JPS59110736A - Continuous spheroidization of steel wire - Google Patents

Abstract

PURPOSE:To perform the titled treatment in high efficiency and high yield, by a method wherein a lubricating under-coat agent and a powdery lubricant are applied to the surface of a hot rolled wire material after descaling and, after wire drawing processing a surface flaw is removed from the obtained wire which is then repeatedly subjected to annealing process to be allowed to cool. CONSTITUTION:After a hot rolled wire material 1 is mechanically descaled, the descaled wire material 1 is passed through a lubricant tank 5-1 in which a powdery lubricating under coat agent is stored and further passed through a pressure bonding die 6-1 to bond a lime powder to said wire material under pressure. Succeedingly, the treated wire material 1 is passed through a lubricant tank 5-2 in which a reinforcing lubricant is received and a pressure bonding die 6-2, subsequently, a lubricant tank 5-3 in which a lubricant before a wire drawing die is stored and the wire drawing die 6-3 to be finished into a predetermined wire diameter. In the next step, the surface flaw of the wire material 1 is detected by a surface flaw detecting machine 7 and the flaw part is selectively treated by a surface flaw removing apparatus 8 cooperated with the flaw detecting machine 7. Subsequently, the wire material is passed through a wire drawing capstan and a tension force detector 10 and, after the formed wire is repeatedly heated and cooled in a temp. region of Ae1+ or -150 deg.C in heating apparatuses 11-1-11-3 and cooling apparatus 12-1-12-3, the treated wire is allowed to cool in a heat holding chamber 13.

Description

[Detailed Description of the Invention] This invention relates to steel wire rods or wire rods (hereinafter referred to as 1 wire rods)
This paper relates to a method of spheroidizing a wire (page) while continuously drawing it in a dry process.

Secondary processing of wire rods for cold forging involves descaling the wire rods with acid, then applying a lubricating base and lubricating treatment.
The general method is to draw the wire, then spheroidize it to prevent work hardening due to wire drawing, and then perform a second step of pickling, lubrication base, and lubrication treatment, followed by secondary elongation using a skin pass. It is.

Here, conventional pickling, lubrication base treatment and lubrication treatment are
This is done using a patch processing method in which wire coils are suspended from hooks, immersed in each processing liquid tank, and transferred one after another. For this reason, there are problems such as low productivity, high cost, high pollution control costs for each treatment liquid, unfavorable working environment due to wet processing, and difficulty in full-length inspection.

Note that liquid phosphate is used as a conventional lubricating treatment base agent, and powdered metal soap or a liquid mixture of lime and metal soap is used as the lubricant. For wire rods for cold forging, the lubricant used during wire drawing also serves as lubrication during cold forging, so the lubricating base is treated with zinc phosphate, which has excellent lubricity despite being expensive. There is.

Next, conventional spheroidizing annealing is carried out by inserting the wire in the form of a coil into a pot annealing furnace and annealing it by giving it the required thermal history, or by letting it run continuously through the furnace in a coil continuous annealing furnace, and during that time A method of annealing by giving a thermal history of However, this conventional method has the following drawbacks.

In other words, ■The thermal inertia is extremely large because the thermal history of heating and cooling is given in the coil state, and it takes a long time to heat up and cool down.In general, the processing time is over 10 hours, so the productivity is extremely low and heat treatment is difficult. In addition to the high cost, ■The thermal history differs significantly in each part of the coil, and there is large variation in quality.As a result, ■Annealing conditions must be made more carefully than necessary in order to obtain good quality over the entire length of the coil. and unnecessary cost increases (fifth)
Page) In order to increase the productivity of annealing, a large pot furnace is required to anneal a heavy coil. Annealing furnaces require extremely large heat treatment equipment, leading to a significant increase in equipment costs and high costs; -If the coil we is made larger in order to increase actual productivity, the drawbacks of ① to ③ above will be further amplified. As a result,
Technically contradictory b1 ■ Since only both ends of the coiled wire can be inspected, it is impossible to inspect and clean the entire length of the wire, and ■ - Next, each process of wire drawing and the heat treatment process Since each coil has its own separate processing step button, the technical and cost problems caused by the discontinuity of the flow between steps are extremely large.

Therefore, the inventors concluded that the above-mentioned patch processing method has problems with efficiency and should be changed to continuous wire drawing processing, and that wet processing is not a good idea because of the increased work environment and equipment costs. ◎ On-line flaw detection and maintenance (page 6); ◎ One-through heat treatment is desirable in order to solve the drawbacks associated with annealing in the coil state. As a result of intensive experimental research on the following five issues: [F] Bringing online the process from hot-rolled material coil to annealing treatment, we have succeeded in creating continuous spheroidized wire rods that can solve all of the above-mentioned conventional problems. I found a way to deal with it.

The gist of this invention is to mechanically descale a hot-rolled wire rod, then pass it through a tank containing a powdered lubricating base agent, or pass it through a crimping die to apply a lubricating base treatment to the surface of the wire. Next, the wire is lubricated through one or more pre-dry lubricant tanks containing a powder lubricant different from the lubricating base agent and arranged in series in the wire drawing direction, and then the wire is drawn to a predetermined wire diameter. After finishing, the wire rod is continuously detected for surface flaws using a surface flaw detector, and the flawed portions are selectively cleaned by a surface flaw removing device linked to the surface flaw detector. ~Ae
Continuous spheroidization treatment method for steel wire, characterized by heating to a temperature range of -150°C, repeating heating and cooling within the temperature range several times, and then allowing it to cool (page 7). , Instead of the final cooling, the temperature range of Ae~As□-150℃ is slowly cooled at the cooling rate below (9)'C/m1nJ-J, or the temperature is kept at a constant temperature within the temperature range. A continuous spheroidizing method for steel wire characterized by uniform heating.

An embodiment of the present invention will be described below with reference to the drawings.

In Figure 1, (1) is a wire rod, (2) is a payo stand, (3-1) is a V-H configuration straightening machine, (3-2) is a roll bender, and (4-1) is a shot blaster. equipment,
r4-2) is a brushing device, (5-1) to (5-3
) #'i Powder lubricant tank, (6-1) and (6-2) are lubricant crimping dies, (6-3) is wire drawing die, (7) is surface flaw detector (for example, eddy current flaw detector) , (8) is a surface flaw removing device, (9) is a capstan for wire drawing, OI is a tension detector,
(n-1) to (11-3) are heating devices, (12-1) to
(12-3) represents a cooling device (air cooling), and (131 represents a heat retention furnace).

That is, the wire (1) is wound into a coil and placed on the stand (2), and then passed through a wire drawing line. This line is passed through the wire rod (
1) Tip attachment to make the tip thinner is done by passing the processed material through it. The wire rod (1) fed out from the good-off stand (2) is passed through a straightening machine (3-1) and then applied to a shot blasting device (4-1), or passed through a roll bender (3-2) and then passed through a brushing device (4-4). -2), then lubricant pressure bonding dies (6-1) (6-2
) and a tandem array of powder lubricant tanks (5-1) (s-2) (5-3) equipped with wire drawing dies (6-3).

For these types, lime powder is used as a lubricating base agent in the lubricant tank (
5-1), sodium stearate is used as a reinforcing lubricant in the lubricant tank (5-2), and calcium stearate or a mixture of sodium stearate and slaked lime is used as a lubricant before the wire drawing die in the j5 lubricant tank (5-1). 5-3)
are stored in each.

In this lubrication step, the descaled wire rod (1) first passes through a lubricant tank (5-1) containing a lubricating base agent, and then passes through a crimping die (6-1). At that time, wire rod (1)
Since the hole diameter of the crimping die (page 9) (6-1) has been selected in advance to be slightly larger than the diameter of the wire (1), the crimping die When the wire (1) passes through the hole (6-1), the wire (1)
Lime powder is pressed onto the surface. The lime powder acts as a base for the lubricant and enhances the adhesion of the subsequent reinforcing lubricant and pre-die lubricant. In addition to slaked lime, quicklime can also be used as the lime powder; however, since quicklime often causes problems in handling, slaked lime is preferable.

Next, the wire rod (1) passes through a lubricant tank (5-2) containing a reinforcing lubricant and a crimping die (6-2).
At this time, in the same way as in the case of lime powder, for example, sodium stearate is pressed onto the surface layer of the wire (1) onto which the lime powder is pressed. When using sodium stearate as a reinforcing lubricant, if the particle size is 2μ or less, the amount of adhesion will decrease due to the so-called tunnel effect, and the 1-slip effect will be insufficient, so it is recommended that the particle size be at least 2μ or more. is preferred. Further, application of this reinforcing lubricant can be omitted when drawing a low-strength material.

(Page 10) After that, the wire rod (1) is guided to the lubricant (5-3) containing a lubricant before the wire drawing die, and a mixture of calcium stearate or sodium stearate and lime is applied to the wire rod (
It is attached onto the surface layer of 1) and drawn at a predetermined processing rate using a wire drawing die (6-3).

The drawn wire (ll#'i) enters the surface flaw detector (7).

Wire rods have inherent material flaws, handling flaws, and die flaws caused by seizure in wire drawing dies. Therefore, this type of flaw is continuously detected online by a surface flaw detector (7), and the flaw portion is removed by a surface flaw removing device (8) based on the flaw detection signal. As the surface flaw removing device, an internal grindstone grinding device that can selectively remove specific portions where surface flaws exist can be used. This device uses the inner surface of a rotating cylindrical grindstone to press a certain circumference part of a running wire rod with a constant load, thereby selectively grinding away a certain part where surface flaws exist. This method uses an internal whetstone grinding method that allows for easy cleaning (Page 11).In addition to being able to clean quickly, the surface of the wire is smooth after cleaning, and there is no change in the size or shape of the wire after cleaning. This has the advantage that there is less impact on the next cutter due to maintenance marks.

The wire rod (1) from which surface flaws have been removed is used as a capstan for wire drawing (
9), passes through the tension detector 00) and enters the annealing process.

In this step, a heating device 1 is used to spheroidize the carbide.
-1) ~(11-3) to set the retrace line to Ae4±150℃,
After heating to a temperature range of preferably A e1 to Δρ, +150°C, the cooling device (12-1') to (12-3
) at Ael±150°C, preferably 1 dAe1 to Ae11
Cool to a temperature wave of 5 (1℃).Here, assuming that the upper limit of the heating temperature is 1℃, 1℃, if the temperature is higher than this, all the carbides will melt, and the volume of austenite will decrease. This is because the spherical precipitation of cementite becomes extremely difficult in the next cooling process.The lower limit temperature was set at 50°C for Ae unit. This is because if it is lower, spheroidization of carbide does not occur within the practical treatment time, and when Ael is reached, dissolution of carbide begins, so even rod-shaped or plate-shaped carbides tend to aggregate and spheroidize.

Next, the temperature in the cooling process was set to Ael±150°C, preferably in the temperature range of Ae knee 150°C to Ae4.
This is because in the temperature range below -150°C, carbide precipitation has already been completed and it has no effect on carbide spheroidization f. This is because if the rMl friction is higher than this, it will be very difficult to redecipitate the carbides dissolved in solid solution.

When the temperature reaches Ael + 100° C., the carbide is no longer precipitated and remains only as a solid solution.

By heating and cooling and maintaining the carbide within the above temperature range, some of the carbide becomes spheroidal due to residual aggregation, and some of the carbide becomes spheroidal due to solid solution precipitation.

These agglomerations and solid solutions are more likely to occur in non-spherical carbides with a large surface area ratio (surface area/volume), so as the above heating and cooling are repeated, the number of spherical carbides with a small surface area ratio increases. .

Then, in the final cooling process, the solid-dissolved carbides re-precipitate, so in order to prevent non-spherical carbides from forming (page 13), the mixture is heated to an Aex temperature of 150°C in a heat retention furnace.
Cool slowly at a cooling rate of /min or less, or Aez ~ Ae
Soak the temperature between l-150'C. here ma', A+4
~ Ael The temperature range was limited to 150°C because carbides precipitate only within this temperature range. This is because carbides are precipitated.

Note that the above heating method can be a tunnel furnace, electrical heating, high frequency heating, infrared heating, etc., but in order to connect directly to the wire drawing process and create a line, it is desirable to shorten the heating zone by rapid heating. . For the purpose of maintaining uniform heat, running in a tunnel furnace, loop running in a heat retention furnace, winding up in a heat retention furnace, etc., can be considered, but from the viewpoint of practicality, it is necessary to reduce the size of the furnace body.

Here, the main features of this invention will be explained in comparison with the conventional system.

This invention method is a dry method and involves continuous wire drawing. Conventional batch processing methods are inefficient and uneconomical, but if continuous elongation (page 14) line processing is used as in this invention, the line speed can be increased to 120, for example.
m/min, which significantly improves processing efficiency. In addition, since flaw inspection and flaw removal are performed on a continuous wire drawing line, processing can be done more quickly than conventional batch methods.If necessary, the line speed can be reduced only during flaw grinding to increase grinding capacity. After scales and grinding, the speed can be increased to the original speed. Also, with the invention of! Since surface flaws can be removed by the internal grindstone grinding method that can selectively remove parts on a specific circumference of r'jSfI material, it is said to have a significant effect on improving yield and productivity. 'Wear.

Furthermore, the dry continuous wire drawing method of the present invention is characterized in that lime powder is used as a lubricating base treatment agent. Conventionally, zinc phosphate, which is expensive but has excellent lubricity, has been used as a lubricating surface treatment agent. Since zinc phosphate is in a liquid state, it cannot be applied to this invention by dry processing. Therefore, lime powder is used as a substitute for zinc phosphate. The drawn wire material obtained by this lubricating base treatment with lime powder and the dry (p. It is not superior to the drawn wire material obtained by cauterizing the base with metal soap (or a mixture of lime and metal soap). However, the primary wire drawing process is a preliminary process prior to the secondary stretching process, and the properties of the surface skin can be improved in the secondary drawing process. It is quite possible to achieve the purpose, and it is also reasonable.

The greatest advantage of using this dry method is that the line length can be shortened and equipment costs can be reduced. For example, if we try to carry out continuous processing using a wet method, it will take a considerable amount of reaction time to obtain the desired film thickness in the lubricating base treatment and one-slip treatment, and this will require a correspondingly large amount of equipment. Since all that is needed is a small tank and die, the line length can be shortened and equipment costs can be significantly reduced.

Furthermore, the working environment is improved in that less acids are used. Furthermore, sodium stearate or lime/calcium stearate is generally in powder form, and conventionally it is used by dissolving it for wet processing, but in the dry method it can be used as it is, making it easier to handle. It is excellent.

In addition, since the spherical annealing in this invention is carried out in a continuous process in which the wire rod is heat treated while it is running, it also overcomes the drawbacks of the conventional heat treatment method of annealing the wire rod to the dimensions of the coil state, namely, the above-mentioned It is possible to solve all the shortcomings. Furthermore, the series of processes from the hot-rolled material coil to the annealing treatment are directly connected, providing continuity in the flow between each process, which has a great effect on productivity and quality assurance. Technical and cost problems resulting from flow discontinuities between process steps can also be resolved.

Next, an embodiment of the invention will be explained.

[Example 1] With the line configuration shown in Fig. 1, shot blasting was adopted as the descaling method, and molten steel having the composition shown in Table 1 was heated to 13.
A wire rod hot-rolled to 5m+++φ was heated to 11.6mφ (first
(page 7), and the drawn wire material was annealed to form a spheroid. The conditions for each process in the line are as shown below.

(Al Descaling conditions Descaling method Rainbow shot blast shot particles Nisteel pole (average particle size 0.3MM
φ) Projection density: 3 (10 kg/m2
μ) Quicklime powder (C) Wire drawing conditions Wire drawing range: 41 m/min Die angle; 2α = addition.

Bearing length: n, 5a (d = die hole diameter) Wire drawing area reduction rate: 26.2 ratio (per 1-4 threads) (D) Flaw detection conditions Flaw detection method: ■Rotating probe type eddy current flaw detector (flaw detection frequency 6)
．． 4KHz) ■Water immersion ultrasonic flaw detector (flaw detection frequency (page 18) 20MH2) (E) Surface care Automatic local care using 32-division internal grindstone grinding method (bound induction heating heating zone, 15 zone heating coil... 10 coil frequency...100KHz (G3 adjusted cooling air cold tube (T()) slow cooling/heat retention furnace atmosphere...low fog point NQ gas winding method...furnace winding present example The results are shown in Tables 2 and 3.Table 2 shows the life of the wire drawing die for steel type B according to the method of the present invention.
This is a comparison with the case where only pre-die lubrication was performed. Table 3 shows a comparison of the quality of the obtained wire rods and the annealing time between the conventional method and the case where only the annealing conditions were changed. In addition, the conventional method is hot-rolled coil - pickling - wire drawing -
Coil (page 19) The coil was processed in a continuous annealing furnace through a process of spheroidizing annealing.

As is clear from Table 2, the method of this invention significantly improves the lubricity and extends the life of the die.

As is clear from Table 3, rapid, stable and uniform annealing is possible.

(Page 22) However, ■ Tensile test test method... JIS test piece... J Engineering No. 814A ■ Upsetting test test piece... 10 to φ・Unrestrained/flat plate compression Number of compression tests: 1 time for each degree of work... 10 pieces for each degree of work Limit compression rate/Degree of compression... 50-inch crack occurrence on the cracking rate curve Degree of processing in terms of ratio ■ Measurement of spheroidization rate Observe and photograph the structure of the annealed material using a scanning electron microscope, measure the major axis and minor axis of each carbide, and calculate the ratio of major axis / minor axis for 100 or more carbides. The ratio of the number of carbides with a ratio value of 3.0 or less to the total number of carbides was expressed as H, and was defined as the spheroidization rate.

[Example 2] With the line configuration shown in Fig. 1, the descaling method was changed from shot blasting to a combination of roll bender and brushing, and steel type B shown in Table 1 was hot rolled to 14.0 m'. The wire rod was drawn to 11.6 mφ, and the drawn wire rod was annealed to form a spheroid. The descaling conditions, wire drawing conditions and annealing conditions at that time are as shown below. Note that the other aspects are the same as in the first embodiment.

(A) Descaling conditions Bending rolls: 5 rolls each with a diameter of 90 mm Brushing: 6 disc-shaped wire brushes with a diameter of 150 mm
φ → 12.2Mφ surface reduction force 24%) (B) Wire drawing conditions elongation and surface reduction force = 10chi (12.2Mφ → 11.6mmφ) (
(Page 24) (C) Annealing conditions Heating ■ 800°C Cooling ■ 680"C Heating ■ 780°C Cooling ■ 670°C Heating Q 750°C Cooling 06 c 7 min The wire drawing results in this example are shown in Table 4. , the annealing results in the fifth
Each is shown in the table. For comparison, Tables 4 and 5 also show the results of wire drawing and annealing performed by the conventional method shown in Example 1.

According to Table 4, when the descaling method is changed to a combination of roll bender and brushing, the life of the die is further extended. Further, from the fifth fit, in this example as well, a product of excellent quality was obtained with short annealing.

(Page 25) (Page 26)

[Brief explanation of drawings]

FIG. 1 is a process diagram showing an embodiment of the present invention. 1...Wire rod, 2...Payoff stand, 3-1...
・Straightening machine, 3-2"°° roll bender, 4-1...
Shot blasting device, 4-2... Brushing device, 5-1 to 5-3... Powder layer lubricant tank, 6-1.6-2
...Lubricant crimping die, 6-3...Wire drawing die, 7
...Surface flaw detector, 8...Surface flaw detector, 11-1
~11-3... Heating device, 12-1~12-3...
Cooling device, 13... heat retention furnace. Applicant: Sumitomo Metal Industries, Ltd.

Claims (2)

[Claims] (1) After mechanically descaling the hot-rolled wire rod, a lubricating base treatment is applied to the wire surface while passing through a tank containing a lubricating base agent made of unhulled rice, or through a crimping die, and then a lubricating base treatment is applied to the wire rod surface. After applying lubrication treatment through one or more pre-dry lubricant tanks arranged in series in the wire drawing direction, which contain a powder lubricant different from the powder lubricant, the wire is drawn and finished to the specified diameter. Next, the surface flaws on the wire are continuously detected using a surface flaw detection system, and the surface flaw detector is linked with the surface flaw detector.After selectively cleaning the flawed area, the wire is removed Ael + 150'C-Ael
A continuous spheroidizing method for steel wire, which comprises heating to a temperature range of 150°C, repeating heating and cooling within the temperature range multiple times, and then continuously cooling in-line. (Page 2) (2) After mechanically descaling the hot-rolled wire rod, a lubricating base treatment is applied to the wire surface while passing through a tank containing a powdered lubricating base agent, or through a crimping die, and then a lubricating base agent is applied to the wire rod surface. The wire is lubricated through one or more pre-dry lubricant tanks arranged in series in the wire drawing direction, which contains a powder lubricant different from the powder lubricant, and then processed to a predetermined wire diameter. After continuously detecting surface flaws on the wire using a flaw detector and selectively cleaning the flawed areas using a two-sided flaw removing device linked to the surface flaw detector, the wire is heated to a steel temperature of Ael + 150°C. −
After heating to a temperature range of 150°C and repeating heating and cooling multiple times in the temperature range, Ael - Ael 150°C
ms characterized in that the temperature range is gradually cooled at a cooling rate of 30'/min or less, or the temperature is maintained at a constant temperature within the temperature range in-line continuously.
Continuous spheroidization processing method.