JPS6052898B2 - Braking method for conveyed objects - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention can be used, for example, in a machine tool, etc., to brake a workpiece driven by a linear motor or the like or a conveyed object such as a work table on which the workpiece is placed. The present invention relates to a suitable method for braking a conveyed object.

Generally, when it comes to braking a conveyed object driven by a drive means such as a linear motor, the speed of the conveyed object is controlled in the same way as the speed control method of a conveyed object conveyed by a normal rotary drive means. The conveyance speed is continuously detected by a tachometer generator, pulse pickup, etc., and the speed of the conveyed object is adjusted by performing speed feedback such as changing the drive voltage applied to the linear motor according to the resulting speed of the conveyed object. It's under control.

By the way, normally, the conveyed object driven by a linear motor has a predetermined length and is often conveyed at high speed. In the method of controlling the speed, it is necessary to continuously detect the speed of the conveyed object within the speed adjustment section, and it is necessary to provide a speed detection means for this on the ground side or on the side of the conveyed object. There are the following disadvantages.

In other words, when speed detection means for detecting the speed of a conveyed object is installed on the ground side, a large number of speed sensors are installed within the speed adjustment section according to the length of the conveyed object whose speed is to be detected. (This speed sensor is, for example, a speed sensor composed of a pulse pickup and a slit plate or a touch roller, etc.). Conversely, when the speed detection means is installed on the side of the conveyed object, The number of speed sensors provided for each conveyed object may be one, but the speed detection signal obtained by this speed sensor is transmitted to the ground side by some means (for example, a slip ring or a signal transmission means such as wireless). It is necessary to transmit it to the speed control unit (control device). In particular, in the case of a speed sensor configured using a touch roller, when an object is being transported at high speed, slipping may occur between the object and the touch roller, causing the speed sensor to The conveyance speed obtained by is different from the actual conveyance speed,
As a result, the speed adjustment device that adjusts the conveyance speed of the conveyed object may malfunction.

In addition, as for the method of braking the conveyed object, the speed of the conveyed object is continuously controlled by continuous velocity feedback as described above (
In addition to the method of braking the conveyed object, there is a method in which the conveyed object is braked by applying reverse phase braking to the conveyed object that is being driven for a period set by a timer, etc., but in this method, the speed of the conveyed object is Even if they are different, anti-phase braking is applied for the same set time, so if the speed of the conveyed object is high, the speed will not be slowed down enough, and conversely, if the speed of the conveyed object is low, the speed will not be sufficiently reduced. However, there is a problem in that the reverse phase braking is applied too much and the conveyed object is driven in a direction opposite to the conveying direction (progressing direction) of the conveyed object. In view of the above points, this invention does not use a large number of speed sensors, and
Even when conveying objects at high speeds, there is no malfunction.
To provide a method for braking a conveyed object that can perform a braking operation according to the speed of the conveyed object, the first passage detection means for detecting the passage of the conveyed object is connected to a predetermined path of the conveyed object. a second passage detecting means for detecting passage of the conveyed object is provided at a predetermined distance from the first passage detecting means in the traveling direction of the conveyed object; The timing means starts a timing operation corresponding to the time when the passing of the conveyed object is detected by the means, and the timing operation corresponds to the time when the passage of the conveyed object is detected by the second passage detecting means. The braking means for braking the conveyed object starts a braking operation, and the braking means ends the braking operation when the timing means finishes counting a predetermined time. .

The present invention will be explained below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of a braking device for explaining the present invention. In this figure, reference numeral 1 denotes a linear motor that drives a conveyed object 2 made up of a conductive work table or a conductive workpiece, etc. This linear motor 1 is connected to a linear motor drive circuit (not shown). When the phase voltage is supplied, the conveyed object 2 is urged in the direction of arrow A,
Conversely, when a reverse phase voltage is supplied from the linear motor drive circuit, the conveyed object 2 is urged in the direction opposite to the arrow A.
Reference numeral 3 denotes a limit switch (first passage detection means) provided on the conveyance path of the conveyed object 2, and this limit switch 3 activates the limit switch 3 when the conveyed object 2 is not on the limit switch 3. It is installed so that the contact 3a (see Fig. 2) is in the open state, and conversely, when the conveyed object 2 is on the limit switch 3, the conveyed object 2 causes the contact 3a of the limit switch 3 to be in the closed state. has been done. Further, 4 is a limit switch (second passage detection means) provided at a predetermined distance from the limit switch 3 in the conveying direction of the conveyed object 2 (arrow A direction), and this limit switch 4 is also the limit switch mentioned above. 3, when the conveyed object 2 is not on the limit switch 4, the contact 4a of the limit switch 4 (see Fig. 2) is in the open state, and conversely, when the conveyed object 2 is not on the limit switch 4. If there is, the limit switch 4 is activated by the conveyed object 2.
The contact point 4a is placed in a closed state. Further, 5 is a stopper constituted by a non-contact holding mechanism or the like for stopping the conveyed object 2 at a predetermined position, and this stopper 5 is located at a position separated from the limit switch 4 by a predetermined distance in the conveying direction of the conveyed object 2. The position of the conveyed object 2 installed and conveyed at low speed is detected, and the non-contact hold mechanism is controlled according to the detection result to stop the conveyed object 2 at a predetermined position. FIG. 2 is a diagram showing an example of the circuit configuration of the same embodiment. In this diagram,
6 is a ground line connected to the negative terminal of a power source (not shown), and 7 is a power line connected to the positive terminal of the same power source. Further, 8 is a timer (timekeeping means) which is inserted between the contact 3a of the limit switch 3 and the ground line 6, and which turns on and starts counting when the contact 3a is closed. , this timer 8 is set in advance for a predetermined period T from the time the timer 8 is turned on. At the time when , the contact (normally open contact) 8a inserted between the contact 3a and the relay 9 is opened for a predetermined period of time. The relay 9 is a relay inserted between the contact 8a and the ground line 6, and is turned on when the contact 8a is closed and the contact 3a is closed. The contact (normally open contact) 9a1 inserted in the row and the contact (normally open contact) 9a2 inserted between the power supply line 7 and the contact (normally open contact) 10a are closed. That is, when the contact 3a is in the closed state, the timer 8 is turned on and starts timing, and the relay 9 is also turned on, which closes the contact 9a1 and forms a hold circuit, and as a result, this state Even if the contact point 3a becomes open again, the timer 8 continues to measure time without turning off. In this state, timer 8
for a predetermined period T from the time when the switch is turned on. When the timer 8 has passed, the timer 8 opens the contact 8a and turns the relay 9 off, which causes the relay 9 to open the contacts 9a1 and 9a2, which had been closed, and turns the timer 8 off. Turn off. Therefore, limit switch 3
When detects the passage of the conveyed object 2 at the timing shown in B of FIG. It remains on only during this period. Reference numeral 10 denotes a relay that is inserted between the contact 4a of the limit switch 4 and the ground line 6 and turns on when the contact 4a is closed. At this time, the contact (normally open contact) 10a inserted between the contact 9a2 and the brake relay 11 is closed. Further, the brake relay 11 is inserted between the contact 10a and the ground line 6, and is turned on when both the contact 10a and the contact 9a2 are closed. When the brake relay 1
A braking signal is supplied from 1 to a linear motor drive circuit (not shown) that drives the linear motor 1 . When the linear motor drive circuit is supplied with a braking signal from the brake relay 11, it outputs a negative phase voltage to drive the linear motor 1 in a negative phase. That is, when the limit switch 4 detects the passage of the conveyed object 2 at the timing shown in the opening C in FIG. 3 while the contact 9a2 is in the closed state, the relay 10 switches the
As a result, the brake relay 11 turns on at timing C'' shown in FIG. 4, and this state is maintained until the timer 8 opens the contact 8a. FIG. 3 is a braking characteristic diagram for explaining the present invention.

In this figure, the horizontal axis represents the displacement S of the conveyed object 2,
The vertical axis represents the speed (2) of the conveyed object 2 with respect to the displacement S of the conveyed object 2 and the time T with respect to the displacement S of the conveyed object 2. Further, 12 is a displacement-speed characteristic curve showing the relationship between the displacement S of the conveyed object 2 that was being driven at high speed and the speed V of the conveyed object 2, and 13 is the displacement of the conveyed object 2 that was being driven at low speed. It is a displacement-velocity characteristic curve showing the relationship between S and the velocity V of the conveyed object 2. Further, 14 is a displacement one-time characteristic curve showing the relationship between the displacement S of the conveyed object 2 driven at high speed and time T, and 15 is the relationship between the displacement S and time T of the conveyed object 2 driven at low speed described above. This is a displacement versus time characteristic curve. In addition, these displacement one-time characteristic curves 14,1
5 are all based on the point in time when the limit switch 3 detects the passage of the conveyed object 2. Further, 16 indicates the position of the stopper 5 that stops the conveyed object 2 at a predetermined position.

In the above configuration, the conveyed object 2 is urged in the direction of the arrow A by the linear motor 1, at the speed (high speed) shown in the displacement-velocity characteristic curve 12 in FIG. 4, and at the timing B in FIG. When the conveyed object 2 passes over the limit switch 3, the limit switch 3 detects the passage of the conveyed object 2 at timing B, closes its contact 3a, and turns on the timer 8 and relay 9.

As a result, at timing B, the timer 8 turns on and starts timing, and the relay 9 turns on, forming a hold circuit of the relay 9 and the timer 8, and the relay 9 turns on. By becoming contact point 9
a2 is in the closed state. Then, when the conveyed object 2 passes over the limit switch 4 at the time when the period Tal has elapsed from timing B, that is, at the timing of the opening in FIG. 3 (or timing C'' in FIG. The passage of the conveyed object 2 is detected and the contact 4a is turned on.As a result, the relay 10 is turned on at timing Cj, the contact 10a is closed, and the brake relay 11 is turned on. .As a result,
The point in time when the conveyed object 2, which has passed over the limit switch 3 at the speed shown in the displacement-speed characteristic curve 12 in FIG. 4, passes over the limit switch 4, that is, at the position LS2 (in FIG.
(This position LS2 corresponds to the position of the limit switch 4), the linear motor drive circuit supplies a negative phase voltage to the linear motor 1, so that the linear motor 1 moves the conveyed object 2 along the arrow A. The conveyed object 2 is biased in the opposite direction to brake the conveyed object 2. As a result, the speed of the conveyed object 2 gradually decreases according to the position shown in the displacement-velocity characteristic curve 12 in FIG. In this state, a period T starts from the time when the timer 8 turns on, that is, timing B in FIG. 3A. When timer 8 has passed, contact 8
When the relay 8 is turned off by opening a, the relay 8 opens the contacts 9a1 and 9a2. As a result, the timer 8 is turned off, and the brake relay 11 is also turned off. As a result, the linear motor drive circuit applies a positive sequence voltage to the linear motor 1 (a low voltage is better for this positive sequence voltage). ) to urge (restart) the conveyed object 2 in the direction of arrow A. Therefore, the conveyed object 2 has a period T from the time when the conveyed object 2 passes over the limit switch 3.
. When the time has passed, that is, when the stopper 5 has passed the position 17 in FIG.
It is conveyed at low speed to a certain position 16, and is positioned at a predetermined position by the same stopper 5 and stopped. Furthermore, when the conveyed object 2 passes over the limit switch 3 at the speed (low speed) shown in the displacement-velocity characteristic curve 13 in FIG. 4 and at timing B in FIG. hand,
At the timing when the conveyed object 2 passes over the limit switch 3, the timer 8 and relay 9 are turned on, and the timer 8 and relay 9 are turned on.
- is started.

Then, when the conveyed object 2 passes over the limit switch 4 at the time when a period Tbi has elapsed from timing B, that is, at timing C at the beginning of FIG. 4, the conveyed object 2 is urged in the direction opposite to the arrow A, and as a result, the speed of the conveyed object 2 increases to the fourth position.
It gradually decreases depending on the position shown in the displacement-velocity characteristic curve 13 in the figure. In this state, period T starts from timing B in FIG. 3A. At one point in time, that is, when the conveyed object 2 passes through the position 18 in FIG. and is positioned at a predetermined position. That is, the conveyed object 2 is connected to the limit switches 3 and 4.
If the conveyed object 2 passes over the limit switch 3 at high speed, the period Tal from when the conveyed object 2 passes over the limit switch 3 to when it passes over the limit switch 4 is counted by a predetermined time after the timer 8 starts counting. Period W until the end. The period Ta2 (Ta2=TO-Tal) obtained as a result of subtracting from is the braking period for the conveyed object 2 that was being conveyed at high speed, and conversely, when the conveyed object 2 passes between the limit switches 3 and 4 at low speed In this case, the period TO2 (Tb, Tb, =TO-Tb
1) is the braking period of the conveyed object 2 that was being conveyed at a low speed. Further, since the above-mentioned period Tal is smaller than the period Tbl, the braking period Ta2 of the high-speed conveyed object 2 is longer than the braking period additional period B2 of the low-speed conveyed object 2.
The timing W of the timer 8 is determined according to the speed range of the conveyed object 2. By setting , braking can be applied to the conveyed object 2 according to the speed of the conveyed object 2. Furthermore, in the embodiment described above, the conveyed object 2 that has been decelerated by applying braking is restarted by supplying a low positive phase voltage to the linear motor 1. The pulse motor is a linear pulse motor for positioning means such as the stopper 5, or a newly installed linear pulse motor)
Alternatively, it is of course possible to restart using other mechanical or electrical drive means.

Furthermore, in the above-described embodiment, the conveyed object 2 is energized by the single-sided linear motor 1, but this may be replaced by a double-sided linear motor. may be provided to urge the conveyed object. In addition, in the embodiment described above, the first and second
Although the limit switches 3 and 4 are used as passage detection means, it is of course possible to configure this using a photo interrupter or the like.
, 4 may be replaced with light emitting elements, and each light output from each light emitting element may be received by a light receiving element provided on the conveyed object 2 side. Further, in the above embodiment, the conveyed object 2 is braked by controlling the braking time of the conveyed object 2, but in addition to this braking time control, the strength of the braking applied to the conveyed object 2 may also be controlled. Of course it is possible. In this case as well, the conveyance object 2 is adjusted so as to correspond to the period from when the first limit switch 3 detects the passage of the conveyance object 2 to when the second limit switch 4 detects the passage of the conveyance object 2. Of course, the strength of the braking applied to 2 is controlled. As explained above,
This invention provides a first passage detection means for detecting the passage of the conveyed object at a predetermined position on the traveling path of the conveyed object, and a second passage detection means for detecting the passage of the conveyed object. The timer is provided at a predetermined distance from the first passage detecting means in the traveling direction of the conveyed object, and operates to measure time in response to the time when the passage of the conveyed object is detected by the first passage detecting means. The braking means for braking the conveyed object starts a braking operation corresponding to the time when passage of the conveyed object is detected by the second passage detecting means, and the timing means Since the braking means finishes its braking operation at the end of the predetermined time measurement, the braking time can be increased or decreased depending on the speed of the conveyed object.

Therefore, there is no possibility of malfunction even when the speed of the conveyed object is high. Further, advantages such as no need to use a large number of speed sensors can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of a braking device for explaining the present invention, FIG. 2 is a diagram showing an example of the circuit configuration of the same embodiment, and FIG. 3 is a waveform diagram for explaining FIG. 2. 4 are braking characteristic diagrams for explaining the present invention. 1...Linear motor (braking means), 2...
...Conveyed object, 3...Limit switch (first
passage detection means), 4... limit switch (
second passage detection means), 8...timer (timekeeping means).

Claims (1)

[Claims] 1. In a method for braking a moving object by applying braking to the moving object for a required period of time to reduce its speed, the first passage detection means for detecting the passage of the object to be moved is placed at a predetermined path of the moving object. a second passage detecting means for detecting the passage of the conveyed object is provided at a predetermined distance from the first passage detecting means in the traveling direction of the conveyed object; The timing means starts a timing operation corresponding to the time when the passing of the conveyed object is detected by the means, and the timing operation corresponds to the time when the passage of the conveyed object is detected by the second passage detecting means. The braking means for braking the conveyed object starts a braking operation, and the braking means ends the braking operation when the timing means finishes counting a predetermined time. Braking method for conveyed objects.