JPH0819814A - Method for cold stretching steel tube and device therefor - Google Patents

Abstract

PURPOSE:To prevent the generation of burning by heating lubricating oil in a circulation system between a centrifugal separator and a tank to a specified temp., providing a cooling means between the centrifugal separator and a stretching machine, cooling the lubricating oil to a specified temp. and applying the oil on the surface of steel tube. CONSTITUTION:The lubricating oil is sprayed on the steel tube 1 from a spray nozzle 7 and the steel tube 1 is stretched with a die 2. The lubricating oil is recoveried in a hopper 8 and sent to permanent magnets 11 which are provided on a inclined plate 10. Scale in the lubricating oil is attracted and removed with the permanent magnets 11. The lubricating oil whose scale is removed is stored in the tank 17. The lubricating oil is circulated between the tank 17 and the centrifugal separator 18, heated to 40-70 deg.C and its fine scale is removed with the centrifugal separator 18. The lubricating oil whose fine scale is removed is cooled to <=39 deg.C with a cooling system 21 and supplied to the spray nozzle 7. By heating the lubricating oil to 40-70 deg.C, the efficiency of scale removal in the centrifugal separator 18 is improved. By cooling the oil to <=39 deg.C, the viscosity of the lubricating oil is raised.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold drawing method and apparatus for steel pipes by an oil lubrication method which is one of the cold drawing lubrication methods for steel pipes.

[0002]

2. Description of the Related Art Cold drawing work applied to high-quality pipes for nuclear power, high-temperature and high-pressure boilers, etc. and steel pipes for machine structures requiring high dimensional accuracy is performed by narrowing one end of the steel pipe (narrowing) and then After pickling, it is lubricated, and the neck drawing part is gripped by the chuck of the cold drawing machine, and the hook of the carriage is hooked on the rotating chain to pull it out. The purpose of the lubrication treatment in this cold drawing is to reduce the friction between the steel pipe and the die or between the steel pipe and the plug, and prevent seizure due to local concentration of friction heat.

The cold drawing lubrication method for steel pipes includes a chemical conversion treatment method,
There are resin coating method and oil lubrication method, but the chemical conversion treatment method is the mainstream at this stage. The chemical conversion treatment method involves immersing a descaled steel pipe in accordance with the type of steel in a base liquid such as phosphate or oxalate to form a certain film, and removing excess base liquid adhering to the surface by washing with water. After neutralizing the acid by neutralization, dip it in a lubricating bath such as sodium stearate solution to react with the underlying coating to form a lubricating coating with metallic soap in the middle and dry it There is a problem in terms of cost and man-hours, and the oil lubrication method, which is the best in terms of simplification of the cold drawing process, is being shifted.

As a cold drawing method of a steel pipe by the oil lubrication method, at least the inner surface of the inner and outer surfaces of the raw pipe is sprayed with particles, and then cold drawing is performed by using a liquid lubricating oil as a lubricant for the raw pipe. (JP-A-57-160515),
A method in which a high-viscosity lubricating oil is charged from the rear end of a steel pipe having a mouth end, is pushed into a die by a plug, and is pulled out through the high-viscosity lubricating oil (Japanese Patent Laid-Open No. 61-172613), wire or When cold drawing the cross-sectional reduction rate of the pipe to 30% or more, after pickling the wire or pipe, 10 to 60% by weight of base oil and dialkyl polysulfide 10 of low temperature separation type sulfur extreme pressure additive -60% by weight and a thickener of 35% by weight or less, or base oil 1
0-60% by weight, low temperature separation type sulfur extreme pressure additive dialkyl polysulfide 10-60% by weight, high temperature separation type sulfur extreme pressure additive 20-60% by weight and thickener 35
Or 10% to 60% by weight of a base oil, 10 to 60% by weight of a low temperature separation type sulfur extreme pressure additive dialkyl polysulfide, and 20 to 20% of a high temperature separation type sulfur extreme pressure additive. 60% by weight and talc powder 10-4
A method in which 0% by weight is mixed and a lubricating oil adjusted to have a viscosity of 100 to 5000 centipoise at 40 ° C. is used (JP-A-62-236896), carbon steel, alloy steel wire, rod or tube. After pickling, the surface of the material is 5 to 40% by weight of a dialkyl polysulfide having a sulfur content of 30% by weight or more, and a compound of fats and oils and an olefin in which the sulfur content is 15% by weight or more. A bound ester, a higher ester compound of an unsaturated higher fatty acid and an unsaturated higher alcohol, in which the sulfur content is 15
Compounds containing more than 1% by weight, and compounds of higher ester compounds and olefins, in which the sulfur content is 1
One or two or more kinds selected from those bound by 5% by weight or more, one or more kinds of base oils selected from fats and oils, synthetic oils, mineral oils and higher fatty acids, polyisobutylene thickeners, olefins It is composed of at least one or more thickeners selected from copolymer thickeners and polymethacrylate thickeners, and has a viscosity of 100 at 20 ° C.
A method (Japanese Patent Publication No. 4-48839) in which a lubricant having a viscosity of 3,000 centipoise is applied and cold drawing is performed is proposed.

In the cold drawing method for steel pipes by the oil lubrication method disclosed in each of the above publications, the lubricating oil is recovered and reused. In the lubrication oil circulation path, if iron powder or other scale is present in the lubrication oil, flaws such as scratches and scratches will occur on the surface of the product steel pipe during cold drawing, and seizure flaws will start from the flaws. There was a problem that it occurred.

As a countermeasure against this, as shown in FIG. 3, a hopper 32 for recovering an excess of the solid lubricant-free lubricant oil supplied to the surface of the steel pipe 31 immediately before cold drawing, An inclined plate 3 which is interposed between the hopper 32 and the lubricating oil supply pipe 33 and which can change the inclination angle.
4 and a drawing device having a lubricating oil circulation circuit provided with a scale removing device 36 having a magnetic device 35 installed on the inclined plate 34 for adsorbing the scale in the recovered lubricating oil. Is installed at the next stage of the tank 37 that primarily stores the scale-removed lubricating oil, and a centrifugal separator 39 that sucks the lubricating oil in the tank 37 through a pipe 38 is installed. After removing fine scale again by 39, return to the tank 37 and pipe 4
Cold drawing device (actual Kaihei 1
No. 143607) has been proposed.

[0007]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the cold drawing apparatus disclosed in Japanese Patent No. 607, scales such as iron powder in lubricating oil are removed by a scale removing device 36 equipped with a magnetic device 35, and then a fine scale is removed by a centrifugal separator 39 again. However, in order to improve the separability of the fine scale in the centrifuge 39, a heater (not shown) is provided in the circulation path to heat the temperature of the lubricating oil to 40 to 70 ° C. The reason is that when the temperature of the lubricating oil is 40 ° C. or less, the viscosity becomes high and the removal efficiency of the iron powder in the lubricating oil decreases, and when it exceeds 70 ° C., the separation of the sulfur compounds in the lubricating oil becomes severe. . However, when the temperature of the lubricating oil is heated to 40 to 70 ° C. by the heater, the viscosity of the lubricating oil decreases as shown in FIG. 4, and as a result, as shown in FIG. The performance could not be obtained, and seizure flaws might occur in the cold drawn product.

An object of the present invention is to eliminate the problems of a cold drawing apparatus for removing fine scale in circulating lubricating oil by a centrifuge and to prevent the occurrence of seizure flaws in cold drawn products. It is to provide a drawing method and apparatus.

[0009]

Means for Solving the Problems The present inventors have conducted various tests and studies to achieve the above object. As a result, the lubricating oil viscosity is reduced by installing a cooling device in the piping system that supplies the lubricating oil from which fine scale has been removed by the centrifugal separator to the oil coating nozzle, and cooling the lubricating oil that is supplied to the oil coating nozzle to 39 ° C or less. Can be held at 500 to 30,000 centipoise,
It has been confirmed that the reduction of the oil film thickness is suppressed, seizure in cold drawing can be prevented, and the tool can be cooled to prolong the life of the tool.

That is, according to the present invention, in a cold drawing method for a steel pipe having a centrifugal separator in a lubricating oil circulation system in a cold drawing step, the lubricating oil in the circulation system between the centrifugal separator and the tank is 40
Characterized by heating to ˜70 ° C., providing a cooling means for lubricating oil between the centrifuge and the cold drawing machine, cooling the lubricating oil to 39 ° C. or less, applying oil to the steel pipe surface, and performing cold drawing. This is a cold drawing method for steel pipes.

Further, in the cold drawing apparatus for steel pipes having a hopper for recovering the residual lubricating oil in the cold drawing step and a centrifugal separator between the hopper and the lubricating oil supply pipe for the cold drawing step, A cold drawing apparatus for steel pipes, wherein a cooling device is provided in a lubricating oil supply system between the centrifuge and the cold drawing machine.

[0012]

In the present invention, by heating the lubricating oil in the circulation system between the centrifuge and the tank to 40 to 70 ° C., the scale removal efficiency in the centrifuge is improved, and moreover, the centrifugal separator and the cooler are cooled. By providing a cooling means for the lubricating oil between the hot drawing machines, cooling the lubricating oil to 25 ° C. or lower, applying the oil to the surface of the steel pipe, and cold drawing, the lubricating oil has a viscosity of 150.
It can be maintained at about 0-3000 centipoise, can form an oil film of sufficient thickness on the surface circumference of the steel pipe, can prevent seizure during cold drawing, and can also cool the tool to extend the tool life. it can.

Further, in the present invention, in a cold drawing apparatus for a steel pipe having a hopper for recovering the residual lubricating oil in the cold drawing step and a centrifuge between the hopper and the lubricating oil supply pipe, By providing a cooling device in the lubricating oil circulation system between the centrifuge and the cold drawing machine, the lubricating oil controlled at 40 to 70 ° C. for improving the scale removal efficiency in the centrifuge is supplied to the steel pipe. An oil film having a sufficient thickness can be formed on the surface circumference and can be cooled to a temperature to prevent seizure in cold drawing, and the tool can be cooled to prolong the tool life.

The cooling temperature of the lubricating oil by the cooling means in the present invention is set to 39 ° C. or lower because the lubricating oil temperature is 40 ° C.
This is because if the temperature exceeds ℃, seizure easily occurs in the cold drawing process. The lower limit of the cooling temperature varies depending on the type of lubricating oil, but may be within the temperature that does not affect the oil coating property. The lubricating oil used in the present invention is not particularly limited, but for example, JP-A-62-236.
10 to 60% by weight of base oil disclosed in Japanese Patent No. 896, 10 to 60% by weight of a low temperature or high temperature decomposition type sulfur extreme pressure additive, and 35% by weight or less of a thickener are mixed, and a viscosity at 40 ° C Is adjusted to be 100 to 5000 centipoise, or a dialkyl polysulfide having a sulfur content of 30% or more disclosed in JP-B-4-48839.
40%, a compound of fats and oils and olefins having a sulfur content of 15% or more bound to the compound, a higher ester compound of an unsaturated higher fatty acid and an unsaturated higher alcohol, and the sulfur content in the compound. 20 to 70% of one or two or more compounds selected from those having 15% or more bonded thereto and compounds of higher ester compounds and olefins having a sulfur content of 15% or more bonded thereto, and fats and oils. , One or more base oils selected from synthetic oils, mineral oils and higher fatty acids, and at least one selected from polyisobutylene thickeners, olefin copolymer thickeners and polymethacrylate thickeners A lubricating oil composed of the above thickeners and having a viscosity of 500 centipoise or more at 20 ° C. can be used.

Examples of the base oil of the lubricating oil include mineral oil such as machine oil, rapeseed oil, lard oil, palm oil, castor oil, animal and vegetable oils such as beef tallow, dioctyl sebacate, synthetic oil such as pentaerythritol derivative, and caprylic acid. And fatty acids such as capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, and erucic acid. As the low temperature decomposition type sulfur extreme pressure additive, 2 to 6 of ethylene or propylene as an alkyl group is used.
A general formula R-Sx-R having a sulfur content of 25 to 50% by weight, which is obtained by reacting 3 to 8 molecules of sulfur with a monomer,
R is an alkyl group having 6 to 12 carbon atoms, and Sx is a dialkyl polysulfide having 3 to 8 molecules of sulfur). High temperature decomposition type sulfur-based extreme pressure additives are sulfurized fats and oils, and examples of fats and oils include rapeseed oil as vegetable oil, cottonseed oil, lard oil as animal oil, beef tallow, sperm oil, orange laffy oil, etc. It is 20% by weight. As a thickener, an average molecular weight of 5,000 to 30,000
0 polyolefin type, average molecular weight 10,000-100
Olefin copolymer system of 0000 (ethylene-propylene-butylene system), average molecular weight 20,000 to 15,000
The polymethacrylate type of No. 00 is mentioned, but the polymethacrylate type is preferable. Polyacrylate is
1 selected from polymethacrylates of the following general formula
Use more than species.

[0016]

Embedded image

As the polar monomer of the polar group in the above structural formula, amines such as diethylaminoethyl methacrylate (1) and 2-methyl-5-vinylpyridine (2), and amide polyalkylene glycols such as N-vinylpyrrolidinone (3) are used. There are esters (4) and maleic anhydride (5). In the present invention, powders of talc, graphite, boron nitride, calcium carbonate, molybdenum sulfide, etc., which are solid lubricants, can be added to the lubricating oil component. The solid lubricant is carried between the drawing tool and the work material to prevent direct contact and prevent seizure. Further, in the present invention, a surfactant can be used in order to enhance the removal efficiency of alkaline degreasing of the lubricating oil after drawing.

In the present invention, as the cooling device provided in the lubricating oil circulation system between the centrifugal separator and the cold drawing machine, 40 to 40
Lubricating oil at 70 ° C is 39 ° C or less, preferably 15 to 30 ° C
It is only necessary that the cold water and the lubricating oil are cooled by using a vapor compression refrigerator or an absorption refrigerator used as an industrial cold water producing device, and the multi-tube cylindrical heat exchanger, plate type A method of cooling using a heat exchanger or the like, or a method of using lubricating oil as a cooled object of a vapor compression refrigerator or an absorption refrigerator can be used.

The drawing tool used for cold working usually uses a tungsten carbide system of cemented carbide.
In order to improve the seizure resistance, for example, a titanium carbide, titanium nitride, boron-titanium-based, boron-zirconium-based coating, or a ceramics-sintered extraction tool can be used for the extraction tool.
In cold drawing of steel pipes, a phosphate film or an oxalate film is usually applied because a film formed on the surface of a work is less likely to seize than a pickled skin. Further, rust, annealed oxide scale and the like have an effect of preventing seizure, but it is preferable to perform pickling treatment in order to improve the surface quality after cold drawing. As the pickling solution in the pickling treatment, 5 to 2
A 0% sulfuric acid aqueous solution, a 5-20% hydrochloric acid aqueous solution, a 5-20% phosphoric acid aqueous solution, or the like is used. The temperature of the pickling solution is 35 to 60 ° C. in the case of sulfuric acid aqueous solution, and room temperature to 40 in the case of hydrochloric acid aqueous solution.
℃, in the case of phosphoric acid aqueous solution, 35 ~ 60 ℃ is suitable.
The pickling time is required to be able to remove the rust and scale on the surface of the material to be treated, but immersion for 10 to 30 minutes is usually sufficient. As the neutralizing solution after pickling, for example, 0.2 to
A 5% sodium hydroxide aqueous solution, a 0.2-5% sodium carbonate aqueous solution, a 0.2-5% sodium borate aqueous solution, a 0.2-5% sodium phosphate aqueous solution, a 0.2-5% lime aqueous solution, etc. may be used. it can. For the neutralization treatment, immersion at room temperature to 90 ° C. for 5 seconds to 5 minutes is sufficient. The lubricating oil can be applied by a dipping method, a pouring method, a spray method, or the like.

[0020]

【Example】

Embodiment 1 Details of the present invention will be described below with reference to FIG. 1 showing an embodiment. FIG. 1 is an overall explanatory view showing an example of an apparatus for carrying out the method of the present invention. In FIG. 1, 1 is a steel pipe to be drawn, 2 is a die, 3 is a charging guide, 4 is a mandrel, 5 is a plug, 6 is a lubricating oil supply device connected to the rear end of the mandrel 4, and 7 is immediately before drawing. Is a spray nozzle for supplying lubricating oil to the outer surface of the steel pipe 1, and 8 is a hopper for collecting the remaining lubricating oil of the lubricating oil supplied from the nozzle 7 to the outer surface of the steel pipe 1. Reference numeral 9 denotes a scale removing device that removes scale in the lubricating oil collected by the hopper 8. The scale removing device 9 has a tilting plate 10 whose tilt angle can be changed, and a permanent plate which is installed on the tilting plate 10 to adsorb the scale contained in the lubricating oil. A magnet 11 and a cylinder 12 for separating the inclined plate 10 from the permanent magnet 11.
And a scraping mechanism 13 for scraping off the scale adsorbed and separated on the inclined plate 10.

For the scale adsorbed and separated by the scale removing device 9, the supply of the lubricating oil is stopped, the cylinder 12 is operated, the inclined plate 10 is separated from the permanent magnet 11, and then the scraping mechanism 13 is operated. The scale is scraped from the surface of the inclined plate 10 into the chute 14. Reference numeral 15 is a dolly for carrying a drum 16 for collecting the scale scraped into the chute 14. Reference numeral 17 is a tank for temporarily storing the lubricating oil from which the scale has been separated, and 18 is a centrifugal separator that sucks the lubricating oil in the tank 17 through a pipe 19, and the lubricating oil from which the fine scale has been removed again by the centrifugal separator 18 Is
It is returned to the tank 17 via the return pipe 20. The lubricating oil temperature in the lubricating oil circulation path between the tank 17 and the centrifuge 18 is controlled to 50 to 55 ° C. 21 is a tank 17
With a cooling device provided in the lubricating oil supply system 6 and the lubricating oil supply system 22 to the nozzle 7, heat is exchanged between the cooling medium 23 and the lubricating oil to cool the lubricating oil to 39 ° C. or less. The lubricating oil cooled to 39 ° C. or less by the cooling device 21 is configured to be supplied to the lubricating oil supply device 6 and the nozzle 7 via the lubricating oil supply system 22. A cooling controller 24 controls the flow rate adjusting valve 26 of the cooling medium 23 based on the temperature measurement result of the temperature detector 25 provided in the outlet lubricating oil supply system 22 of the cooling device 21 so that the lubricating oil temperature is The temperature is controlled to reach a preset temperature. Reference numeral 27 is a lubricating oil supply pipe, and 28 is a discharge pipe for the cooling medium 23.

With the above construction, the lubricating oil supplied to the outer surface of the steel pipe 1 to be drawn by the nozzle 7 and the lubricating oil supply device 6 connected to the rear end of the mandrel 4 are used to plug the plug 5. The lubricating oil supplied to the inner surface of the steel pipe 1 from the section is 39 ° C. in the cooling device 21.
Hereinafter, since the temperature is desirably cooled to 15 to 30 ° C., the viscosity of the lubricating oil is maintained at 500 to 5000 centipoise,
The viscosity is sufficient to apply oil evenly to the outer and inner surfaces of the steel pipe 1. Also, the temperature of the lubricating oil is 39 ° C or lower,
Desirably, by cooling to 15 to 30 ° C., the oil film thickness of the applied lubricating oil becomes thicker, and seizure due to insufficient lubrication can be prevented in the drawing process.
The tools such as the die 2 and the plug 5 are also cooled, and the tool life can be extended.

Example 2 Using the apparatus described in Example 1, C: 0.18%, S
i: 0.35%, Mn: 0.45%, P: 0.035
%, S: 0.035%, a balance steel having an outer diameter of 31.8 mm and a thickness of 4.5 mm consisting of Fe and unavoidable impurities, the lubricating oil shown in Table 1 was used, and the oil coating temperature was 15 ° C. ,
Change to 30 ℃ and 45 ℃, surface reduction rate 30.9%, drawing speed 40m / min, drawing tool semi-floating die, 4 pieces each with cold floating drawing, outer diameter 25.0mm, wall thickness A 4.0 mm steel pipe was manufactured. Then, the seizure rate in the cold drawing process was investigated. The result is shown in FIG.

[0024]

[Table 1]

As shown in FIG. 2, the oil coating temperature of the lubricating oil is set to 3
By keeping the temperature below 9 ° C, seizure can be prevented from occurring in the cold drawing process, but the lubricating oil coating temperature is 45
In the case of ° C, seizure occurs in 50%, and the effect of the method of the present invention is clear.

Example 3 Using the apparatus described in Example 1, C: 0.18%, S
i: 0.35%, Mn: 0.45%, P: 0.035
%, S: 0.035%, balance Fe and unavoidable impurities with an outer diameter of 54.0 mm and a wall thickness of 3.4 mm, when artificial defects were given to the surface of the raw pipe before the drawing process. When not applied, the lubricating oils shown in Table 1 were used, and when the oil coating temperature was 40 ° C and 25 ° C,
Area reduction rate 18.0%, drawing speed 20 m / min and 4
0m / min, drawing tool semi-floating die,
Cold drawing with semi-floating plug, outer diameter 5
A steel pipe having a thickness of 0.0 mm and a thickness of 3.0 mm was manufactured. The Max die temperature and the drawing condition in that case were investigated. The results are shown in Table 2.

[0027]

[Table 2]

As shown in Table 2, the drawing speed is 40 m /
When the oil painting temperature is 40 ° C, seizure occurs during cold drawing at a min. of min. However, in the case of the present invention where the oil painting temperature is 25 ° C, even if the drawing speed is 40 m / min, If no flaws were applied, no seizure occurred, and even if artificial flaws were applied, a linear gloss was generated and no seizure occurred.

[0029]

As described above, according to the present invention,
By setting the lubricating oil to 39 ° C. or less, it is possible to prevent seizure from occurring during cold drawing of the steel pipe, and further to extend the tool life by cooling the drawing tool.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing an example of a cold drawing apparatus for steel pipes for carrying out the method of the present invention.

FIG. 2 is a graph showing the relationship between the oil application temperature of lubricating oil and the seizure rate in Example 2.

FIG. 3 is a schematic explanatory diagram of an oil coating device including a scale removing device for lubricating oil disclosed in Japanese Utility Model Laid-Open No. 1-143607.

FIG. 4 is a graph showing the relationship between lubricating oil temperature and viscosity.

FIG. 5 is a graph showing the relationship between lubricating oil temperature and oil film thickness.

[Explanation of symbols]

 1, 31 Steel tube 2 Die 3 Charging guide 4 Mandrel 5 Plug 6 Lubricating oil supply device 7 Spray nozzle 8, 32 Hopper 9, 36 Scale removing device 10, 34 Slanting plate 11 Permanent magnet 12 Cylinder 13 Scraping mechanism 14 Chute 15 Truck 16 Drum Cans 17, 37 Tanks 18, 39 Centrifuges 19, 38 Piping 20, 40 Return Piping 21 Cooling Device 22 Lubricating Oil Supply System 23 Cooling Medium 24 Cooling Control Device 25 Temperature Detector 26 Flow Control Valve 27 Supply Pipe 28 Discharging Pipe 33 supply pipe 35 magnetic device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiei Nagaei 1-151-1 Nihonbashi, Chuo-ku, Tokyo Japan Parkerizing Co., Ltd. (72) Inventor Takashi Koyama 1-15-1 Nihonbashi, Chuo-ku, Tokyo Japan Parkerizing Within the corporation

Claims (2)

[Claims] 1. In a cold drawing method for a steel pipe having a centrifugal separator in a lubricating oil circulation system in a cold drawing process, the lubricating oil in the circulation system between the centrifugal separator and the tank is heated to 40 to 70 ° C.,
Lubricating oil cooling means is provided between the centrifuge and the cold drawing machine, the lubricating oil is cooled to 39 ° C. or lower and applied to the surface of the steel pipe,
A cold drawing method for a steel pipe, characterized by cold drawing. 2. A cold drawing apparatus for a steel pipe having a hopper for collecting the residual lubricating oil in the cold drawing step and a centrifugal separator between the hopper and the lubricating oil supply pipe for the cold drawing step, A cold drawing apparatus for steel pipes, wherein a cooling device is provided in a lubricating oil supply system between the centrifuge and the cold drawing machine.