JPS5885291A - Induction heater - 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 The present invention relates to an apparatus for induction heating of a sheared surface of a steel bar. Steel bars commonly used for automobile parts are called mechanical structural steels, and many contain chromium, molybdenum, and manganese in addition to carbon.

Traditionally, these steel bars were cut with a saw after being rolled.
In recent years, from the standpoint of bulkiness, it has become common to use shears to cut to custom lengths.

In this case, when the steel bar is sheared, strain occurs inside the steel bar, resulting in residual stress.

For this reason, as time passes, hydrogen diffuses into the areas with high residual stress, and a phenomenon occurs in which the shear plane becomes distorted as shown in FIG.

This phenomenon is considered to be a type of age cracking, and when the material is cut into small pieces at a processing factory, if small pieces with such cracks get mixed in, it poses a serious problem that could endanger the safety of the final product. There are two methods being used to deal with this problem.

The first method involves annealing the bundled product to release stress.

This is a bundle of dozens of products piled up for participation.
The end face of each acetylene gas or LPG A is heated one by one, and this is normally done while checking with a thermocrayon or the like to ensure that the surface temperature is at least 500°C. However, with this method, the amount of heat added cannot be large, the added heat is directly conducted through the long steel bar, so it takes an extremely long time, it consumes a lot of fuel, and is inefficient. During the winter season, the worker's environment is poor because the workpiece is handled with no-manner, and during the winter season, only the hill or end face is heated to 500-600°C, so heat transfer and It had major drawbacks such as being cooled by radiation and becoming a hardened structure.

Another method is to suppress cooling in a cooling bed so that the steel bar is sheared while still at a high temperature, and is annealed to remove strain using its own heat. However, if sheared at a temperature exceeding 400°C, the sheared surface will bend or become deformed, and the sheet must be cut with a saw again after cooling.

Therefore, shearing must be carried out at the lowest possible temperature at which the sheared surface does not deform, but there is a contradiction that if this is done, the annealing effect will not be sufficient. The present invention eliminates the drawbacks of such conventional methods and provides a steel bar with good shear surface quality.

The apparatus of the present invention will be explained below with reference to the drawings. Fig. 1112 is a plan view showing the layerer after the cooling bed of the steel bar manufacturing facility. After rolling, the steel bar is cooled while being transported by a walking arm mechanism on the cooling bed 1. At this time, if the conveying speed is increased, the temperature of the steel bar on the exit side of the cooling bed becomes high. Normally, the temperature of the steel bar at the inlet of cooling bed 1 is around 800℃, but if the conveying speed is selected according to the diameter of the steel bar, the temperature at the outlet of the cooling bed can be raised to 300℃.
Can be controlled around ℃. Cooling bed outlet temperature is 30
If the temperature is about 0°C, the shape of the sheared surface of the steel bar can be maintained well even if it is subsequently sheared by the cold shearing machine 2 on the conveyance table 3. The sheared steel bar is aligned at its front end on a conveyance table 3 and sent to an inspection floor 4, where it is fed laterally by a walking mechanism or a chain tranner, and at the same time its front end is annealed by a Kn induction coil. It is transported backwards on the transport table 1O, its rear ends are aligned, and while it is transported across again by the forking beam mechanism, its rear end is annealed by the induction coil 9, and then passed through the second transport table 5 and the sorting floor 6. A predetermined number of pieces are tied together by a tying machine 7 and delivered.

The mosquito induction coil 8゜9 installed in the middle of the test bed 4 is the third
With a spiral flat plate coil as shown in the figure.

101! The steel pipe is wound three times in a spiral shape and the inside is water-cooled. Approximately 10
Install the air earcups facing each other.

The steel bars 12 are continuously or intermittently conveyed on the inspection floor 4 by a fixed beam 11m and a moving beam 1lb, etc.
When the corresponding positions of the induction coils 8 and 9 are reached, the induction coil control device applies a current for a certain period of time determined by the dimensions (diameter) and chemical composition of the steel bar and the current temperature. Alternatively, the current may be kept constant and the energization time may be varied.

At this time, the applied current value and time are set so that the ends of the steel bar are heated to a predetermined temperature by eddy current.

This has been determined in advance through experiments. In the example, 60
0A current for 8 seconds, 6sp with 10■ air gap;
When six steel bars were heated, the temperature at the center of the shaft reached 400°C at a distance of 20 cm from the end face of the steel bar. It was found that in this state, the residual stress was sufficiently released, and no end cracks would occur thereafter.

The thus heated steel bar is then gradually cooled by thermal radiation and heat transfer in the axial direction, but since the steel bar before heating has a retained heat of about 300°C, or at least 200°C or more after rolling, Not only does the amount of electric power required during induction heating be small, but the cooling rate is slow even when cooling after heating. There are great advantages that should be avoided.

Here, the air gap is necessary to avoid interference with the heating coil when the steel bar is transversely fed by the walking beam, and is also transferred from table o-2 (not shown) to the walking beam of the bar. This is unavoidable due to unevenness between the ends of the steel bar. However, the heating efficiency decreases at an accelerating rate as the amount of heat increases.

Fig. 4 shows the difference in temperature rise of steel material when the gap is changed.It is necessary to make this air ear as small as possible from the viewpoint of energy saving and the transportation efficiency of the conveying device), and the present invention solves this problem. This was done in consideration of the situation.

Generally, when induction heating is performed with the senryo fill 8 shown in Figure 11113 (m) iC facing the end face of the main material, an electromagnetic force P! between the strip 12 and the coil 8! A stronger attraction force than iK acts and the coil 8 is deformed. Therefore, unless the coil 8 is strongly supported by a rigid body, a portion of the coil 8 may warp and come into contact with the steel bar, causing uneven heating temperature.

The present invention is based on the idea of actively utilizing adsorption force based on such electromagnetic action to improve heating efficiency.

That is, in FIG. 3, 1x>tlc, the walking beam type conveyance device 11 is provided with grooves at predetermined intervals between the fixed beam 11a and the moving beam 1lbK in order to convey the plurality of strips so that they do not overlap. After scooping up the strip 12 on the fixed beam lla, the movable female 11b moves laterally in one block's worth of strokes, and then lifts up the fixed beam 11a again.
Transfer the strip material to the top and wait at the initial position. An induction heating coil 8 is installed in the middle of this conveying device 110 so that its coil surface forms a predetermined gap between the ends of the conveyed strip, and the strip 12 is transferred to the fixed beam 11aK at the same time. Power supply starts. '*When heating of the end face of the strip material is completed by energizing for a predetermined time determined by the size and temperature of the material, conveyance is started again. A grooved roller 14 having the same groove spacing as that of the fixed beam is provided in the part corresponding to the fixed beam heating coil 8, and the strip material transferred to the heating position of the conveying device is 12 is shown in Figure 3(b) K
As shown, since it has a gap d with the heating coil 8, it can move freely in the longitudinal direction. When the heating coil is energized in such a state, heat is generated in the single strip 12 by the eddy electric current fiK, and at the same time, the heating coil 8 is heated by the electromagnetic force.
A suction force acts on the strip material 2, and the strip material 2 is drawn toward the heating coil 8. K utilizes the suction effect even when the end surface of the strip material 2 is uneven with respect to the coil 8. As shown in FIG.
4 may be structured to be able to rotate independently for each groove.

In this way, heating is completed, but if you leave it as it is, it will not work.
- When the heating film is driven, the surface of the coil 8 and the strip 12 will rub and the heating coil 8 will be damaged.
b) The mechanism is such that it can be retracted backward by a predetermined stroke using the cylinder 8-4> shown by K. Therefore heating coil 8
can slide on 8 layers of rails. When the heating coil 8 is retracted, a gap is generated again, so the conveyance device starts the transfer, and the cylinder 1-5b operates again just before or after the transfer is completed, and the heating coil moves forward to a predetermined ear contact position with the end surface of the strip. .

The above is one phase of conveyance and heating.

As another embodiment of the present invention to increase the heating efficiency by adsorption, as shown in FIG. It is also effective to leave the heating coil 8 in an open state and allow the heating coil 8 itself to attract harm by the single strip 12. In this case, when heating is completed, the heating coil 8 can be moved back from cylinder/-8bK, but if the strip 12 is lightweight, it will be attracted to the strip, so the first strip 12 should be fixed to the e-me. A flange mechanism 15 is required. Furthermore, in the case of this embodiment, a chain-type toranosaur can also be used as the conveying device. Furthermore, since rapid heating can be achieved simply by increasing the voltage, it is possible to effectively heat only the end face, which would otherwise be separated due to loss due to heat conduction in the longitudinal direction of the steel bar, which occurs when heating with conventional acetelene caustic. can. In addition, because the coil is shaped like a vortex and faces the end face of the steel bar, less power is required to heat unnecessary parts, which is the case with other transformer type coils, and only the end face is heated. can.

As described above, according to the apparatus of the present invention, since the air intake can be made extremely small, highly efficient induction heating is possible, and there is a great effect in terms of energy saving.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of cracks at the sheared end of a steel bar, Figure 2 is a layout of the steel bar manufacturing equipment, and Figure 3 is a diagram of the equipment configuration of the present invention.
1) is an overall view, (b) is an elevation view, Fig. 4 is a graph showing the relationship between the gap d between the end of the steel bar and the coil surface and the temperature rise of the steel bar, and Fig. 5 is the fixation of the conveyor device. Beam 11aK
FIG. 6 is a mechanical diagram showing another example of the present invention, in which the grooved p-lar can be rotated according to the attached groove. 1-...Cooling bed, 2...Shearing machine% 3#5,1G...
・Transportation table, 4... Inspection floor, -°... Sorting floor,
7... Binding machine, 8, 9... Induction heating coil, 11.
... Walking beam conveyance device, 111... Fixed beam, 11b... Moving beam, 12... Strip material, 8 Otori... Rail for heating coil movement, 8b... Air cylinder for heating coil movement, 14...grooved roller, 15
...Strip flange device. Agent Patent attorney Masanobu Akizawa 2 persons Figure 3/1 (b)

Claims (2)

[Claims] (1) An induction heating device consisting of a strip transverse transport device having a fixed beam with a roller for moving the strip in the length direction attached to the upper i1, and a heating coil that advances and retreats facing the end surface of the strip. (2) An induction heating device comprising a strip transverse conveyance device, a heating coil that advances and retreats in opposition to the end face of one strip, and a flange device that holds the strip on the transverse conveyance device.