JPH05338884A - Method and device for detecting sag in work for use with work feeder - Google Patents

Abstract

PURPOSE:To readily adjust the amount by which work is supplied so as to hold the tension of the work constant by detecting the amount of rotation of an arm using a pulse encoder when the arm is lowered because of a sag in the work, thus controlling the speed of rotation of a servo motor for rotating a roll. CONSTITUTION:A roll 3 of work 2 is supported on axis to a stanchion 6 erected on a mount 7. An arm 4 has a roller 8 at one end and is journalled to the stanchion 6 at the other end by a rotary shaft 41 and is pushed downward by a coil spring 5; i. e., a shutter type cutter 9 cuts the supplied work 2 into a predetermined length. In this case, the arm 4 is lowered when there is a sag in the work 2. Then the amount of this lowering, i. e., the angle of rotation is detected by an absolute encoder 1. Then pulse signals detected are input to a control circuit and are counted and then control pulse signals from which the count is subtracted are output. The speed of rotation of the roll 3 is thereby reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slack of an unrolled work in an apparatus for rolling a long work such as a plastic film or paper, a metal foil or a non-woven fabric around a roll, and unwinding the work. And a device therefor.

[0002]

2. Description of the Related Art It is desirable that the amount of work delivered is always constant in order to cut into a constant length. However, due to the deviation of the rotation speed of the roll on the sending side and the other rolls leading to the cutter, slack occurs in the fed work,
An error may occur in the cutting length. So conventionally,
As shown in FIG. 4, a plurality of photoelectric switches (10), (10) ...
Between the rollers (6) and (6) so as to face the work (1), each photoelectric switch detects the distance to the work, and the looseness of the work activates the photoelectric switch at the location that exceeds the set distance. The slack was adjusted by controlling the speed of the motor for rotating the roll by the switching operation and adjusting the feed amount of the work.

[0003]

However, since the photoelectric switch is based on the principle of projecting light onto an object and detecting the distance to the object, it is not possible to detect the slack at a portion deviated from the detection surface. Therefore, in order to detect all the slack, it is necessary to arrange a large number of photoelectric switches facing the workpiece, but this cannot be realized in terms of cost. In addition, the photoelectric switch is a simple principle of detecting the distance to the object on the detection surface and performing the ON / OFF switching operation when the set value is reached. It could not be detected as a continuous quantity, and smooth speed control of the servomotor could not be performed. Furthermore, it is necessary to adjust the sensitivity of the photoelectric switch depending on the transparency of the work, and it is extremely difficult to detect even a transparent work.

[0004]

According to the present invention, it is possible to eliminate the slack of a work piece so that the work piece is always in an optimum tension state and to reduce the cost of the detection device. That is, the method is to detect the amount of rotation of the arm body by a pulse encoder, to convert the detected amount of rotation into a digital signal, and control the rotation of the roll rotation servomotor based on the digital signal, This is to remove the slack in the work by adjusting the amount of work delivered.

A servo motor is used as a roll rotation motor to detect the rotation amount of the arm and
A pulse encoder that converts the detected rotation amount into a digital signal and a control circuit that inputs the digital signal output from this pulse encoder and converts it into a signal for controlling the rotation speed of the servo motor are provided at appropriate places. is there.

[0006]

When the work is loosened, the arm is lowered and the rotation amount is detected by the pulse encoder. Then, the rotation speed of the servo motor for rotating the roll is controlled based on the signal output from the pulse encoder, and the feed amount of the work fed from the roll is adjusted. In this way, the slack of the work is detected as the amount of rotation of the arm, and at the same time, it is converted into the continuous amount of pulses, so that the speed of feeding the work can be adjusted quickly and smoothly.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view of a work slackness detecting method and its device in a work feeding device according to the present invention. (3) shows the roll around which the work (2) is wound, and the base
It is rotatably supported by a column (6) standing on (7) and rotated by a servo motor (not shown).
(4) shows an arm body, which has a roller (8) at the tip, is pivotally supported at the base end by a rotation shaft (41), and is urged downward by a coil spring (5). . A tension mechanism is configured by the arm body and the spring body. (9) is a shear-type cutter that cuts the delivered work into a predetermined length. (1) shows an absolute encoder which is an example of an encoder, and FIG.
As shown in, it is connected to a control circuit (12) provided at a predetermined location.

The control circuit (12) includes a CPU which inputs the digital signal output from the absolute encoder (6), counts the number of pulses of the digital signal, and outputs a control pulse signal corresponding to the number of counts. ing.

Next, the operation of the present invention will be described with reference to the flow chart of FIG. When the work (2) fed from the roll (3) is loosened, the arm (4) begins to descend, and the descending amount of this arm, that is, the rotation angle, is detected by the absolute encoder (6), and the It is converted into a pulse signal. Then, this pulse signal is output to the control circuit (12) at the next stage, and the number of pulses is counted by the CPU in the control circuit. Next, the control pulse signal obtained by subtracting the count number is output to the servo motor, the number of steps per unit time of the servo motor is reduced, and the rotation speed of the roll is reduced.

In this way, the rotation amount of the servo motor is decelerated, so that the amount of feeding the work is reduced and the work is loosened. At this time, the pulse signal corresponding to the deceleration of the servo motor is fed back to the control circuit, and the servo motor returns to the speed before the work loosens.

Here, when the feeding speed of the work becomes slower than the set speed, the arm is pulled upward by the tension of the work, so the absolute encoder outputs a pulse signal corresponding to the raised rotation angle to the control circuit. The servo motor accelerates and the arm returns to the normal position due to the restoring force of the coil spring.

As described above, the slack amount is sequentially converted as the rotation amount of the arm as soon as the work starts to slack, and the servomotor is decelerated at the same time, so that the slack can be removed quickly and smoothly. In addition, it is possible to adjust the feed amount of the work with high accuracy. In addition, when the absolute encoder is used, the output characteristics are close to the analog output characteristics, so that it is difficult to be affected by external noise.

According to the present invention, it is possible to immediately detect the start of slackening of the work, adjust the work delivery amount quickly and smoothly, and always keep the work tension constant. Therefore, an excessive load is not applied to the work and the cutting length of the work is not uneven. In addition, since many sensors are unnecessary, cost can be reduced.

[Brief description of drawings]

FIG. 1 is an explanatory view of a work looseness detection method and a device thereof in a work feeding device according to the present invention.

FIG. 2 is a flowchart showing a method for detecting a work slack in a work feeding device according to the present invention and an operation of the device.

FIG. 3 is a block diagram for explaining a work slackness detecting method and device in the work feeding device according to the present invention.

FIG. 4 is an explanatory diagram of a work looseness detection method and a device thereof in a conventional work feeding device.

[Explanation of symbols]

(1) ・ ・ Absolute encoder, (2) ・ ・ Workpiece, (3) ・ ・ Roll, (4) ・ ・ Arm, (41) ・ ・ Rotating shaft, (5) ・ ・ Coil spring, (6) ・ ・Prop, (7) ・ ・ Base, (8) ・ ・ Roller, (9) ・ ・ Shear cutter, (1
0) ・ ・ Photoelectric switch, (11) ・ ・ Servo motor, (12) ・
-Control circuit.

Claims (2)

[Claims] 1. A roller having, at its tip, a roller around which a workpiece unwound from a roll around which the workpiece is wound is wound,
In a work feeding device having a tension mechanism provided with an arm whose base end is pivotally supported in the vicinity of a work feeding position, a pulse encoder detects a rotation amount of the arm body and detects the detected rotation amount. Slack detection of the work in the work feeding device characterized by converting to a digital signal, controlling the rotation of the roll rotation servomotor based on this digital signal, and adjusting the feed amount of the work to remove the work Method. 2. A roller having a roll around which a work is unwound from a roll around which the work is wound, is provided at the tip,
In a work feeding device in which a tension mechanism having an arm whose base end is rotatably supported is provided near a work feeding position, a servo motor is used as the roll rotation motor to detect the rotation amount of the arm body. Along with this, a pulse encoder that converts the detected rotation amount into a digital signal and a control circuit that inputs the digital signal output from the pulse encoder and converts into a servo motor rotation speed control signal are provided at appropriate locations. A slack detecting device for a work in a work feeding device.