5 weight%. It can be processed at a rotation speed of 180 rpm or more by using a non-chlorine lubricant.

  The work material is preferably low carbon steel. The lubricating oil to be used comprises (C) an oily agent and (D) a sulfur-based extreme pressure agent in addition to the components (A) and (B), and the component (C) is 1 to 5% by weight. It is preferable to contain the said (D) component 10 to 20weight%.

  According to the present invention, since non-chlorine-based lubricating oil is used, it is possible to avoid the environmentally friendly tool and the incinerator from being shortened. On top of that, the composition is suitable for rolling screw processing, so that it retains good lubricity without having a special rotation speed, and the recess at the top of the screw thread, specifically its width L (see Fig. 1). Can be reduced to 0.3 mm or less. That is, if the lubricating oil contains the basic calcium sulfonate (B) in an amount of more than 0% by weight and 1.5% by weight or less with respect to the base oil (A), it is rolled at a general rotational speed of 100 to 300 rpm. Even if processed, the width L of the recess at the top of the screw thread can be kept to 0.3 mm or less. Further, if the lubricating oil contains 2.0 to 2.5% by weight of the component (B) with respect to the base oil (A), even if the rolling process is performed at a rotational speed of 180 rpm or more, the dent at the top of the screw thread Can be kept below 0.3 mm, and the production speed can be increased. If it has good lubricity, the surface roughness of the thread will also be good.

  If low-carbon steel is used as a workpiece for screw machining, it is possible to form a screw thread with higher accuracy because it has better elongation than medium-carbon steel and high-carbon steel. If appropriate amounts of the oily agent (C) and the sulfur extreme pressure agent (D) are added to the lubricating oil, the properties of the lubricating oil are further improved. In addition, if such a relatively simple composition is used, the quality of the screw can be improved but the dent at the top of the screw thread becomes larger when the composition is complicated to support various characteristics in the lubricating oil. The danger like this can be avoided.

[About lubricating oil]
The lubricating oil of the present invention has a composition suitable for rolling screw processing, and basically comprises a base oil (A) as a main component of the lubricating oil and a basic calcium sulfonate (B) as a lubricant. Contains.

(A) Base oil The kind of base oil is not specifically limited, For example, what is generally used by metal material processing, such as mineral oil and synthetic oil, can be used widely. These may be used alone or in combination. As mineral oils, lubricating oil fractions obtained by subjecting crude oil to atmospheric distillation and vacuum distillation are subjected to solvent removal, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, hydrorefining, sulfur washing, What refine | purified by performing one or more processes, such as a white clay process, is mentioned. Examples of the synthetic oil include poly α-olefin, α-olefin copolymer, polybutene, alkylbenzene, polyoxyalkylene glycol, polyoxyalkylene glycol ether, and silicone oil.

(B) Basic calcium sulfonate Calcium sulfonate is a kind of sulfonate of alkaline earth metal, for example, petroleum sulfonic acid obtained by sulfonated aromatic component in petroleum distillate component, or dodecylbenzene sulfonic acid, Examples thereof include Ca salts of synthetic sulfonic acids such as dinonylnaphthalene sulfonic acid. In the present invention, basic calcium sulfonate is used. Basic calcium sulfonate is produced by adding an excess amount of calcium hydroxide to neutral calcium sulfonate and then blowing carbon dioxide. By adding the basic calcium sulfonate to the base oil, the dent generated at the top of the screw thread can be reduced to 0.3 mm or less while ensuring good lubricity suitable for rolling screw processing. The base number (TBN) of calcium sulfonate is preferably 250 mgKOH / g or more, more preferably 280 mgKOH / g or more. If the base number is less than 250 mgKOH / g, good lubricity may not be ensured. A basic calcium sulfonate may be used individually by 1 type, and multiple types may be mixed and used for it.

  An appropriate amount of basic calcium sulfonate is added according to the number of rotations during rolling. Specifically, when the rolling process is performed at a rotational speed of 100 to 300 rpm, it is more than 0% by weight and 1.5% by weight or less (lubricant X), and when the rolling process is performed at a rotational speed of 180 rpm or more, 2. 0 to 2.5% by weight (lubricant Y). The basic calcium sulfonate content exceeds 1.5% by weight during rolling at 100 to 300 rpm, or the basic calcium sulfonate content exceeds 2.5% by weight during rolling at 180 rpm or higher. If so, the lubricity becomes too high and the dent at the top of the screw thread becomes relatively large. However, even in this case, it is possible to form a screw thread satisfying JIS class 2 (0.5 mm or less), so that it can be used as a product. When basic calcium sulfonate is not added, or when the content of basic calcium sulfonate is less than 2.0% by weight during rolling at 180 rpm or more, good lubricity cannot be ensured, surface roughness and Seizure resistance also decreases.

  Further, in addition to the above component (B), the lubricating oil base oil does not impair the purpose of the present invention. For example, an oil agent, a sulfur-based extreme pressure agent, a viscosity adjusting oil, a rust inhibitor, an antioxidant, Various known additives such as anticorrosives, colorants, antifoaming agents, and fragrances can be appropriately blended. However, when a complicated composition is added with a large number of additives, the quality of the screw and the properties of the lubricating oil itself can be improved, but there is a risk that the dent at the top of the screw thread will become large. Therefore, it is preferable to have a composition that guarantees the minimum lubricating oil characteristics for rolling screw processing, and among the above-mentioned additives, a simple composition that adds an oily agent and a sulfur-based extreme pressure agent and It is preferable to do.

(C) Oily agent As oily agent, various synthetic ester compounds having ester groups, beef tallow, lard, linseed oil, safflower oil, soybean oil, sesame oil, corn oil, rapeseed oil, cottonseed oil, olive oil, rice bran oil Palm oil, palm oil, palm kernel oil, and hydrides thereof can be used. Since the oily agent adjusts the lubricating oil, its content may be about 1 to 5% by weight regardless of the number of rotations during rolling. Examples of ester compounds include caproic acid, caprylic acid, pelargonic acid, capric acid, undecylic acid, undecylenic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, oleic acid, elaidic acid , Linoleic acid, linolenic acid, stearolic acid, nonadecanoic acid, arachidic acid, arachidonic acid, behenic acid, celetic acid, erucic acid, brassic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, mellicic acid, lactelic acid, Mention may be made of ester compounds synthesized from carboxylic acids such as naphthenic acid, abietic acid, adipic acid, sebacic acid, phthalic acid, trimellitic acid, lanolin fatty acid, alkenyl succinic acid, oxidized wax and various alcohols.

  Alcohols employed for the synthesis of ester compounds include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol, n-amyl alcohol, isoamyl alcohol, hexyl. Alcohol, heptyl alcohol, octyl alcohol, capryl alcohol, nonyl alcohol, decyl alcohol, undecyl alcohol, lauryl alcohol, tridecyl alcohol, myristyl alcohol, pentadecyl alcohol, cetyl alcohol, heptadecyl alcohol, stearyl alcohol, isostearyl alcohol, oleyl Alcohol, nonadecyl alcohol, eicosyl alcohol, seryl alcohol , Mention may be made melissyl alcohol, neopentyl glycol, trimethylol propane, pentaerythritol, glycerol, polyalkylene glycols and the like.

(D) Sulfur-based extreme pressure agent Sulfur-based extreme pressure agents exhibit extreme pressure effects due to sulfur atoms, such as sulfurized fats, sulfurized fatty acids, sulfurized esters, sulfurized olefins, polysulfides, thiocarbamates, sulfide mineral oils. ZnDTP can be used, and one of these may be used, or two or more may be used in combination. Specifically, sulfurized fats and oils are obtained by reacting sulfur with fats and oils (lard oil, whale oil, vegetable oil, fish oil, etc.), and examples thereof include sulfurized lard, sulfurized rapeseed oil, sulfurized castor oil, and sulfurized soybean oil. . Examples of the sulfurized fatty acid include sulfurized oleic acid, and examples of the sulfurized ester include sulfurized methyl oleate and sulfurized rice bran fatty acid octyl. Examples of the polysulfides include dibenzyl polysulfide, di-tert-nonyl polysulfide, didodecyl polysulfide, di-tert-butyl polysulfide, dioctyl polysulfide, diphenyl polysulfide, dicyclohexyl polysulfide and the like. Examples of thiocarbamates include zinc dithiocarbamate, dilauryl thiodipropionate, and distearyl thiodipropionate. Sulfide mineral oil is obtained by dissolving elemental sulfur in mineral oil.

  The content of component (D) is 10 to 20% by weight, preferably 12 to 18% by weight, regardless of the number of rotations during rolling. When the content of the component (D) is less than 10% by weight, the extreme pressure effect cannot be effectively exhibited. On the other hand, when the content of the component (D) exceeds 20% by weight, there is a possibility that stains or rust may be generated on the workpiece or the lubricity becomes too high.

Thus, the lubricating oil X and the lubricating oil Y having the components (A) and (B) and, if necessary, the components (C) and (D) can be appropriately selected and used according to the rotational speed. At this time, 40 ° C. kinematic viscosity of the lubricating oil X and lubricants Y is preferably ^{10~20mm 2 / s, 12~18mm 2 /} s is more preferable.

[About rolling]
The rolling process may be performed by a known method in which the inner peripheral surface of the pilot hole is plastically deformed using a rolling tap and is raised so that surrounding materials gather together along the shape of the rolling tool by bending. . The principle of forming the thread and the dent at the top is as described above. The screw material as the workpiece is preferably low carbon steel. Carbon steel includes low carbon steel with a carbon content of about 0.3 mass% or less, medium carbon steel with about 0.3 to 0.7 mass%, and high carbon steel with about 0.7 mass% or more. As the hardness increases, the hardness increases but tends to become brittle. On the other hand, when the carbon content is low, elongation and drawing are good. Therefore, low-carbon steel is preferable in rolling screw processing for plastic deformation of the material. In addition, when using the above-described lubricating oil that is appropriately blended according to the number of rotations in rolling screw machining, the dent at the top of the screw thread can be reduced.

  The rolling process is generally performed at a rotation speed of about 100 to 300 rpm, but the rotation speed greatly affects the formation of a recess at the top of the screw thread. That is, even if the same lubricating oil is used, the size of the recess at the top of the screw thread varies depending on the number of rotations. Therefore, when it is desired to reduce the recess at the top of the screw thread, it is not sufficient to improve the characteristics of the lubricating oil, and it is necessary to adjust the rotational speed. However, various problems may occur if the rolling process is performed at a rotational speed that is not generally performed. Therefore, the lubricating oil of the present invention can reduce the dent at the top of the screw thread without using a special rotational speed by using a lubricating oil appropriately blended in accordance with a rolling process at a general rotational speed. Is noticed. Specifically, when rolling at a relatively low rotational speed of 100 to 300 rpm, the lubricating oil X containing 0% by weight to 1.5% by weight or less of basic calcium sulfonate is used. When the rolling process is performed at 180 rpm with a high rotational speed, a lubricating oil Y containing 2.0 to 2.5% by weight of basic calcium sulfonate may be used. The upper limit of the rotational speed when rolling using the lubricating oil Y is not particularly limited, but is preferably about 400 rpm, more preferably about 300 rpm.

  Here, in JIS class 2, the width dimension of the recess at the top of the screw thread is defined as 0.5 mm or less. Therefore, unless quality is taken into consideration, a screw product can be established if the width of the dent is 0.5 mm or less. In addition, if the width dimension of a dent is large, the depth will also become deep along with this. Therefore, if the width dimension of the dent is large, the dent itself is also large. However, in order to obtain a high-quality screw, it is preferable that the recess at the top of the screw thread be as small as possible. For example, if the width dimension of the dent is close to 0.5 mm, even if there is basically no major inconvenience in use, a fastening failure sometimes occurs. This is not a big problem when used in a general household, but is low in reliability when used as a part that requires high accuracy such as an automobile part. On the other hand, if the width of the recess at the top of the screw thread can be reduced to 0.3 mm or less, the possibility of fastening failure can be greatly reduced. This has been demonstrated from the experience of the inventors. In addition, according to the rotational speed at the time of rolling, the width of the recess at the top of the screw thread should be 0.3 mm or less by properly using the lubricating oil X and the lubricating oil Y having appropriate lubricity. Can do.

(Example)
<Lubricity test>
First, using each lubricating oil having the composition shown in Table 1, the torque when the rolling process was performed was measured at various rotational speeds (specifically, 100 rpm, 140 rpm, 170 rpm, 200 rpm, 280 rpm). The result is shown in FIG. Here, basic calcium sulfonate having a base number of 280 mgKOH / g was used. The lubricating oil 3 corresponds to the previous lubricating oil X, and the lubricating oil 4 corresponds to the previous lubricating oil Y.

The rolling process at this time was performed under the following conditions.
Rolling processing equipment: Hitachi Seiko's Machining Center VG45 type Tap: 3 / 4-16UNF RH11-P 7558 OSG HSSE UD-8117-6
Workpiece: Material; SOHE-P pilot hole diameter; 80mm length; 5mm
Torque measuring machine: Nippon Kisler 4 component dynamometer 9272 for tapping

  From the results shown in FIG. 2, the rotation speeds of the lubricating oil 3 and the lubricating oil 4 containing basic calcium sulfonate are higher than those of the lubricating oil 2 containing no chlorine-based lubricating oil 1 and basic calcium sulfonate. Torque was low even with numbers. Thereby, it turns out that lubricity can be improved when basic calcium sulfonate is added to lubricating oil. Further, when the lubricating oil 3 and the lubricating oil 4 were compared, the torque was lower when the content of the basic calcium sulfonate was higher. Thereby, it turns out that the one where there is much content of basic calcium sulfonate has high lubricity. It has been found that the torque tends to decrease as the rotational speed increases.

<Indentation size>
Next, the width dimension L (refer FIG. 1) of the dent of each screw thread top part manufactured by the previous lubricity test was measured. The result is shown in FIG.

  From the results of FIG. 3, the lubricating oil 1 and lubricating oil 2 that do not contain basic calcium sulfonate have any rotational speed compared to the lubricating oil 3 and lubricating oil 4 that contain basic calcium sulfonate. It can be seen that the width L of the dent is small. Accordingly, it can be seen that it is preferable that the lubricity of the lubricating oil is low in order to reduce the recess at the top of the screw thread. This is due to the fact that the rolling process is plastic deformation by bending. However, if the lubricity is low, the processing itself cannot be performed smoothly. On the other hand, in the lubricating oil 3, the width L of the recess at the top of the screw thread is 0.3 mm or less at any number of rotations, and the thread is small and accurate while having good lubricity. It can be seen that can be formed. That is, according to the lubricating oil X, it can be seen that an accurate thread can be formed even at a general rotational speed. On the other hand, in the lubricating oil 4, the width L of the dent exceeded 0.3 mm at the rotation speeds of 100 rpm, 140 rpm, and 170 rpm, whereas the width L of the dent was less than 0.3 mm at the rotation speeds of 200 rpm and 280 rpm. It was. Accordingly, in the case of the lubricating oil Y, it can be seen that if the rolling process is performed at a rotational speed of about 180 rpm or more, a precise thread can be formed. Further, from the result that the lubricating oil 3 having a lower basic calcium sulfonate content than the lubricating oil 4 can make the dent smaller, when the rolling process is performed at a rotational speed of 100 to 300 rpm, the basic calcium sulfonate content of the lubricating oil is 1. It can be derived that the content should be about 5% by weight or less. On the other hand, when rolling at a rotational speed of 180 rpm or more, it can be derived that the content may be about 2.0 to 2.5% by weight.

It is sectional drawing of a screw thread. It is a graph which shows the relationship between a rotation speed and a torque. It is a graph which shows the relationship between a rotation speed and the width dimension of a dent.

Explanation of symbols

1 Thread 2 Thread Top 3 Thread Top Recess 4 Frank L Recess Width

Claims (3)

(A) a base oil, (B) a basic calcium sulfonate, (C) an oil-based agent, and (D) a sulfur-based extreme pressure agent,
Non-chlorine type containing (B) component more than 0% by weight and 1.5% by weight or less, (C) component 1-5% by weight, and (D) component 10-20% by weight Using the lubricating oil
A rolling screw machining method for machining at a rotational speed of 100 to 300 rpm. (A) base oil, (B) basic calcium sulfonate, (C) oil-based agent, and (D) sulfur-based extreme pressure agent ,
Non-chlorine lubrication containing 2.0 to 2.5% by weight of component (B) , 1 to 5% by weight of component (C), and 10 to 20% by weight of component (D). Using oil,
A rolling screw machining method for machining at a rotation speed of 180 rpm or more. The rolling screw machining method according to claim 1 or 2, wherein the workpiece is low carbon steel.

Images