Abstract
A method of removing a magnetic tooling pin from a planar ferromagnetic support surface, comprises providing a pin-placement tool comprising an engagement body and an electrically conductive coil, supplying electrical power to the conductive coil to create a magnetic field which causes the magnetic attraction between the tooling pin and the support surface to be reduced, and moving the engagement body and engaged tooling pin away from the support surface.
Claims
1. A tooling pin placement system, comprising: a tooling table having a planar ferromagnetic support surface at an upper side thereof in use, a tooling pin comprising: a pin body having at an end thereof a head for supporting a workpiece thereon in use, and at a distal end thereof a base which in use rests on the support surface, so that the head is located at the top of the pin body, and a pin magnet having an associated magnetic field to magnetically attract the tooling pin to the support surface in use, a pin-placement tool comprising: an engagement body for engaging with the tooling pin during a pin placement operation, and an electrically conductive coil, an electrical supply electrically connected to the conductive coil, and control means for controlling the electrical supply, wherein the control means is operable to supply electrical power to the conductive coil to create a magnetic field which causes the magnetic attraction between the tooling pin and the support surface to be reduced.
2. The tooling pin placement system of claim 1, wherein the control means is operable to supply electrical power to the conductive coil to create a magnetic field which, during the pin placement operation, at least partially counteracts that of the pin magnet and thereby reduce the magnetic attraction between the tooling pin and the support surface.
3. The tooling pin placement system of claim 1, wherein the pin magnet comprises a permanent magnet.
4. The tooling pin placement system of claim 1, wherein the pin magnet comprises a non-permanent magnet, and wherein the control means is operable, during the pin placement operation, to supply electrical power to the conductive coil to create a magnetic field to reverse the polarity of the pin magnet and thereby reduce the magnetic attraction between the tooling pin and the support surface.
5. The tooling pin placement system of claim 4, wherein the control means is operable to supply pulses of electrical power to the conductive coil, with each pulse effecting reversal of the polarity of the pin magnet, and wherein the tooling pin further comprises a permanent magnet, such that the pin magnet and permanent magnet together form an electropermanent magnet, with the polarity of the pin magnet latched between each pulse.
6. The tooling pin placement system of claim 1, comprising a vertical drive for moving the engagement body in a vertical direction towards or away from the support surface.
7. The tooling pin placement system of claim 1, wherein the pin body comprises magnetically permeable material, and the pin magnet is located within a region of the pin body which is spaced from the base.
8. The tooling pin placement system of claim 1, wherein the engagement body comprises an engagement means for engaging with the tooling pin during a pin placement operation and restraining the tooling pin to the engagement body.
9. The tooling pin placement system of claim 8, wherein the engagement means comprises a mechanical latch.
10. The tooling pin placement system of claim 1, wherein the pin-placement tool comprises a horizontal drive for moving the engagement body in a plane parallel to the support surface.
11. A printing machine comprising a tooling pin placement system of claim 1.
12. The printing machine of claim 11 comprising a camera gantry, wherein the pin placement tool is mounted on the camera gantry.
13. A placement machine comprising a tooling pin placement system of claim 1.
14. A method of removing a tooling pin from a planar ferromagnetic support surface, the tooling pin being magnetically attracted thereto by a pin magnet located in the tooling pin, comprising the steps of: i) providing a pin-placement tool comprising an engagement body and an electrically conductive coil, ii) moving the engagement body into engagement with the tooling pin, iii) supplying electrical power to the conductive coil to create a magnetic field which causes the magnetic attraction between the tooling pin and the support surface to be reduced, and iv) moving the engagement body and engaged tooling pin away from the support surface.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0038] The invention will now be described with reference to the accompanying drawings (not to scale), in which:
[0039] FIG. 1 schematically shows, in sectional view, a known auto-place system;
[0040] FIG. 2 schematically shows, in sectional view, a known tooling pin and pin-picker for use in a placement machine;
[0041] FIGS. 3A and 3B schematically show, in sectional view, a tooling pin and part of a pin-placement tool in accordance with a first embodiment of the present invention using a radial permanent pin magnet in separated and engaged configurations respectively;
[0042] FIGS. 4A and 4B schematically show, in sectional view, a tooling pin and part of a pin-placement tool in accordance with a second embodiment of the present invention using an axial permanent pin magnet in separated and engaged configurations respectively; and
[0043] FIGS. 5A-C schematically show, in sectional view, a tooling pin and part of a pin-placement tool in accordance with a third embodiment of the present invention, during a magnetic latching sequence.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
[0044] A first embodiment of the present invention is schematically shown in FIGS. 3A and 3B, which show, in sectional view, a tooling pin 20 having a radially-magnetised permanent pin magnet 21 and an engagement body 22 of a pin-placement tool, in separated and engaged configurations respectively.
[0045] FIG. 3A shows the tooling pin 20 as it may be positioned during a printing operation for example, resting on and supported by a support surface 23 of a tooling table, the support surface being planar and formed from a ferromagnetic and therefore permeable material, such as steel for example. For clarity, only a small part of the support surface 23 is shown in FIGS. 3A and 3B, and it is to be understood that in practice it may extend over a large enough area to underlie a range of sizes of workpieces and accommodate many tooling pins. The tooling pin 20 comprises a pin body 24, here formed from a rigid and magnetically permeable material, such as steel for example. The permeability of the pin body material may optionally be different to that of the support surface 23. At a top end of the pin body 24 is a head 25 for supporting a workpiece (not shown) thereon in use, and at its lower, distal end, a base 26 which in use rests on the support surface 23, so that the head 25 is located at the top of the pin body 24. The base 26 has a flat end face which in use minimises magnetic circuit reluctance. The pin body 24 includes a lower body section 27, which includes the base 26, and an upper body section 28 which includes the head 25, with the lower body section 27 in this embodiment being of greater thickness than the upper body section 28. The upper body section 28 includes a detent 31 for engaging with the engagement body 22 as will be described in more detail below. The lower body section 27 includes an annular recess 29 which extends from the base 26 and through almost the entire extent of the lower body section 27. It should be noted that the pin body 24 may be integrally or monolithically formed from permeable material, or alternatively formed from a plurality of permeable sub-components, such as a central component which comprises the upper body section 28 and the part of the lower body section 27 which is radially inward of the annular recess 29, and a collar component forming the part of the lower body section which is located radially outwardly of the annular recess 29, joining the central component at the top end of the lower body section 27. The upper end of the annular recess 29 accommodates pin magnet 21, which is of corresponding annular form. Pin magnet 21 is a radially-magnetised permanent magnet, such as a bonded NdFeB grade material, which has an associated magnetic field 30 schematically illustrated in FIG. 3A in dashed lines. As can be seen from FIG. 3A, the magnetic field 30 is substantially constrained to a looped path from the pin magnet 21, through the pin body 24 radially outside the annular recess 29, through a portion of the support surface 23, then through the pin body 24 radially inside the annular recess 29 and back to pin magnet 21. This serves to provide sufficient magnetic attraction between the tooling pin 20 and the support surface 23 to avoid unwanted movement while supporting a workpiece during a printing operation.
[0046] The pin-placement tool includes an engagement body 22, for engaging with the tooling pin 20 during a pin placement operation, and which may conveniently be supported from a gantry (not shown) of a placement or a printing machine (not shown), for example from a camera gantry of a printing machine, an electrically conductive coil 32, formed for example from coated copper, housed within the engagement body 22, and various parts not shown in FIG. 3A or 3B for clarity. These include an electrical supply electrically connected to the conductive coil 32, and control means for controlling this electrical supply, and thus operable to supply electrical power to the conductive coil 32. The control means could for example comprise a processor, motherboard, suitably-programmed computer or the like, which may be located remote from the engagement body 22. In addition, a vertical drive for moving the engagement body 22 in a vertical direction towards or away from the support surface 23 may be provided between the engagement body 22 and the supporting gantry. This may configured in a variety of different ways, for example using a linear drive, a ball screw arrangement, or a pneumatic drive, all of which being well-known in the art per se. Furthermore, the pin-placement tool comprises a horizontal drive (not shown) for moving the engagement body 22 in a plane parallel to the support surface 23. This horizontal drive may be provided additionally to the gantry, or form part of the gantry, and may be configured in various ways, or example using a linear drive, a ball screw arrangement, or a pneumatic drive, all of which being well-known in the art per se.
[0047] The engagement body 22 shown is generally cylindrical, having a circular hollow shaft 33 extending upwardly from its lower end in use, dimensioned to receive the upper body section 28 of tooling pin 20. An engagement means, in this embodiment a mechanical latch, more particularly a ball latch 34, is provided in the engagement body 22 to protrude into the shaft 33, for latching engagement with the detent 31 of the tooling pin 20 during engagement with the tooling pin 20 during a pin placement operation and thus restraining the tooling pin 20 to the engagement body 22. The engagement body 22 has a two-piece construction, with an upper cylinder 35 formed from a magnetically inert material, such as aluminium, carbon fibre etc, which is mechanically connected to the vertical and horizontal drives and hence the gantry. A lower cylinder 36, which depends from the upper cylinder 35, is formed from a magnetically permeable material, such as steel for example. The conductive coil 32 is mounted within this lower cylinder 36, at a radially inward position, so that it is located proximate to, and vertically above, the pin magnet 21 during engagement (see FIG. 3B). At the lower end of lower cylinder 36 is a flux-guidance element 37 of annular form, which may be provided to direct magnetic flux as required. As shown, the flux-guidance element 37 is dimensioned so as to fit around the uppermost end of the lower body section 27 during engagement with the tooling pin 20. It should be noted that this flux-guidance element 37 is optional only, and, while it may improve performance, is not necessary for the present invention to be achieved.
[0048] FIG. 3B shows the engagement body 22 engaging with the tooling pin 20, for example after the engagement body 22 has been moved by the horizontal drive to overlie the tooling pin 20, and then lowered by the vertical drive so that the shaft 33 receives pin body 24 until the ball latch 34 engages with detent 31. In this engaged configuration, the air gap between tooling pin 20 and engagement body 22 is designed to provide an optimum coil current vs release force compromise (see below). When so engaged, the control means is operated to supply electrical power to the conductive coil 32 to create a magnetic field which causes the magnetic attraction between the tooling pin 20 and the support surface 23 to be reduced. When electrical power is supplied to the conductive coil 32, a magnetic field is produced (shown by the dashed lines) by that conductive coil 32 which at least partially counteracts the field produced by the pin magnet 21. If the produced magnetic field is strong enough, it will “overpower” the magnetic field 30 of the pin magnet 21, so that the magnetic flux is effectively constrained within lower cylinder 36. In FIG. 3B, the resulting magnetic field 38 is shown, which very schematically illustrates the resulting flux path. It can be seen that redirecting the flux here causes the magnetic flux in the region of the base 26 and support surface 23 to be reduced, so that the magnetic attraction therebetween is correspondingly reduced. This reduction in magnetic attraction means that the tooling pin 20 can be removed from the support surface 23, for example by lifting the engagement body 22 with the vertical drive, with a reduced release or lifting force.
[0049] A second embodiment of the present invention is schematically shown in FIGS. 4A and 4B, which show, in sectional view, a tooling pin 40 having an axially-magnetised permanent pin magnet 41 and an engagement body 42 of a pin-placement tool, in separated and engaged configurations respectively. This embodiment is of particular utility where a tooling pin 40 with a relatively thin (for example in comparison to that shown in FIG. 3A) upper body section 48 is required. Many of the components are generally similar to those previously-described with reference to FIGS. 3A and 3B, and so need not be described further here. In particular, for clarity no mechanical latching mechanism is shown.
[0050] The pin magnet 41, which could for example be formed from high energy NdFeB, is here axially magnetised, i.e. parallel to the vertical length of the tooling pin 40, to produce an associated magnetic field 50, with flux lines passing vertically through the pin magnet 41, constrained within a lower body section 47, into the support surface 23 and returning through a central pin body 44.
[0051] The engagement body 42 comprises a lower cylinder 56 formed from a magnetically permeable material, which forms a central shaft 53 therein, for snugly accommodating the upper body section 48 during engagement. Although not shown for clarity, it is to be understood that other components as previously described with reference to FIG. 3A may also be present. A conductive coil 52 is here mounted within an annular recess set into the lower end of the lower cylinder 56.
[0052] As shown in FIG. 4B, when the engagement body 42 and tooling pin 40 are engaged, the conductive coil 52 is operated so that it creates an associated magnetic field 51. It can be seen that in an “opposition” region 54 between the conductive coil 52 and pin magnet 41, the magnetic fields 51 and 50 are in opposition, so that the magnetic field 51 at least partially counteracts that field 50 of the pin magnet 41. In other words, the magneto-motive force (mmf) associated with the conductive coil 52 at least partially cancels that of the pin magnet 41 at the boundary between the tooling pin 40 and engagement body 42. This results in a reduced net magnetic field 50′ in the region of the base of the tooling pin 40 and support surface 23, and thereby the magnetic attraction between the tooling pin 40 and the support surface 23 is reduced.
[0053] FIGS. 5A-C schematically show, in sectional view, a tooling pin 60 and an engagement body 62, being part of a pin-placement tool, in accordance with a third embodiment of the present invention, during a magnetic latching sequence. Many of the components are generally similar to those previously-described with reference to FIGS. 3A and 3B, and so need not be described further here.
[0054] FIG. 5A shows the engagement body 62 and tooling pin 60 in a mutually engaged configuration, in a default state, which would occur for example as soon as the engagement body 62 has been moved into an engaging position with tooling pin 60. The tooling pin 60, which is standing on a support surface 23, here comprises a substantially cylindrical pin body 64, for example formed from a moulded, e.g. an injection-moulded, electro-static dissipative plastics material, which houses a soft magnet 61, such as magnetised steel, at its lower end. As shown, the soft magnet's South pole is located at the lower end of tooling pin 60, the North pole being located closer to the upper end of tooling pin 60, and so the tooling pin 60 is magnetically attracted to the support surface 23. The tooling pin 60 also comprises a hard or permanent magnet 66 which is retained within the cylindrical pin body 64 at the uppermost end of tooling pin 60. As shown, the permanent magnet 66 has its North pole located topmost, and the South pole located at its lower extent.
[0055] It can be seen that the soft magnet 61 and hard magnet 66 together constitute a electropermanent magnet (EPM). In the default state, while the tooling pin 60 is not engaged with the engagement body 62 and also as shown in FIG. 5A, the tooling pin 60 is relatively strongly magnetically attracted to support surface 23.
[0056] The engagement body 62 comprises a substantially cup-shaped container 65 which may be formed from a magnetically permeable material dimensioned to snugly receive tooling pin 60 within a central shaft thereof during engagement. The shaft of container 65 comprises a conductive coil 67, which is arranged to circumferentially surround an upper portion of the soft magnet 61 during engagement.
[0057] If an electrical pulse is fed to the conductive coil 67 by the control means, then the EPM will switch to the configuration shown in FIG. 5B, in which the soft magnet 61 has its polarity reversed with respect to the default state shown in FIG. 5A. In this state, the North pole of soft magnet 61, which is now located at the base of tooling pin 60, is not magnetically attracted to the support surface 23, and so the release or lifting force needed to lift the tooling pin 60 is reduced. The tooling pin 60 may then be lifted and placed in any desired location on the support surface 23. Separate latching means (not shown) would be required to enable lifting to occur. To restore the magnetic attraction between the tooling pin 60 and the support surface 23, a reverse current pulse is applied to the conductive coil 67 by the control means, with the result shown in FIG. 5C that the polarity of the soft magnet 61 reverts to the default state of FIG. 5A.
[0058] The above-described embodiments are exemplary only, and other possibilities and alternatives within the scope of the invention will be apparent to those skilled in the art. For example, while the above-described embodiments make use of a mechanical latch, such as a ball latch, to enable the engagement body to lift the tooling pin, other forms of mechanical latch, or indeed non-mechanical latches may be used for this purpose. As a simple alternative, the detent may be provided in the engagement body rather than the tooling pin, with the ball latch provided in the tooling pin to engage with the detent in use. As an example of an alternative mechanical latch, a canted coil spring or the like may be provided either within the tooling pin or the engagement body to engage with a detent in the other of the tooling pin and engagement body. As an example of a non-mechanical latch, by providing suitable coil configurations or a permanent magnet within the engagement body, there may be sufficient magnetic attraction between the tooling pin and engagement body to effect lifting of the tooling pin, at least once the magnetic attraction between the tooling pin and support surface has been reduced as described above.
REFERENCE NUMERALS USED
[0059] 1—Tooling pin
[0060] 2—Pin-picker
[0061] 3—Pin body
[0062] 4—Base
[0063] 5—Pin-picker shaft
[0064] 6—Pin shaft
[0065] 7—Detent
[0066] 8—Ball latch
[0067] 9—Electro-magnet
[0068] 10—Electrical interface
[0069] 11—Contact pins
[0070] 12—Support surface
[0071] 20, 40, 60—Tooling pin
[0072] 21—Pin magnet (radially magnetised)
[0073] 22, 42, 62—Engagement body
[0074] 23—Support surface
[0075] 24, 64—Pin body
[0076] 25—Head
[0077] 26—Base
[0078] 27, 47—Lower body section
[0079] 28, 48—Upper body section
[0080] 29—Annular recess
[0081] 30, 50—Magnetic field of pin magnet
[0082] 31—Detent
[0083] 32, 52, 67—Conductive coil
[0084] 33, 53—Shaft
[0085] 34—Ball-latch
[0086] 35—Upper cylinder
[0087] 36, 56—Lower cylinder
[0088] 37—Flux-guidance element
[0089] 38—Magnetic field (when coil energised)
[0090] 41—Pin magnet (axially magnetised)
[0091] 50′—Reduced magnetic field of pin magnet
[0092] 51—Magnetic field of conductive coil
[0093] 54—Magnetic field opposition region
[0094] 61—Soft magnet
[0095] 65—Container
[0096] 66—Permanent magnet
[0097] 101A, 101B—Tooling pins
[0098] 102—Pin-picker
[0099] 110—Storage magazine
[0100] 120—Gantry
[0101] 130—Workpiece
[0102] 131—Substrate
[0103] 132—Components
[0104] 133—Via
