JPS6357334B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stop control device for a rotating rack having a plurality of endlessly connected trays moving on a circulation path.

In this type of rotary rack, in order to use the automatic load transfer device, it is necessary to stop a specific called tray at a load handling position (home position) with a high stopping accuracy of, for example, ±10 mm. On the other hand, for safety reasons and to allow the tray to be rotated by hand, the tray drive device does not use a mechanical brake, but is configured to stop the tray at the load handling position by dynamically braking the induction motor. are doing.

However, motor load factors such as the number of trays, the weight of the trays themselves, and the weight of the load to be handled vary greatly, and the distance traveled by inertia from the time the stop command switches to dynamic braking until the tray stops, that is, the braking distance. is changing. Therefore, if the timing at which the stop command is output is constant, the accuracy of stopping the tray will change.

One way to solve these problems is to use a pulse oscillator linked to the conveyor, as described in Utility Model Application Publication No. 54-178380, and when the pulse counter reaches the set value, In the method of outputting the stop command, it is possible to use a method in which the set value is adjusted according to the amount of coasting of the conveyor, but since all control must be performed based on the pulse count value, this method is simple. It is not easy to implement. Furthermore, if the spacing between the trays changes due to replacing the trays with ones of different widths, all the setting conditions must be changed, which results in a lack of versatility.

The present invention proposes a stop control device for a rotating rack that can solve the above-mentioned conventional problems.

Hereinafter, one embodiment of the present invention will be described based on the attached illustrative drawings. In FIG. 1, 1 is a drive gear 2.
4 is a tray attached to the endless chain 1 at regular intervals; This is a driving induction motor that is linked together. As shown in FIGS. 2 and 3, each tray 4 includes a detection plate 7, a support guide roller 8, a support guide rail 9, a steady rest guide roller 10, and a steady rest guide rail 11. It is supported so that it can circulate in a fixed position on a horizontal circulation path. PHS
-F, PHS-R are a pair of photoelectric switches for detecting the plate 7 to be detected, and are attached at a fixed location beside the tray movement path at a distance that allows both ends of the plate 7 to be detected at the same time.

Incidentally, among the series of trays 4, the origin tray 4a, which is tray No. 1, is attached with an origin detection plate 7a, and a photoelectric switch PHS for origin detection detects only this origin detection plate 7a. X is arranged between the pair of photoelectric switches PHS-F and PHS-R.

Next, the structure and operation of the stop control device as a whole will be explained based on FIG. F,
Utilizing the detection signal from the PHS-R, an addition/subtraction counter function that adds up during normal rotation and subtracts during reverse rotation outputs a unique tray number for each tray passing through the cargo handling position. In addition, the photoelectric switch
The PHS-X detection signal is used to return the counter value to its origin (No. 1). Reference numeral 13 is a comparison circuit, and the call tray number inputted to this is a comparison circuit.
and the detected tray number inputted from the tray number detection means 12, and output a deceleration command A when the next tray in the tray movement direction passes the called tray, Call tray no.
When the detection tray number and the detection tray number match, a match signal C is output.

Reference numeral 14 indicates an OR gate element, and reference numeral 15 indicates an AND gate element. Due to the functions of these two gate elements, when the deceleration command A is being output, either the photoelectric switch PHS-F or PHS-R is activated. When the detection signal is output, a stop command B is output. This stop command B is input to the timing adjustment means 16 constituted by, for example, a digital timer, is delayed by an arbitrary set delay time (for example, 0 to 2 seconds), and becomes an adjusted stop command D. The signal is inputted to a drive device 17 including. 18
is a stop position check circuit, which outputs a coincidence signal C after a certain period of time (a time set slightly longer than the expected time required for stopping) after the stop command B is output, and checks both the photoelectric switches PHS. If a detection signal is output from either -F or PHS-R, a stop completion signal E is output, which is used as a start signal for the automatic load transfer device at the load handling position, and if not, the stop completion signal E is output. A stop position correction command F for inching the drive device 17 so that it is in a stopped state is output.

According to the above configuration, in order to call the tray 4 of the selected specific number to the handling position, the drive device 17 is operated with the call tray number set and the series of trays 4 are circulated and moved by the motor 5. , the numbers of the trays 4 passing through the cargo handling position are sequentially output from the detection means 12, and the detected tray numbers and the called trays are
No. is compared in the comparison circuit 13, and when the tray 4 one place before the loaded tray passes the cargo handling position, a deceleration command A is output, and the drive device 17 receives this deceleration command and rotates the motor 5. The speed will be automatically reduced to a predetermined low speed (point A in Figure 5).
After the series of trays 4 have been moved at low speed in this way, the photoelectric switch PHS-F (when the tray is moving forward) or PHS-R (when the tray is moving backward) is placed at the front in the direction of tray movement. When detecting the detected plate 7 of the tray 4, a stop command B is output (point B in Fig. 5).

When this stop command B is output, the timer of the timing adjustment means 16 is activated, and the adjustment stop command D is output after a preset delay time T1 has elapsed, as shown in FIG. Upon receiving the adjustment stop command D, the drive device 17 stops driving the tray by the motor 5, and switches the motor 5 to a dynamic braking state. Therefore, the series of trays 4 will move a certain distance due to inertia and then stop. As a result, the calling tray 4, at the cargo handling position, connects both ends of one detection plate 7 with a pair of photoelectric switches PHS-F and PHS.
- This means that it has stopped accurately within the range detected by R, for example within ±10mm.

If the usage conditions of the rotary rack change and the load applied to the motor 5 changes, the tray movement distance (braking distance) due to inertia after the adjustment stop command D is output as shown by the broken line in Fig. 5. changes, tray 4
If a situation arises in which the stop position accuracy of The delay time set in the timing adjustment means 16, that is, the delay time T1 from when the stop command B is output until the adjusted stop command D is output, is increased or decreased as shown by T2 or T3, and the virtual In other words, both photoelectric switches PHS-F and PHS-R are adjusted so that the stop position accuracy of tray 4 is within ±10 mm as shown by the line.
It can be adjusted so that it stops within the range where it is in the detection state.

As with stacker cranes used in automated warehouses, the weight of the crane itself is very large compared to the weight of the load being handled, and when transporting a single load to and from a rack, the weight of the load being handled is somewhat large. Even if the load changes, the change in the load applied to the motor that drives the crane is relatively small, so the accuracy of the stop position of the crane does not deteriorate to the extent that it becomes a problem. Moreover, the crane is not used by pushing it by hand to move it.
Generally, a mechanical brake is also used, and the stopping position accuracy is relatively stable.

However, as shown in the above embodiment, in a rotating rack that circulates and moves a large number of endlessly connected trays, the load on the motor that circulates this series of cranes is due to the weight of the trays themselves. Even if the number is constant, it will vary greatly depending on the weight of the load being handled. Moreover, as mentioned above, since it is not possible to stabilize the stopping position accuracy by using a mechanical brake in combination, depending on the usage conditions of the rotary rack, the tray may be moved with the stopping position accuracy set in advance at the design stage. There is a strong possibility that stable stopping will not be possible.

However, in the control device of the present invention, a detection plate is provided on each tray that is connected in an endless manner and moves on a circulation path, and at a fixed position beside the path, there is a gap that allows simultaneous detection of both ends of each detection plate in the moving direction. Two detection switches are installed in parallel, and after a deceleration command is output and one of the detection switches detects the front end of the detected plate, a drive motor stop command is output after an arbitrarily set delay time has elapsed. Since it is equipped with a timing adjustment means, even if the load on the motor changes significantly as described above and the braking distance due to dynamic braking deviates from the initially expected distance range, By simply adjusting the delay time set in the timing adjustment means, the tray can be accurately stopped with the two detection switches simultaneously detecting both ends of one detection target plate.

Furthermore, since the delay time measurement starts when one of the detection switches detects the front end of the detection plate after the deceleration command is output, a detection plate of a certain length is attached to the center of the tray. As long as the tray is replaced with a tray of any width, the stop control can be performed as expected without any problem, and the tray count for tray call control, deceleration command output, or tray stop position is within the specified accuracy range. There is also the advantage that all other controls, such as checking whether the tray is in the tray, can be easily performed using the two detection switches and the detection plate of each tray.

In the embodiments, individual control means or circuits are used, but in reality, a computer can be used in conjunction with the program control method.

[Brief explanation of the drawing]

Fig. 1 is a schematic perspective view explaining the configuration of the rotary rack, Fig. 2 is a plan view showing the relationship between the tray and the detection switch, Fig. 3 is a side view of the same, and Fig. 4 is an illustration of an embodiment of the present invention. The block diagram shown in FIG. 5 is a graph showing the relationship between the speed of the tray and the moving distance when the tray is stopped. 1...Endless chain, 2...Drive gear, 3...Idle gear, 4...Tray, 5...Induction motor,
7, 7a...Detected plate (detected part), 12...Tray
No. Detection means, 13...Comparison circuit, 16...Timing adjustment means, 17...Drive device, 18...Stop position check circuit, PHS-F, PHS-R, PHS-X...Photoelectric switch (detection switch), A...Deceleration Directive, B
...stop command, D...adjustment stop command.

Claims (1)

[Claims] 1. A detection plate is provided on each tray that is connected in an endless manner and moves on a circulation path, and two detection switches are arranged at fixed positions beside the path at intervals that allow simultaneous detection of both ends of each detection plate in the direction of movement. and timing adjustment means for outputting a drive motor stop command after an arbitrarily set delay time has elapsed after one of the detection switches detects the front end of the detected plate after a deceleration command is output. Rotating rack stop control device.