DE202021004185U1 - Effector for an industrial robot - Google Patents

Abstract

Effector (10) for an industrial robot, comprising
- two gripping fingers (36), each with a gripping section (40) and a guide section (38), whose gripping sections (40) each have a gripping edge (46) and the gripping edges (46) of the two gripping fingers (36) are parallel to one another,
- a guide rail (12) extending perpendicularly to the direction of longitudinal extension of the gripping edges (46), on which the guide sections (38) of the gripping fingers (36) are mounted in a rotationally fixed and linearly displaceable manner, and
- a spindle rod (20) which is oriented parallel to the guide rail (12) and is mounted thereon such that it can rotate about its longitudinal axis and has two axially separate threaded sections (26a, b) which have primary threads (34a, b) oriented opposite to one another, the two gripping fingers ( 36) are assigned to different threaded sections (26a, b) and the guide section (38) of each gripping finger (36) has a secondary thread (44a, b) corresponding to the primary thread (34a, b) of the associated threaded section (26a, b) and above it with is screwed to the associated threaded section (26a, b), characterized in that the gripping sections (40) in the region of their free ends each have a catch hook (48) which is aligned perpendicularly to their direction of longitudinal extension and projects away from the respective other gripping finger (36).

Description

field of invention

• - zwei Greiffinger mit jeweils einem Greifabschnitt und einem Führungsabschnitt, deren Greifabschnitte jeweils eine Greifkante aufweisen und die Greifkanten der beiden Greiffinger parallel zueinander stehen,
• - eine senkrecht zur Längserstreckungsrichtung der Greifkanten erstreckte Führungsschiene, an der die Führungsabschnitte der Greiffinger drehfest und linearverschieblich gelagert sind, und
• - eine parallel zu der Führungsschiene orientierte und an dieser um ihre Längsachse rotierbar gelagerte Spindelstange mit zwei axial getrennten Gewindeabschnitten, die einander entgegengesetzt orientierte Primärgewinde aufweisen,

wobei die beiden Greiffinger unterschiedlichen Gewindeabschnitten zugeordnet sind und der Führungsabschnitt jedes Greiffingers ein zu dem Primärgewinde des zugeordneten Gewindeabschnitts korrespondierendes Sekundärgewinde aufweist und darüber mit dem zugeordneten Gewindeabschnitt verschraubt ist.The invention relates to an effector for an industrial robot, comprising

• - two gripping fingers, each with a gripping section and a guide section, whose gripping sections each have a gripping edge and the gripping edges of the two gripping fingers are parallel to one another,
• - a guide rail extending perpendicularly to the direction of longitudinal extension of the gripping edges, on which the guide sections of the gripping fingers are mounted in a rotationally fixed and linearly displaceable manner, and
• - a spindle rod which is oriented parallel to the guide rail and is mounted on it so that it can rotate about its longitudinal axis and has two axially separate threaded sections which have primary threads oriented in opposite directions,

wherein the two gripping fingers are assigned to different threaded sections and the guide portion of each gripping finger has a secondary thread that corresponds to the primary thread of the associated threaded section and is screwed to the associated threaded section.

State of the art

Such effectors are known from DE 20 2005 019 060 U1 .

In the context of the present description, according to the general definition, an industrial robot is understood to mean a universal, programmable machine for handling workpieces, which essentially consists of a manipulator, also known as a robot arm, an effector arranged at the free end of the manipulator, which is designed in particular as a gripper can be, and an associated controller. Such industrial robots are often additionally equipped with sensors in order to be able to monitor details of the handling of the workpiece.

Such industrial robots are often used in the beverage industry, for example to automate the transfer of bottles from or into bottle crates. The effectors of such industrial robots are designed to grip bottles individually or in groups as required. An interaction with the bottle crate itself is regularly not desired. Rather, the bottle crates are regularly transported as such with horizontal and / or vertical conveyors.

This is also the case when unpacking stacks from bottle crates—or more generally when unpacking stacks from uniform containers. That's it DE 43 29 180 A1 a device is known in which a stack of bottle crates is delivered on a pallet and positioned on a lifting table by means of a horizontal conveyor, the space above the lifting table being laterally enclosed by vertical shaft walls. The shaft serves to stabilize the stack against lateral forces that can act on the stack during unpacking. One of the side walls can be opened like a door so that the stack can be moved upright into the shaft and onto the lifting table using the horizontal conveyor. When unpacking, the stack is lifted by the height of one pack layer by means of the lifting table, so that the top pack layer protrudes over the top edge of the shaft. There it is gripped by a clamping gripper that grips the entire circumference of the layer and pushed sideways onto a discharge conveyor.

From the U.S. 3,139,993A a similar system is known, but here the stack is unpacked downwards. The stack is clamped over its entire circumference and the bottom layer of packs is released so that it can be removed. Such a downward unpacking system is also available from the FR 2 450 220 A1 known.

All such systems have proven themselves for applications in which uniform packs, in particular packs of the same height, are grouped together in each pack layer. However, so-called “magic cubes” often cause problems, especially in the empties industry. In technical jargon, a “magic cube” is understood to mean unordered, “wild” crates piled up in a pile, mostly completely or partially filled with empty bottles, of different origins and correspondingly different shapes, in particular different heights. Empties dealers regularly receive such "magic cubes" from supermarkets, which shy away from the costs, effort and space required for sorting and stacking by type, in particular by type of crate. Such “magic cubes” could in principle be unpacked using an industrial robot. However, no effectors suitable for this purpose are known which could reliably grasp the bottle crates of different shapes that are in direct lateral contact with one another in order to lift them and position them on a discharge conveyor.

The effector known from the generic publication mentioned above is constructed in such a way that a rotation of the spindle rod results in an opposing linear movement of the gripper fingers leads. The gripping fingers screwed to the threaded sections of the spindle rod cannot follow the rotation of the spindle rod due to their non-rotatable mounting on the guide rail. Therefore, there is a relative rotation of the primary and secondary threads, which translates the rotation of the spindle rod into a linear movement of the fingers, this linear movement being entirely permitted by the mounting of the gripper finger guide sections on the guide rail. Due to the opposite orientation of the primary threads (and accordingly the corresponding secondary threads), the rotation of the spindle rod causes a differently directed linear movement of the associated gripping finger on each of its threaded sections. The gripping sections of the gripping fingers can thus be pressed from the inside against the walls of a box that is open at the top, so that the box is fixed in a non-positive manner and can be lifted up by a suitable movement of the manipulator. This is disadvantageous in that such an approach may not be sufficient to provide reliable fixation in the case of wet boxes, and in the case of damaged box walls may result in their complete rupture. Both cases are not uncommon in practice. The known effector is therefore not suitable for individually gripping bottle crates.

task

It is the object of the present invention to provide an effector for an industrial robot that allows bottle crates to be gripped individually.

Presentation of the invention

This object is achieved by an effector having the features of the preamble of claim 1 in that the gripping sections in the region of their free ends each have a catch hook that is aligned perpendicular to their direction of longitudinal extension and projects away from the respective other gripping finger.

Preferred embodiments are subject of the dependent claims.

The basic principle of the effector according to the invention is known from the prior art and has already been explained above.

The spectrum of the distances between the gripper fingers that can be adjusted in this known manner depends on the length of the threaded sections and on their axial distance from one another. These dimensions are preferably selected in such a way that the minimum distance that can be set between the gripping fingers is smaller than the minimum distance between two opposite walls of the smallest type of bottle crate permitted for handling by means of the effector. In addition, said dimensions are preferably selected such that the largest adjustable distance between the gripping fingers is greater than the largest distance between two side walls of the largest type of bottle crate permitted for handling by means of the effector according to the invention. In this way it is in fact possible to reliably seize any crate of a permitted type of crate. For this purpose, the gripping fingers are first moved together by a suitably oriented rotation of the spindle rod to ensure that they fit between two side walls of the box to be gripped. The effector can then be moved approximately parallel to one side of the crate over the bottle crate to be taken and lowered so far that its gripping fingers protrude below the top edge of the crate. The gripping fingers can then be moved apart by rotating the spindle rod in opposite directions until they each rest against a box wall in a non-positive manner. In this state, the effector is stuck inside the box. If the clamping force is sufficiently high, the clamped box can then also be lifted when the effector is lifted. By controlling the manipulator accordingly, it can then be positioned almost anywhere within the reach of the industrial robot. Then moving the gripper fingers together again releases the effector from the bottle crate.

In order to alleviate the problem of the correct clamping force, as explained above, it can be provided that the surface of the gripping edges of the gripping fingers consists of an elastic material. For example, a corresponding surface coating can be provided. The elastic surface improves the static friction between the crate wall and the gripping finger, in particular its gripping section, so that a high level of reliability when lifting the crate is ensured even with a reduced clamping force.

In order to prevent a bottle crate that has already been lifted from falling if the non-positive connection between the effector and the bottle crate fails, the invention provides that the gripping sections in the region of their free ends each have a catch hook that is aligned perpendicular to their longitudinal direction and projects away from the other gripping finger. The side walls of bottle crates usually have openings that are also used as handles for manual crate transport. In the mentioned development of the invention, the catch hooks reach into said openings from the inside, ie interact in the Normally not with the side walls. Only if the frictional connection between the gripping edge and the side wall of the crate fails, i.e. if the crate slips down on the gripping finger, does the catch hook grip behind the upper edge of said opening and support the fixing of the bottle crate on the effector with this form fit.

The adhesion between the gripper fingers and the bottle crate can also be weakened by the bottle crate rocking relative to the effector. In order to counteract such rocking, a development of the invention provides that the gripping sections each have a baffle plate aligned perpendicular to their longitudinal extension in the area of their non-free ends. This baffle limits the possible rocking angle. It can also serve as a stop when the effector is lowered onto or into the bottle crate, which can then be registered by a corresponding sensor system of the manipulator.

The effector according to the invention thus represents a reliable gripper for bottle crates, which is particularly suitable for reliably gripping bottle crates even if they are closely surrounded by neighboring crates in the stacked state, so that access from the outside is not possible. The effector according to the invention is therefore particularly suitable for unpacking stacks of bottle crates using an industrial robot, in particular “magic cubes” that contain different types of bottle crates.

It is structurally particularly simple if the primary threads are designed as external threads and the secondary threads as internal threads of through-openings in the guide sections. In principle, a reverse arrangement would also be conceivable, although this would be extremely complicated to implement in terms of construction.

As explained above, it is necessary for the function of the effector according to the invention that its spindle rod is rotated during operation. For this purpose, it is preferably provided that the spindle rod, in addition to the threaded sections, also has a drive section, via which a torque rotating the spindle rod about its longitudinal axis can be introduced. Typically, this drive section will be located centrally between the threaded sections. In principle, however, arrangements are also conceivable in which the threaded sections are directly adjacent to one another and the drive section is arranged at the end on the spindle rod. The first-mentioned variant is to be preferred in particular if the effector according to the invention is to be articulated in a pendulum-like manner at the free end of the manipulator of the industrial robot, as is considered favorable for many unpacking applications.

As mentioned at the beginning, the use of industrial robots in the beverage industry and especially in the empties industry primarily serves to automate processes. It is therefore favorable if the spindle rod is rotated by a motor. For this purpose, it can be provided that as part of the effector according to the invention, an internal motor controllable by means of a motor controller is also included, the rotatable output element of which is operatively connected to the drive section of the spindle rod. The motor controller can be integrated into the controller of the industrial robot, for example. In this case, in addition to an absolutely necessary mechanical linkage of the effector at the free end of the manipulator, a control line connection and, if the internal motor does not have its own energy supply, which is also internal to the effector, an energy supply line would suffice. In particular, no torque-transmitting connection between the manipulator and the effector would be required.

In an alternative embodiment, on the other hand, it is provided that the drive section of the spindle rod can be brought into operative connection with a rotatable output element of an external motor that can be controlled by means of a motor controller. In this embodiment, the motor itself is not part of the effector, but can in particular be part of the manipulator. In this embodiment, the energetic and control-related coupling of the effector is therefore unnecessary, although there must be a torque-transmitting connection to the manipulator, in particular to its external motor. When choosing between the two variants, the person skilled in the art will primarily have to pay attention to the specifications defined by the construction of the manipulator.

Regardless of the positioning of the motor, it is preferably provided that the motor has a torque sensor that is operatively connected to the motor controller. This allows the engine control to be set up to end operation of the engine when a predetermined torque is reached. This means that there is no need for an optical identification of the crate to be taken in each case. Optical detection, for example by means of a camera, may be helpful for the basic positioning of the effector in the center above the box to be gripped and approximately parallel to one of its side walls. However, an exact box measurement or an identification with subsequent retrieval of the exact box dimensions from a database is not absolutely necessary. Before entering the box the gripper fingers are pushed together so far that they always fit into the box. When the gripper fingers move apart, the torque sensor mentioned detects the impact of the gripper fingers on the crate walls and can prevent them from moving apart further at the moment when, on the one hand, a clamping force required to lift the crate is realized, but, on the other hand, there is no danger of the crate breaking. However, in order to comply with the latter condition in particular, it can be helpful, contrary to the explanation above, to carry out an individual box identification. Different crate types can have significantly different stabilities, so that individual knowledge of the breaking point can be helpful with regard to maximizing the clamping force and thus the reliability when lifting the crate.

The side walls of most bottle crates have a not inconsiderable degree of flexibility in terms of shape and material. This means that the side walls deform elastically when force is applied by the gripping fingers moving apart. After the gripper fingers have stopped, an elastic restoring force acts on them. This must not lead to the gripper fingers moving together again, as this would reduce the clamping force that has built up again. It is therefore conceivable to set up the motor control to constantly energize the motor even in this situation and to control it to output a torque that exactly compensates for the restoring force. However, this is unfavorable in terms of both energy and control technology. In a more favorable embodiment of the invention, it is therefore provided that the operative connection between the output element of the motor and the drive element of the spindle rod is designed to be self-locking. In particular, this active connection can be realized in the form of a worm drive. Alternatively or additionally, it can be provided that the thread pairings between the spindle rod and the guide sections of the gripping fingers are designed to be self-locking. As the expert knows, this is a question of the selected thread pitch. In any case, in each of the self-locking variants, the motor can be switched off after the gripper fingers have reached the target position, which is preferably detected by means of the torque sensor. This means that no holding energy is required while the box is being lifted and moved. Also, no further control is required to maintain the clamping force.

Further details and advantages of the invention result from the following specific description and the drawings.

character list

• 1: eine schematische Darstellung einer Ausführungsform eines erfindungsgemäßen Effektors.

It shows:

• 1 : a schematic representation of an embodiment of an effector according to the invention.

Description of Preferred Embodiments

1 shows an embodiment of an effector 10 according to the invention in a highly schematic form. The effector 10 has a sleeve-like guide rail 12, which has a lower longitudinal slot 14 extending essentially over its entire length along its lower crest line. In its central area, it has a short, upper longitudinal slit 16 along its upper apex line. The function of the longitudinal slots 14, 16 will be discussed in more detail below.

At its two ends, the guide sleeve 12 is provided with radial bearings 18 in which a spindle rod 20 is rotatably mounted. The spindle rod 20 has at each end a bearing section 22 interacting with the associated bearing 18, a drive section 24 in its central area and two threaded sections 26a, 26b on the side of the drive section 24. The drive section 24 is provided with an external worm thread, via which it interacts through the upper longitudinal slot 16 with a worm wheel 30 acting as the output element of an electric motor 28 . In the embodiment shown, the stator or the housing of the motor 28 is fixed to the guide sleeve 12 . In addition, in the embodiment shown, the motor housing carries a linkage device 32, by means of which the effector 10 can be linked to a manipulator of an industrial robot (not shown in any more detail). The connection to the manipulator also includes in 1 Power supply and control lines, not shown, for the motor 28. The worm wheel 30 and thus the spindle rod 20 can be rotated in different directions depending on the control via a motor controller coupled via these lines and preferably positioned in the industrial robot.

The threaded sections 26a, 26b are provided with oppositely oriented primary threads 34a, 34b designed as external threads. A gripping finger 36 is screwed onto the threaded sections 26a, 26b of the spindle rod 12 in each case. Each gripping finger 36 includes a guide section 38 and a gripping section 40. The guide sections 38 are provided with through openings 42, the inner wall of which is provided with a secondary thread 44a, 44b designed as an internal thread, which belongs to the Pri March thread 34a, 34b of the associated threaded portion 26a, 26b corresponds.

The guide sections 38 of the gripping fingers 36 protrude through the lower longitudinal slot 14, which thus represents a rotational fixation and at the same time a linear guide for the guide sections 38. A rotation of the worm wheel 30 thus leads to a rotation of the spindle rod 20, which via the interacting threads 34a, 44a; 34b, 44b is converted into a linear movement of the guide sections 38 and thus also into a linear movement of the gripping sections 40 of the gripping fingers 36. Due to the opposite orientation of the primary threads 34a, 34b and the corresponding secondary threads 44a, 44b, the movement of the gripping fingers 36 takes place in opposite directions to one another, in particular with the same absolute pitch of the threads 34a, 44a; 34b, 44b symmetrical. In the illustrated embodiment, the outer edges of the gripping sections 40 serving as gripping edges 46 are coated with an elastic plastic material in order to achieve improved friction with the side walls (not shown) of bottle crates to be lifted.

At their lower, free end, the gripping edges 46 or the gripping sections 40 have catch hooks 48 directed outwards, which can serve to positively secure a bottle crate (not shown) gripped by the effector 10 . With regard to the operation of the effector 10 according to the invention, reference is made to the detailed explanation in the general part of the description.

Of course, the embodiments discussed in the specific description and shown in the figures only represent illustrative exemplary embodiments of the present invention. In particular, it is conceivable that the motor 28 is not a component of the effector 10 according to the invention but a component of a connected manipulator of an industrial robot. In this case, power supply and control lines at the interface between manipulator and effector 10 can be dispensed with. However, a torque-transmitting coupling is then required, which transmits the torque of the external motor to the drive section 24 of the spindle rod 20 .

Reference List

10

effector

12

guide rail

14

lower longitudinal slit

16

upper longitudinal slit

18

radial bearing

20

spindle rod

22

camp section of 20

24

Drive section of 20

26a, b

Threaded section of 20

28

engine

30

worm wheel

32

articulation device

34a, b

primary thread

36

gripping fingers

38

Lead section of 36

40

Gripping section of 36

42

passage opening in 38

44a, b

secondary thread

46

gripping edge

48

catch hook

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 202005019060 U1 [0002]
• DE 4329180 A1 [0005]
• US3139993A [0006]
• FR 2450220 A1 [0006]

Claims (11)

Effector (10) for an industrial robot, comprising - two gripping fingers (36), each with a gripping section (40) and a guide section (38), whose gripping sections (40) each have a gripping edge (46) and the gripping edges (46) of the two gripping fingers (36) are parallel to one another, - a guide rail (12) which extends perpendicularly to the longitudinal extension of the gripping edges (46) and on which the guide sections (38) of the gripping fingers (36) are mounted in a rotationally fixed and linearly displaceable manner, and - a parallel to the guide rail (12 ) oriented spindle rod (20) which is mounted on it so that it can rotate about its longitudinal axis and has two axially separate threaded sections (26a, b) which have primary threads (34a, b) oriented in opposite directions, the two gripping fingers (36) having different threaded sections (26a, b ) are assigned and the guide section (38) of each gripping finger (36) corresponds to the primary thread (34a, b) of the associated threaded section (26a, b). ing secondary thread (44a,b) and is screwed to the associated threaded section (26a,b), characterized in that the gripping sections (40) in the region of their free ends each have a perpendicular to their direction of longitudinal extension and which is separated from the respective other gripping finger (36 ) have catch hooks (48) projecting away. Effector (10) after claim 1 , characterized in that the primary threads (34a, b) are designed as external threads and the secondary threads (44a, b) as internal threads of through openings (42) of the guide sections (38). Effector (10) according to one of the preceding claims, characterized in that the spindle rod (20) also has a drive section (24) via which a torque rotating the spindle rod (20) about its longitudinal axis can be introduced. Effector (10) after claim 3 , characterized in that it further comprises an internal motor (28) which can be controlled by means of a motor controller and whose rotatable output element is operatively connected to the drive section (24) of the spindle rod (20). Effector (10) after claim 3 , characterized in that the drive section of the spindle rod can be brought into operative connection with a rotatable output element of an external motor which can be controlled by means of a motor controller. Effector (10) according to one of Claims 4 until 5 , characterized in that the motor (28) has a torque sensor operatively connected to the motor controller. Effector (10) after claim 6 , characterized in that the motor controller is set up to end operation of the motor (28) when a predetermined torque is reached. Effector (10) according to one of Claims 4 until 7 , characterized in that the operative connection between the output element of the motor (28) and the drive section (24) of the spindle rod (20) is designed to be self-locking. Effector (10) according to one of the preceding claims, characterized in that the pairs of threads between the spindle rod (20) and the guide sections (38) of the gripping fingers (36) are designed to be self-locking. Effector (10) according to one of the preceding claims, characterized in that the gripping sections (40) in the region of their non-free ends each have a baffle plate aligned perpendicularly to their direction of longitudinal extent. Effector (10) according to one of the preceding claims, characterized in that the surface of the gripping edges (46) consists of an elastic material.

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