JPH0432511A - Method for measuring temperature of round-shaped steel tube heated in shifting type induction heating apparatus - Google Patents

Abstract

PURPOSE:To execute quenching to a roll into uniform hardness over the whole length by measuring roll temp. at the highest temp. part in roll decided from ratio of outer diameter of the roll and inner diameter of a coil for induction heating at outer periphery of the roll at the time of executing hardening to surface of the forged steel-made columnar roll. CONSTITUTION:At the time of forming high hardness hardened layer by heating and quenching the surface of columnar roll material 11 of the forged steel-made rolling roll, etc., the coil 10 for induction heating is concentrically set at the outer periphery of roll diameter 11, and after heating the surface of roll material 11 to the quenching temp. with the induction current, the hardening is executed by rapidly cooling with cooling water. In this case, at the time of using dw for the diameter of roll material 11 and dc for the inner diameter of coil 10 for induction heating, from the value of ratio dw/dc, the highest temp. part P having distance lt from upper end of length (l) of the heating coil 10 is decided, and a probe for a non-contacting type temp. measuring instrument is set at this P point, and by adjusting so as to become the optimum quenching temp., the high hardness hardened layer on the whole surface of roll material is uniformly formed without any unevenness.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is applicable to the heat treatment of a cylindrical or cylindrical-shaped heated steel material (hereinafter referred to as circular heated steel material) such as a forged steel roll for pressure grinding. This invention relates to a method of measuring the temperature with a probe of a non-contact thermometer such as a radiation temperature needle while inductively heating a shaped steel material with a mobile induction heating device.

<Prior art> Forged steel rolls, which are steel materials with a C-shaped columnar or cylindrical shape, have a shore hardness of 90 on the surface of the roll to prevent wear caused by rolling operations and scratches caused by foreign matter such as scale. It is then cured and ready for use. As a method of hardening the surface layer of a forged steel roll, a mobile induction heating device is used to heat the surface layer above the austenitizing temperature of the roll material, and then immediately quenched with water, etc. (This operation is called surface hardening treatment. ) The desired hardness is obtained.

As shown in FIG. 7, the mobile induction heating device performs surface hardening treatment by induction heating a circular heated steel material 11 (hereinafter referred to as steel material) such as a forged steel roll while moving it. An induction heating coil 10 is provided along the quenching movement direction, and a cooling device j13 is arranged below the induction heating coil 10.

The rope 11 is coaxial with the induction heating coil 10 and is supported by support devices 14 and 15 at its upper and lower shaft ends in a vertical position, and the support device 14 at the lower end is a rotating device with the axis of the induction heating coil 10 as the rotation axis. 16, it can be rotated.

A rotating device 16 that rotatably supports this supporting device 14 is arranged on a movable table 17 that is attached to the supporting device 15 at the upper end so that it can be moved up and down, and a water tank is arranged below the cooling device 13. has been done. With such a structure, the rope 11 is vertically and rotatably supported on the movable table 17.

The surface hardening treatment of the steel material 11 is carried out by rotating the steel material 11 supported between the support devices 14 and 15 with the rotating device 16 while gradually lowering the movable table 17 from an upper position to a lower position. This process starts from the time when the lower end enters the inside of the induction heating coil 10.

In this way, the rope material 1, which is heated to a predetermined heating temperature while gradually descending inside the induction heating coil 10, is surface hardened by the jet water from the cooling device t13 provided below, and then gradually descends to the lowest part. It enters a water tank 18, where it is immersed and cooled to room temperature down to its center, completing the surface hardening process.

The hardness of the surface layer of a roll made of forged steel as the steel material 11 to be heated, for example, is determined by the heating temperature (austenitization temperature) during surface hardening treatment, and fluctuations in the heating temperature will cause variations in the hardness of the roll surface layer after surface hardening treatment. It has been empirically confirmed that this is the dominant factor that causes However, there are many types of forged steel rolls with body diameters ranging from 280 to 720 m.
mφ has a wide range, and the induction heating coil 10 is complicated and expensive, so it is economically possible to minimize the number of pieces, so the range of the target material diameter per coil is 150 to 260 mm. Therefore, the maximum heating temperature position changes depending on the material diameter of the forged steel roll.

By the way, a circular heated steel material 1 typified by a forged steel roll
A radiation thermometer is generally used as a non-contact thermometer to measure the heating temperature when steel material 11 is induction heated by a mobile induction heating device, and the temperature of the steel material 11 is adjusted to a predetermined temperature according to the measured temperature. It is heated by induction.

To measure the heating temperature of the circular steel material 11 to be heated by the induction heating coil IO in the mobile induction heating device, as shown in FIG. Steel material to be heated 1
The temperature is measured with a radiation temperature needle via a fiber cable 2 connected to the rear of the probe 1 and facing the probe 1 .

<Problems to be Solved by the Invention> However, as described above, in the conventional technology in which the probe 1 of the radiation thermometer is passed through the induction heating coil 10 in multiple stages to measure the temperature, the measurement position is fixed, and the measurement position is fixed. Depending on the position, it may not be possible to capture the highest heating temperature, which is the most important point, and there are also the following problems.

1) Due to the change in the diameter of the steel material to be heated, it becomes impossible to capture the maximum temperature within the heating region, and the true heating temperature cannot be measured.

2) Stabilize the heating temperature by increasing the number of induction heating coils.
If you try to do this, operating costs will increase.

3) Providing a large number of probes within the induction heating coil makes it easier to capture the maximum temperature, but not only is the existing heating coil inapplicable, but it also becomes expensive.

4] Even if a contact type thermometer is used, it is difficult to solve the above-mentioned problem 1), and the contact type causes a delay in temperature rise of the contact portion, which causes the temperature of the heated I shrine to increase.

5) Insufficient uniform temperature maintenance causes uneven hardness of the product.

When surface hardening is performed using an induction heating coil, for example, the product, a forged steel roll, is an important tool in the production of cold-rolled copper sheets and a factor that determines the surface quality of the steel sheet. In recent years, forged steel rolls have been required to suppress surface hardness unevenness more strictly than before due to higher quality steel sheet surfaces.

In order to suppress this surface hardness unevenness, the desired uniform hardness cannot be obtained unless variations in heating temperature during surface hardening treatment are suppressed to a minimum.

In order to control the variation in heating IA temperature within ±1%, it is necessary to detect the true maximum heating temperature and perform temperature control. However, with existing conventional technology and equipment, it is structurally difficult to measure the true maximum heating temperature.

The present invention has been made in view of the above circumstances, and
This method easily and accurately measures the maximum heating temperature of a circular heated steel material such as a forged steel roll that is induction heated by an induction heating coil, and performs surface hardening treatment to obtain a steel material with uniform hardness distribution. The object of the present invention is to provide a method for measuring the temperature of a circular heated steel material in a mobile induction heating device.

<Means for Solving the Problem> The present inventors have developed an induction heating coil 10 as shown in FIG.
(Total length r in the height direction, inner diameter dc) When a circular steel material 11 to be heated with an outer diameter d1 is heated by induction while being gradually screened inside, the highest temperature position P (hereinafter referred to as temperature peak position) is the temperature of the induction heating coil. Various experiments were conducted using heated steel materials 11 having different outer diameters, assuming that the heated steel materials 11 were located at a position moved by a distance IL from the upper end.

As a result, when the temperature peak position i1P is expressed as the ratio C1t/l of the moving distance l to the total length of the induction heating coil 10, the change in the temperature peak position P is as shown in FIG. It changes depending on the ratio (d, /de) of the outer diameter d8 of the circular heated steel material 11 to the outer diameter d8. That is, the outer diameter d of the heated steel material 11 is relative to the inner diameter dc of the induction heating coil 10. As the ratio (,d,/dc) becomes smaller, d, /dc becomes smaller, and the temperature peak position approaches the upper end of the induction heating coil 10, and conversely, as the ratio (,d,/dc) becomes smaller, the ratio (4L/fc) becomes smaller. It has been found that the coil becomes larger and moves away from the upper end side of the induction heating coil 10.

The present invention was completed based on the above-mentioned findings, and
The main points are as follows.

That is, the present invention uses a non-contact thermometer 20 to measure the temperature of a circular steel material 11 to be heated by induction while moving within an induction heating coil 10 in a mobile induction heating device, as shown in FIGS. 1 to 3. A method of measuring with probe 1,
The induction heating coil 1 is determined by the diameter ratio of the outer diameter of the circular heated steel material 11 to the inner diameter of the induction heating coil 10.
Insert the probe 1 of the non-contact thermometer into the gap formed between the induction heating coil 10 and the circular heated steel material II and move it to the temperature peak position within the entire length range of 0. This is a method for measuring the temperature of a circular heated steel material in a mobile induction heating device, which is characterized by measuring the temperature of a steel material 11.

The structure and operation of the mobile radiation temperature measuring device used in the method of the present invention will be explained in detail.The probe 1 of the non-contact temperature measuring thermometer 20 is inserted into the gap between the induction heating coil 10 and the steel material 11 to be heated. , for example, as explained above with reference to FIGS. 4 and 5, the inner diameter (d
c) to the temperature peak position (Nt/e) within the range of the total length l of the induction heating coil IO determined from the ratio (d/d,) of the outer diameter (d, ) of the circular heated steel material II, The heated surface temperature of the heated @shrine 11 is measured in a non-contact manner. The temperature is input to a temperature converter 3 through a hot wire connected to the rear of the probe 1 via a hot wire at the tip of the probe 1, and is converted into a temperature value. The converted temperature value is recorded in record 5
112 or an indicator light or heating temperature controller (not shown).

The probe 1, including the fiber cable 2 and temperature converter 3, is held and fixed to an arm 6 so as to be movable up and down. The arm 6 has a sufficient length to be assembled to the pedestal 4 which is installed and fixed at an outside position where it does not interfere with the induction heating coil IO, and is fixed to the main rod 5. Further, in order to smoothly move the probe l up and down, the arm 6 is provided with gyrtron doors A and 7B on both sides. The arm 6 uses a drive motor 9 installed on the pedestal 4 as a power source to rotationally drive a drive device 8, and moves up and down by the torsional rotation of the main rod 5, thereby moving the probe l to a desired position and stopping it. ing.

Mobile number 4 I/I of the present invention! ! The procedure for surface hardening treatment using a mobile induction heating hardening machine using a degree measuring device will be explained below.

(+) Insert and set the probe 1 into the induction heating coil 10. At this time, the setting position is adjusted to the maximum value of the heating temperature generated from the outer diameter of the steel material 11 to be heated and the inner diameter of the coil 10, as shown in FIG.

(II) Steel material (roll) to be heated in the induction heating coil 10
11, move the end of the roll to the heating start position, and stop.

(II) At the same time as the start of heating by the induction heating coil 10, the steel material to be heated (roll) 11 descends at a preset movement speed while rotating on its axis, and is rapidly heated within the induction heating coil IO.

(IV) In the rapid heating, the induction heating coil 10 performs induction heating using a preset application type cover turn. The heating temperature is detected at its highest value by probe 1, and temperature converter 3
It is passed through the heating thermometer 20.

(V) Heating temperature 9120 calculates the excess or deficiency of the input temperature value with respect to the preset target temperature value and issues a command to the applied power control device to adjust the applied power, and the applied power control device issues a command to adjust the applied power. The electric power of the induction heating coil 10 is adjusted based on the following.

(Vl) The heating operation is performed by repeating (rV) and (V) to maintain and control a preset target temperature value and heat to the required range.

(■) The steel material (roll) 11 to be heated is the induction heating coil 1
0, it is heated to the target temperature, moves to a cooling nozzle section set at the lower part of the induction heating coil IO, and is rapidly cooled by jetted water.

(■) ■ to ■ are carried out continuously to carry out surface hardening treatment of the necessary portion (roll body) of the steel material to be heated II.

<Example> The method of the present invention was carried out using the apparatus shown in FIGS. 1 to 3. That is, as shown in Table 1, the height of the induction heating coil 10 is determined from the diameter ratio (d, /dc) of the heated steel material 11 (in this case, a forged steel roll) to the inner diameter dimension (dc) of the induction heating coil 10. The temperature peak position (distance Mp, L from the upper end of the coil) within the direction total length (1) region was determined.

Table 1 Thus, in response to changes in the temperature peak position within the height direction total length (ffi) tIJl of the induction heating coil 10 caused by the diameter ratio (d, /dc), the radiant temperature needle is moved to the determined temperature peak position. The temperature was measured by positioning the probe, and the heating was controlled by the induction heating coil IO so that the heated steel material 11 reached the target temperature value.

As a result, the range of fluctuation in the heating temperature of the steel material 11 to be heated is suppressed to ±0.7% of the target temperature, and the variation in surface hardness of the steel material 11 to be heated, which has been subjected to surface hardening treatment, is within the range of variation of products treated by the conventional method. ΔH, L=, ±2) is halved ΔH
A result of 5≦±1 was obtained. This is the roughness variation R of roll dull roughness during rolling of cold-rolled steel sheet, ≦±0.02
It satisfies μR1 and can contribute to the production of high-grade surface treatments.

<Effects of the Invention> As explained below, in the present invention, the circular shaped steel material to be heated is heated by moving the I-b of the rotary contact thermometer to the temperature peak position within the entire length region of the induction heating coil. It becomes possible to easily and accurately measure the peak temperature of the temperature without using a large number of 10-beams for temperature measurement.

Therefore, variations in the heating temperature of circular steel materials such as forged steel rolls are reduced, and surface hardening treatment with uniform surface hardness can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a plan view of the apparatus according to the method of the present invention, FIG. 2 is a side view of FIG. A schematic perspective view showing the relationship between heating coil dimensions and heated steel material τj method, Figure 5 shows the coil inner diameter (dc)
/A graph showing the relationship between the diameter ratio of the outer diameter (d8) of the copper material and the temperature peak position. Figure 6 is a perspective view showing the arrangement of a conventional radiation thermometer. Figure 7 is a general mobile induction heating device. FIG. DESCRIPTION OF SYMBOLS 1... Proof, 3... Temperature converter, 5... Main rond, 7A... Guide rond, 8... Drive device, 10... Induction heating coil, 12... Old record, 14... Support device, 16... Rotating device, 18... Water tank.

Claims (1)

[Claims] A method of measuring the temperature of a circular steel material to be heated by induction heating while moving inside an induction heating coil in a mobile induction heating device using a probe of a non-contact thermometer, the method comprising: Inserting the probe of the non-contact thermometer into the gap formed between the induction heating coil and the circular heated steel material at a temperature peak position within the entire length range of the induction heating coil determined by the diameter ratio with the outer diameter of the steel material to be heated. 1. A method for measuring the temperature of a circular heated steel material in a mobile induction heating device, the method comprising: moving the heated circular steel material at the relevant position; and measuring the temperature of the circular heated steel material at the position.