JPS582611B2 - Method for testing the quality of flash butt welds - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for testing the quality of flash butt welds of strips in a continuous strip pickling line.

Generally, in a continuous pickling line for strip, a flash butt welder is used to connect the preceding strip and the following strip at the entry side of the line so that the strip can be threaded continuously without stopping in the pickling tank. is used.

Further, a flash trimmer is installed next to the flash butt welding machine as equipment for removing a weld bulge (usually referred to as a "burr") of the flash butt weld.

In other words, in the flash butt welding method, the end surfaces of the strips are butted against each other, a large current is passed through them to generate concentrated heat, and then pressure is applied to connect them, so the molten part is inevitably pushed out to the outer periphery, cooled and solidified. This causes the above-mentioned "burrs", and it is necessary to cut and remove these "burrs" with a flash trimmer so as not to prevent smooth threading.

By the way, the welded portions of the strips must be securely connected so that they do not break during threading.

Conventionally, the test method for determining the quality of this welded part is to remove the "burr" with the flash trimmer, and then
Transfer the strip, stop it at a desired position on the back of the flash trimmer, and manually hammer (
The only known method was the so-called hammer test, in which the quality of the welding was determined by repeatedly hitting the weld with an object weighing approximately 3 to 6 kg to determine whether there were any cracks or abnormal deformation.

The disadvantages of this hammer test method are: (1) It requires more than 10 hammer strokes per welding site, and in some cases, more than 20 strokes are required for particularly hard plate materials, resulting in great worker fatigue.

■ A large amount of time is lost during the above hammer operation.

■ To judge whether the weld is good or bad, it is necessary to visually check the back side of the strip, which makes the working posture unstable.

There were problems with work efficiency and safety.

The present invention solves the problems of the conventional method as described above, and provides a method that uses the existing flash trimmer mechanism to accurately test the quality of flash butt welds in a short time and safely without relying on human power. The main objective is to provide it.

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

1 and 2 show a flash trimmer according to the present invention, in which an upper clamp beam 2 pressed by a beam pressing device 1 is connected to a lower clamp beam 3 and a tie rod 4 so as to be slidable in the vertical direction.

An upper ram 5 is slidably engaged with the upper clamp beam 2 in the width direction (left and right) of the strip 7, and a lower ram 6 is similarly slidably engaged with the lower clamp beam 3.

A truck 8 is provided to pull the upper and lower rams 5 and 6 via rods 9a and 9b.

On the sides of the upper and lower rams 5, 6 facing the strip 7, a plurality of cutting blades 10a to 10b are arranged in a row along the axial center line of the rams.

The above configuration shows a well-known flash trimmer, but the feature of the method of the present invention is that a removable pressing protrusion 11 is provided on the upper surface of the lower ram 6, and the pressing protrusion 11 forms a bulge at the welded part of the strip 7. This will be explained in more detail below.

In FIG. 3, the suppressing protrusion 11 is formed to fit into a bottomed hole 12 bored on the upper surface of one end of the lower ram 6, and the top of the suppressing protrusion 11 is lower than the cutting level L on the back surface of the strip. It is set to protrude by a height of h.

The cutting level L and the cutting edge of the cutting blade 10a located at the end of the lower ram 6 are at the same height, and the cutting edge 10a is located at the end of the lower ram 6.
As is well known, a line M connecting the cutting edges of the cutting blades 10b and 10c successively attached to the carriage 8 side and the cutting level plane L are set to form a taper angle θ.

By the way, the pressing protrusion 11 is a so-called punch whose top part is formed into a semicircular shape, and the material may be selected from a material having an appropriate hardness (for example, HS90 or higher) that can withstand the bending test of the strip handled by the flash trimmer.

Now, a method for testing welds using the apparatus configured as described above will be described below.

First, the first step is to cut and remove the "burr" of the welded part. After the strip T is held between the clamp beams 2 and 3 under the soil, the upper and lower rams 5 and 6 are pulled by the trolley 8, and the "barrel" is removed in the width direction of the strip. Cutting blades 10d, 10c from the top to the bottom of
, 10b, and 10a are cut and finished in this order.

After this, when the upper clamp beam 2 is pulled upward,
The strip 7 is lifted up to the height of guide rollers (not shown) provided before and after the flash trimmer in the sheet passing direction (corresponding to the position of the strip 7 in Figures 1 and 2).
.

Next, the upper and lower rams 5 and 6 are pushed back to their initial standby positions by the truck 8.

Now, the next two steps to perform a weld test are to attach the pressing protrusion 11 to the bottomed hole 12 of the lower ram 6, pull the upper and lower rams 5 and 6, and place the suppressing protrusion 11 in the weld test position of the strip 7.
When the tip of the ram is reached, stop moving the ram.

Next, when the upper clamp beam 2 is pushed down, the strip 7 is pushed up by the pressing protrusion 11 around the welded part 7a, forming a bulge as shown in FIG.

Subsequently, the clamp on the strip 7 is released, the ram is moved and stopped at another weld test position as necessary, and the above-described suppression operation is repeated.

Three weld test locations are usually sufficient: one at each edge of the strip and one in the center.

Next, in the third stage to judge the quality of the welded part after pressing, the pressing test area is moved to a position where it can be visually observed on the rear surface of the flash trimmer, and when it is stopped, there is no crack or abnormal deformation in the Oshikawa area. Verify whether

As a result of observation, if cracks or abnormal deformation are found at the pressed location, rewelding will be performed.

The present invention is carried out as described above, but in order to standardize the criteria for determining the quality of the pressed portion, the diameter of the top of the pressing protrusion and the height of the projection are determined as follows.

First, if the top diameter is too pointed, it will be difficult to capture the weld, and the bulge after suppression will bend when passed through the pinch roll installed after the flash trimmer. Because it is difficult to obtain a clear deformation effect when a hemispherical shape has a kana radius of curvature, in this example a semispherical shape with a radius of curvature of 25 mm gave practically satisfactory results.

In addition, in determining the protrusion height, we used the conventional hammer test described above and the method of the present invention for the same strip material, and determined the protrusion height at which a change in the welded part appears to be equivalent to the hammer test result that can withstand threading. We determined and set the following.

Specifically, as shown in FIG. 5, the welded portion 7 of the strip γ
Strip 7 when a crack showing the permissible limit for stripping occurs in a.
It has been found that the height of the pressing protrusion 11 may be set so that the ratio of the depth t and the diameter D of the recess is 12% to 15%.

When setting the top diameter and protrusion height of this pressing protrusion, the properties that appear in the weld will vary slightly depending on the thickness of the strip, the material, the dimensions of the flash trimmer, etc., so this should be taken into consideration. .

As mentioned above, the present invention can perform a pass/fail test of flash butt welds on strips by using an existing flash trimmer and adding a simple device to make accurate judgments in an extremely short time without relying on human power. It also has practical effects such as safety because it is necessary to observe only the surface of the strip.

[Brief explanation of the drawing]

Fig. 1 is a schematic partial cross-sectional front view of a flash trimmer explaining the method of the present invention, Fig. 2 is a schematic side view of Fig. 1, Fig. 3 is a partially enlarged view of Fig. 1 showing the mounting state of the pressing protrusion, and Fig. 4 The figure is a partial cross-sectional side view showing the state of the pressing test, and FIG. 5 is an explanatory diagram illustrating the criteria for determining the quality of the pressed portion of the strip. 1: Beam pressing device, 2: Upper clamp beam, 3: Lower clamp beam, 4: Quirod, 5: Upper ram, 6
: Lower ram, 7: Strip, 8: Dolly, 9a, 9b:
Rod, 10a-10d: Cutting blade, 11: Pressing protrusion, 1
2: Bottomed hole.

Claims (1)

[Claims] 1. Clamp both sides of the flash butt welded part with underground clamp beams in the width direction of the strip, and cut the strip using cutting blades fixed to the L section ram and the lower ram, respectively, which are slidably engaged with the upper and lower clamp beams. After cutting the welding bulge, the strip clamp is released, a desired number of pressing protrusions for pressing the welding part are attached to the upper surface of the lower ram, and the strip is again clamped by the upper and lower clamp beams, and the pressing protrusions 1. A method for testing the quality of flash butt welds, comprising: forming a bulge in the weld, and determining the presence or absence of cracks or abnormal deformation in the bulge.