Gripper finger with integrally arranged and separately pressurizable finger segments for gripping objects

Abstract

The invention relates to a gripping finger (1) for gripping objects, comprising a finger segment (51, 71) made of rubber-elastic material, in which a supply channel (69, 89) and several branch channels (56, 57, 58, 59, 76, 77, 78, 79) branching off from the supply channel (69, 89) are formed, wherein the supply channel (69, 89) extends from a coupling interface (2) of the finger segment (51, 71) along a curve (69, 89) in the finger segment (51, 71) and wherein extension axes (60, 61, 62, 63, 80, 81, 82, 83) of the branch channels (56, 57, 58, 59, 76, 77, 78, 79) along the course curve (69, 89) are arranged at a distance from one another and wherein the extension axes (60, 61, 62, 63, 80, 81, 82, 83) of at least two branch channels (56, 57, 58, 59, 76, 77, 78, 79) arranged adjacent to one another assume angles (64, 65, 66, 67, 84, 85, 86, 87) with the course curve (69, 89) which differ from one another in a pressure-free neutral state.

Description

The invention relates to a gripping finger with finger segments which are arranged in one piece next to one another and can be separately pressed for gripping objects.WO 2017 / 127497 A1 discloses an actuator and a method for manufacturing such an actuator, wherein the actuator has a complex inner shape produced by providing a core having a shape defining an inner cavity of an actuator and forming an actuator around the core, wherein the core occupies the inner cavity of the actuator, wherein the cavity has an opening. A pressure differential is then created between an outer surface of the actuator and the inner cavity of the actuator, the outer pressure being less than the inner pressure to expand the cavity of the actuator and allow removal of the core through the opening of the expanded actuator cavity.CN 1 11 113 459 A discloses a flexible finger comprising a finger base plate, a connecting hole and at least one ankle part arranged on the finger base plate, wherein a driving cavity is defined between the ankle part and the finger base plate, and wherein a rib plate is provided which is contained in the driving cavity and is arranged between the ankle part and the finger bottom plate, wherein the driving cavity communicates with the connecting hole to form a bag body structure which is defined by the ankle part and the finger bottom plate and is divided into at least two parts by the rib plate, thereby improving the structural strength and loadability of the flexible finger.CN 1 13 427 503 A discloses a manipulator having an undulated structure and a basic structure and an end structure and an air pipe, wherein the basic structure and the end structure are both beveled cylinders and are adapted to the internal shape of the undulated structure to form a closed air cavity, and wherein a through hole is formed in the axis of the basic structure, into which the air pipe can be inserted, wherein the undulated structure can be a symmetrical undulated or a spiral undulated structure.DE 10 2015 204 986 B3 discloses a gripper element having at least one bending element which is elastically deformable in a preferred direction and a holder, wherein the bending element which is provided on one end side with an opening and is otherwise hollow on the inside and is made of elastically deformable material has, in a region which is not provided for bending and in which the opening is also arranged, a radially encircling flange which is designed such that it bears against a surface of a base element of the holder and bears, on the opposite surface, against a surface of a fastening element which can be connected to the base element, and the fastening element presses the flange against the surface of the base element with a predeterminable compressive force.DE 10 2016 125 271 A1 discloses a modular actuator system with which it is possible to construct multi-actuator systems or actuator devices and multi-actuator devices which are complex in a quick and simple manner and can be used as grippers, manipulators for movement or for applications from robotics, wherein the modular actuator system has at least one fluid actuator and at least one coupling device, wherein the at least one fluid actuator and the at least one coupling device can be connected to form an actuator device, wherein the at least one fluid actuator comprises a connection element, wherein the at least one coupling device comprises a connection complement, and wherein the connection element and the connection complement define a system-uniform mechanical and / or fluidic interface, such that actuator devices with different geometries can be formed.US 2014 / 0 109 560 A1 discloses a robot device having a flexible body comprising at least one channel arranged within the flexible body, wherein the channel is defined by an upper, a lower and a side wall, wherein at least one wall is strain-limiting and wherein the channel has a pressure inlet and is positioned such that the wall preferably expands opposite the strain-limiting wall when the soft robot device is pressurized through the inlet.The object of the invention is to provide a gripping finger which has an improved gripping behavior.This object is achieved for a gripping finger of the type mentioned at the beginning in that the gripping finger has a finger segment which is produced from a rubber-elastic material and in which a supply channel and a plurality of branch channels branching off from the supply channel are formed for supplying pressure to the finger segment, wherein the supply channel, starting from a supply connection which is formed at a coupling interface of the finger segment, extends along a course curve in the finger segment and wherein axes of extent of the branch channels are arranged spaced apart from one another along the course curve and wherein the axes of extent of at least two branch channels arranged adjacent to one another assume mutually different angles with the course curve in a non-pressurized neutral state.The gripping function of the gripping finger is made possible in that the at least one finger segment of the gripping finger is transferred from the neutral state to a functional state starting from a non-pressurized neutral state by providing a pressurized fluid, in particular compressed air, to the supply channel, in which state a considerable change in a curvature, in particular a reduction in a radius of curvature, of the course curve, which describes a longitudinal extent of the supply channel, is present compared to the neutral state. By way of example, it can be provided that the curve has a constant radius of curvature over its entire length in the functional state of the finger segment. Alternatively, it can be provided that the curve has different radii of curvature in the functional state of the finger segment.The curvature of the finger segment is effected when the supply channel and the branch channels connected to the supply channel in a fluidically communicating manner are pressurized in that the finger segment produced from a rubber-elastic material has regions of different flexibility, wherein these differences in the flexibility of the individual regions can be realized by different material thicknesses and / or by different materials and / or by different geometries for the respective regions of the finger segment.In the finger segment, it is provided that a plurality of branch channels branch off starting from the supply channel, which extends along the course curve starting from a coupling interface of the finger segment through the finger segment. Each of these branch channels can be described as a blind hole which, starting from an orifice opening of the branch channel which ensures the fluidically communicating connection to the supply channel, extends a cavity which has no further opening. Each of the branch channels has an extension axis that forms a neutral fiber for the branch channel. The extension axis is preferably, but not necessarily, formed as a straight line and has a maximum distance from wall regions of the respective branch channel. For example, in the case of a stitch channel formed rotationally symmetrically, the axis of rotational symmetry also forms the axis of extension. In a branch channel that is not formed rotationally symmetrically, the extension axis can be formed by connecting area centers of cross sections of the branch channel, which each have a minimum cross-sectional area.The stitch channels and thus the extension axes are arranged spaced apart from one another along the course curve, whereby a comb-like arrangement of course curve and stitch channels results. Deviating from a typical comb, however, it is provided in the finger segment that at least two of the stitch channels, which project in the manner of comb teeth from the supply channel serving as the comb base, have mutually deviating angles with the course curve. An angular deviation between adjacent extension axes is at least 2 degrees, preferably at least 4 degrees, in particular at least 6 degrees.It is expedient if the finger segment has a gripping region and a stretching region which is sealingly connected to the gripping region and wherein an inner surface of the stretching region delimits an upper side of the supply channel and the stitch channels and wherein an inner surface of the gripping region delimits an underside of the supply channel.The gripping region is that region of the finger segment which has a gripping surface which is intended to serve for direct mechanical contact with an object which is intended to be acted upon by a gripping force with the aid of the gripping finger. By way of example, it is provided that the gripping finger is used to initially press an object which is located on a surface against a supporting surface which is in mechanical connection with the gripping finger, in order subsequently to be able to lift the object off the surface and to enable the object to be displaced to a location. It is particularly preferred that a plurality of gripping fingers are used, which can be transferred into a functional state by providing a pressurized fluid starting from a respective neutral state, wherein in the respective functional state a curvature enhancement is produced for the respective course curve of the gripping fingers and thereby an approach of the respective gripping fingers to the object to be moved is produced in order to be able to grip the object.The gripping region is accordingly deformed during the transfer from the neutral position into the functional state, but this deformation predominantly results from the expansion region performing an expansion movement by the provision of a pressurised fluid at the supply connection of the supply channel.The expansion region of the finger segment is optimized in such a way that it ensures the most efficient possible conversion of the pressure energy provided via the pressurized fluid into a deformation of the finger segment. For this purpose, the branch channels protrude into the expansion region and thus allow a local fluid supply at a plurality of points of the expansion region in order to promote the desired deformation effect by the pressurized fluid.The gripping region and the stretching region can be regarded as differently contoured material layers of the finger segment which are sealingly connected to one another. By way of example, it can be provided that the gripping region and the stretching region are each produced separately and are subsequently connected to one another by a materially bonded connection process, for example adhesive bonding or vulcanization. It is particularly preferably provided that the gripping region and the stretching region are formed in one piece and produced in a common production method, in particular by an injection molding process or a casting process or a generative production process.Preferably, it is provided, characterized in that the expansion region has a plurality of expansion pockets arranged along the course curve of the supply channel and designed in the form of bellows, each of the expansion pockets defining one of the branch channels. The expansion pockets are designed with regard to their wall thickness and geometry in such a way that, when the gripping finger is used as intended, they undergo a strong elastic deformation as a result of the pressurization of the supply channel and the stitch channels connected thereto and projecting into the respective expansion pockets. This intended use provides, in particular, that in the neutral position of the gripping finger there is no substantial pressure difference between the supply channel and the stitch channels connected thereto and an ambient atmosphere of the gripping finger. In order to transfer the gripping finger from the neutral position into the functional position and thus to achieve a clear amplification of a curvature for the gripping finger and its course curve, it is provided to provide a fluid pressure of at least 1 bar, preferably at least 2 bar, particularly preferably at least 4 bar, in particular up to 6 bar, at the supply connection. By way of example, it is provided that the course curve in the neutral position corresponds substantially to a straight line and the finger segment in the functional position is angled approximately 90 degrees with respect to an end region of the finger segment arranged remote from the supply connection. Preferably, each of the expansion pockets is designed like a hood, wherein a length amount of the extension axis, which extends from an opening relative to the supply channel to a closed end region of the expansion pocket, as well as a length amount of a width extension of the expansion pocket oriented transversely to the extension axis, are at least twice greater than a length amount of a longitudinal extension of the expansion pocket oriented longitudinally to the supply channel and transversely to the extension axis. It is particularly preferably provided that a geometry of the respective expansion pocket is optimized such that between the neutral position and the functional position an elastic deformation of the expansion pocket takes place substantially in the direction of the longitudinal extension, while changes in the length amounts of the extension axis and the width extension are, in contrast, considerably smaller. The expansion pockets are arranged spaced apart from one another along the course curve of the supply channel, so that each of the expansion pockets can expand substantially freely during the transfer from the neutral position into the functional position. Particularly preferably, a distance between adjacent expansion pockets is selected such that, when approaching the functional position, a direct contact of adjacent expansion pockets is made possible in order to ensure a stable support between the adjacent expansion pockets and thus a largely dimensionally stable development of the finger segment.By aligning the extension axes of the individual expansion pockets, a transverse rigidity of the gripping finger is increased, so that an undesired deformation of the gripping finger in a spatial direction transverse to a plane of curvature or deformation in which the curve is contained is increased. This increase in transverse rigidity is attributable to the fact that, owing to the different angular orientation of the axes of extent, an improved force flow between the adjacent expansion pockets is already present in the neutral position of the gripping finger than would be the case with a parallel orientation of the axes of extent of the branch channels.In a further development of the invention, it is provided that at least one of the expansion pockets has an expansion in a spatial direction transverse to the curve and transverse to the axis of extension which is equal to or greater than an expansion of the supply channel in this spatial direction. This achieves that a volume of the supply channel, the task of which is to ensure a supply and discharge of pressurized fluid to the branch channels in the expansion pockets and from the branch channels in the expansion pockets, is as small as possible, in order to be able to realize the transfer of the finger segment between the neutral position and the functional position and between the functional position and the neutral position with a volume of pressurized fluid that is as small as possible.It is advantageous if at least one of the expansion pockets delimits a cavity which is connected to the supply channel in a fluidically communicating manner and which has a parabolic sectional surface in a cross-sectional plane in which the extension axis, which is arranged in particular centrally in the cavity delimited by the expansion pocket, is accommodated. It is particularly preferably provided that the expansion pocket also has cross-sectional planes parallel to the cross-sectional plane in which the axis of extension is accommodated, wherein these parabolic cross-sectional planes have an increasingly smaller surface area as the distance of the respective cross-sectional plane from the cross-sectional plane in which the axis of extension is accommodated increases.In a further embodiment of the invention, it is provided that the expansion pocket has an outer surface which is formed by extrusion of a parabolic cross section along a parabolic extrusion curve. In this case, it is provided that the two parabolic branches of the parabolic extrusion curve are oriented mirror-symmetrically to that cross-sectional plane in which the parabolic cross-section of the expansion pocket is accommodated. Furthermore, the two parabolic branches of the parabolic extrusion curve preferably each have the same and finite length.It is preferably provided that a reinforcing projection extruded along the parabolic extrusion curve and extending outwards in the radial direction, in particular with a rectangular cross section, is formed on the outer surface of the expansion pocket. The task of the reinforcing cross section, which extends in an arc shape on the outer surface of the respective expansion pocket, is to reduce, in particular minimize, an expansion of the respective expansion pocket in spatial directions transversely to the course curve of the supply channel. By way of example, the reinforcing projection has a rectangular, in particular a square, cross section.It is expedient if the reinforcement projections are each connected at the end with a reinforcement web which borders a gripping surface determined by the gripping region and facing away from the expansion pockets. The reinforcing web protrudes outwards in a spatial direction transversely to the course curve and transversely to the respective extension axes and extends on the edge side at the gripping surface of the gripping region. The task of the reinforcing web is to be seen in limiting, when the finger segment is transferred from the neutral position into the functional position, a deformation of the finger segment as exclusively as possible to a deformation plane or curvature plane which contains the course curve and the extension curves of the stitch channels.Accordingly, in an advantageous development of the invention, it is provided that the extension axes of the branch channels are arranged in a common axis plane, in particular comprising the course curve.Additionally or alternatively, it can be provided that the angles that the axes of extent of the branch channels assume with the course curve decrease with increasing distance from the supply connection. This assists in enhancing the curvature of the finger segment that is to be caused when the finger segment is transferred from the neutral position into the functional position. In a side view of the finger segment, the extension axes of the branch channels are oriented fan-like to one another, wherein branch channels arranged adjacent to one another each assume acute angles in a range between 2 degrees and 10 degrees to one another. In this case, it does not necessarily have to be provided that all branch channels assume the same angles in each case to the adjacent branch channels. In particular, it can be provided that with increasing distance from the supply connection, the respective angular amount between the preceding and the following branch channel likewise increases.It is advantageous if a fluid channel is formed in the gripping region, which is oriented parallel to the supply channel and opens out on a gripping surface of the gripping region facing away from the stretching region. This fluid channel can be used, for example, as a sensor channel to which a vacuum source and a pressure sensor are connected in order to be able to determine, when the gripping finger is transferred from the neutral position into the functional position, whether the gripping surface is in contact with an object, whereby an inflow of ambient air into the fluid channel is interrupted, which can be detected as a pressure drop at the pressure sensor. Additionally or alternatively, a gripping effect of the gripping finger can also be improved by applying a vacuum to the fluid channel.Furthermore, it is provided according to the invention that a plurality of finger segments are arranged in one piece in a row, which finger segments can be acted upon separately from one another with fluid pressure. This allows the functionality of a human finger to be simulated and an object to be gripped to be gripped more reliably than would be the case with a single finger segment. For the separate supply of the two finger segments, a second supply channel for the second finger segment extends starting from the coupling interface, which is formed on the end side on a first finger segment, independently of a first supply channel for the first finger segment. In this case, the second supply channel preferably passes through the gripping region of the first finger segment in order then to open into the second finger segment which is attached to an end region of the first finger segment which rejects the coupling interface of the first finger segment.Preferably, a wall section with a wall thickness that is at least 1.5 times, in particular at least 2 times, a wall thickness of the expansion pockets is arranged between adjacently arranged finger segments. This results in decoupling between the two finger segments, with which only a slight deformation effect on the other finger segment is ensured when the one finger segment is pressurized.It is expedient if the finger segment is produced in a generative production process, in particular in a three-dimensional laser printing process, from an elastic polymer material, in particular a thermoplastic polymeric elastomeric polyurethane. This allows complex geometries and undercuts to be realized, so that when optimizing the respective finger segments for the desired deformation properties, almost no consideration has to be taken of the production method, as would be required, for example, when producing the finger segment in a casting method in which, for example, cores would have to be used in order to keep the desired cavities free during the production process.In an advantageous development of the invention, it is provided that the course curve is formed as a straight line in the pressureless neutral state of the finger segment and that each of the branch channels assumes an angle with the course curve deviating from 90 degrees. Thus, a typical configuration of a human finger can be simulated with the gripping finger even in the neutral position, in which configuration a straight course of the individual finger members is usually also present in the case of a complete stretching. By aligning all stitch channels with angles that deviate from 90°, an advantageous curvature behavior for the finger segment is effected. By way of example, it is provided that the angles of adjacent stitch channels differ from one another by a predefined difference amount. Purely by way of example, it is provided that a first branch channel, which is arranged directly adjacent to the coupling interface, assumes an angle of 6 degrees with respect to a normal to the course curve in the neutral position of the finger segment and thus assumes an angle of 84 degrees with respect to the course curve. Furthermore, it is provided that the subsequent branch channels are each pivoted by an additional 6 degrees with respect to the respective normal onto the course curve with increasing distance from the coupling interface, so that the second, third and fourth branch channels following the first branch channel and thus, purely by way of example, are aligned with angles of 78 degrees, 72 degrees and 66 degrees with respect to the course curve.An advantageous embodiment of the invention is shown in the drawing. The following shows: FIG. 1 shows a perspective illustration of a gripping finger which, starting from a coupling interface, is equipped with a first finger segment and a second finger segment, FIG. 2 shows a schematic illustration of an extrusion curve and an extrusion profile to be extruded along the extrusion curve, FIG. 3 is a bottom view of the gripping finger according to FIG. 1 , FIG. 4 shows a side view of the gripping finger according to FIGS. 1 and 2, FIG. 5 shows a lateral sectional illustration of the gripping finger according to FIG. 1, and FIG. 6 shows a sectional top view illustration of the gripping finger according to FIG. 1.A gripping finger 1 shown in FIG. 1 is provided for use in a gripping device, not shown, with which, for example, delicate goods such as fruits, vegetables or bakery products can be gripped and locally displaced.The gripping finger 1 is shown in a neutral position in FIG. 1 and can be transferred starting from this neutral position into a curved position or functional position, not shown, by the application of pressure to a first finger segment 51 and / or a second finger segment 71. In this functional position, not shown, a shape of a gripping surface 5 changes from the planar configuration, as it is present in the neutral position according to FIG. 1, into a concave shape. In this case, a radius 11, which in the neutral position is to be assumed to be infinite or at least to be many times greater than a greatest extent 12 of the gripping finger 1, decreases to a radius 11, which is only shown symbolically in FIG. 4 and is smaller than the greatest extent 12 of the gripping finger 1. By way of example, the gripping finger 1 can be curved in such a way that a distal end region 15 of the gripping surface 5, which in the neutral position according to FIG. 1 has a maximum distance from a coupling interface 2 of gripping finger 1, is arranged adjacent to a proximal end region 14 of the gripping surface 5, wherein the proximal end region 14 is arranged directly adjacent to the coupling interface 2. Purely by way of example, the gripping finger 1 can be curved in the functional position in such a way that the gripping surface 5 can be described in a side view of the gripping finger 1 as a curve 16, in particular a spiral curve, as is schematically depicted in FIG. 4.The gripping finger 1 is divided, starting from the coupling interface 2, which is designed for the fixed coupling of the gripping finger 1 to a gripping device, not shown, into the first finger segment 51 arranged directly adjacent to the coupling interface 2 and the second finger segment 71, wherein the second finger segment 71 adjoins an end region of the first finger segment 51 facing away from the coupling interface 2. The two finger segments 51 and 71 define the gripping surface 5 which is at least largely planar in the neutral position and in principle have a virtually identical structure. The gripping finger 1 has a gripping region 3, the outer surface of which defines the gripping surface 5 and which, purely by way of example, can be described substantially as being plate-shaped. An upper side of the gripping region 3, which is remote from the gripping surface 5, is adjoined by the stretching region 4, the task of which is to provide the expansion movement required for changing the curvature of the gripping surface 5. By way of example, the gripping region 3 and the stretching region 4 are jointly defined by the first finger segment 51 and the second finger segment 71, which, according to the description below, can be actuated in a fluidically separated manner from one another and thus enable a broadband influence on the curvature profile for the gripping surface 5.To influence the curvature of the gripping surface 5, the first finger segment 51 comprises a first expansion pocket 52, a second expansion pocket 53, a third expansion pocket 54 and a fourth expansion pocket 55, and the second finger segment 71 comprises a first expansion pocket 72, a second expansion pocket 73, a third expansion pocket 74 and a fourth expansion pocket 75. Since the first expansion pocket 52 of the first finger segment 51 directly adjoins the coupling interface 2, the configuration of the first expansion pocket differs significantly from the further expansion pockets 53 to 55 and 72 to 75 and can also be referred to as half an expansion pocket. The expansion pockets 53 to 55 and 72 to 75 have essentially the same configuration, so that the following description for the expansion pocket 53 also applies in the same way to the other expansion pockets 54, 55 and 72 to 75.The expansion pocket 53 is formed like a hood, wherein an outer surface 31 of the expansion pocket 53 can be produced by a geometric extrusion operation, as is shown schematically in FIG. 2. FIG. 2 shows a parabolic extrusion curve 32 along which a likewise parabolic extrusion profile 33 can be extruded, in order thereby to describe the outer surface 31 of the expansion pocket 53. As can be seen from the sectional illustration of FIG. 5, the expansion pocket 53 is realized with a constant wall thickness 34 in order to ensure as uniform an expansion behavior as possible when the expansion pocket 53 is pressurized. Furthermore, a reinforcing web 35 is assigned to the expansion pocket 53, which, according to the illustration of FIG. 5, has a substantially rectangular profile, which can be described in the same way by an extrusion of this rectangular profile along the extrusion curve 32.Between the adjacently arranged expansion pockets 52 to 55 and 72 to 75 there are arranged respectively arcuate connecting portions 36 which are dimensioned such that the outer surfaces 31 of the adjacently arranged expansion pockets 52 to 55 and 72 to 75 in the neutral position according to FIGS. 1 and 5 are spaced apart from one another by a gap 37.Each of the expansion pockets 52 to 55 and 72 to 75 defines a stitch channel 56 to 59 and 76 to 79, which is formed as a depression. Each of the branch channels 56 to 59 and 76 to 79 has an extension axis 60 to 63 and 80 to 83 which shows a spatial orientation of the respective branch channel 56 to 59 and 76 to 79.As can be seen from the illustration in FIG. 5, each of the axes of extent 60 to 63 assumes an individually different angle 64 to 67 with respect to a course curve 68 of a supply channel 69, which extends from the coupling interface 2 through the gripping region 3 of the first finger segment 51. In this case, the supply channel 69 is bounded by an inner surface 9 of the gripping region 3 and by an inner surface 10 of the stretching region 4.As can be further seen from the illustration in FIG. 5, each of the extension axes 80 to 83 assumes an individually different angle 84 to 87 with respect to a course curve 88 of a supply channel 89, which extends from the coupling interface 2 through the gripping region 3 of the second finger segment 71. By way of example, the axes of extent 60 to 63 of the first finger segment 51 and the axes of extent 80 to 83 of the second finger segment 71 are each arranged at the same pitch along the respective course curve 68 and 88.Purely by way of example, it is provided that the angles 64 to 67 and 84 to 87 of the expansion pockets 52 to 55 and 72 to 75 arranged adjacent to one another differ in each case by the same angle amount, and that the angle amounts decrease with increasing distance from the coupling interface 2.In order to ensure an independent fluidic supply of the second finger segment 71, the second supply channel 89 extends through the gripping region 3 of the first finger segment 51 independently of the first supply channel 69 and opens out into the expansion pockets 72 to 75 of the second finger segment 71.For determining a gripping state of the gripping finger 1, a sensor channel 41 is formed in the gripping region 4, which extends from the coupling interface 2 in the direction of the distal end region 15 and is formed as a blind hole. At the distal end region 15, a sensor bore 42 branches off from the sensor channel 41, which opens out at the gripping surface 5 and which is partially or completely closed when an object, not shown, is gripped by this object, which leads to a pressure change in the sensor shaft 41 provided this is supplied with a vacuum at the coupling interface 2. The pressure change, in particular the pressure drop, can be determined with the aid of a pressure sensor, not shown, assigned to the sensor channel. The pressure sensor can optionally be arranged directly in the gripping finger 1 or integrated in a vacuum source, not shown, connected to the sensor channel 41. The sensor channel 41 can additionally or alternatively also be used as a receiving space for a leaf spring, not shown, which has a greatest (longitudinal) extension along the sensor channel 41 and which has a width extension transverse to the plane of illustration of FIG. 5, which can be located in particular in a range from 20 percent to 80 percent of a width extension of the gripping finger 1 visible in FIG. 3. A thickness of the leaf spring, not shown, however, is only a fraction of the longitudinal extension, for example less than 1 percent of the longitudinal extension. The leaf spring, not shown, can be made of a spring-elastic material, for example of a spring steel or a fiber-reinforced plastic material.The supply channel 69 of the first finger segment 51 opens out at an axial end face of the coupling interface 2 at a first supply connection 6. The supply channel 89 of the second finger segment 71 opens out at the axial end face of the coupling interface 2 at a second supply connection 7. The sensor channel 41 opens out at the axial end face of the coupling interface 2 at a sensor connection 8.By way of example, the wall thickness 34 of the expansion pocket 53 is identical to the wall thicknesses, not designated, of the remaining expansion pockets 54, 55 and 72 to 75; furthermore, the wall thickness 34 is dimensioned such that, during intended use of the gripping finger 1, the expansion pockets 52 to 55 and 72 to 75 are caused to bear against mutually opposite outer surfaces 31 when the respective supply channels 69 and 89 are pressurized, such that the expansion pockets 52 to 55 and 72 to 75 are supported mutually as the expansion increases.Due to the geometric configuration of the expansion pockets 52 to 55 and 72 to 75, expansion is to take place predominantly in a spatial direction 38 which is drawn only for the expansion pocket 53 and is oriented transversely to the respective axis of extent 60 to 63 and 80 to 83 and parallel to the respective course curve 68 and 88. This is especially aided by the configuration of the cross sections of the individual expansion pockets 52 to 55 and 72 to 75 and the respective associated reinforcing webs 35. In particular, the expansion pockets 52 to 55 and 72 to 75 have a considerably greater flexibility in the spatial direction 38 and a lower resistance to deformation than in the other spatial directions, so that the desired curvature of the gripping surface 5 can thereby be limited at least almost exclusively to the sectional plane of FIG. 5, which is also to be referred to as the plane of curvature 39. This plane of curvature 39 also contains all axes of extension 60 to 63 and 80 to 83.In order to be able to realize the most homogeneous possible curvature of the gripping surface 5 without undesired bending points, a reinforcing web 40 extends around the edge of the gripping surface 5, which web connects the end regions of the respective reinforcing projections 35 to one another and thereby brings about a standardization of the expansion forces acting on the gripping region 3 and generated by the respective expansion pockets 52 to 55 and 72 to 75.A production of the gripping finger 1 is provided in a generative or additive laser printing method, in which an initially shapeless powder or an initially liquid, curable resin material can be locally solidified with the aid of laser beams, in order thereby to produce the desired geometry of the gripping finger 1.

Claims

Gripping finger (1) for gripping objects, having a finger segment (51, 71) which is produced from a rubber-elastic material and in which a supply channel (69, 89) and a plurality of branch channels (56, 57, 58, 59, 76, 77, 78, 79) branching off from the supply channel (69, 89) are formed for supplying pressure to the finger segment (51, 71), wherein the supply channel (69, 89) extends, starting from a supply connection (6, 7) which is formed at a coupling interface (2) of the finger segment (51, 71), along a course curve (68, 88) in the finger segment (51, 71) and wherein extension axes (60, 61, 62, 63, 80, 81, 82, 83) of the branch channels (56, 57, 58, 59, 76, 77, 78, 79) are arranged spaced apart from one another along the course curve (68, 88) and wherein the extension axes (60, 61, 63, 80, 81, 82, 83) are arranged spaced apart from one another, 62, 63, 80, 81, 82, 83) of at least two adjacent branch channels (56, 57, 58, 59, 76, 77, 78, 79) assume different angles (64, 65, 66, 67, 84, 85, 86, 87) with the course curve (68, 88) in a non-pressurized neutral state, characterized in that several finger segments (51, 71) are arranged in one piece in a row, which can be pressurized separately from one another with fluid pressure.Gripping finger (1) according to claim 1, characterised in that the finger segment (51, 71) has a gripping region (3) and an expanding region (4) which is sealingly connected to the gripping region (3) and wherein an inner surface (10) of the expanding region (4) delimits an upper side of the supply channel (69, 89) and the stitch channels (56, 57, 58, 59, 76, 77, 78, 79) and wherein an inner surface (9) of the gripping region (3) delimits an underside of the supply channel (69, 89).Gripping finger (1) according to Claim 1 or 2, characterized in that the stretching region (4) has a plurality of stretching pockets (52, 53, 54, 55, 72, 73, 74, 75) which are arranged along the course curve (68, 88) of the supply channel (69, 89) and are designed in the form of bellows, each of the stretching pockets (52, 53, 54, 55, 72, 73, 74, 75) defining one of the stitch channels (56, 57, 58, 59, 76, 77, 78, 79).Gripping finger (1) according to Claim 3, characterized in that at least one of the expansion pockets (52, 53, 54, 55, 72, 73, 74, 75) has an extent in a spatial direction transversely with respect to the course curve (68, 88) and transversely with respect to the axis of extent (60, 61, 62, 63, 80, 81, 82, 83) which is equal to or greater than an extent of the supply channel (69, 89) in this spatial direction.Gripping finger (1) according to Claim 3 or 4, characterized in that at least one of the expansion pockets (52, 53, 54, 55, 72, 73, 74, 75) delimits a cavity which is connected to the supply channel (69, 89) in a fluidically communicating manner and which has a parabolic sectional surface in a cross-sectional plane in which the axis of extent (60, 61, 62, 63, 80, 81, 82, 83), which is arranged in particular centrally in the cavity delimited by the expansion pocket (52, 53, 54, 55, 72, 73, 74, 75), is accommodated.Gripping finger (1) according to claim 3, 4 or 5, characterised in that the stretching pocket (52, 53, 54, 55, 72, 73, 74, 75) has an outer surface which is formed by extrusion of a parabolic cross-section along a parabolic extrusion curve.Gripping finger according to claim 6, characterised in that a reinforcing projection (35) is formed on the outer surface (31) of the stretching pocket (52, 53, 54, 55, 72, 73, 74, 75), which projection is extruded along the parabolic extrusion curve and extends outwards in the radial direction, in particular with a rectangular cross-section.Gripping finger (1) according to claim 7, characterised in that the reinforcement projections (35) are each connected at the end with a reinforcement web (40), which borders a gripping surface (5) determined by the gripping region (3) and facing away from the expansion pockets (52, 53, 54, 55, 72, 73, 74, 75).Gripping finger (1) according to one of the preceding claims, characterized in that the axes of extent (60, 61, 62, 63, 80, 81, 82, 83) of the branch channels (56, 57, 58, 59, 76, 77, 78, 79) are arranged in a common axis plane (39), in particular comprising the course curve (68, 88), and / or in that the angles (64, 65, 66, 67, 84, 85, 86, 87) which the axes of extent (60, 61, 62, 63, 80, 81, 82, 83) of the branch channels (56, 57, 58, 59, 76, 77, 78, 79) assume with the course curve (68, 88) decrease with increasing distance from the supply connection (6, 7).Gripping finger (1) according to claim 2, characterised in that a fluid channel (41) is formed in the gripping region (3) which is aligned parallel to the supply channel (69, 89) and opens out at a gripping surface (5) of the gripping region (3) facing away from the stretching region (4).Gripping finger (1) according to Claim 1, characterized in that a wall section having a wall thickness which is at least 1.5 times, in particular at least 2 times, a wall thickness of the expansion pockets (52, 53, 54, 55, 72, 73, 74, 75) is arranged between adjacently arranged finger segments (51, 71).Gripping finger (1) according to one of the preceding claims, characterized in that the finger segment (51, 71) is produced in a generative production process, in particular in a three-dimensional laser printing process, from an elastic polymer material, in particular a thermoplastic polymeric elastomeric polyurethane.Gripping finger (1) according to one of the preceding claims, characterized in that the course curve (68, 88) is formed as a straight line in the pressureless neutral state of the finger segment (51, 71), and in that each of the branch channels (56, 57, 58, 59, 76, 77, 78, 79) assumes an angle (64, 65, 66, 67, 84, 85, 86, 87) with the course curve (68, 88) which deviates from 90 degrees.

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