JPH0426722A - Catenary type continuous furnace for strip - Google Patents

Abstract

PURPOSE:To continuously heat-treat a strip with high quality while preventing slipping, meandering, etc., by controlling and driving supporting rollers disposed in the furnace so as to tune the driving with the strip and controlling the tension of the strip in the furnace. CONSTITUTION:The strip 10 is passed in the horizontal type furnace 2 via bridle rolls 15 and is heated by upper and lower burners 8; thereafter, the strip is cooled in an air cooling zone 12. Plural pieces of the supporting rollers 1 thermally sprayed with heat resistant ceramics are disposed in the above- mentioned furnace. The strip 10 is cetenary-supported by these rollers and is made to travel. The driving means provided in the supporting rollers 1 of the above-mentioned catenary type continuous furnace for strips are controlled to tune the rollers by which the slipping and meandering between the supporting rollers 1 and the strip 10 are prevented. Further, the in-furnace tension of the strip 10 is detected with a load cell 14 having a tension meter roll 13 and the above-mentioned bridle rolls 15 are controlled via a strip tension control mans (not shown in Fig.). The generation of the rubbing flaws, deformation, etc., of the strip 10 is prevented in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] The present invention relates to a catenary-type continuous furnace for stripping, which appropriately synchronizes and controls the peripheral speed of the rolls and the running speed of the strip.
The present invention aims to provide a continuous furnace that can effectively prevent shape defects and meandering.

(Industrial application field) (A catenary-type continuous furnace used for continuous annealing and pickling of strips.

(Prior art) When continuously annealing stainless steel strips, the beauty of the surface is important and maintaining a good surface condition is required, so catenary furnaces that use heat-resistant asbestos support rollers are used. is a special public official in 1972.
This method has been proposed in Publication No. 26723, etc.

That is, several heat-resistant asbestos rollers that can withstand high temperatures are installed in the furnace outside the entrance and exit rollers of the furnace body, and a plurality of catenaries are formed in the running strip by these rollers, and heat treatment is performed continuously in the furnace. It is an integrated furnace with a long furnace length, and when multiple furnaces are installed in series, it has higher thermal efficiency than a conventional catenary furnace that forms a catenary (suspension) for each furnace, and provides high-quality heat treatment. It is considered possible.

(Problems to be Solved by the Invention) In the above-mentioned conventional device, the heat-resistant asbestos that serves as the furnace support roller is easily worn out, and the roll diameter changes when used for a long period of time, so the drive means for driving the roll must be adjusted. It is not possible to properly synchronize and control the roll circumferential speed and the strip running speed.

When the roll as described above is used for a long time, asbestos abrasion powder and scale powder 32 are appropriately pushed into the asbestos layer on the surface layer of the heat-resistant asbestos layer 31 as shown in FIG. The coefficient of friction with the roll 30 decreases rapidly. Furthermore, slipping occurs between the strip IO and the roll 30 when the line operating conditions are changed, and scratches occur on the strip surface, especially due to scale powder, which deteriorates the quality of the stainless steel strip.

In addition, in high-speed lines aimed at high productivity, which have been increasing in recent years, fluctuations in strip tension occur when line operating conditions are changed, and the amount of catenary changes, and when the amount of catenary changes in this way, heating In a furnace, the distance between the combustion burner and the strip becomes uneven, resulting in poor shape due to thermal distortion and meandering.

Similarly, if the amount of catenary changes in the cooling zone, shape defects will occur due to non-uniform cooling, resulting in meandering.

"Structure of the Invention" (Means for Solving the Problems) The present invention was devised through repeated tests to solve the technical problems of the conventional products as described above, and is as follows. .

A plurality of strip support rollers formed by thermal spraying of heat-resistant ceramic are disposed in a horizontal continuous heat treatment furnace, and the support rollers are provided with driving means, and strip tension control devices are provided on the inlet and outlet sides of the heat treatment furnace. A catenary type continuous furnace for stripping.

(Function) A plurality of support rollers are disposed in a horizontal continuous heat treatment furnace, and a driving means is provided on the support rollers to form a catenary of the strip between the inlet coke and outlet rollers and the support cola.

Each time the support roller is sprayed with heat-resistant ceramic, the feed amount is optimized and the catenary amount is optimized.

Furthermore, by providing tension control devices on the inlet and outlet sides of the heat treatment furnace, the tension is controlled individually to minimize changes in the amount of catenary and to ensure stable sheet threading within the furnace.

Specifically, when the strip is annealed at a high temperature, such as in a catenary-type annealing furnace for stainless steel strip, the strip unit tension in the heating furnace is 0.2 to 0.4 kgf/
The tension is controlled constantly at a low tension of about mm2, while the strip unit in the cooling furnace has a tension of 0.4 to 0.8 kgf/Otori12.
Control to a certain degree.

Since the frictional force F between the roll and the strip is F-(Tcosθ+W)Xμ, the transmission torque T of the powder clutch does not cause slip between the support roll and the strip.

can be obtained by satisfying the condition Tr<F.

(Example) To explain the specific embodiment of the present invention, the overall structure of the furnace according to the present invention is as shown in FIG.
An inlet 3 is formed at one end of a horizontal furnace 2 made of refractory material, and an outlet 4 is formed at the other end.
, the outlet 4 is provided with an inlet roller 5 and an outlet roller 6, respectively, and a plurality of support rollers 1 are disposed in the middle of the furnace 2, and the inlet and outlet rollers 5, 6 and these The strip 10 is supported and run by supporting rollers 1, 1. However, the strip 10 running like this
Combustion burners 8.8 are disposed above and below the furnace to heat the strip 10, and a waste gas flue 9 is provided at the upper part of the inlet side of the furnace body 2, and the support roll 1. 1 is provided with a water-cooled box 7 for roll protection.

A cooling zone 11 is provided between the horizontal furnace 2 and the outlet 6 as described above.
Air cooling zones 12, 12, 12 are connected to each other to form a cooling zone, and in the present invention, a priddle roll 15° 15 is provided at the inlet 3 and the outlet 4 described above.
A load cell 14 having a tension meter roll 13 is provided between the inlet 3 and the outlet 4 and the priddle rolls 15, respectively.

The support roller l is rotatably supported horizontally by a bearing 20, and a cooling joint 21 is provided at one end of the shaft to allow cooling water to flow therethrough, and a sprocket is provided at the other end of the shaft. 17 is attached, and a chain 22 is suspended between the sprocket 17a at the end of the motor rotation shaft, which is driven by the motor 18 and supported by the bearing 19.19, so that the drive by the motor 18 is obtained. is provided with a slip clutch 16, and this slip clutch 1
As mentioned above, a powder clutch or the like is used as the clutch 6, and by using magnetic iron powder and an excitation coil, a transmission torque accurately proportional to the excitation current can be obtained and proper control can be achieved.

The state of the strip 10 supported on the support roller 1 as described above is as shown separately in FIG. A catenary is formed, and cooling water is fed into the support roller 1. In the heat-resistant spray coating 17, the strip tension and the strip weight W
In addition, an accurate feeding action determined from the strip winding angle θ and the friction coefficient of the roller 1 can be obtained.

Support rollers 1, 1 and inlet roller 5 as described above,
An example of the control system for the exit rollers 6 is shown in FIG. The motor 18 is provided with a speed detector 23, and a signal from the speed detector 23 and a signal from the slip clutch 16 are sent to a synchronization control device 24 to control the motor 18. A tension control device 25 is provided for such a priddle roll 15. That is, the tension control device 25 includes a tension deviation calculator 2 that receives a signal from the load cell 14.
The tension deviation calculator 26 and the speed deviation calculator 27 receive signals from the speed detector 23 of the motor 18 for the 6 and priddle rolls 15, the tension setting device 28, and the speed deviation calculating device 28a. A correction signal is sent to the motor 18 of the priddle roll 15 through the device 29.

The above-mentioned synchronization control device 24, as shown in FIG. 31 is set with a torque setting device 30, a signal from the slip clutch 16 is applied to this, a torque deviation as shown in FIG. 7 is obtained, and this is sent to a corrector 32. On the other hand, the speed setting device 34 sets the speed in the speed deviation calculator 33, and the signal from the speed detector 23 as described above is sent to the speed deviation calculator 33 to calculate the speed deviation as shown in FIG. , this is corrector 3
The correction command obtained by the corrector 32 is sent to the motor 1.
It is designed to be given to 8.

That is, by such synchronization control, there is no slip between the support roll 1 and the strip 10, and the occurrence of scratches on the strip 10 can be appropriately prevented. In addition, by controlling the rotational torque of the support roll 1 within a certain range corresponding to the size of the strip 10, etc., changes in the amount of catenary are suppressed and meandering in the furnace is prevented.

In this synchronization control, a torque setting device using magnetic iron powder or the like described above is provided to measure the rotational torque of the support roll, and the rotational torque is determined to be 30% of the frictional force F between the support roll 1 and the strip 10. The above F-
It is determined by the formula (Tcosθ+W)xμ, and the value set in the torque setting device 30 is determined by the strip size, the surface roughness of the strip, etc.

FIG. 8 summarizes the changes in the coefficient of friction over the usage time (over time) when the ceramic spray roll according to the embodiment of the present invention described above and the conventional heat-resistant asbestos roll described above are specifically used in a stainless steel strip annealing furnace. As shown in the figure, the coefficient of friction [μ] of heat-resistant ceramic spray rolls hardly changes even after continuous use for quite a long time, as shown by the a--a curve, whereas that of heat-resistant asbestos As shown by the bb curve, the friction coefficient of the roll decreases to 30% or less after some use.

However, the ninth table summarizes the tension fluctuation amount in the case of the present invention in which control is performed by the synchronization control device 24 and the tension control device 25 of the present invention described above, and the tension fluctuation amount in the conventional technology in relation to the line speed. In the figure, the tension variation of the conventional technology is ±50% or more, whereas the tension variation of the product according to the present invention is ±10% or less,
It is clear that a significant reduction effect has been obtained.

"Effects of the Invention" According to the present invention as explained above, a stable catenary is formed when a metal band material such as a stainless steel strip is subjected to heat treatment such as continuous annealing, and the amount of tension fluctuation can be reduced even under continuous high-speed processing conditions. It is industrially effective because it can significantly reduce the occurrence of shape defects, meandering, etc., enable accurate operation, and smoothly carry out favorable continuous processing with less occurrence of scratches. This is a great invention.

[Brief explanation of the drawing]

The drawings show the technical contents of the present invention, in which Fig. 1 is a longitudinal cross-sectional view of the continuous furnace according to the present invention, Fig. 2 is a cross-sectional view of the support roller portion thereof, and Fig. 3 is a heat resistance diagram of the support roller. An explanatory diagram of the contact drive relationship between the ceramic sprayed coating and the strip, Fig. 4 is a block explanatory diagram of the catenary furnace tension control and synchronization control, and Fig. 5 is an explanatory diagram of the synchronization control, and Fig. 6 is a speed diagram. Deviation calculation graph, Fig. 7 is a torque deviation calculation graph, Fig. 8 is a chart showing the friction coefficient and change over time regarding the support roll for the embodiment of the present invention and the conventional method, and Fig. 9 is a graph for the conventional method and the graph. FIG. 10 is a graph showing a comparison of the amount of tension variation according to the technology of the present invention, and a cross-sectional view of the state of adhesion of foreign matter such as asbestos abrasion powder and scale in an asbestos roller according to the prior art. Thus, in these drawings, 1 is a support roller, 2 is a horizontal furnace, 3 is an inlet thereof, 4 is an outlet thereof, 5 is an inlet roller,
6 is an exit roller, 7 is a water-cooled box for roll protection, 8 is a combustion burner, 9 is a waste gas flue, 10 is a strip, 11
is a cooling zone, I2 is an air cooling zone, I3 is a tension meter roll, 14 is a load cell, 15 is a bride roll, 16 is a slip clutch, 17.17a
is a sprocket, 18 is a motor, 19 and 20 are bearings, 23 is a speed detector, 24 is a synchronization control device, 25 is a tension control device, 26 is a tension deviation calculator, 27 is a speed deviation calculator, 28 is a tension setting 28a is a speed setting device, and 29 is a corrector. Patent applicant Nippon Kokan Co., Ltd. Inventor Masakazu Ishizono Haruyuki Nakanishi

Claims (1)

[Claims] A plurality of strip support rollers formed by thermal spraying of heat-resistant ceramic are disposed in a horizontal continuous heat treatment furnace, and the support rollers are provided with driving means, and strip tension control devices are provided on the inlet and outlet sides of the heat treatment furnace. A catenary type continuous furnace for stripping.