FR2763877A1 - DEVICE FOR FIXING A FLAT PART BY AIR DEPRESSION OF THE VACUUM TABLE TYPE FOR A MACHINING CENTER - Google Patents

Abstract

The invention relates to a device for fixing a flat part by air depression of the vacuum table type, characterized in that it essentially comprises: - a horizontal panel (1) comprising on its upper surface a plurality of cylindrical cavities (2) the inner wall of which has a vacuum orifice (15) and a pressure orifice (16); - positioning studs (3) fitting into said cylindrical cavities (2) of the horizontal panel (1), said studs comprising a cylindrical body (5) in which slides a movable element (4) movable vertically between a low position and a high position, the upper face of said movable element comprising a distributor sensor (6) and on its periphery a seal (7) , said distributor sensor (6) controlling an air passage from a pneumatic circuit (8) communicating with the vacuum port (15) to an intermediate circuit (9) provided with a chamber in which a piston slides ( 11), said p iston (11) comprising a distribution means controlling the passage of air from a pneumatic circuit (14) communicating with the pressure port (16) to a circuit (17) provided with a chamber (23). The increase in pressure in said chamber (23) allows the movement of the movable element (4) of the positioning pad (3).

Description

The invention relates to a device for fixing a flat part by

  air depression type vacuum table for machining center.

  There are already a number of devices or machines for machining

  using a fastening system to raise the workpiece.

  Thus, French patent 2,699,846 in the name of the applicant describes an articulated wedging element for use on a workbench, a machine table, a vacuum table or the like. This element is composed of a flexible joint comprising, for raising a part to a predetermined height (H), rigid raising elements, for example studs, distributed over the length of the joint and separated from each other by functional games allowing to bend the articulated wedging element. Although satisfactory, such a fixing system by air depression allowing the workpiece to be raised requires a relatively long installation since it is necessary to delimit the vacuum zone according to the shape of the workpiece hence some trial and error to find the

  ideal fixing area before you can start machining work.

  In addition, with each new series of parts, it is necessary to reposition

  articulated wedging elements to redefine the vacuum zone.

  The object of the invention is to overcome the drawbacks of the prior art by proposing a device of the vacuum table type which allows the automatic creation of a vacuum zone for fixing the workpiece according to the shape of said workpiece. and which then automatically enhances this area of

  vacuum to allow the machining of the part on its periphery.

  According to the invention, this result is obtained by a device for fixing a flat part by air depression of the vacuum table type, characterized in that it essentially comprises: - a horizontal panel comprising on its upper surface a plurality of cylindrical cavities, the inner wall of which has a vacuum port and a pressure port; positioning studs fitting into said cylindrical cavities of the horizontal panel, said studs comprising a cylindrical body in which slides a movable element vertically displaceable between a low position and a high position, the upper face of said movable element comprising a distributor sensor and a seal on its periphery, said distributor sensor controlling an air passage coming from a pneumatic circuit communicating with the vacuum orifice towards an intermediate circuit provided with a chamber in which a piston slides, said piston comprising a distribution means controlling the passage of air from a pneumatic circuit communicating with the pressure orifice towards a circuit provided with a chamber, the increase in pressure in said

  chamber allowing the movement of the mobile element of the positioning pad.

  When a workpiece is placed by an operator on the device according to the invention, only the positioning pads which are completely in contact with the surface of the workpiece are placed under vacuum, thereby creating a vacuum area on the surface of the table. with depression. Positioning pads which are partially in contact with the surface of the part, for example with a flange of said part, or

  which are not at all in contact with the part are not put under vacuum.

  This vacuuming causes a vertical automatic rise of the positioning pads in contact, these emerging from the other pads for

  allow the part to be machined over its entire periphery.

  The invention will be better understood using the following description given in

  reference to the appended figures in which: - figures LA and lB are perspective views of a device according to the invention, - figure 2 is a partial longitudinal section view of a device according to the invention, - figure 3 is a view in partial longitudinal section of an alternative embodiment of a device according to the invention, FIG. 4 is a view in partial longitudinal section of another embodiment of a device according to the invention, - Figure 5 is a partial longitudinal sectional view of another alternative embodiment of a device according to the invention, - Figure 6 is a perspective view of a device with studs

  positioning illustrated in figure 5.

  Referring to the figures illustrating several nonlimiting examples of embodiment of the invention, the device comprises a horizontal panel (1) whose surface has several cylindrical cavities (2) arranged vertically. In each of these cylindrical cavities is fitted a positioning pad (3) (see

Figures 1A and 1B).

  This positioning stud (3) comprises a mobile element (4) capable of sliding vertically from bottom to top in a cylindrical body (5). The movable element has an upper section (4a) external to the cylindrical body (5), said upper section (4a) having an upper face (4b) whose periphery is provided with a seal (7) intended to be in contact with the flat workpiece. This

  face (4b) further comprises a distributor sensor (6).

  For example, this distributor sensor (6) consists, without limitation, of a vertical cylindrical element (6a), the upper part (6b) of which protrudes from the upper face (4b) of the movable element (4). This projecting upper part (6b) advantageously has a rounded shape, for example substantially the shape of a hemisphere, allowing better contact with the workpiece. The lateral surface of the vertical cylindrical element (6a) is provided with an annular groove

  horizontal (6c) or another means of communication.

  When a flat part (2a) is placed on a positioning stud (3.), the distributor sensor (6) retracts and creates an air passage for example through the horizontal annular groove (6c) or another means of communication between a pneumatic circuit (8) communicating with a vacuum orifice (15)

and an intermediate circuit (9).

  This intermediate circuit (9) has a chamber (10) in which can be

  move a piston (11) under the action of vacuum.

  The originality of the invention comes from the fact that the vacuum capable of displacing the piston is sufficient only if and only if the workpiece (7) is perfectly positioned on the positioning stud (3), thus creating a space (12) perfectly closed between the upper face of the movable element (4) and the lower surface (24a) of the workpiece (24), the sealing of the space (12) being ensured

by the peripheral seal (7).

  On the contrary, if the workpiece is not perfectly positioned on the positioning stud (3), the space is no longer closed and thus the loss of vacuum generates a vacuum in the intermediate circuit and therefore in the chamber ( 10)

  insufficient to move the piston (11).

  The displacement of the piston (11) comprises a distribution means allowing the passage of air between a pneumatic circuit (14) communicating with a pressure orifice (16) and a circuit (17) provided with a lower chamber (23) or

  upper according to the embodiment.

  The increase in pressure in said chamber (23) activates the stroke of

  the movable element (4) of the positioning stud (3) towards its high position.

  According to a preferred embodiment illustrated in Figures 3 and 4, the distribution means consists of a vertical axis (18) placed in a chamber, said axis comprising a horizontal annular groove (18a) capable of allowing the passage of air between the circuit pneumatic (14) pressure and the circuit (17) provided with the

  chamber (23) when the vacuum in the chamber (10) is sufficient.

  Advantageously, the pneumatic vacuum circuit (8) can comprise a vacuum chamber (22) as illustrated in FIG. 4, which, when a sufficient vacuum is created there, activates the upward stroke of the movable element of the positioning pad. We then have a simultaneous action of depression and

  pressure on the movable element (4) of the positioning pad (3).

  In addition, the intermediate circuit (9) may include a chamber (13) opening onto the upper face (4b) of the movable element (4), said chamber being covered with a filter (21) making it possible to prohibit the entry of dust or

  chips removed during machining of a part.

  According to an embodiment illustrated in FIG. 2, the depression (15) and pressure (16) orifices are located at the level of the lateral internal wall of the cylindrical cavities (2) of the horizontal panel (1), the cylindrical body ( 5) positioning pads (3) having horizontal annular grooves (19a, 19b) on these side walls (5a) allowing the communication of the vacuum orifices (15) and pressure (16) respectively with the circuits

tires (14 and 8).

  According to an embodiment illustrated in FIGS. 3 and 4, the depression (15) and pressure (16) orifices are located on the inner bottom wall of the cylindrical cavities (2) of the horizontal panel (1), the cylindrical body ( 5) positioning pads (3) further comprising conduits (26,20) on the inner wall of its bottom (5b) allowing the communication of the vacuum orifices (15) and pressure (16) respectively with the pneumatic circuits (14 and 8). The transverse or horizontal section of the upper face (4b) of the element

  mobile (4) positioning pads can be circular or square.

  Furthermore, the vacuum (15) and pressure (16) ports are

  supplied by two separate and independent networks.

  The advantages and performances of the device according to the invention are numerous and in particular: - the device is ready for use practically immediately after the pump or compressor which powers the vacuum and pressure networks of the device is put into operation, - the workpiece is automatically held in position by the air depression and raised, - the vacuum pads are independent of each other and therefore it is possible to lower a stud which hinders the passage of the machining tool (25), - stability of the device, the depression in the studs avoids all vibrations and positioning faults of the movable element of each stud, - no particular adjustment, to move from one room to another it is enough at each change of part to cut the depression and to reactivate it to fix a new part, - cleanliness of the device since these constituent elements are not in direct contact with dust and cope due to the machining of the pieces of wood, - the positioning studs are raised without the intervention of

the operator.

  The device according to the invention is particularly used in machining centers

intended for the wood industry.

Claims (10)

  1. Device for fixing a flat part by air depression of the vacuum table type, characterized in that it essentially comprises: - a horizontal panel (1) comprising on its upper surface a plurality of cylindrical cavities (2) the inner wall of which has a vacuum port (15) and a pressure port (16); - positioning pads (3) fitting into said cylindrical cavities (2) of the horizontal panel (1), said pads comprising a cylindrical body (5) in which slides a movable element (4) movable vertically between a low position and a high position, the upper face of said movable element comprising a distributor sensor (6) and on its periphery a seal (7), said distributor sensor (6) controlling an air passage coming from a pneumatic circuit (8) communicating with the vacuum opening (15) to an intermediate circuit (9) provided with a chamber in which a piston (11) slides, said piston (11) comprising a distribution means controlling the passage of air from a circuit tire (14) communicating with the pressure orifice (16) towards a circuit (17) provided with a chamber (23), the increase in pressure in said chamber (23) allowing the movement of the movable element (4 ) from the stud positioning (3).   2. Device according to claim 1, characterized in that the dispensing means consists of a vertical axis (18) integral with the piston (11) placed in a   chamber (17), said axis (18) having a horizontal annular groove (18a).   3. Device according to any one of claims 1 to 2, characterized in that   that the intermediate circuit (9) comprises a chamber (13) opening onto the upper face (4b) of the movable element (4), said chamber (13) being equipped with a filtration means.   4. Device according to any one of claims 1 to 3, characterized in that   that the pneumatic circuit (8) includes a chamber (22) allowing the stroke   vertical of the mobile element of the positioning pad.   5. Device according to any one of claims 1 to 4, characterized in that   that the upper face (4b) of the movable element (4) of the positioning stud (3) is of circular horizontal section.   6. Device according to any one of claims 1 to 4, characterized in that   that the upper face (4b) of the movable element (4) of the positioning stud (3) is of square horizontal section.   7. Device according to any one of claims 1 to 6, characterized in that   that the depression (15) and pressure (16) orifices are situated at the level of the lateral internal wall of the cylindrical cavities (2) of the horizontal panel (1), the cylindrical body (5) of the positioning studs (3) comprising grooves   horizontal annulars (19a, 19b) on these side walls (5a).   8. Device according to any one of claims 1 to 6, characterized in that   that the depression (15) and pressure (16) orifices are located on the inner bottom wall of the cylindrical cavities (2) of the horizontal panel (1), the cylindrical body (5) of the positioning studs (3) comprising conduits (26,20) allowing the respective communication ports of depression (15) and   pressure (16) with the pneumatic circuits (14 and 8).   9. Device according to claim 1, characterized in that the distributor sensor (6) consists of a cylindrical element (6a) the upper part of which protrudes relative to the upper face (4b) of the movable element (4), said cylindrical element (6a) comprising a means of communication between the circuit   pneumatic (8) vacuum and the intermediate circuit (9).   10. Device according to any one of claims 1 to 9, characterized in that   that the vacuum (15) and pressure (16) ports are supplied by two   separate and independent networks.