JP7415132B2 - Adsorption state detection device - Google Patents

Description

The present invention relates to a suction state detection device that detects the suction state of a suction head.

As a suction state detection device for an apparatus for holding an article by suction, a configuration is known in which a pressure switch is provided in each suction part to detect the suction state of each suction part (Patent Document 1). Furthermore, in a configuration in which a suction head including a plurality of suction parts holds one article by suction, a configuration has also been proposed in which the suction state of the suction head is judged based on the difference in pressure values detected by a pressure sensor (Patent Document 2). ).

JP2012-232380A Japanese Patent Application Publication No. 2004-344987

Although pressure switches are inexpensive, they have a structure in which the contacts are turned on and off at a specific pressure (set point), so in the configuration of Cited Document 1, it is necessary to provide a pressure switch at each suction part in order to grasp the suction state. , which increases costs. On the other hand, in the configuration of Cited Document 2, it is possible to grasp the suction state in a suction head including a plurality of suction parts using one pressure sensor. However, with this configuration, it is necessary to monitor the output value of the pressure sensor and process and evaluate the value itself and its increase/decrease, resulting in a heavy signal processing load, complicating the structure of the equipment and software, and increasing costs. do.

An object of the present invention is to make it possible to determine the suction state of a suction head including a plurality of suction parts with a simple configuration.

A suction state detection device according to a first aspect of the present invention includes a suction head including a plurality of suction parts, and a plurality of suction heads that connect the suction parts and negative pressure supply means to supply negative pressure to each of the suction parts. a negative pressure supply passage, a plurality of first passages whose one end communicates with each of the negative pressure supply passages, and a plurality of first passages connected to each of the first passages via a confluence between the other ends of the first passages. a second passageway, a single pressure switch provided in the second passageway, and a plurality of check valves provided in each of the first passageways whose forward direction is from the second passageway to the negative pressure supply passageway. and determining means for determining the suction state of the suction head based on the output of the pressure switch.

The adsorption state detection device according to the second aspect of the present invention is characterized in that, in the first aspect, a pressure supply source that supplies a pressure equal to or higher than the set point of the pressure switch is provided in the second passage.

In the adsorption state detection device according to a third aspect of the present invention, in the second invention, during a period from the start to the end of suction by the suction head, the determination means determines that the pressure switch is set to the set position for the first time. The suction state of the suction head is determined based on whether or not a pressure below the point is detected, and from the second time onwards, after temporarily supplying pressure from the pressure supply source, the pressure switch returns to below the set point. The suction state of the suction head is determined based on whether or not the pressure of the suction head is detected.

According to the present invention, the suction state of a suction head including a plurality of suction parts can be determined with a simple configuration.

FIG. 1 is a side view showing the arrangement of an article holding device including a suction head according to an embodiment of the present invention. FIG. 2 is a piping diagram illustrating a suction mechanism by the suction head 10. FIG. FIG. 7 is a diagram showing a negative pressure state when one article is held by all the suction parts (suction cups) of the suction head. FIG. 6 is a diagram showing a negative pressure state when one article is held by only some suction parts (suckers) of the suction head. It is a figure which shows the negative pressure state after the inside of the 2nd passage in which the pressure switch was provided becomes below adsorption pressure once. It is a figure showing a negative pressure state at the time of reset processing. It is a figure explaining the negative pressure state in a 2nd passage according to the suction state of an article. It is a graph showing the pressure change and the output change of the pressure switch from the start of the adsorption process until the end of the adsorption process after performing the reset process.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side view showing the arrangement of an article holding device including a suction head according to an embodiment of the present invention.

The article holding device 10 of this embodiment includes a suction head 12 that suction-holds an article M, and the suction head 12 is attached to the tip of an arm of a robot 14, for example. The suction head 12 includes a plurality of suction parts, and in FIG. 1, it includes two suction parts 12A and 12B. In this embodiment, the article holding device 10 transfers, for example, articles M that are sequentially conveyed on the article supply conveyor 16 into cases C that are sequentially conveyed on the empty case supply conveyor 18 while being guided by the side guides 18A. do.

The robot 14 moves the suction head 12 above the article supply conveyor 16, presses the suction parts 12A and 12B against one article M on the article supply conveyor 16, and starts suctioning the suction parts 12A and 12B. Thereby, the article M is attracted and held by the suction parts 12A and 12B. When the article M is attracted and held by the suction head 10, the robot 14 moves the suction head 12 above the empty case C on the empty case supply conveyor 18, and lowers the suction head 12 into the case C. The suction to the suction parts 12A and 12B, through which the article M is moved into the case C, is stopped, and the article M is transferred into the case C.

FIG. 2 is a piping diagram illustrating the suction mechanism by the suction head 10. The suction parts 12A and 12B each include suction cups 20A and 20B that are in close contact with the article M and suction the article M. The suction cups 20A, 20B are attached to the lower ends of the negative pressure supply passages 22A, 22B, respectively, and the ejectors 24A, 24B are attached to the upper ends of the negative pressure supply passages 22A, 22B, respectively. A suction air supply source 26 is connected to each ejector 24A, 24B, and the ejector 24A, 24B uses air supplied from the suction air supply source 26 as a driving fluid to pass through the negative pressure supply passages 22A, 22B to the suction cup 20A. , 20B.

One ends of first passages 28A, 28B are connected to the negative pressure supply passages 22A, 22B between the suction cups 20A, 20B and the ejectors 24A, 24B, respectively. On the other hand, the other ends of the first passages 28A and 28B are joined together at a merging portion Q1 and connected to one second passage 30. Note that the first passages 28A, 28B are provided with check valves 32A, 32B, respectively, whose forward directions are from the second passage 30 to the negative pressure supply passages 22A, 22B.

In addition, in the second passage 30, an adsorption release air supply source 33 is connected via an air supply pipe to a connecting part Q2 located near the merging part Q1, which is opposite to the merging part Q1 of the second passage 30. A reset air supply source 34 is connected to the side end. Further, in the second passage 30, a pressure switch 36 is connected to a connecting portion Q3 located between the connecting portion Q1 and the reset air supply source 34.

3 and 4 are diagrams illustrating the suction state of the article M in the suction mechanism of the suction head 10. 3 shows a case where one article M is held by all the suction parts 12A and 12B (suction cups 20A and 20B) of the suction head 10, and FIG. It is a diagram when one article M is held in the container. Note that in FIGS. 3 and 4, the pipes drawn with thick solid lines indicate that the pressure inside the pipes has been reduced to an adsorption pressure (predetermined negative pressure) that is sufficient to adsorb the article M.

In the state shown in FIG. 3 in which the suction cups 20A and 20B are attracted to the article M, when the air in the negative pressure supply passages 22A and 22B is sucked by the ejectors 24A and 24B, the check valves 32A and 32B are opened and the first passage is 28A, 28B, and the second passage 30 are all reduced to the adsorption pressure.

In the state shown in FIG. 4 where only some of the suction cups of the suction head, for example, only the suction cups 20A, are suctioned to the article M, the pressure of the negative pressure supply passage 28A connected to the suction cups 20A is reduced to the suction pressure. On the other hand, the inside of the negative pressure supply passage 28B and the first passage 28B connected thereto on the side of the negative pressure supply passage 28A from the check valve 32B is in a state close to the atmospheric pressure because outside air is supplied from the suction cup 20B. maintained. As a result, while the check valve 32B is maintained in a closed state, the check valve 32A is opened by the suction force of the negative pressure supply passage 28A, and the first passage 28A, the second passage 30, and the first passage 28B are The pressure inside the pipe on the second passage 30 side of the stop valve 32B is reduced to the adsorption pressure.

That is, in the state shown in FIGS. 3 and 4 in which the article M is attracted and held by any one of the suction heads 12 or all of the suction parts 12A and 12B, the connection part Q3 of the second passage 30 reaches the suction pressure. The pressure is reduced. Therefore, by setting the set point (pressure value at which the switch is turned on/off) of the pressure switch 36 in accordance with the same predetermined negative pressure, when the conditions shown in FIGS. 3 and 4 occur, the pressure switch 36 is switched on/off, and it can be detected that either of the suction parts 12A, 12B (suction cups 20A, 20B) is suctioning and holding the article M. Note that when releasing the suction of the article M by the suction head 12, a check valve is supplied from the suction release air supply source 33 so that the inside of the negative pressure supply passages 28A and 28B becomes slightly positive pressure (release pressure). Air is supplied to the negative pressure supply passages 28A and 28B through 32A and 32B.

However, as shown in FIG. 5, once the suction pressure in the second passage 30 where the pressure switch 36 is installed becomes lower than the suction pressure, the suction head 12 loses suction of the article M and the negative pressure supply passages 28A, 28B Even when outside air flows in, the negative pressure state within the second passage 30 does not change due to the effects of the check valves 32A and 32B. Therefore, the pressure switch 36 can only detect the first state of suction, and cannot detect whether the suction of the article M is maintained thereafter.

In this embodiment, when determining the suction state from the second time onwards, air is supplied from the reset air supply source 34, and as shown in FIG. 6, the pressure applied to the pressure switch 36 is set to a reset pressure higher than the set point. A reset process is performed in which the pressure switch 36 is reset. In the reset process, the air supplied from the reset air supply source 34 to the second passage 30 temporarily raises the connection part Q3 to the reset pressure, and the air that The amount is set to maintain a negative pressure inside the two passages 30.

The air supplied from the reset air supply source 34 to the second passage 30 is supplied through a solenoid valve (not shown), a regulator, and a speed controller between the reset air supply source 34 of the second passage 30 and the connection part Q3. It is controlled by providing . That is, by controlling these, the flow rate of air supplied from the reset air supply source 34 to the second passage 30 and the supply time of air are adjusted, and the amount of air supplied is suitably controlled.

In addition, in order to set the supply amount of air supplied from the reset air supply source 34 to an appropriate ratio to the total volume of the piping up to the check valves 32A and 32B, in this embodiment, for example, the reset air supply The length of the piping from the source 34 to the connection part Q2 (or the amount of air supplied from the reset air supply source 34) is set as follows. That is, let L1 be the length of the piping from the reset air supply source 34 to a position Q4 arbitrarily set between the connecting parts Q2 and Q3, and let L2 be the length of the piping from the position Q4 to the connecting part Q2. Sometimes, the piping volume from the reset air supply source 34 to the connection part Q3 is made to correspond to the amount of air supplied from the reset air supply source 34, and the ratio L1:L2 is set to a predetermined ratio (for example, about 1:10). It is set to .

With the above configuration, the connection part Q3 can be temporarily raised to the reset pressure more easily, and even after the reset process, the negative pressure ( It is possible to obtain a configuration in which the pressure can be maintained at (below the reset pressure). In addition, the piping diameter from the reset air supply source 34 to the connection part Q2 in the second passage 30 is made smaller than the piping diameter of the remaining part of the second passage 30 and the first passages 28A and 28B. It's okay. This further facilitates adjustment to maintain the negative pressure after the reset process.

During the reset process, if the article M is attracted and held by either the suction cup 20A or 20B, the ejector (24A) of either negative pressure supply passage (22A, 22B) is maintained in the suction state immediately after the reset process. , 24B), the air in the second passage 30 is sucked through the check valves (32A, 32B) in the first passage (28A, 28B), and the entire second passage 30 up to the reset air supply source 34 (Fig. 7 (dashed line) is again reduced to the adsorption pressure.

On the other hand, when neither of the suction cups 20A and 20B of the suction head 12 is suctioning or holding the article M, the negative pressure supply passages 22A and 22B are filled with outside air from the suction cups 20A and 20B, so that almost all of them are outside. It becomes atmospheric pressure. Since the second passage 30 side of the check valves 32A, 32B is maintained at negative pressure (reset pressure) after the reset process as described above, the check valves 32A, 32B do not open. Therefore, the entire inside of the second passage 30 (the broken line portion in FIG. 7) is maintained at a reset pressure higher than the suction pressure.

Next, details of the adsorption state determination process will be described with reference to the graph of FIG. 8. FIG. 8 shows the pressure change at the connection part Q3 (pressure switch 36) from the start of the suction process until the reset process and the end of the suction process, and the output change of the pressure switch 36 at that time. . In addition, in FIG. 8, the horizontal axis shows time T, the vertical axis in the pressure change graph shows pressure P, and the vertical axis in FIGS. 8(a) and 8(b) showing output changes of the pressure switch 36 shows the pressure switch. 36 on/off states are shown.

Before suction in the negative pressure supply passages 22A and 22B starts in the adsorption process, the pressure at the connecting portion Q3 is equal to the external pressure P0 (for example, 0 kPa). When suction is started and the article M is suctioned, the pressure in the second passage 30 is reduced to the suction pressure P1 through one or both of the check valves 32A and 32B (solid line S1). The set point pressure (set point pressure) P2 of the pressure switch 36 is set to a value lower than the external pressure P0 and higher than the adsorption pressure P1 (P1<P2<P0), and the pressure at the connection part Q3 is set to the set point pressure. When the pressure falls below P2, the pressure switch 36 is turned on/off. Note that the pressure switch 36 of this embodiment is in an OFF state when the pressure is higher than the set point pressure P2, and is in an ON state when the pressure is lower than the set point pressure P2.

The article M on the article supply conveyor 16 is suctioned, and the suction head 12 of the robot 14 comes near the upper part of the empty case C on the empty case supply conveyor 18 (see FIG. 1). 6), air is supplied from the reset air supply source 34 to the second passage 30 for a predetermined period of time, and the inside of the piping on the side of the pressure sensor 36 rather than the check valves 32A, 32B is shaded as shown in FIG. The pressure at the connecting portion Q3 is increased to the reset pressure P3. The reset pressure P3 is lower than the external pressure P0 and higher than the set point pressure P2 (P2<P3<P0), and the pressure at the connection part Q3 rises to the reset pressure P3 (state in FIG. 6). As a result, the pressure switch 36 is turned off again.

When either or both of the suction cups 20A, 20B are suctioning the article M, the air in the second passage 30 is immediately sucked through either or both of the check valves 32A, 32B, and the suction pressure P1 is increased from the reset pressure P3. The pressure is reduced to (solid line S1), and the pressure switch 36 is turned on again. After that, at timing T2 when the article M is put into the empty case C, air is supplied from the adsorption release air supply source 33 to the second passage 30, and the pressure at the connection part Q3 is a release pressure P4 that is slightly higher than the outside pressure P0. , and the suction of the article M by the suction head 12 is released.

On the other hand, when all the suction cups 20A and 20B of the suction head 12 are not suctioning the article M, the negative pressure supply passages 22A and 22B become approximately external pressure P0, so the check valves 32A and 32B do not open, and the first Air within the two passages 30 is not sucked. As a result, the pressure in the second passage 30 is maintained at the reset pressure P3, as shown by the dashed line C2 in FIG. 8, until air is supplied to the second passage 30 from the adsorption release air supply source 33. Note that at this time, since the article M has fallen from the suction head 12, the supply of air from the suction release air supply source 33 may be performed immediately after it is determined that the article M has fallen off, without waiting for timing T2. .

FIGS. 8A and 8B show changes in the on/off state of the pressure switch 36 when the article M does not fall off from the suction head 12 and when it falls off after the reset process, respectively. When the suction of the article M is started and the pressure of the connection part Q3 falls below the set point pressure P2 (time t1), the output of the pressure switch 36 is turned on, and the suction of the article M is successfully determined by the control section (not shown). It is determined that the pick is complete. Thereafter, when air is supplied from the reset air supply source 34 and the pressure at the connection portion Q3 becomes higher than the set point pressure P2, the output of the pressure switch 36 is switched to the OFF state.

As shown in FIG. 8(a), when the pressure at the connection part Q3 falls below the set point pressure P2 within a predetermined period ΔT after the switch is turned off and the output of the pressure switch 36 is turned on, the control It is determined that suction of the article M by the suction head 12 is maintained. On the other hand, as shown in FIG. 8(b), the pressure at the connection part Q3 does not fall below the set point pressure P2 within the predetermined period ΔT after the switch is turned off, and the output of the pressure switch 36 remains in the off state. In this case, the control unit determines that the article M has fallen off from the suction head 12.

Note that if the suction of the article M on the article supply conveyor 16 does not go well from the beginning, the pressure at the connection part Q3 remains the external pressure P0, so the control unit determines that the suction (picking) has failed. Ru.

As described above, according to the suction head (suction state detection device) of the present embodiment, the suction state of the suction head including a plurality of suction parts can be determined with a simple configuration using only a single pressure switch. I can do it.

The second and subsequent adsorption state determination processes that involve the reset process may be performed multiple times after the first determination process. Further, the on/off switching of the pressure switch may be reversed with respect to the set point as in this embodiment. Further, in this specification, since air is assumed to be the outside air, air is supplied from the supply source, but a configuration may also be adopted in which some kind of gas is supplied.

10 Article holding device 12 Suction head 12A, 12B Suction part 20A, 20B Suction cup 22A, 22B Negative pressure supply passage 24A, 24B Ejector 26 Adsorption air supply source 28A, 28B First passage 30 Second passage 32A, 32B Check valve 33 Air supply source for suction release 34 Air supply for reset 36 Pressure switch M Article Q1 Merging section Q2, Q3 Connection section

Claims (3)

a suction head including a plurality of suction parts;
a plurality of negative pressure supply passages connecting the adsorption unit and negative pressure supply means to supply negative pressure to each of the adsorption units;
a plurality of first passages, one end of which communicates with each of the negative pressure supply passages;
a second passage connected to each of the first passages via a confluence between the other ends of the first passages;
a single pressure switch provided in the second passage;
a plurality of check valves provided in each of the first passages and whose forward direction is a direction from the second passage to the negative pressure supply passage;
A suction state detection device comprising: determination means for determining a suction state of the suction head based on an output of the pressure switch. 2. The adsorption state detection device according to claim 1, wherein the second passage is provided with a pressure supply source that supplies a pressure equal to or higher than a set point of the pressure switch. During the period from the start to the end of suction by the suction head, the determining means first determines the suction state of the suction head based on whether or not the pressure switch detects a pressure equal to or lower than the set point; From the second time onwards, after temporarily supplying pressure from the pressure supply source, the suction state of the suction head is determined based on whether or not the pressure switch again detects a pressure below the set point. The adsorption state detection device according to claim 2.

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