JPH033774A - Descaling method for steel material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for descaling steel materials, and more specifically,
The present invention relates to a method for descaling steel materials that enables highly efficient descaling and improves the quality of the skin after treatment.

(Prior Art) Stainless steel scales produced by forging, hot rolling, heat treatment, etc. are dense and robust. Various methods have been adopted to remove such scale, one of which is shot blasting.

This method involves projecting a steel ball with a predetermined particle size and hardness at a predetermined speed onto a material to be treated that has scale attached to its surface, and using the impact energy generated at that time, the scale is detached from the surface. be.

Industrially, this method is carried out by moving the material to be treated into a shot blasting chamber of a predetermined volume, and during this process, projecting a predetermined shot onto the material from a projection jig.

(Problem to be solved by the invention) By the way, in actual production sites where this descaling treatment is performed, it is necessary to flow the material to be treated as fast as possible to increase production efficiency and at the same time improve the skin quality of the steel material after descaling. Efforts are being made to encourage this.

Generally, when the projection speed is constant and the hardness of the shots is also the same, shots with larger particle sizes exhibit a greater descaling effect. However, on the other hand, after descaling, the surface of the steel material becomes more uneven and its surface quality deteriorates. On the other hand, if you use shot with a small particle size,
Although improvement in skin quality can be achieved, a problem arises in that the descaling effect is reduced.

In addition, in order to increase the efficiency of descaling, it is possible to reduce the feeding speed of the material to be processed through shot blasting. The impact energy applied, for example, the shot weight fit (kg/n) applied per unit area of the surface of the material to be treated, and the shot density expressed in kg/n () become small, and the descaling effect is not sufficiently exerted. In other words, using shot of a certain particle size, shot plus 1
-, there is a problem in that the feeding speed of the material to be processed cannot be increased above a certain value.

The present invention solves the above-mentioned problems by arranging at least two shot blasters in series, introducing the material to be treated there at a higher speed than ever before, and reducing the particle size of the shot used in each shot blast. The purpose of the present invention is to provide a method for descaling a steel material by increasing the diameter on the upstream side so that the material to be treated can be descaled with high efficiency, and in addition, a steel material with excellent skin quality can be obtained.

(Means for Solving the Problems) In order to achieve the above-mentioned object, in the present invention, a group of plural shot blasters arranged in series are made to pass through the steel material to be treated at the same speed. The steel material removal process is characterized in that the shot blasting process is performed on the steel material by making the particle size of the shot I used in the shot blasting process located on the downstream side larger than the particle size of the shot used in the shot blasting process located downstream. A scaling method is provided.

First, in a line where the method of the present invention is carried out, a plurality of shot blasters are arranged in series, and the material to be treated is flowed through these shot blasters.

That is, the material to be treated continuously flows from the upstream side to the downstream side. In this process, the material to be treated is sequentially introduced into each shot blast, where it undergoes shot blast treatment, and then introduced into the next downstream shot blast.

Therefore, the feed speed of the material to be treated in each shot/nodblast is the same.

In the method of the present invention, the particle size of the shot used in the shot blast located on the upstream side is larger than the particle size of the shot used in the shot blast located on the downstream side.

For example, when descaling 5US304 stainless steel, two shot blasters are arranged in series, and the first stage uses steel shot with a grain size of 1.0 to 1.3 mm, and the second stage uses steel shot with a grain size of 1.0 to 1.3 mm. In shot blasting, the particle size is 0.4~
When descaling is carried out using a 0.8 mm shot, the feed rate of stainless steel can be reduced to 5 to 8 m/min, and the quality of the surface is improved. However, in the treatment only for the first stage described above, if the stainless steel feed rate is higher than 6 m/min, the projection density will become small and the descaling effect will not be sufficient.
Besides, the skin feels rough. In addition, in processing only in the latter stage, even if the feed rate is slowed down and the projection density of Shoku1- is increased, the skin quality will be good, but descaling will not proceed well.

(Embodiment of the invention) Two shot blasts A and B were arranged in series. The shot used in Jontogerast A has a particle size of 1.2nw.
The shot used in Shot Blasting B had a grain size of 0.6 mm and was made of steel.

A hot-rolled 5US304 steel plate was transferred to these two Shot Plus l-A and B at a feeding speed of 3 m/min.
The flow rate was 4 m/min, 5 m/min, 6 m/min, 8 m/min, and 10 m/min.

At each feed rate, the descaling state of the top, bottom, and side surfaces of the steel plate coming out of shot blasting B was visually observed, and the state of complete descaling was judged as ○, and the case where scale remained was judged as ×. The results are shown in Table 1. Note that Table 1 also shows the shot projection density at each feed speed.

Furthermore, the surface roughness of the obtained steel plate was measured in accordance with JTS, and the results are shown in FIG.

For comparison, a state in which descaling was performed only with Shot Plus I-A is also shown in Table 1 as Comparative Example 1. Moreover, the results of the surface roughness of the obtained steel plate are shown in FIG.

Furthermore, descaling was performed using only Shot Plus) B. The steel plate was fed three times at a feeding speed of 3 m/min (the projection speed was 100 kg/r4 each time), but descaling was insufficient. This result is also shown in Table 1 as Comparative Example 2. Moreover, the results of the surface roughness at this time are shown in FIG.

(The following is a blank space) JP-A-3-3774 (4) As is clear from the results in the table, in the case of the method of the present invention, a good descaling state can be achieved even if the steel plate feeding speed is stopped to 8 m/min. Moreover, the surface roughness of the obtained steel plate is comparable to that of the surface roughness of the grooves, etc., when shot with a grain size of 0.6 mm is used.

On the other hand, in the case of Comparative Example 1, the feed rate of the steel plate was 6 m
/min or more, the descaling condition deteriorates and the surface roughness also decreases. Furthermore, in the case of Comparative Example 2, descaling was not sufficient even if shot blasting was repeated three times.

As described above, according to the method of the present invention, the feed rate of the steel material can be reduced by about 1.6 times compared to the case where only Shot Plus LA is used. That is, the efficiency of the descaling process can be increased by about 1.6 times.

(Effects of the Invention) As is clear from the above explanation, the method of the present invention enables descaling of steel materials at a higher speed than conventional methods, and also improves the surface texture of the obtained steel materials. Therefore, it has great industrial value as a highly efficient descaling method.

[Brief explanation of the drawing]

Figure 1 is a chart showing the surface roughness of a steel plate treated by the method of the example, Figure 2 is a chart showing the surface roughness of a steel plate treated by the method of Comparative Example 1, and Figure 3 is a comparative example. 2 is a chart showing the surface roughness of a steel plate treated by method 2. FIG.

Claims (1)

[Claims] A group of multiple shot blasters arranged in series are made to pass through the steel material at the same speed, and the grain size of the shot used in the shot blasting located on the upstream side is changed from the grain size of the shot used in the shot blasting located on the downstream side. A method for descaling a steel material, comprising subjecting the steel material to be shot blasted to a diameter larger than the diameter of the steel material.