JPS6139713Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a two-sheet detection device in a material conveying device that utilizes changes in electrical resistance of materials.

(Prior Art) As a two-sheet detection device in a material conveying device that adsorbs and conveys materials loaded on a stacker's magnetic floating device with a vacuum cup that can be raised and lowered, the following methods are used: (a) Clamping using a proximity switch; A detection device that detects two sheets based on magnetic changes. (b) A detection device that detects changes in the amount the limit switch is pressed by installing a limit switch according to the thickness of the material. (c) A detection device that uses a magnetic change such as Magnescale or a differential transformer and performs two-sheet determination by comparison with a set value. etc.

(Problems to be solved by the invention) Each of the detection devices (a), (b), and (c) has its own merits and demerits.

In (a), it is troublesome to install and adjust the proximity switch, and furthermore, the method of inserting the material requires some ingenuity. It is difficult to detect two sheets unless they are inserted parallel to the proximity switch surface.

In (b), the installation of the limit switch must be adjusted each time according to the thickness of the material, which is inconvenient for work.

Although it is relatively easy to detect two sheets using a differential transformer as shown in (c), the device is large-scale and has problems in terms of cost and stability.

(Means for Solving the Problems) The present invention aims to provide a two-sheet detection device for materials that solves these problems.

The device of the present invention utilizes the fact that the electrical resistance value changes depending on the thickness of the material. The upper end and the other end are placed in contact with the lower side of the material to avoid interference with the material, and when a constant current is passed through the material, when the electrical resistance value exceeds that of one sheet, it is detected as two sheets and pressed. This is an attempt to stop the operation.

(Example) An example of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 denotes a magnetic floating device of a stacker, in which materials 2 are stacked while electromagnetically repelling each other. The material conveying device T includes a vacuum cup 3 and a lifting cylinder 4.
is set up like a conventional structure. Electrode A,
B is for detecting the electrical resistance value of the material 2 by contacting the material 2 with electricity, and holding the vacuum cup in place, fixing the electrode A on one side downward and the electrode B on the other side from a vertical position. It is installed so that it can freely swing in a horizontal position (the swing mechanism is not described in detail). When the vacuum cup 3 for transporting the material adsorbs the material 2 and rises, and the upper surface of the material 2 comes into contact with the lower end of the electrode A, the electrode B, which had been in the vertical position, swings to the horizontal position, and the electrode B swings to the horizontal position. The upper end contacts the lower surface of the material 2. When the electrodes A and B come into contact with the material 2, electricity is applied between the electrodes A and B, and the electrical resistance value of the material 2 is detected. When the detection is completed, the electrode B returns from the horizontal position to the vertical position again.

Next, the operation of the two-sheet detection device of the present invention will be explained.
FIG. 2 is a block diagram of the electric control circuit of the two-sheet detection device of the present invention.

When the vacuum cup 3 adsorbs the material 2 and rises to convey the material, the upper surface of the material 2 contacts the lower end of the electrode A, and the lower surface of the material 2 contacts the upper end of the electrode B, as described above. Next, when a constant current is caused to flow between the electrodes A and B from the constant current source 5, the current is blocked from passing depending on the electrical resistance of the material 2. The electrical resistance value of the material 2 is detected as a voltage level value via the interface 6 and I/V converter 7. First, the setting device 12 is turned on, and the electrical resistance value detected in the case of one sheet of the material 2 is input to the storage device 9 as a voltage level, and is outputted to the comparison device 8 as a reference value D. Next, let's start the main work. The vacuum cup 3 successively attracts the material to be transported and ascends, but each time the material to be transported comes into contact with the electrodes A and B, and the electrical resistance value is outputted to the comparison device 8 as a detected value C at a voltage level.
In the comparing device 8, the detected value C is compared with the reference value D, and when it exceeds the reference value D, it means that the electrical resistance value of one or more sheets of conveyed material has been detected. When it is determined that "adsorption" is detected, an abnormal signal is issued, and the press operation stop relay 11 is actuated through the amplifier 10 to stop the press operation.

When the conveyed material is replaced, the reset device 12
By eliminating the reference value D input into the storage device 9, and obtaining the reference value D and detection value C for a new material in the same manner as described above, two-piece detection can be performed in the same manner.

(Effects of the invention) According to the invention, it is possible to automatically detect two pieces by bringing the electrode into contact with the material during material transportation without interference with the material, resulting in extremely high productivity. It has a compact structure that detects two sheets by clamping them in contact with each other, and eliminates the need for cumbersome alignment adjustments and cylinder devices for insertion when changing materials, unlike conventional detection devices that insert a limit switch from the side. Yes, and it is easy to handle. Furthermore, since the electrodes are brought into direct contact with the material from above and below, the difference in electrical resistance between the first and second materials is clear and the operation is stable, making it possible to reliably detect two materials. Furthermore, when replacing materials, it is only necessary to use the electrical resistance of the first sheet of material conveyed as a reference value and then detect the subsequent materials, which is highly effective in terms of work, as no special operations are required.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of one embodiment of the device of the present invention;
The figure is a block diagram of the electrical control circuit of the present invention. 1 is a magnetic floating device, 2 is a material, 3 is a vacuum cup, 4 is a cylinder, 5 is a constant current source, 6 is an interface, 7 is an I/V converter, 8 is a comparison device, 9 is a storage device, 10 11 is a press operation stop relay, 12 is a setting device, and 13 is a reset device.

Claims (1)

[Scope of utility model registration request] It is installed in a material device that adsorbs and conveys materials loaded on a stacker's magnetic floating device with a vacuum cup that can be raised and lowered. An electrode contact device is provided to be able to swing freely from the horizontal position, a device for detecting the electrical resistance value of the material between the electrodes, and the electrical resistance value successively detected from the material being transported is used as a reference for one material. 1. A two-sheet detection device based on changes in electrical resistance, comprising a control device that outputs a press operation stop signal when the electrical resistance value exceeds the reference value.