JPH0134910B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a free loop control device installed in a continuous processing line for strip-shaped materials such as steel plates, and equipped with a photoelectric detector for detecting the position of the free loop in the height direction. Regarding.

Conventionally, as a method for non-contact detection of the position in the height direction of a free loop of a steel plate (not necessarily a continuous quantity) using a photoelectric detector, the emitter and receiver of the photoelectric detector are placed parallel to the direction of travel of the loop. There are two methods: one is to install the loop horizontally, and the other is to install it horizontally at right angles to the direction in which the loop travels. Figures 1 and 2 are front and side views showing the former method, respectively, and Figures 1 and 2 show the former method.
are a front view and a side view, respectively, showing the latter method. 1 is a strip-shaped steel plate that moves in the direction of the arrow. PR ₁ and PR ₂ are pinch rollers. PHus,
PHur is the emitter and receiver of the photoelectric detector that detect the upper limit of the loop, respectively, and PHls and PHlr are the emitter and receiver of the photoelectric detector that detect the lower limit of the loop, respectively. In the former method, if the width of the steel plate 1 is narrow, the loops will move in the width direction (lateral to the direction of travel).
If the free loop sways or shifts in lateral position, it may become impossible to detect the free loop's height position, so it is necessary to line up multiple photoelectric detectors in the width direction of the loop. It is difficult to resolve this issue. Although the latter method is good for changes in the width direction of the loop, it is almost impossible to completely block the beam of the photoelectric detector due to the thickness of the steel plate.

The present invention was proposed in view of the above-mentioned problems, and an object of the present invention is to provide a free loop control device that can reliably detect any point in the height direction of a narrow free loop without malfunctioning. purpose.

Hereinafter, the present invention will be explained based on drawings of embodiments. FIG. 3 is a block diagram of an embodiment of the free loop control device of the present invention. In this example, the pinch roller
PR ₁₁ sends the strip 1 in the direction of the arrow at a constant speed, passes through a free loop between pinch rollers PR ₂₁ and PR ₁₂ , reaches pinch roller PR ₂₂ , and sends it to the rear equipment by pinch roller PR ₂₂ .
M ₁ and M ₂ are electric motors that drive pinch rollers PR ₁₁ and PR ₂₂ , respectively, and these are controlled by speed controllers 2 and 3, respectively. PG ₁ and PG ₂ are speed detection generators that are attached to electric motors M ₁ and M _2, respectively, and detect rotational speeds Vi ₁ and Vi ₂ of electric motors M ₁ and M ₂ , respectively. 4 is the reference speed Vs to the speed controller 2.
It is a speed command device that gives The speed controller 3 has
In order to drive the pinch roller PR ₂₂ to follow the pinch roller PR ₁₁ , the speed signal Vi ₁ of the electric motor M ₁ detected by the speed detection generator PG ₁ is given as a speed command. Even if the speed of the pinch roller PR ₂₂ is strictly controlled, the free loop position will fluctuate up and down with some error. The photoelectric detector consists of the emitter PH′us and the receiver PH′ur, and the photoelectric detector consisting of the emitter PH″us and the receiver PH″ur is strip 1.
It is installed symmetrically with respect to the upper limit position of the loop, and is used to detect the upper limit position of the loop.
A photoelectric detector consisting of PH'lr, a light emitter PH''ls and a light receiver PH''lr are arranged symmetrically with respect to the strip 1, and are for detecting the lower limit position of the loop. 6, when the photoelectric detector (PH′us, PH′ur) or (PH″us, PH″ur) detects that the loop has moved to the upper limit position, the speed of the pinch roller PR ₂₂ is changed to a minute speed △V This is a micro-velocity generator that generates this micro-velocity -ΔV in order to correct the loop position downward. 5
When the photoelectric detector (PH′ls, PH′lr) or (PH″ls, PH″lr) detects that the loop has moved to the lower limit position, the speed of the pinch roller PR ₂₂ is changed by a minute speed △V. This is a micro-velocity generator that generates this micro-velocity +ΔV in order to increase the loop position and correct the loop position upward. Reference numeral 7 denotes a speed corrector that changes the correction value linearly to the minute speed ΔV, since it is not preferable to perform the speed correction of the minute velocity ΔV in a stepwise manner.

Figure 4 shows the above photoelectric detectors (PH′us, PH′ur),
(PH″us, PH″ur) is a side view showing the installation.
Since the mounting of both photoelectric detectors is the same, the upper photoelectric detectors (PH'us, PH'ur) will be described below. The light emitter PH'us and the light receiver PH'ur are arranged so that their beam axes are perpendicular to the direction of travel of the strip 1 and inclined with respect to the horizontal plane. FIG. 4 shows the state in which the light beams of the photoelectric detectors (PH'us, PH'ur) are blocked by the strips 1.

FIG. 5 is an explanatory diagram showing the dimensional relationship between the optical axes of the strip 1 and the photoelectric detectors (PH'us, PH'ur) in FIG. 4. Here, the width of strip 1 is W,
If the inclination angle of the optical axis of the photoelectric detector (PH'us, PH'ur) is θ, and the component of the width of strip 1 in the direction perpendicular to the optical axis is h, then h=W・sinθ...(1) To establish. Also, if the effective beam width of the light receiver PH'ur (the width that allows the light receiver PH'ur to reliably recognize light interruption, and not necessarily the beam width of the emitter PH'us) is b, then strip 1 can be reliably recognized. The condition for this is h>b, that is, from equation (1), W・sinθ>b (2). Therefore, the inclination angle θ of the optical axis may be selected so as to satisfy θ>sinθ ⁻¹ (b/W) (3).

In FIG. 4 (FIG. 5), it is assumed that the lower end of the strip 1 has a normal shape and is not inclined in the width direction, but the strip 1 may be inclined in the width direction. FIG. 6 shows the case where the lower end of the strip 1 is inclined in the same direction as the photoelectric detectors (PH'us, PH'ur). If the angle of inclination of the lower end of the strip 1 is θ', the angle between the optical axis of the photoelectric detector and the lower end of the strip 1 is (θ - θ'), so
The component of the width of strip 1 in the direction perpendicular to the optical axis that contributes to light shielding, that is, the component h' that contributes to light shielding, is h'≒W・sin(θ−θ')...(4), and the lower end of the loop is smaller than h (formula (1)) when the shape is normal and there is no inclination in the width direction (Fig. 5). On the other hand, the component h'' that contributes to light shielding of the photoelectric detectors (PH″us, PHur) is h″≒W·sin(θ+θ′) (5) and is larger than h.

From the above, in order to eliminate the influence of the inclination in the width direction of the strip 1, two sets of photoelectric detectors should be used for one position detection so that both optical axes are symmetrically inclined with respect to each other, and the inclination angle θ is h. >b, that is, from equation (2), W・sinθ>b...(6) Therefore, θ>sin ^-1 (b/W)...(7) should be selected so as to satisfy. That is, by symmetrically installing two sets of light emitters and receivers, even if the loop is tilted, it is possible to always detect with one of the light emitters and receivers.

The present invention can reliably detect any point in the height direction of the free loop using a commercially available photoelectric detector without being limited by the beam width. Moreover,
Only the mounting position of the photoelectric detector needs to be changed, and there is no modification of peripheral equipment or addition of parts, so the total cost is lower than conventional methods.

[Brief explanation of drawings]

Figures 1 and 2 are diagrams showing the conventional method of detecting the free loop position using a photoelectric detector, and Figure 3 is a diagram showing the conventional method of detecting the free loop position using a photoelectric detector.
The figure is a configuration diagram of an embodiment of the free loop control device of the present invention, and Figure 4 shows the arrangement of the photoelectric detectors (PH'us, PH'ur) and (PH″us, PH″ur) in Figure 3. 5 is an explanatory diagram showing the dimensional relationship between the optical axes of the strip 1 and the photoelectric detectors (PH'us, PH'ur) in FIG. 4, and FIG. PH′us, PH′ur) is a diagram showing the dimensional relationship of the optical axis when tilted in the same direction. 1...Strip, PH″us, PH′us, PH″ls,
PH′ls……Floodlight, PH″ur, PH′ur, PH″lr,
PH′lr……Photoreceiver.

Claims (1)

[Claims] 1. A free loop control device provided in a continuous processing line for strip-shaped materials and equipped with a photoelectric detector for detecting the position of the free loop in the height direction, comprising: 2 photoelectric detectors. The light beam axis of the photoelectric detector is perpendicular to the traveling direction of the line, and the light beam axis of the photoelectric detector is at an angle with respect to the horizontal plane that allows at least the light beam width of the photoelectric detector to be blocked by the width of the material. 1. A free-loop control device, wherein the beam axes of each photoelectric detector are tilted in opposite directions with respect to a horizontal plane.