JPS6344446B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a dry continuous wire drawing method for continuously drawing a wire rod or a steel bar (hereinafter referred to as "wire rod"). The secondary processing of wire rods for cold forging involves descaling the wire rods by pickling, then applying a lubricating base and lubrication treatment, then performing primary wire drawing, and then spheroidizing annealing to deal with work hardening caused by wire drawing. A common method is to perform a second stage of pickling, a lubrication base, and a lubrication treatment, followed by secondary wire drawing using a skin pass. Here, the conventional pickling, lubrication base treatment, and lubrication treatment are performed by a batch treatment method in which a cotton coil is suspended by a C-shaped hook, immersed in each treatment liquid tank, and transferred sequentially. For this reason, there are problems such as low productivity and high costs, high costs for pollution prevention measures for each treatment liquid, an unfavorable working environment due to wet processing, and difficulty in inspecting the entire length. Note that liquid phosphate is used as a conventional lubricating 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 during wire drawing also serves as lubrication during cold forging, so zinc phosphate, which is expensive but has excellent lubricity, is used as a lubrication base treatment. . On the other hand, in response to increasingly strict quality assurance requirements in recent years, flaw detection and care of drawn wire materials are extremely important processes. However, online flaw detection and automatic maintenance of wire rods is generally very difficult and is performed exclusively offline. Specifically, after the drawn wire material is wound up, it is inspected during the finishing process using non-destructive or destructive flaw detection equipment, or surface flaws are detected visually, and the flaws are manually removed using a grinder or the like. Grinding is being carried out. However, this is inefficient and uneconomical, as it takes a lot of time and effort, requires additional equipment space, and complicates transportation work. On the other hand, in order to remove the above-mentioned surface flaws, the conventional general method involves cutting or grinding the entire circumference of the wire rod, but since this method results in a decrease in yield, recently it has been For the purpose of improving efficiency, a partial flaw removal method has been reported in which only surface flaws are removed. In this method, a flaw detector detects surface flaws on the wire, and the signal is transmitted as a cutting command to a partial flaw removing device, and a rotating cutting tool moves in the radial direction to remove the flaw. It is. However, although this cleaning method using a partial flaw removal device has a higher yield than the conventional full-length skinning method, it cannot be said to be sufficient as a measure to improve yield because it cuts the entire circumference of the area where surface flaws exist. Moreover, when the wire rod is pulled out after being treated, the effects of cutting remain as dimensional changes. As mentioned above, the inventors believe that the batch processing method has problems in terms of efficiency and should be changed to continuous wire drawing processing, and that wet processing is not a good idea due to the increased work environment and equipment costs. In this respect, dry processing is desired, and the process from flaw detection to care should be made online.
As a result of intensive experimental research focusing on the following three issues,
We have developed a continuous dry drawing method for wire rods that allows for online flaw cleaning with good yield. That is, in this invention, after mechanically descaling the wire rod fed out from the payoff stand,
A lubricating base treatment is applied to the surface of the wire while passing through a tank containing a powder lubricating base agent, or through a crimping die, and then a powder lubricant different from the lubricating base agent is stored, and the wire is placed in series in the wire drawing direction. After lubrication treatment is performed through one or more dry lubricant tanks in front of the dies, the wire is drawn for the first time, and then surface flaws on the wire are continuously detected using a surface flaw detector, and based on the surface flaw information. The flaws are cleaned using an internal whetstone grinding device that selectively removes only the portion where surface flaws exist on the inner surface of a cylindrical rotary whetstone, and the wire after the flaws are cleaned as is or after being drawn and wound up. That is. Hereinafter, one embodiment of the present invention will be described based on the drawings. In Fig. 1, 1 is a wire rod, 2 is a payoff stand, 3 is a straightening machine with a V-H configuration, and 4 is a descaling device (shot blasting device, roll bender).
5-1 to 5-3 are powder lubricant tanks, 6-1, 6-2
6-3 is a lubricant crimping die, 6-3 is a wire drawing die, 7 is a surface flaw detector (for example, an eddy current flaw detector), 8 is a flaw removal device (internal grindstone grinder), 9 is a wire drawing die, 10
indicate the respective winders. That is, the wire 1 is installed in a payoff stand 2 in a coiled state, and then passed through a wire drawing line. This line threading is carried out by passing the wire 1 through which the tip has been pre-applied in a previous step to make it thinner. The wire rod 1 fed out from the payoff stand 2 passes through a straightening machine 3 and a descaling device 4 to remove oxide films and the like from the wire surface, and then passes through a lubricant crimping die 6-1,
6-2 and powder lubricant tanks 5-1 to 5-3 arranged in tandem, each having a wire drawing die 6-3. In each of these tanks, lime powder as a lubricating base agent is placed in lubricant tank 5-1, reinforcing lubricant such as sodium stearate is placed in lubricant tank 5-2, and pre-lubricating die lubricant such as calcium stearate or stearin is placed in lubricant tank 5-2. A mixture of sodium acid and slaked lime is stored in each lubricant tank 5-3. In this lubrication process, the wire rod 1 after descaling
First, it passes through a lubricant tank 5-1 containing a lubricating base agent, and then passes through a crimping die 6-1. At that time, lime powder adheres to the wire rod 1 and the crimping die 6
Since the diameter of the hole -1 is pre-selected to be a predetermined diameter slightly larger than the diameter of the wire 1, lime powder is crimped onto the surface of the wire 1 when the wire 1 passes through the hole of the crimping die 6-1. 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 1 passes through a lubricant tank 5-2 containing reinforcing lubricant and a crimping die 6-2, but at this time, the lime powder of the wire 1 is crimped in the same way as in the case of lime powder. For example, sodium stearate is pressed onto the surface layer. Note that when sodium stearate is used 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 lubricating effect will be insufficient, so it is preferably at least 2μ or more. Furthermore, application of this reinforcing lubricant can be omitted when drawing a low-strength material. Thereafter, the wire rod 1 is guided to a lubricant tank 5-3 containing a pre-lubricant for the wire drawing die, a mixture of calcium stearate or sodium stearate and lime is deposited on the surface layer of the wire rod 1, and the wire rod 1 is introduced into the wire drawing die. 6-3, wire drawing is performed at a predetermined processing rate. The drawn wire 1 is continuously inspected online by a surface flaw detector 7, and surface flaws are removed by an internal grindstone grinder 8 based on the surface flaw information. The automatic care machine according to the present invention employs an internal grindstone grinding method for the purpose of further improving yield and dimensional accuracy. The basic principle of this internal grindstone grinding method is to use the inner surface of a rotating cylindrical grindstone to press against a certain circumference of a running wire rod under a constant load, thereby removing specific areas with surface flaws. This is a method of selectively abrasive and removing. According to this method, only a specific circumferential portion of the wire rod can be selectively treated, so the yield is much higher than the previously reported method using a wire rod partial flaw removal device that uses the entire circumference cutting or grinding method. It can be taken care of. In addition, there are advantages in that the surface flaws are smooth, the dimensions and shape of the wire rod after the treatment are less likely to change, and the influence of the cleaning marks on the next process is small. Fig. 2 shows the principle configuration of the automatic care machine, in which 17 is an eddy current flaw detector, and 18 is an internal grinding wheel that works in conjunction with the flaw detector to selectively remove only a specific circumferential portion of the wire. The device 11 is a calculation control device that calculates the circumferential position, flaw length, and flaw depth based on signals from the flaw detector, and transmits the results to the internal grindstone grinding device 18 as a grinding command. The internal grindstone grinding device 18 has a mechanism in which a cylindrical rotary grindstone 18-1 swings in a direction perpendicular to the wire rod 1, and has a function of being pressed in any direction at any position on the circumference with any pressure. Use something similar. FIG. 3 shows an example of this, in which a cylindrical grinding wheel is attached to the tip of a cylindrical body 18-2 that is swingably supported in the diametrical direction around the base end and is rotationally driven by an autorotation motor _M1 . 18-1, and a hydraulic servo cylinder 18-4 that presses the cylinder in the diametrical direction is mounted on the outer cylinder 18-3, which is located outside the cylinder and is rotatable by the revolution motor _M2 . A grinding device arranged at several locations can be used.
That is, this device includes a cylindrical grindstone 1 that is rotated integrally with a cylinder 18-2 by an autorotation motor _M1 .
8-1 is pressed and ground by a hydraulic servo cylinder 18-4 arranged at several points around the circumference of the cylinder, and the outer cylinder 18-1 is pressed by a revolution motor _M2 .
3 is rotated to position the hydraulic servo cylinder 18-4 at the circumferential position of the flaw, and the grindstone is pressed against the wire rod 1 with a predetermined pressure depending on the depth and length of the flaw. Now, when a surface flaw on the wire 1 is detected by the eddy current flaw detector 17, the arithmetic and control unit 11 uses the signal to determine the depth of the flaw, the flaw length, and the position in the circumferential direction of the flaw (for example, the circumference is divided into 36 equal parts. ) is calculated, and the circumferential setting position of the hydraulic servo cylinder, pressing pressure, and pressing timing are instructed to the internal grindstone grinding device 18. Based on the instructions, the cylindrical grindstone 18-1
is activated, and only the portion of the inner surface of the grindstone where the flaw exists is ground and the flaw is removed. The wire from which surface flaws have been removed in this way is 2
After the wire is drawn at a predetermined processing rate by the wire drawing die 9, the wire is wound up by the winder 10. Also,
If there is a process that requires wire drawing again off-line, the wire may be wound as is without performing secondary wire drawing. Here, the main features of the present invention will be explained based on comparison with the conventional system. This invention is a dry method and performs continuous wire drawing processing. Conventional batch processing methods are inefficient and uneconomical, but if continuous wire drawing processing is used as in this invention, the line speed can be increased to, for example, 120
m/min, which significantly improves processing efficiency. In addition, since flaw detection and flaw removal are performed on a continuous wire drawing line, faster processing is possible compared to the conventional batch method.If necessary, the line speed can be reduced only during flaw grinding to improve grinding capacity. After grinding, the speed can be increased again to the original speed. In addition, in this invention, surface flaws are removed by an internal grindstone grinding method that can selectively remove parts on a specific circumference of the wire, so it is not necessary to remove the flaws by conventional full-length scraping or by cutting the entire circumference of the flawed part. Compared to flaw removal using a partial flaw removal device, this method has a remarkable effect on improving yield and productivity. Further, the dry continuous wire drawing treatment 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 lubrication base treatment with lime powder and dry lubrication treatment does not necessarily have surface properties such as pickling, zinc phosphate base, metal soap (or It is not superior to the drawn wire material obtained by lubrication (lime/metal soap mixture). However, the primary wire drawing process is a preliminary process prior to the secondary wire drawing process, and the properties of the surface skin can be improved in the secondary wire drawing process. However, the purpose can be fully achieved,
It's even more 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 perform continuous processing using a wet method, it takes a considerable amount of reaction time to obtain the desired film thickness during the lubrication base treatment and lubrication treatment, which requires a correspondingly large amount of equipment, whereas with a dry method, 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 because acids are not used. Furthermore, sodium stearate or lime/calcium stearate is generally in powder form, and conventionally this is used after being dissolved for wet processing, but in dry processing it can be used as is, making it easier to handle. It is excellent. As described above, the method of the present invention allows wire drawing to be carried out in a dry and continuous manner, and because the lubricating base treatment is performed using inexpensive lime powder, wire drawing can be carried out extremely economically. Furthermore, since the lubricating base agent and reinforcing lubricant are squeezed and crimped using a die, there are advantages such as improved adhesion. Furthermore, since only the surface flaws are removed by the internal grindstone grinding method, there is an advantage that the yield rate or productivity is significantly improved. Next, embodiments of the invention will be described. Example 1 Wire drawing equipment with the line configuration shown in Fig. 1 and the internal grindstone grinding device shown in Fig. 3 was used to improve the material quality.
A 14.0 mmφ AS roll material was drawn using S45C under the conditions shown below, and a wire drawing material of 11.6 mmφ5 was finally obtained. Operating conditions Γ descaling conditions Approximately 300 kg of steel balls with an average particle diameter of 0.3 mmφ
Shot blasting is carried out with a projection density of m ² . Γ Lubrication conditions Lime powder with an average particle size of 15μ is used as a base lubrication, sodium stearate with an average particle size of 12.5μ is used as reinforcement lubrication, and lime/calcium stearate is used as lubrication before the die. Γ wire drawing conditions Primary wire drawing die: die angle 2α = 20°, area reduction rate 20.3
%, bearing length 0.5d (d: die diameter) Secondary wire drawing die: die angle 2α = 20°, area reduction rate 13.9
%, bearing length 0.5d (d: die diameter) Wire drawing speed: 60m/min Γ Detection conditions Flaw detector: Rotating probe type eddy current flaw detector, flaw detection frequency
64KHz Γ Automatic maintenance conditions Internal grinding wheel grinding device: Grinding wheel inner diameter 50mmφ, outer diameter 100mm
φ, width 50mm, grinding wheel circumferential speed 1000m/min, 4 hydraulic servo cylinders, grinding depth _MAX 0.2mm Table 1 compares the life of the primary wire drawing die with the case where only pre-die lubrication is performed. This is what is shown. In the same table, die life indicates the amount of wire drawn until the wire drawing die seizes. No seizing means that the wire rod has good lubricity, so it measures the quality of the drawn wire material obtained. This is one measure.

[Table] As is clear from Table 1 above, it is shown that high quality drawn wire material can be obtained according to the method of the present invention. Table 2 shows the results of investigating the adhesion amount by varying the average particle size of sodium stearate.
When the average particle size is less than 2 μm, a so-called tunneling phenomenon occurs and a satisfactory amount of adhesion cannot be obtained, making it impractical.

[Table] Table 3 also shows the product yield in comparison with the conventional full-length skinning method and partial cutting method. As is clear from Table 3, by applying the method of the present invention, the yield could be further improved compared to the conventional scratch removal method.

[Table] Furthermore, Table 4 shows the results of investigating the effect of removing care marks by secondary wire drawing. As is clear from Table 4, it is clear that maintenance marks can be sufficiently eliminated by secondary wire drawing, especially in secondary wire drawing.
It was found that scratch care marks can be completely removed by applying an area reduction rate of about 15%.

[Table] In this example, by performing up to the secondary wire drawing online, the area reduction rate of each wire drawing die can be lowered, and the life of the die can be greatly extended. . At the same time, the wire drawing texture was markedly improved compared to the case where only the primary wire drawing was used.
The area reduction rate distribution in the primary and secondary wire drawings is determined by the thinning of the finished wire diameter (the primary wire drawing area reduction rate affects the secondary wire drawing as a back tension, resulting in thinning). ), and should be selected appropriately depending on the material, etc.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing an embodiment of the present invention, Fig. 2 is an explanatory diagram of the automatic scratch removal method in the above, and Fig. 3 is a schematic diagram showing an embodiment of the present invention.
The figure is a schematic diagram showing the internal grindstone grinding device in the same as above. 1...Wire rod, 2...Payoff stand, 3...
Straightening machine, 4...Descaling device, 5-1 to 5-3
... Powder lubricant tank, 6-1, 6-2 ... Lubricant crimping die, 6-3 ... Primary wire drawing die, 7 ... Surface flaw detector, 8 ... Flaw removing device, 9 ... Secondary wire drawing die, 10... Winder, 17... Eddy current flaw detector, 1
8... Internal grindstone grinding device.

Claims (1)

[Claims] 1 After mechanically descaling the wire rod fed out from the payoff stand, the wire rod is subjected to a lubricating base treatment while passing through a tank containing a powdered lubricating base agent, or is further passed through a crimping die, and then lubricated. A powder lubricant different from the base agent is stored, and the wire is lubricated through one or more pre-dry lubricant tanks arranged in series in the wire drawing direction, followed by primary wire drawing. The wire rod is continuously detected for surface flaws, and based on the surface flaw information, the flaws are cleaned using an internal grindstone grinding device that selectively removes only the portion of the inner surface of a cylindrical rotary grindstone where surface flaws exist. A dry continuous wire drawing method for wire rods, which is characterized in that the wire rods are wound as they are after they have been treated, or they are then subjected to secondary wire drawing and wound up.