JPS6334013A - Shearing method for hot steel - Google Patents

Abstract

PURPOSE:To reduce a collapse factor and to enable execution of automation and a precise work at an after-process, by a method wherein, after the portion, intended to be sheared, of a material to be sheared is forcibly cooled before shearing, it is sheared. CONSTITUTION:A truck 7 is run and moved to a position located length two times as long as a cutting length l away from a constant sizing machine 1 in linkage with movement of a steel W conveyed on rollers 6 along rails 5. The portion, intended to be sheared, of the SCM case hardening steel W with a diameter of 32mm cooled to, for example 400 deg.C at a cooling bed, is forcibly cooled for seconds by means of spray water through a nozzle 10. In which case, since the portion, intended to be sheared, of the steel W to be sheared conveyed to a shear 2 is cooled down to 300 deg.C, which is detected by a radiation thermometer 12, the steel can be shearted by means of upper and lower bites 3 and 4 without increasing a collapse factor so much. This method shortens a residence period on a cooling bed, improves productivity, and reduces a collapsion factor, resulting in the possiblity to execute automation and a precise work at a process at a unser's place.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a shear cutting method for reducing the deformation rate of the cold shear cut surface when a warm steel bar is cut with a cold shear in a steel manufacturer. It is.

(Prior Art) Conventionally, steel manufacturers have hot-rolled and then cooled warm steel bars on a cooling bed and then cut them with a cold shear, having a circular or square cross section. However, in order to increase productivity, the reality is that instead of waiting for the material to cool down to a low temperature before performing cold shear cutting, cutting is performed at a relatively high temperature.

When this hot steel bar is cut with a grooved shervite, the end face 4 of the steel bar is crushed and deformed.

(Problems to be Solved by the Invention) In the recent processing industry, steel users' quality requirements for steel bars are becoming increasingly sophisticated in order to automate and improve precision of processing processes.

In particular, steel manufacturers have extremely strict requirements regarding the "crumpleness" of cold shear cut surfaces, and currently each steel manufacturer is struggling to meet these requirements.

Here, "collapse" refers to the degree of end face deformation of a steel bar cut with a grooved shervite, as shown in Part 4, expressed as the collapse rate of the following formula (see Figure 5) (a: major diameter , b: short axis) In PESSA, the crushing rate is 10% or less.

(Means for Solving the Problems) As a result of various studies on cold shear cutting methods that can meet the above-mentioned user requirements, the inventor found that during running work, the temperature at the time of cutting the steel material to be cut has an effect. Based on this discovery, the present invention has been made.

The gist of the present invention is a method for shear cutting a warm steel material, which is characterized in that the cut portion of the material to be cut is forcibly cooled before cutting, and then shear cutting is performed.

The objects of forced cooling include warm steel materials having a circular or square cross section. Forced cooling is performed by pouring water itself or spraying water onto the material to be cut. However, depending on the steel type of the material to be cut, the temperature before forced cooling, etc., if forced cooling is performed using water itself, the material to be cut may become hardened, causing cracks during cutting, or may cause problems during the processing process by the user. Problems may arise.

Although it is preferable for forced cooling to be carried out locally at the cutting site of the material to be cut in terms of economical use of the coolant, it may be carried out over the entire length of the material to be cut.

Forced cooling is performed on the cutting part of the material to be cut before cutting, and by the time the upper blade shear descends and starts cutting,
It is sufficient to carry out cutting until the temperature is below a predetermined temperature specific to the material to be cut. Therefore, as long as it is before cutting, it is not limited to the case where the next cut section after the section currently being cut is forcibly cooled in advance (see FIG. 3 of the embodiment described in t&). Further, it is sufficient to forcefully cool the material to below the specific temperature, and it is not necessarily necessary to cool it to room temperature. Whether or not the cut region has been forcibly cooled to a predetermined temperature or lower can be confirmed by measuring with a radiation temperature needle or the like.

Forced cooling can also be performed by spraying water onto a predetermined area using a hose or the like, or by providing a dedicated spray cooling device as in the embodiment described below.

(Example) Next, an example of the present invention will be described based on the drawings.

1.2 shows an embodiment of a cooling device used in the present invention, and FIG. 1 shows a front view and FIG. 2 shows a plan view.

1 is an elevating type sizing machine that serves as a stopper for the material to be cut W, and 2 is a grooved shear consisting of upper and lower bits 3.4 provided in front of the sizing machine. Reference numeral 11 denotes a cutting section cooling device, which consists of the following components.

5 is a conveyed material at a position approximately twice the cutting length l from the sizing machine 1, and about 30 CIl higher than the cut material W, which is conveyed to the right in FIG. 4 by the conveying roller 6.6. This is a rail extending parallel to the transport direction of W. 7 is a cart that straddles between the rails 5.5. Reference numeral 8.9 denotes water and air tanks provided on the truck 7, which are supplied from flexible pipes (not shown).

10 has a diameter of φ to cool the workpiece W below by mixing water and air (air pressure: 5.5 kg/cal) supplied from water and air tanks 8.9 and ejecting the mixture.
There are 15 nozzles.

Next, the effects of the above embodiment will be explained.

The cutting section cooling device 11 of the above embodiment moves the trolley 7 to a position twice the cutting length l from the sizing machine 1 as shown in FIG. φ32
The SCM case-hardened steel wire section of wI was forcedly cooled for several seconds with the mist sprayed from the nozzle 10.

As a result, when the part of the material to be cut W was measured using the radiation thermometer 12 at the shear 2, it was found that it had been cooled to 300°C. The workpiece W that has been locally forcedly cooled in this manner is carried into the groove 41 of the lower cutting tool 4 and is cut by the upper cutting tool 3 and the lower cutting tool 4.

As a result of this cutting, we measured the crushing rate, which was 10% compared to the conventional method.
This has improved from about 10% to 6%.

Measurements were also made when the temperature was lowered from 300°C to room temperature, and the crushing rate was the same as when the temperature was cooled to 300°C. Therefore, it has been found that this SCM case-hardened steel substrate is most efficient if it is cut when it has cooled to 300°C.

(Effects of the Invention) According to the present invention, the crushing rate can be reduced by forcibly cooling and shear cutting the cut portion of the material to be cut before cutting.

Therefore, the material to be cut is not allowed to cool on the cooling bed and waits until it cools to a predetermined temperature before cutting, which shortens the residence time of the material to be cut on the cooling bed, which improves production at steel manufacturers. Improves sex.

In addition, since the material to be cut is forcedly cooled before being cut, the crushing rate is reduced, and the material to be cut is of high quality and can be processed without any problems even in automated and precision processing processes. Becomes the property of

[Brief explanation of drawings]

1 to 4 are detailed explanatory diagrams of the present invention.
The figure is a front view of the cutting section cooling device, the second figure is a plan view of the same, and the third figure is a front view of the cutting section cooling device.
The figure is a front view for explaining the cooling part, FIG. 4 is a partially enlarged view of the grooved upper and lower cutting tools, and FIG. 5 is a diagram for explaining the crushing rate. 1: Sizing machine, 2: Grooved shear, 3.4: Upper and lower shear bits, 5: Rail 6: Conveyance roller, 7: Cart 8.9: Water/air tank, 10: Nozzle 11: Cutting Part cooling device 12: Radiation thermometer, l: Cutting length W: Material to be cut (case hardened steel material)

Claims (1)

[Claims] A method for shear cutting warm steel materials, the method comprising forcibly cooling the cut portion of the material to be cut before cutting, and then shear cutting the material.