Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25B—TOOLS OR BENCH DEVICES NOT OTHERWISE PROVIDED FOR, FOR FASTENING, CONNECTING, DISENGAGING, OR HOLDING
  • B25B11/00—Work holders not covered by any preceding group in the subclass, e.g. magnetic work holders, vacuum work holders
  • B25B11/005—Vacuum work holders

Definitions

• the invention mainly relates to the field of maintaining the workpieces on work tables and in particular the field of vacuum vices.
• the vise must therefore allow the positioning and maintenance of very varied workpieces, which means that on the other hand that the fastening surface of the workpiece in the vice must deliver a constant holding force irrespective of the size of the workpiece and its geometry, and secondly that the workpiece must be located precisely in a direction perpendicular to the surface of the vise.
• Another known constraint for the realization and design of the vises is that the holding operation must be carried out under optimal conditions from the point of view of the time required, either to maneuver the workpiece between two configurations of the vice, or to switch the parts between the already shaped element and an element to be machined, for example on a production line, cutting, drilling, grinding etc.
• the holding device must not interfere with the access of the workpieces so as to easily fit into an automated processing chain,
• the vice must be able to maintain flat parts of varying sizes with complex contours but also pieces of complex shapes, not flat, and in this tools currently available are particularly poorly suited.
• the vice must be able to accurately position the workpiece.
• the device responding to the above problems must also satisfy the general constraints of this type of tool namely a satisfactory distribution of the suction pressure on the work surface and optimal sealing of the points not covered by the surface to be maintained, while ensuring a reduced cost of operation of the process.
• the invention therefore aims to solve these major difficulties by proposing a new vice operating by vacuum suction.
• the prior art knows devices for holding parts or objects operating by vacuum suction.
• the suction devices are shutter ball devices for closing or releasing the outlet of the suction ducts of the cells located under a support plate. These devices are complex to implement, with many parts to assemble and difficulties to ensure a reliable seal between the balls and the support plate of the part.
• the prior art discloses another device described in DE 92 04 704 U1 and using a flexible membrane as a means for closing the suction ducts opening into chambers located under said membrane.
• the membrane When maintaining a part, the underside of which may be flat or non-planar, the membrane may be crushed in several areas of the bearing surface. The stability of the part and its precise positioning in a direction perpendicular to the bearing surface can not be guaranteed.
• the invention consists of a vice connected to a suction device so as to vacuum press a workpiece to be held on a work surface and immobilize it, said vise having a working plate in contact with the workpiece to be immobilized and a support plate in contact with said work plate, and in which vise:
• the working plate is pierced with orifices, each orifice being in communication with an underlying chamber,
• the support plate comprises a set of chambers, each chamber being in communication with the suction device via a conduit,
• Vacuum-displaceable closing means is present in each chamber so as to close the duct when no part to be maintained is disposed at the outlet of an orifice on the work surface
• the closure means is formed by a flexible and deformable working plate pierced with orifices, an orifice not being axially aligned with a conduit of the underlying chamber so that a non-perforated zone of the working plate is deformed under the effect of a depression in an underlying chamber when no part to be maintained is disposed at the outlet of the orifice corresponding to this chamber, and in that the work plate is maintained at the periphery of each chamber by a plurality of pads of the support plate engaging in perforations of the working plate, said pads providing a reference surface for positioning the part to be maintained.
• said pads are removable and replaceable in case of wear or machining accident.
• the advantages of the vice according to the invention are multiple:
• the vice can be used for maintaining and positioning flat structures such as panels or plates, for example, but also for immobilizing three-dimensional parts and complex shapes, which is quite new and innovative, this advantage can in particular be exploited for the rapid prototyping of the parts and in the stratoconception® device as developed by the applicant and described in her patent EP 585 502,
• the vise as described in the invention can be easily inserted into a machining chain in particular by the fact that the structure of the working surface can be smooth, without moving element, in contrast to the known devices of maintenance using valves, suction cups or pistons,
• the vise according to the invention allows the effective closure of the suction points not covered by the surface to be immobilized, thereby avoiding pressure losses detrimental to the operation of the vise.
• the system detects and adapts in real time to the possible evolution of the useful surface of maintenance which can thus evolve during the manufacture of the part without the maintenance quality is altered. For example when machining a part, part of the holding surface can be completely clear of the work surface thus generating a leak. The system is then able to adapt dynamically by obstructing the generated leak. This self-adaptation also makes it possible to limit the losses of depression and thus to propose a low energy consumption.
• Figure 1 shows the principle of operation of the vice for a preferred embodiment of the invention whose working surface is a flexible membrane serving as a sealing means.
• Figure 2 is a detail AA of Figure 1.
• Figure 3 is detail BB of Figure 1.
• FIG. 4 is a view from above of a vice (3) showing an example of shape and repair of the chambers of the support plate optimizing the holding surface of a vice according to the invention, a sheet 2 being placed on the support plate.
• Figures 5a and 5b are schematic diagrams of two variants, enlarged and sectional views, for producing the suction orifices (7) of a work plate.
• the vise according to the invention is connected to a suction device so as to vacuum press a workpiece (1) on a work surface and immobilize it.
• the vise in its general form comprises at least one support plate (3) contiguous to a work plate (2).
• the working surface is represented by the interface between the part to be held and the work plate.
• the support plate (3) comprises a set of chambers, each chamber (4) being in communication with a suction device via a conduit (5), which conduit passes through the support plate (3) and is connected to a device generating a depression, for example a vacuum pump.
• a conduit (5) as described in the invention may have any shape, that is to say of square section, oval or irregular, however the section is preferably circular and therefore the conduit of cylindrical shape.
• the working plate (2) in contact with the part to be held is pierced with orifices (7), which orifices are in communication with underlying chambers (4) connected with the suction device, so that the vacuum generated by the suction device is applied to the working surface, under the part to be maintained, through the suction duct and said holes.
• the working plate is a thin plate (2) of deformable material under the effect of a depression on one side of said thin plate and able to return by elasticity to its initial shape in the absence of pressure difference between both sides of the sheet.
• the plate (2) is a sheet of material made of flexible material, for example a polymer sheet.
• the plate (2) has a thickness of between 0.1 mm and 5 mm, and it is in one or more parts.
• the plate (2) is pierced with orifices (7), the orifices (7) not being axially aligned with the conduits (5) so that an imperforate area (10) of the work plate deforms under the effect of a depression in an underlying chamber (4) when no part to be maintained is disposed at the outlet of the orifice (7) corresponding to this chamber.
• the plate (2) is held at the periphery of each chamber (4) by a plurality of studs (8) of the support plate (3) engaging in perforations (9) of the working plate (2), said studs making contact between the support plate (3) and the part to be held (1), thus ensuring a reference for its positioning.
• the figures show that, when the depression is switched on, the part to be held (1) comes to rest on the studs (8) surrounding a chamber (4) and the zone (10) placed above this chamber does not deforms, while the zones (10) located above the rooms not covered by the part (1) deform and close the ducts (7) located below said zones (10) which deform.
• the deformable sheet acts as a sealing means and sealing around the chamber (s) (4) located (s) in the room.
• the upper surfaces of the pads (8) which are in contact with the underside of the workpiece form a reference surface for precise positioning of the workpiece along an axis Oz perpendicular to the work plate (2).
• the preferred and nonlimiting form of the chambers (4) shown in FIG. 4 makes it possible to increase the number of suction points for an equivalent surface.
• the system operates through two holes: a suction hole which is the perforation (7) of the membrane and a vacuum hole which is the mouth of the duct (5).
• a suction hole which is the perforation (7) of the membrane
• a vacuum hole which is the mouth of the duct (5).
• the depression hole (5) must suck the flexible membrane to seal it tightly around its perimeter.
• This operation is governed by the behavior of the material and in particular by its radius of plating. This radius is governed by a physical law of deformation of the material which is a function of the elasticity properties of the material, its thickness but also the geometry of the chamber and the level of depression.
• the mouth of the duct (5) must (for a vacuum included in 0.95 and 1 bar and a material thickness of 1.5 mm) be placed in the center of a cylinder theoretical free radius of 10 to 14 mm and a height of 0.8 to 1.1 mm, free cylinder which defines the minimum chamber radius to be provided around the mouth of the duct (5).
• the suction chamber forms having the best relationship between the optimization of the suction surface and the simplicity of manufacture are the ovoid forms with an acute end or radius of curvature weaker than the radius of curvature of the other end, recalling shapes in "egg" or "drop of water”.
• the mouth of the duct (5) is placed in the widest part of the chamber while this chamber may be less wide under the face of the orifice (7).
• This distribution makes it possible to reduce the size of each chamber and generates a naturally staggered shape of the chamber on all or part of the support plate (3), which further reduces the distance between two suction points.
• the chambers of the same row are placed side by side with the smallest part alternately on one side and the other of the direction of the row, and the chambers in a row are offset from those in the next and / or previous row.
• the pads may be removable or dismountable, for example by screwing means.
• This arrangement is particularly advantageous because it allows the adjustment of the height of the pads, especially when the work surface is a left surface, and / or allows the replacement thereof in case of wear or accident of machining.
• Two variants may also be provided for an orifice (7), either a single hole (7a) or a surface element (6) perforated with a plurality of perforations or micro-perforations (7b), this variant acting as a flow accelerator and as a filter to stop chips and other machining residues and prevent them from entering the underlying chamber.
• the vice there are no moving parts dependent on gravity which increases the holding possibilities, in particular it allows the use of the vice with a work surface vertically or in an oblique position for example for applications in robotics.
• the part can even be maintained in the event of a vacuum cut.
• the size of the vice, the thickness of the various plates, the power of the depression and the various dimensional parameters can be adjusted within a wide range without departing from the scope of the invention.
• the vise according to the invention can also be used as a pneumatic valve or for object gripping, for example at the end of a robotic arm or on a conveyor chain.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Jigs For Machine Tools (AREA)
• Manipulator (AREA)
• Auxiliary Devices For Machine Tools (AREA)
• Hooks, Suction Cups, And Attachment By Adhesive Means (AREA)
• Moulds For Moulding Plastics Or The Like (AREA)
• Catching Or Destruction (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=39253847

Family Applications (1)

Country Status (8)

Families Citing this family (5)

Family Cites Families (14)

• 2007
  • 2007-08-29 FR FR0757232A patent/FR2920329B1/fr not_active Expired - Fee Related
• 2008
  • 2008-08-28 CA CA2696561A patent/CA2696561C/fr active Active
  • 2008-08-28 DE DE602008006208T patent/DE602008006208D1/de active Active
  • 2008-08-28 AT AT08829167T patent/ATE505299T1/de active
  • 2008-08-28 WO PCT/FR2008/051538 patent/WO2009030861A2/fr not_active Ceased
  • 2008-08-28 US US12/674,657 patent/US8646764B2/en active Active
  • 2008-08-28 ES ES08829167T patent/ES2365030T3/es active Active
  • 2008-08-28 EP EP08829167A patent/EP2185322B1/de active Active

Non-Patent Citations (1)

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