Suction pad

A suction device includes an adapter having a supply passage to which a negative pressure fluid is supplied, a bellows connected to a lower end of the adapter, and a pad member formed at the distal end of the bellows. The pad member has plural first and second ribs on a suction surface that attracts a workpiece under suction. The first ribs are disposed on an outer circumferential side of an attachment provided in the center of the pad member and extend toward the outer circumferential side. The second ribs are provided on an outer circumferential side of the first ribs, and are disposed in a circumferentially offset manner with respect to the first ribs. Additionally, between the respective first ribs which are disposed alongside one another in the circumferential direction of a skirt, supply paths are formed to which the negative pressure fluid is supplied from the attachment.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2018-149076 filed on Aug. 8, 2018, the contents all of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a suction pad used in a suction device capable of attracting under suction and transporting a workpiece under a supply action of a negative pressure fluid.

Description of the Related Art

Heretofore, a suction device has been known in which there is included a suction pad for attracting under suction and transporting a workpiece by a supplied negative pressure fluid. In such a suction device, in the case of transporting a workpiece which is formed from a film in a bag shape and is filled with fluid contents, when the contents move inside the workpiece and the workpiece becomes deformed, the suction pad cannot follow along with the deformation, and the suction applied to the workpiece becomes defective.

Thus, in order to solve the aforementioned problem, for example, in the suction pad disclosed in Japanese Laid-Open Patent Publication No. 2018-065194, there are provided a support body having a suction path in the center thereof, and a skirt member disposed on a lower part of the support body and which contacts the workpiece. The skirt member is formed in a truncated conical shape, and in an interior space thereof, a plurality of rib portions are provided that extend radially from the center toward an outer circumferential side, and project toward the workpiece.

In the interior space of the skirt member, the suction path to which a negative pressure fluid is supplied opens in the center thereof, and convex surface portions, which are fan-shaped in cross section, are formed to project toward the workpiece at positions facing the suction path on respective inner sides of the rib portions.

In addition, when the bag-shaped workpiece having the contents filled in the interior thereof is attracted under suction with the suction pad, by placing an inclined surface of the skirt member in close contact with a surface of the workpiece, and supplying the negative pressure fluid to the internal space through the suction path, the skirt member is elastically deformed in close contact with the surface of the workpiece, and by the negative pressure fluid passing between the convex surface portions and being supplied between the respective rib portions, the workpiece is attracted under suction.

SUMMARY OF THE INVENTION

However, with the suction pad discussed above, when the workpiece is deformed due to flowing of the contents therein or the like at the time that the workpiece is attracted under suction, the negative pressure fluid, which is supplied to the outer circumferential side of the skirt member between the convex surface portions and flows between the rib portions, flows in a linear manner toward the outer circumferential side, and there is a concern that the negative pressure fluid may leak to the exterior from the outer circumferential sides of opened rib portions, thus leading to a decrease in suction power and bringing about a suction defect.

A general object of the present invention is to provide a suction pad which is capable of reliably and stably attracting a workpiece under suction, by causing the suction pad to follow a workpiece having a bag shape that undergoes deformation by flowing of the contents therein.

An aspect of the present invention is characterized by a suction pad configured to be fixed to an end of a body having therein a passage to which a negative pressure fluid is supplied, the suction pad including ribs on a suction surface of a suction member to which a workpiece is attracted under suction, the ribs including:

a plurality of first rib portions configured to project toward the workpiece, wherein the first rib portions are formed on an outer circumferential side of the passage, and extend radially outward; and

a plurality of second rib portions formed on outer circumferential sides of the first rib portions, and which are disposed in a circumferentially offset manner with respect to the first rib portions;

wherein supply paths through which the negative pressure fluid flows are formed between adjacent ones of the first rib portions, and at least parts of the second rib portions are disposed so as to face toward directions in which the supply paths extend.

According to the present invention, the suction surface of the suction pad that attracts the workpiece under suction includes the ribs that project toward the workpiece. The ribs include the plurality of first rib portions which are formed on the outer circumferential side of the passage formed in the body, and extend radially outward, and the plurality of second rib portions which are formed on the outer circumferential side of the first rib portions, and are disposed in a circumferentially offset manner with respect to the first rib portions. The supply paths through which the negative pressure fluid flows are formed between adjacent ones of the first rib portions.

In addition, for example, when a bag-shaped workpiece in which fluid contents are contained is attracted under suction and transported by the suction pad, even in the case that the shape of the workpiece changes due to movement of the contents or under the influence of gravity or the like, the suction pad is deformed in a manner so as to follow the shape of the workpiece, and by the first rib portions and the second rib portions being kept in abutment with the workpiece accompanying such deformation, the supply paths are surrounded by the first and second rib portions, and the negative pressure fluid can suitably be maintained in the interior of the supply paths. Further, since the supply paths of the negative pressure fluid are configured in a non-linear shape by the first and second rib portions in radial directions of the suction pad, leakage of the negative pressure fluid to the exterior can be prevented, in comparison with the suction pad according to the conventional art.

Accordingly, even in the case that the shape of the workpiece being attracted under suction changes, the suction pad is deformed so as to follow the changed shape, and the workpiece is reliably attracted under suction with a stable suction force by the negative pressure fluid that is retained in the supply paths.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown inFIGS. 1 to 4, the suction device10includes an adapter (body)12connected through a tube to a non-illustrated negative pressure supply device, a bellows (bellows portion)14connected to a lower end of the adapter12, and a pad member (suction member)16formed at the distal end (lower end) of the bellows14.

The adapter12is formed, for example, in a cylindrical shape from a metal material, and on a lower end thereof, a connecting part18is formed to which the bellows14is connected, whereas on an upper end thereof, a threaded portion22is formed to which a joint20is connected. Between the connecting part18and the threaded portion22, a flange portion24is formed that projects in a direction perpendicular to the axial direction. In addition, a seal ring26is attached to the flange portion24via an annular groove on an end surface on the side of the threaded portion22. Moreover, when the joint20is connected to the adapter12, the joint20abuts against the seal ring26, thereby preventing the negative pressure fluid from leaking between the two members.

Further, a supply passage (passage)28is formed in the interior of the adapter12along the axial direction (the direction of arrows A and B) so as to penetrate through the connecting part18, the flange portion24, and the threaded portion22. The negative pressure fluid, which is supplied from the negative pressure supply device (not shown) to the tube and the joint20connected to the threaded portion22, is supplied to the supply passage28.

The bellows14is formed in a cylindrical shape, for example, from elastic rubber or the like, and has an expandable/contractible and bendable bellows structure. The bellows14has, on an upper end thereof, a cylindrical portion30which is formed in a cylindrical shape with a constant diameter, and by being mounted in a manner so as to cover the connecting part18of the adapter12, the cylindrical portion30is connected coaxially to the lower end of the adapter12.

Further, annular peak portions32that are expanded in diameter and annular valley portions34that are contracted in diameter are formed alternately along the axial direction (the direction of arrows A and B) on the bellows14. The pad member16, which is placed in contact to the workpiece W (seeFIG. 5A) and applies suction thereto, is formed integrally on the lower end of the bellows.

Moreover, the interior of the bellows14which is formed in a hollow shape functions as a flow path through which the negative pressure fluid is supplied and flows.

The pad member16is provided at the lower end of the bellows14, and includes an attachment36disposed substantially in the center, and a skirt38provided on the outer circumferential side of the attachment36.

The upper end of the attachment36is formed in a conical shape which is gradually expanded in diameter in an upward direction (the direction of the arrow A), and is engaged with the lowermost annular peak portion32in the bellows14, and is thereby held integrally in the center of the lower end of the bellows14.

Further, a center of the lower end of the attachment36is formed with a circular arcuate shape in cross section which is shaped convexly toward a direction (the direction of the arrow A) separating away from the workpiece W, and a first communication hole40and a plurality of second communication holes42are formed to penetrate in the axial direction (the direction of arrows A and B) through the attachment36.

As shown inFIGS. 3 and 4, the first communication hole40is disposed in the axial center of the attachment36, and the six second communication holes42are arranged at equal intervals from one another on a circumference of a predetermined diameter centered about the first communication hole40. Stated otherwise, the attachment36is provided with seven communication holes in total. It should be noted that the number of the second communication holes42is not necessarily limited to six as described above.

Furthermore, on the lower end of the attachment36, guide grooves44are formed that extend outwardly in radial directions from each of the second communication holes42. The guide grooves44are formed with U-shapes in cross section opening toward the workpiece W (in the direction of the arrow B). The guide grooves44are provided so as to allow the second communication holes42to communicate with the skirt38that is disposed on the outer circumferential side of the attachment36. Stated otherwise, the guide grooves44are formed in a recessed manner upwardly (in the direction of the arrow A) from a lower surface of the attachment36.

The skirt38is formed, for example, in a thin film annular shape from rubber or the like having an elasticity similar to that of the bellows14, and is formed so as to spread out obliquely downward, together with being formed to be freely flexible. Moreover, the skirt38may be formed by way of two-color molding or the like using a material that differs from that of the bellows14.

Further, on the skirt38, on an inner surface (suction surface)38awhere a distal end thereof forms a location in contact with the workpiece W, and which is on the side of the workpiece W (in the direction of the arrow B), there are provided a plurality of first ribs (first rib portions)46formed so as to face an outer edge portion of the attachment36, and a plurality of second ribs (second rib portions)48disposed on an outer circumferential side with respect to the first ribs46. The first and second ribs46and48are formed so as to project at respective predetermined heights toward the workpiece W with respect to the inner surface38aof the skirt38. A case will be described in which fifteen first ribs46and fifteen second ribs48are provided on the skirt38.

As shown inFIG. 3, the first ribs46are formed with V-shapes (concave shapes) in cross section having bottom portions on the inner circumferential side and opening toward the outer circumferential side of the skirt38as viewed from the axial direction of the suction device10. At bifurcated outer circumferential side end portions on the outer circumferential side, inclined portions50are formed which are inclined toward the central recesses46a. More specifically, each of the first ribs46is formed in a manner so that one of the inclined portions50and the other of the inclined portions50form a pair in a symmetrical shape with the recess46abeing interposed therebetween.

Additionally, the plurality of first ribs46are arranged at equal intervals from one another along the circumferential direction (the direction of the arrow D) of the skirt38, and supply paths52to which the negative pressure fluid is supplied are formed between two adjacent ones of the first ribs46. The first ribs46and the supply paths52extend radially along radial directions of the skirt38.

Further, the guide grooves44of the attachment36are disposed so as to face toward inner sides of the first ribs46and the supply paths52.

As shown inFIG. 3, the second ribs48are formed with V-shapes (concave shapes) in cross section, which are bent to project toward the outer circumferential side of the skirt38as viewed from the axial direction of the suction device10. Among two of the first ribs46, which are arranged adjacent to each other, each of the second ribs48is arranged so as to straddle over an outer circumferential side end portion of one of the first ribs46and an outer circumferential side end portion of another of the first ribs46. More specifically, concerning the second ribs48, central portions thereof, which face toward the supply paths52formed between adjacent ones of the first ribs46, make up top portions48athat project maximally toward the outer circumferential side of the skirt38, and from the top portions48atoward both ends thereof, the second ribs48are formed in an inclined manner toward insides in radial directions, respectively, so as to gradually approach toward the outer circumferential side end portions of the first ribs46.

The angles of inclination centered about the top portions48aof the second ribs48are formed to be substantially the same as the angles of inclination of the inclined portions50of the first ribs46.

Further, as shown inFIG. 3, a total length of the lengths L of the inner circumferential side ends (bottom portions) of the first ribs46along the circumferential direction is set to lie within a range of from 40% to 70% of an inner circumference (length) C1of the skirt38, and together therewith, is set to be less than or equal to 40% of a circumference (length) C2of a circumscribed circle passing through the top portions48aforming the outermost circumference on the second ribs48.

Furthermore, the total area of the first and second ribs46and48as viewed from the axial direction of the suction device10is set to lie within a range of from 5% to 40% of the surface area of the skirt38.

The suction device10according to the first embodiment of the present invention is constructed basically as described above. Next, operations and advantages thereof will be described. In this instance, as shown inFIGS. 5A and 5B, a description will be given concerning a case in which a workpiece W formed of a thin film in a bag shape and in which fluid contents are contained in the interior thereof is attracted under suction and transported.

First, the suction device10is attached to an arm or the like of a non-illustrated transport apparatus, and is disposed in a displaceable manner, together with the adapter12being connected via the tube and the joint20to a non-illustrated negative pressure supply device.

After having completed such preparatory operations, as shown inFIG. 5A, based on operations of the arm of the non-illustrated transport apparatus, the suction device10is displaced downward (in the direction of the arrow B), and the skirt38is placed in close contact with an upper part of the workpiece W, together with supplying a negative pressure fluid from the non-illustrated negative pressure supply device to the supply passage28of the adapter12via the tube and the joint20.

At this time, since the workpiece W is placed on a floor surface or the like, the upper surface thereof that faces toward the suction device10is substantially flat, and for example, even in the case that the workpiece W is inclined, or when the upper part of the workpiece W is not flat, by an expanding/contracting operation of the bellows14corresponding to the workpiece W, it is possible to follow the workpiece W and to securely place the pad member16in close contact therewith.

Consequently, the skirt38of the pad member16is placed in close contact with the surface of the workpiece W, and the negative pressure fluid supplied to the supply passage28of the adapter12passes through the interior of the bellows14and is supplied to the internal space of the pad member16from the first and second communication holes40and42of the attachment36. Further, a portion of the negative pressure fluid supplied to the second communication holes42passes through the guide grooves44and flows to the side of the skirt38on the outer circumferential side thereof, and flows to the outer circumferential side along the respective supply paths52. As a result, the upper part of the workpiece W that is placed in close contact with the skirt38is attracted under suction to the pad member16by the negative pressure fluid, and simultaneously, the bellows14undergoes contraction in the axial direction. At this time, since the outer edge portion of the skirt38is held in close contact with the flat shaped upper part of the workpiece W, the negative pressure fluid supplied to the outer circumferential side along each of the supply paths52does not leak to the exterior, and the suction force applied with respect to the workpiece W is maintained.

Then, as shown inFIG. 5B, in a state in which the workpiece W is attracted under suction by the suction device10, by causing the workpiece W to be moved upwardly (in the direction of the arrow A) by the arm of the non-illustrated transport apparatus, the workpiece W becomes deformed so as to bend downward in the direction of gravity (the direction of the arrow B) due to the weight of the contents, and accordingly, the skirt38elastically deforms so as to follow the shape of the upper part of the workpiece W that is attracted under suction, and becomes a downwardly bent curved shape.

In this manner, in the case that the shape of the workpiece W changes during conveyance of the workpiece W, then as shown inFIG. 6, accompanying the elastic deformation of the skirt38, the plurality of first ribs46approach toward each other in the circumferential direction (the direction of the arrow D), and the second ribs48approach toward the outer circumferential side end portions of the first ribs46and come into abutment against the outer circumferential side end portions, together with the first ribs46and the second ribs48approaching toward each other in the radial direction, whereby a state is brought about in which the outer circumferential sides of the supply paths52are blocked by the second ribs48.

Furthermore, accompanying the elastic deformation of the skirt38, by both ends of the second ribs48undergoing bending so as to approach toward each other, it is possible for the second ribs48to abut against the inclined portions50of the first ribs46and thereby block the supply paths52.

Therefore, the negative pressure fluid, which is supplied toward the outer circumferential side through each of the supply paths52in the skirt38, does not flow any further toward the outer circumferential side from the supply paths52due to the second ribs48, and the negative pressure fluid is retained within the supply paths52that are surrounded by the second ribs48and the first ribs46, whereby the deformed upper part of the workpiece W is reliably and suitably attracted under suction by the negative pressure fluid that is retained inside the respective supply paths52.

Stated otherwise, the skirt38undergoes elastic deformation in accordance with the change in shape of the workpiece W, and the workpiece W is attracted under suction by the negative pressure fluid inside the respective supply paths52, thereby making it possible to prevent a decrease in the suction force and avoid the occurrence of a suction defect.

Further, even in the case that the lower surface of the attachment36is covered by the attracted workpiece W, the negative pressure fluid is securely supplied to the respective supply paths52of the skirt38by the guide grooves44that communicate with the second communication holes42and extend toward the outer circumferential side, thereby enabling the suction power applied with respect to the workpiece W to be maintained.

In addition, after the suction device10to which the workpiece W is attracted under suction has been transported to a predetermined position by an arm of the transport apparatus, supply of the negative pressure fluid with respect to the supply paths52is stopped, whereby the attracted state of the workpiece W by the pad member16of the suction device10is released.

In the foregoing manner, according to the first embodiment, the pad member16that constitutes the suction device10comprises the attachment36to which the negative pressure fluid is supplied, and the elastically deformable skirt38disposed on the outer circumferential side of the attachment36and which is in the form of a thin film, wherein on the inner surface38aof the skirt38to which the workpiece W is attracted under suction, there are provided the plurality of first ribs46, which are formed on the outer circumferential side of the attachment36and extend radially, and the plurality of second ribs48, which are formed on the outer circumferential side of the first ribs46and are disposed in a circumferentially offset manner (in the direction of the arrow D) with respect to the first ribs46, together with the first and second ribs46and48being formed to project toward the workpiece W.

Consequently, for example, when a bag-shaped workpiece W in which fluid contents are contained is attracted under suction and transported by the suction device10, even in the case that during conveyance thereof the shape of the workpiece W changes due to movement of the contents or under the influence of gravity or the like, the skirt38is elastically deformed in a manner so as to follow the shape of the workpiece W, and accompanying such elastic deformation, the second ribs48cover the outer circumferential side end portions of the first ribs46. Therefore, the negative pressure fluid supplied to the supply paths52formed between the first ribs46is prevented from flowing toward the outer circumferential side of the skirt38and leaking to the exterior.

As a result, even in the case that the shape of the workpiece W changes during conveyance by the suction device10, the skirt38undergoes deformation corresponding to the change in shape, thereby securely placing the skirt in close contact with the workpiece W, and enabling the negative pressure fluid to be reliably retained in the supply paths52in the form of closed spaces which are blocked on the outer circumferential side thereof by the second ribs48. Therefore, the suction force with respect to the workpiece W can be maintained, and the workpiece W can continue being reliably attracted under suction in a stable manner.

Further, in the skirt38, since the first ribs46and the second ribs48are disposed so as to overlap one another in the radial direction, in the case that the attracted and transported workpiece W is deformed and the skirt38accordingly undergoes deformation accompanying the deformation of the workpiece W, the outer circumferential side end portions of the first ribs46and the second ribs48are suitably brought into contact with each other, thereby reliably blocking the supply paths52provided between both members, and enabling the negative pressure fluid to be retained inside the supply paths52. Therefore, even in the case that the workpiece W that is attracted under suction undergoes deformation, the suction force is not reduced, and the workpiece W can be reliably attracted under suction and transported.

Furthermore, the inclined portions50are provided on the outer circumferential side end portions of the first ribs46that are formed with V-shapes in cross section, and the second ribs48that face toward the first ribs46are formed with V-shapes in cross section opening toward the inner circumferential side. Owing to this configuration, in the case that the workpiece W which is attracted under suction is deformed, and the skirt38undergoes deformation along therewith, the inclined portions50of the first ribs46can be securely brought into close contact with the second ribs48to thereby block the supply paths52.

Therefore, it is possible to more reliably prevent leakage of the negative pressure fluid from the interior of the supply paths52, and to increase the suction force applied with respect to the workpiece W.

Still further, the first and second ribs46and48are formed so as to have V-shapes in cross section, so that it becomes easy for the skirt38to be bent when it is deformed. Further, by arranging the plurality of divided first and second ribs46and48along the circumferential direction (the direction of the arrow D), compared to a case in which the first and second ribs of single type are provided, deformation of the skirt38can be easily brought about, and it is possible to smoothly and freely cause the skirt38to undergo deformation so as to follow the change in shape of the workpiece W.

Further still, the attachment36is provided with the guide grooves44having U-shapes in cross section, which communicate with the respective second communication holes42and extend radially outward. Therefore, when the workpiece W is attracted under suction, even in the case that a portion of the thin film workpiece W is brought into close contact with the attachment36so as to cover the attachment36, and the second communication holes42are blocked, since the negative pressure fluid supplied to the second communication holes42can be reliably and stably supplied through the guide grooves44to the skirt38on the outer circumferential side, the suction force of the workpiece W can be maintained, and it is possible to avoid the occurrence of a suction defect.

Still further, by providing the plurality of first and second ribs46and48on the skirt38, the rigidity of the skirt38can be enhanced, and accordingly, drawing in of the skirt38itself with respect to the first and second communication holes40and42can be prevented.

Further, by providing the bellows14between the adapter12and the pad member16, it is possible to suitably alleviate shocks when the suction device10is placed in contact with the workpiece W.

Furthermore, the skirt38and the bellows14may be formed separately from different materials, and the hardness of the bellows14may be set to be higher than the hardness of the skirt38.

Next, a suction device70according to a second embodiment is shown inFIGS. 7 and 8. The same reference numerals are used to indicate the same constituent elements as those of the suction device10according to the above-described first embodiment, and detailed description of such features is omitted.

The suction device70according to the second embodiment differs from the suction device10according to the first embodiment, in that a suction pad72thereof is directly connected to the lower end of the adapter12.

In the suction device70, the suction pad72which is made of an elastic material is connected to the connecting part18provided at the lower end of the adapter12. Moreover, in relation to the adapter12, it has the same configuration as that of the suction device10according to the first embodiment, and therefore, detailed description of the adapter12will be omitted.

The suction pad72includes on an upper end thereof a cylindrical portion74which is formed in a cylindrical shape, and by being mounted in a manner so as to cover the connecting part18of the adapter12, the cylindrical portion74is connected coaxially with respect to the lower end of the adapter12.

Further, the pad member76that attracts the workpiece W under suction is formed at the lower end of the suction pad72, the pad member76being constituted from the attachment36disposed substantially in the center, and the skirt38provided on the outer circumferential side of the attachment36. The plurality of first and second ribs46and48are provided on the skirt38. In relation to the skirt38, it has the same configuration as that of the suction device10according to the first embodiment, and therefore, detailed description of the skirt38will be omitted.

In the manner described above, with the suction device70according to the second embodiment, in comparison with the suction device10according to the first embodiment, since the bellows14having a bellows shape is not included therein, it is possible to make the dimension in the axial direction (the direction of arrows A and B) smaller.

Further, the first and second ribs46and48provided on the skirt38of the suction devices10and70are not limited to having the shapes described above. For example, as in the suction device100shown inFIGS. 9A and 9B, the ribs may be constituted from a plurality of first ribs102that extend in a linear manner radially outward from the side of the attachment36that is located in the center of the skirt38, and a plurality of second ribs104disposed on the outer circumferential side of the first ribs102, and disposed so as to face the supply paths52formed between adjacent ones of the first ribs102.

The first ribs102and the second ribs104are disposed in a manner so that portions thereof overlap each other in the radial direction of the skirt38.

Even in this case, in a state in which the workpiece W is attracted under suction by the suction device100, as shown inFIG. 9B, in the case that the skirt38is deformed accompanying a change in the shape of the workpiece W, by the second ribs104coming into abutment against the outer circumferential side end portions of each two adjacent ones of the first ribs102, the negative pressure fluid can be suitably retained in the interior by reliably blocking the outer circumferential sides of the supply paths52provided between the first ribs102and to which the negative pressure fluid is supplied.

As a result, when the workpiece W is attracted under suction and transported, even in the case that the shape of the workpiece W changes, the suction force can be stably maintained by the negative pressure fluid that is retained inside the supply paths52, and it becomes possible to transport the workpiece W in a state of being securely attracted under suction without the occurrence of a suction defect.

More specifically, the first ribs46and102and the second ribs48and104are not limited to the shapes described above, and any configuration may be adopted which is capable of maintaining the negative pressure inside the supply paths52by the outer circumferential side end portions of the first ribs46and102being blocked by the second ribs48and104when the skirt38undergoes elastic deformation in accordance with a change in the shape of the workpiece W.

The suction pad according to the present invention is not limited to the embodiments described above. It is a matter of course that various alternative or additional configurations could be adopted therein without departing from the essence and gist of the present invention as set forth in the appended claims.