Apparatus For Controlling The Shape Of Rolled Product

Abstract

An apparatus for controlling the shape of rolled product characterized in that an image reflected from the surface of the rolled product is detected, that the pressure working on the central and edge portions of the rolling machine is regulated in accordance with the degree of displacement of the image, and that the shape of the rolled product in the process of being rolled is automatically kept uniform.

Description

DETAILED EXPLANATION OF THE INVENTION

This invention relates to an automatic apparatus for maintaining the shape of a rolled product always uniform.

Roll crown is one of the most important factors in the rolling machine which influence the shape in transversal direction of iron strip, etc. The roll crown is determined according to the operation condition and given to the roll at the polishing thereof. Though minute control of crown in the course of operation has been recently enabled by a so-called "crown control" system in which control of crown is realized by means, for example, of an oil cylinder incorporated in the roll chock, said control has usually been carried out based on the judgment of an experienced operator on the shape of strips, and therefore it is not always possible to obtain optimum control in the shape of rolled product.

The purpose of this invention is to provide an apparatus capable of automatically controlling the shape of rolled product always at the optimum state.

The purpose of this invention can be realized by projecting a band-shaped image onto the rolled product in the transversal direction thereof, and detecting the position and form of the image by means, for example, of TV camera or photoelectric element. Then in accordance with the deviation of position in the central and edge parts of the detected image with respect to the predetermined position, the oil pressure devices are actuated to regulate the pressure of the rolls in the central and edge parts thereof so as to increase and decrease crown respectively.

This invention will be further clarified by an example, with particular reference to the attached drawing.

FIGS. 1a, 1b and 1c show the straight and distorted reflections of images of a linear object, such as a band-shaped light, as reflected from the surface of the rolled product and viewed from a point where the reflections appear to lie in transversal direction thereof;

FIG. 2 is a block diagram representing an embodiment of the shape-controlling apparatus according to this invention;

FIG. 3 is a block diagram representing another embodiment;

FIG. 4 is a block diagram representing still another embodiment; and

FIG. 5 shows an example of detector employed for detecting the shape.

As shown in FIG. 2, a linear object, exemplified as a light source 12 connected with the power source 11 is provided in the transversal direction of the strip rolled on the rolling machine, and the light from said light source is projected onto said strip thereby obtaining a linear band-shaped light image 13 (or the reflected image of another linear object) extending across the entire width of said strip.

When the shape of the rolled strip is uniform in the transversal direction, the reflected image is linear as shown in FIG. 1a. On the other hand if the central part of the strip is excessively rolled, the image formed on said strip shows an irregular curve at the central part of said strip as shown in FIG. 1b. The case of FIG. 1c in which the irregularity is shown in the end portions of the image is encountered when the plate is subjected to excessive rolling in the edge portions thereof.

The image 13 formed on the rolled strip 10 is viewed by a TV-camera 14 using vidicon tube, etc. and projected on the image monitor 15. At the same time the output of TV-camera 14 is supplied to the control unit 16, which is composed of reforming circuits 1a, 2a and 3a in which the image signal resulting from said TV-camera is reformed, sampling circuits 1b, 2b and 3b which picks up standard position signal form the output of said reforming circuits in a manner as explained in the following, and comparing circuits 1c, 2c and 3c by which the output of sampling circuits is compared with the standard value. Thus the sampling circuits 1b, 2b and 3b collect the data along the dotted lines 1, 2 and 3 on the strip when this is projected on the monitor 15. Now, when the projected image is formed linearly and located at the predetermined position, the sampling circuits 1b, 2b and 3b generate the image signals periodically at the frequency of sampling. On the other hand, if the position of the image at the central part thereof is displaced from the predetermined position as shown in FIG. 1b, the sampling circuit 2b does not generate the image signal due to the absence of the image at the expected position whereas the circuits 1b and 3b supply normal signals. Also if the image is displaced at the end portions thereof as shown in FIG. 1c, the sampling circuit 2b provides a normal image signal while the circuits 1b and 3b do not. The output of said sampling circuits is compared with the standard value in the comparing circuits 1c, 2c and 3c, and the differences between these two sets of values are supplied to the amplifiers 1d, 2d and 3d. The output of sampling circuits is regulated so as to be equal to the said standard value when the shape of strip is uniform as shown in FIG. 1a, and thus no input is applied to the amplifiers 1d, 2d and 3d in this case. In case of excessive rolling in the central portion of strip as shown in FIG. 1b, then a difference is formed between the output of sampling circuit 2b and the standard value, and this difference is supplied to the amplifier 2d. Also in case of excessive rolling on the edge portions of strip as shown in FIG. 1c, input appears in the amplifiers 1d and 3d.

The outputs of the amplifiers 1d, 2d and 3d are respectively supplied to the control valves 1e, 2e and 3e. The control valves 1e and 3e regulate respectively the pressure of oil pressure cylinders B.sub.1 and B.sub.2 mounted correspondingly with the respective detectors between the shafts of upper and lower working rolls 17 and 18, while the control valve 2e regulates the pressure of oil pressure cylinders A.sub.1 and A.sub.2 provided between the shafts of upper work roll 17 and upper backup roll 19. The lower backup roll supporting the lower work roll is represented by 20, and the strip 10 is rolled between the upper and lower work rolls 17 and 18 in an already known manner. The dotted lines 1, 2 and 3 indicated on the strip 10 represent the positions of sampling.

In case of excessive rolling in the central portion of the strip, the output signal of the amplifier 2d, generated in a manner as explained above, opens the control valve to increase the pressure in the oil pressure cylinders A.sub.1 and A.sub.2. As the result, the pressure of upper work roll 17 at the end portions thereof increases with respect to the pressure in the central part of said roll thereby decreasing the crown. Consequently the rolling pressure applied on the strip becomes uniform to correct the shape of rolled strip.

On the contrary in case of excessive rolling in the edge portions of strip, the output signals of the amplifiers 1d and 3d generated as explained before, open the control valves 1e and 3e to increase the pressure of oil cylinders B.sub.1 and B.sub.2. As the result, the pressure between upper and lower work rolls 17 and 18 at the end portions thereof decreases with respect to that at the central portion thereby resulting in the decrease of crown. Thus the rolling pressure applied onto the strip becomes uniform and the shape of rolled strip is thus corrected.

Also in another embodiment of this invention shown in FIG. 3, the image 13 formed on the strip 10 is detected by a TV-camera 14, and is projected on a cathode-ray tube 21. The image thus projected on the cathode-ray tube is divided into central and edge portions, and the deviations of these images from the predetermined position are respectively measured by photoelectric elements 21a and 21b such as phototransistors, of which outputs are amplified by the amplifiers 22a and 22b respectively and then supplied to the comparing circuits 23a and 23b wherein the signals are compared respectively with a standard value. The deviations from the standard value are respectively fed to another set of comparing circuits 24a and 24b in which said deviations and partial feedback signals supplied from, via the amplifiers 26a and 26b, the circuits 25a and 25b which electrically indicate the final cylinder pressures. The outputs of comparing circuits 24a and 24b are amplified by the servoamplifiers 27a and 27 b and regulate the servo valves 28a and 28b to control the pressures in oil cylinders A.sub.1, A.sub.2, B.sub.1 and B.sub.2. The displacement on the cathode-ray tube of image in the central or edge portion leads to, in accordance with the change in the output of photoelectric element 21a or 21b respectively, the generation of deviation signals in the comparing circuit 23a or 23b respectively and the pressures in the cylinders A.sub.1 and A.sub.2 or B.sub.1 and B.sub.2 respectively are regulated so as to bring this deviation to zero.

In the embodiment represented in FIG. 4 in which corresponding parts are endowed with corresponding numbers with FIG. 2, the detection of shape is carried out by the photoelectric unit 30 which is located in the reflected light path of said image 13, being the reflection of a light source producing a linear image. Said photoelectric unit 30 consists of three groups of photoelectric elements arranged correspondingly with the dotted lines 1, 2 and 3 of FIG. 2, each of said groups being composed of a series of, for example, phototransistors 30' arranged in longitudinal direction of the strip, and said phototransistors being arranged in a manner that the reflected light from the strip falls on a phototransistor located in the center of such series when the shape of strip is uniform. The outputs from the said phototransistor groups are supplied to the identifying circuits 31a, 31b and 31c in which the transistors on which reflected light falls are identified and which supply output signals to the amplifiers 1d, 2d and 3d when the values of said signals are different from those predetermined. The amplified signals are respectively supplied to control valves 1e, 2e and 3e. Similar to the case shown in FIG. 2, the control valves 1e and 3e control the oil pressure cylinders B.sub.1 and B.sub.2 located between the shafts of upper and lower work rolls 17 and 18 thereby performing the correction corresponding to the detectors located at the edge portions of the rolled products, whereas the control valve 2e regulates the pressure in the cylinders A.sub.1 and A.sub.2 mounted between the shafts of upper work roll 17 and upper backup roll 19.

The working principle of the example shown in FIG. 4 will not be discussed here as this is quite similar to that in FIG. 2.

FIG. 5 shows a photopotentiometer of known structure which can be utilized as the substitute for the phototransistor shown in FIG. 4, and which is composed of photoconductive layer 32 between a conductor 34 and a resistance layer 33 of which extremities are connected with a direct current electric source 35, thereby making it possible to obtain a potential between the terminals 36 and 37 in correspondence with the position of light reflected from the rolled product and falling on said photoconductor 32. Thus the output potential indicates the displacement of light image, i.e. actual shape of rolled product when such photopotentiometer is used instead of phototransistor.

As thus far explained, the apparatus of this invention makes it possible to realize uniform rolling of strip and therefore provides an advantage of increasing the value of produced merchandise and of decreasing the mental burden of rolling machine operator.

Although the explanation in the above examples has been limited to the application to rolling of iron strip, it will be readily understandable that the present invention is not limited to the above application, but is applicable for various purposes such as plastic calendaring; production of roll-type paper will also be within the scope of this invention. Also it will be readily understood that the light source 12 is not necessarily limited to a single linear one, but can also be composed of a series of light sources arranged on a line or a single source with lens producing a beam linear cross section.

Claims

What we claim is:

1. An apparatus for controlling the shape of a rolled product traveling in a longitudinal direction comprising means for projecting a linear image on the surface of the rolled product in the transverse direction thereof, means for detecting the longitudinal deviation of a portion of said linear image at least at the central and end portion of said image, and oil pressure means for regulating the pressure actions on the central and edge portions of the rolled product in accordance with the output of said detecting means.

2. An apparatus for controlling the shape of a rolled product traveling in a longitudinal direction comprising light source means for forming a linear light image on the surface of the rolled product in the direction thereof, a television camera for detecting said images on said rolled product, means for detecting the degree of longitudinal displacement of a portion of said linear light image from its original position at least at the central and edge portions of the rolled product, and oil pressure means for regulating the pressure working on the central and edge portions of the rolled product in accordance with the output of said detecting device.

3. An apparatus for controlling the shape of a rolled product traveling in a longitudinal direction comprising light source means for forming a linear light image on the surface of the rolled product in the transverse direction thereof, photoelectricity conversion means for detecting the degree of displacement to which portions of the image are subjected in accordance with the shape of the rolled product, said conversion means receiving reflected light from at least the central and edge portions of said image, and oil pressure means for regulating the pressure working on the central and edge portions of the rolled product in accordance with said photoelectric conversion means.