Suction fixture for warped workpieces

Abstract

A fixture for clamping a workpiece includes a body having a flat fixture surface. The fixture surface includes a plurality of openings distributed on the fixture surface, each of which is connectable to a suction source. At least one flow restrictor is located between the plurality of openings and a connector of the fixture to the suction source to restrict inflow through each of the plurality of openings. When suction is applied to the plurality of openings, a portion of the workpiece surface covers at least one of the plurality of openings and another of the openings remains uncovered, the suction force at the covered opening is strong enough to clamp the workpiece surface.

Description

Technical Field

[0001] The present invention relates to wafer processing. More particularly, the present invention relates to a suction fixture suitable for clamping a warped workpiece. Background Art

[0002] Many applications require the gripping and manipulation of flat, thin workpieces. For example, in the manufacture of semiconductor devices, such as integrated circuits and other electronic components, semiconductor substrates, typically in the form of wafers, must be manipulated in order to apply processing steps to the substrates, or to inspect the substrates. Arms gripping the substrates can be manipulated to carry the substrates to a desired location for processing or inspection.

[0003] A typical gripper arm for gripping semiconductor substrates can apply suction to hold the substrate on the arm. Typically, suction needs to be applied at three different points on the surface of a flat substrate so that the arm can firmly and stably grip the substrate during manipulations such as translation, rotation, or tilting of the substrate. Summary of the invention

[0004] Therefore, according to an embodiment of the present invention, a clamp for clamping a workpiece is provided, the clamp comprising: a body having a flat clamp surface, the clamp surface comprising a plurality of openings distributed on the clamp surface, each opening being connectable to a suction source; and at least one flow restrictor located between the plurality of openings and a connector of the clamp to the suction source to limit the flow through each of the plurality of openings, so that when suction is applied to the plurality of openings, a portion of the workpiece surface covers at least one of the plurality of openings and another of the openings remains uncovered, the suction force at the covered opening is strong enough to clamp the workpiece surface.

[0005] Furthermore, according to an embodiment of the present invention, the body includes a plurality of arms extending from a single base.

[0006] Furthermore, according to an embodiment of the present invention, a conduit from the connector to one of the plurality of openings extends along one of the plurality of arms.

[0007] Furthermore, according to an embodiment of the present invention, the clamp surface is continuous.

[0008] Furthermore, according to an embodiment of the present invention, the at least one flow restrictor is located between one of the plurality of openings and a pipe forming a fluid connection between the opening and the connector.

[0009] Furthermore, according to an embodiment of the present invention, the flow restrictor includes a plurality of baffles.

[0010] Furthermore, according to an embodiment of the present invention, the restrictor includes a segmented adaptive orifice (SASO) having staggered opposing fins mounted inside.

[0011] Furthermore, according to an embodiment of the present invention, the flow restrictor comprises a constriction.

[0012] Furthermore, according to an embodiment of the present invention, the flow restrictor includes a needle valve.

[0013] Furthermore, according to an embodiment of the present invention, one of the plurality of openings comprises a resilient sealing structure configured to form a seal between the opening and the workpiece surface when suction is applied to the opening when the workpiece surface is in contact with the resilient sealing structure.

[0014] Furthermore, according to an embodiment of the present invention, the elastic sealing structure includes an elastic cup.

[0015] Furthermore, according to an embodiment of the present invention, the elastic sealing structure includes a gasket or a washer.

[0016] Furthermore, according to an embodiment of the present invention, the elastic sealing structure includes a polymer.

[0017] Furthermore, according to an embodiment of the present invention, the polymer includes silicone.

[0018] Furthermore, according to an embodiment of the present invention, the elastic sealing structure may be connected to the fixture surface via a rod that may be inserted into the opening of the plurality of openings.

[0019] Furthermore, according to an embodiment of the present invention, the rod is in the form of a cylinder which is laterally truncated to form flat sides.

[0020] Furthermore, according to an embodiment of the invention, the at least one flow restrictor is located in the space between the side surface and the surface of the cylinder surrounding the rod.

[0021] Furthermore, according to an embodiment of the present invention, one of the plurality of openings includes an extension mechanism to extend the opening outwardly from the fixture surface toward the workpiece surface.

[0022] Furthermore, according to an embodiment of the present invention, the extending mechanism is configured to extend the opening outward when the opening is not in contact with the surface of the workpiece.

[0023] Furthermore, according to an embodiment of the present invention, the extending mechanism is configured so that when suction is applied to the opening and the opening is in contact with the surface of the workpiece, a suction force can be generated to suck the opening toward the jig surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to better understand the present invention and realize its practical application, the following drawings are provided and referenced in the following text. It should be noted that the drawings are given as examples only and do not limit the scope of the present invention in any way. The same parts are represented by the same reference numerals.

[0025] Figure 1 is a schematic top view of a workpiece clamp having arms configured to clamp a warped workpiece in accordance with an embodiment of the present invention.

[0026] Figure 2 yes Figure 1 A schematic top view of a variation of a workpiece clamp having a continuous clamping surface is shown.

[0027] Figure 3 yes Figure 1 A schematic cross section of a suction fixture of a workpiece fixture is shown.

[0028] Figure 4A Schematically shows Figure 3 A variation of the suction clamp shown.

[0029] Figure 4B yes Figure 4A A schematic cross section of a suction fixture is shown.

[0030] Figure 5 is a schematic side view of a variation of a suction clamp in which the suction clamp is extendable from a workpiece clamp. DETAILED DESCRIPTION

[0031] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be appreciated by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, processes, components, modules, units and / or circuits are not described in detail in order to avoid obscuring the present invention.

[0032] Although embodiments of the present invention are not limited in this regard, discussions using terms such as "processing", "calculating", "computing", "determining", "establishing", "analyzing", "examining", etc. may refer to operations and / or processes of a computer, computing platform, computing system or other electronic computing device that manipulate and / or transform data represented as physical (e.g., electronic) quantities within a computer's registers and / or memory into other data similarly represented as physical quantities within a computer's registers and / or memory or other information non-transitory storage medium (e.g., memory) that can store instructions to perform operations and / or processes. Although embodiments of the present invention are not limited in this regard, the terms "multiple" and "multiple" as used herein may include, for example, "multiple" or "two or more". The terms "multiple" or "multiple" may be used throughout the specification to describe two or more components, devices, elements, units, parameters, etc. Unless explicitly stated, the method embodiments described herein are not limited to a particular order or sequence. In addition, some of the method embodiments or elements thereof may occur or be performed simultaneously, at the same point in time, or simultaneously. Unless otherwise stated, the conjunction "or" as used herein should be understood as inclusive (any or all of the options).

[0033] According to an embodiment of the present invention, a fixture for clamping a workpiece includes a fixture body having a flat fixture surface, on which a plurality of suction openings are distributed. In some examples, the fixture body can be divided into one or more separate arms, for example, arms extending or branching from a single base, or other arms.

[0034] Each suction opening may be connected to a suction source via a conduit. For example, the suction source may include a blower, a vacuum pump or other suction source. Each suction opening may be connected to a suction source via one or more connectors. When suction is provided to a suction opening in contact with the surface of the workpiece, the suction force may hold the workpiece to the suction opening.

[0035] One or more flow restrictors are located in the fluid path between each suction opening and the suction source. The flow restrictor is configured to limit the inflow rate through each suction opening, for example, when the suction opening is not in contact with the surface of the workpiece. Due to the effect of the flow restrictor, the suction openings on the fixture surface in contact with the workpiece surface can also firmly clamp the non-planar surface of the warped workpiece even when some openings are not in contact with the workpiece surface (for example, due to warping or tilting of the workpiece surface). Typical workpieces can include thin and nominally flat semiconductor substrates or wafers, glass panes, or another type of workpiece that is ideally flat but may become warped during, for example, one or more processing steps.

[0036] In some examples, a sufficient number of openings may be distributed on the flat clamping surface such that at least two openings (preferably at least three) may be able to suck a portion of the workpiece surface to the openings so as to hold the portion of the workpiece surface to the arm at the openings (e.g., due to suction and friction generated between the workpiece surface and the clamping surface of the arm). Alternatively or additionally, one or more suction openings may be provided with an extension mechanism configured to extend the suction opening from the clamping surface toward the workpiece surface. Such extension may ensure that a sufficient number of openings contact the warped workpiece surface and thereby clamp the warped workpiece surface.

[0037] When the workpiece surface is warped, at least some of the suction openings can remain uncovered by the workpiece surface. The restrictor of each suction opening can limit the suction so that the inflow of air through the uncovered suction openings does not destroy the suction applied by the covered surface. For example, the suction can produce a vacuum that is deep enough to reliably clamp the workpiece. Therefore, the clamp arm can continue to firmly clamp the workpiece surface. Therefore, for example, manipulating the clamp to translate, rotate or tilt the arm can reliably manipulate the clamped workpiece. For example, when all suction openings are sealed by the workpiece, the vacuum can reach a gauge pressure of -800mbar. When all suction openings are not covered by the workpiece, the vacuum can reach a gauge pressure of -100mbar. In other examples, other vacuum levels can be obtained.

[0038] It may be noted that, without a flow restrictor, unrestricted inflow through the uncovered openings may result in direct flow from the uncovered openings to the suction connector with little or no pressure drop. Thus, no suction will be applied at points where the workpiece surface contacts some of the suction openings.

[0039] In one example, the suction duct extends from the suction connector to the position of each suction opening along the inside of the clamp arm. The open duct between the suction duct and each suction opening includes a flow restrictor. For example, the flow restrictor may include baffles, fins, contractions or other structures that limit the inflow rate through the suction opening. In some cases, the flow restrictor may include an adaptive segmented orifice (SASO, self adaptive segmented orifice), which includes staggered relative fins installed inside, and is configured to increase flow resistance by enhancing the generation of eddy currents in the flow. The flow restrictor may include other types of flow limiting structures, and may be located at other positions between the suction opening and the connection with the suction source.

[0040] Each suction opening can be provided with a structure that enhances the friction between the clamp arm and the workpiece. For example, each suction opening can be surrounded by an elastic sealing structure, which is in the form of a cup, a liner, a gasket or a socket made of an elastic material. When suction draws the workpiece surface toward the suction opening, the inward pulling force can flatten the elastic sealing structure against the surface of the clamp arm. The elastic sealing structure against the flattening of the arm surface can increase the contact area between the workpiece surface and the arm surface, thereby increasing the friction that prevents the workpiece from sliding on the arm surface. The material for making the elastic sealing structure can be selected to provide the required friction while minimizing the risk of contaminating the workpiece surface due to the elastic sealing structure material adhering to the workpiece surface. For example, suitable materials can include silicone, or another polymer or other suitable materials.

[0041] The suction opening provided with a flow restrictor can provide a favorable compromise when processing a warped workpiece. On the one hand, when the clamp arm or surface has a limited number of suction openings, since the wafer may only contact the portion of the clamp arm without the suction opening, it is not possible to ensure that the suction opening is sealed by contact between the warped workpiece and the suction opening. Increasing the inflow rate through the suction opening can suck a portion of the workpiece to the suction opening to produce a seal. On the other hand, in order for the clamp arm to clamp the workpiece with sufficient strength so that the workpiece can be reliably and accurately manipulated, the vacuum level at the point where the workpiece seals the suction opening must be deep enough to provide the required friction. In order for the suction source to provide the required deep vacuum to all suction openings, the inflow through the unsealed suction openings must be limited. Therefore, providing a flow restrictor for each suction opening to limit the inflow through the suction opening can enable the suction opening sealed by contact with the warped workpiece to provide sufficient friction to hold the workpiece to the clamp arm. Therefore, when the workpiece does not seal some suction openings, the workpiece can be firmly and reliably manipulated by the clamp arm.

[0042] Figure 1 is a schematic top view of a workpiece holder configured to hold a warped workpiece according to an embodiment of the present invention.

[0043] The workpiece clamp 10 comprises a clamp body which comprises at least one flat clamp surface 13. A plurality of suction clamps 14 are distributed on the clamp surface 13.

[0044] In the example shown, the fixture body 11 includes two fixture arms 12 extending outwardly from a fixture base 20. A plurality of suction fixtures 14 are distributed along the length of each fixture arm 12. Each suction fixture 14 includes a suction opening 16, and when the workpiece 15 is clamped by the fixture arm 12 of the workpiece fixture 10, the workpiece 15 can be placed to cover some of the suction fixtures 14. When a surface area of ​​the workpiece 15 is in close proximity to the suction fixture 14, suction applied to the suction opening 16 of the suction fixture 14 can draw the area toward the suction opening 16 and the fixture surface 13 to be clamped by the suction fixture 14.

[0045] In other instances, there may be more than two clamp arms 12, or the clamp surface 13 may include a continuous surface rather than separate arms. The number of suction clamps 14 may be greater or less than the number shown, and their distribution on each clamp arm 12 may be different from the pattern shown. The suction clamps may have a shape different from the illustrated example, such as symmetrical or asymmetrical. In other instances, the suction opening of each suction clamp may not be in the center of the suction clamp. In another instance, the clamp body 11 may include two clamp surfaces 13, for example, on opposite sides of the clamp body 11.

[0046] In some cases, the clamp arms 12 or suction clamps 14 can be arranged so that the workpiece clamp 10 can clamp workpieces 15 of various sizes. For example, one group of suction clamps 14 can be arranged in an area that is sized for smaller workpieces or smaller than smaller workpieces. One or more other groups of suction clamps 14 can be arranged outside the first group, but in an area corresponding to one or more larger sized workpieces. For example, one or more additional clamp arms 12 (each clamp arm having a suction clamp 14) can be arranged between the two clamp arms 12 of the illustrated example to enable clamping of workpieces having a diameter or other dimension that is smaller than the distance between the two clamp arms 12 shown.

[0047] For example, the workpiece fixture can be configured to handle workpieces 15 of different sizes. In this case, some suction fixtures 14 can be positioned on the fixture surface 13 to clamp the outer area of ​​the large workpiece 15 beyond the edge of the smaller workpiece 15. When clamping the small workpiece 15, these outer suction fixtures 14 can remain uncovered. However, since these outer suction fixtures 14 (and other suction fixtures 14) are provided with restrictors, the inner suction fixtures 14 covered by the smaller workpiece 15 can be clamped by the covered inner suction fixtures 14.

[0048] The workpiece fixture 10 can be connected to a manipulation mechanism via a fixture base 20, for example, the manipulation mechanism can include a mechanism that can be operated to translate, rotate or tilt the workpiece fixture 10 connected to the mechanism. A suction connector 18 can be connected to a suction source. For example, the suction source can include a vacuum pump, a blower or other suction mechanisms. The suction connector 18 can be located on the fixture base 20 as shown in the figure, or can be located at other positions on the workpiece fixture 10.

[0049] In some examples, the workpiece clamp 10 may include two or more suction connectors 18. For example, each clamp arm 12 of the workpiece clamp 10 may be connected to a single or separate suction source via a separate suction connector 18.

[0050] Typically, each suction opening 16 is connected to a suction connector 18 via, for example, a conduit located inside the clamp body 11. One or more flow restrictors are located between each suction opening 16 and a suction source connected to the suction connector 18.

[0051] In another example, the clamp surface 13 may form a single continuous branchless surface, and the clamp body 11 may include a single branchless body.

[0052] Figure 2 yes Figure 1 A schematic top view of a variation of a workpiece clamp having a continuous clamping surface is shown.

[0053] The fixture body 11 of the workpiece fixture 40 is in the form of a continuous body without branching arms. Equivalently, the fixture body 11 of the workpiece fixture 40 can be considered to be composed of a single arm. Similarly, the fixture surface 13 is in the form of a continuous surface (so that any two suction fixtures 14 on the fixture surface 13 can be connected by a line segment, the entire length of which extends along the fixture surface 13 without crossing any intermediate space). In some examples, the fixture body 11 can have two similar or different fixture surfaces 13 on opposite faces of the fixture body 11.

[0054] In the example shown, the suction fixtures 14 are arranged in two rows, for example, each row corresponding to a position along the internal suction channel. In other examples, the suction fixtures 14 can be arranged on the fixture surface 13 in other ways.

[0055] Arranging the suction fixtures 14 along a continuous fixture surface 13 can allow for increased flexibility in clamping workpieces 15 of different sizes, for example, by eliminating the possibility of a small workpiece 15 being located mostly or entirely in the space between different arms of the fixture surface 13. As described above, a flow restrictor that limits inflow through each suction fixture 14 can limit inflow through any suction fixture 14a that is not covered by a workpiece 15, or through a suction fixture 14b that is partially covered by a workpiece 15.

[0056] Figure 3 yes Figure 1 A schematic cross section of a suction fixture of a workpiece fixture is shown.

[0057] In the example shown, the suction clamp 14 includes a single suction opening 16. In other examples, the suction clamp may include more than one suction opening.

[0058] Suction can be applied to the suction opening 16 via a suction channel 26, which can extend internally to the fixture body 11, such as along a fixture arm 12 along which the suction fixture 14 is positioned. For example, the proximal end of the suction channel 26 can be fluidly connected to the suction connector 18 of the workpiece fixture 10. Generally, a single suction channel 26 can be connected to more than one suction opening 16. For example, all of the suction openings 16 along a single fixture arm 12 can lead to a single suction channel 26.

[0059] In the example shown, the suction opening 16 is connected to the suction channel 26 via the flow restrictor 24 (e.g., via Figure 3 In the example shown, the restrictor 24 is in the form of a tortuous channel in which the flow is deflected by a plurality of baffles 28. Alternatively or additionally, the restrictor 24 may have another form, for example, including a SASO structure, or another arrangement of one or more baffles, fins, constrictions, bends, twists, tortuosity or other structures to limit the inflow rate of air or other fluid through the suction opening 16 and the restrictor 24. The restrictor 24 may include an adjustable or non-adjustable needle valve or other constriction.

[0060] In the example shown, the flow restrictor 24 is located between the suction opening 16 and the suction channel 26. Alternatively or additionally, the flow restrictor 24 can be located in the suction channel 26 or the suction connector 18, between the suction channel 26 and the suction connector 18, or at other locations in the fluid path between the suction opening 16 and the suction connector 18 (for example, at a point where the suction channel 26 branches into two or more branch channels, each branch channel is connected to a different suction opening 16). For example, a single flow restrictor 24 can be used to limit the inflow via two or more suction openings 16. The flow restrictor 24 can be located in the fixture base 20, or in a conduit between the suction source and the suction connector 18.

[0061] In the example shown, the suction opening 16 is surrounded by a resilient sealing structure in the form of a resilient cup 22. When the surface of the workpiece 15 is placed near the suction opening 16 and suction is applied to the suction opening 16, the workpiece 15 can be drawn toward the suction opening 16 and the fixture surface 13. When the workpiece 15 contacts the edge 23 of the resilient cup 22, the contact between the workpiece 15 and the edge 23 of the resilient cup 22 can form a seal. Thus, the suction can create a partial vacuum within the resilient cup 22, so that the ambient air pressure pushes the workpiece 15 toward the suction opening 16.

[0062] Further suctioning the workpiece 15 toward the suction opening 16 can press the elastic cup 22 toward the fixture surface 13. The flexibility and elasticity of the elastic cup 22 can enable the elastic cup 22 to flatten between the workpiece 15 and the fixture surface 13. The flattening of the elastic cup 22 can increase the contact area between the elastic cup 22 and the workpiece 15. The increase in the contact area can increase the friction between the workpiece 15 and the flattened elastic cup 22, thereby increasing the friction between the workpiece 15 and the suction fixture 14.

[0063] Alternatively or additionally, the elastic sealing structure can have another form. For example, the elastic sealing structure can have the form of a gasket, a washer, a deformable nozzle, or other structures that can form a seal between the suction opening 16 and the workpiece 15 and promote the friction between the workpiece 15 and the suction fixture 14.

[0064] In some cases, for example, when the surface of the workpiece 15 is warped, one or more suction fixtures 14 may not be able to sufficiently suck the surface of the workpiece 15 toward the suction openings 16 of the suction fixture 14 so as to cover the suction openings 16 and form an airtight seal between the workpiece 15 and the suction openings 16. The presence of a restrictor 24 in the inflow path between the suction openings 16 and the suction connector 18 may limit the inflow rate through the uncovered suction openings 16. Due to the inflow rate through all uncovered suction openings 16, the suction applied to the covered and sealed suction openings 16 (assuming that the workpiece 15 surface contacts at least some, preferably at least three, of the suction openings 16) can remain sufficient to firmly clamp the workpiece 15 and allow reliable and precise manipulation of the workpiece 15. (In the absence of a restrictor, all suction applied via the suction connector 18 would result in increased inflow through the uncovered suction openings, thereby disrupting or preventing the application of any suction via the covered suction openings.)

[0065] In the example shown, each suction clamp 14 and its resilient cup 22 (or similar resilient sealing structure) extend a fixed distance from the surface of the clamp arm 12 facing the workpiece 15. The number and position of the suction clamps 14 on each clamp arm 12, as well as the number and shape of the clamp arms 22, can be designed to ensure that the minimum number of suction clamps 14 can clamp the surface of even a warped workpiece (e.g., within the range of warping that does not make the workpiece 15 unusable). For example, in some cases, clamping the workpiece by two or more suction clamps 14 may be sufficient for the workpiece clamp 10 to firmly clamp the workpiece. In some cases, clamping the workpiece by three or more suction clamps 14 may be considered sufficient to stably and reliably clamp the workpiece.

[0066] Figure 4A Schematically shows Figure 3 A variation of the suction clamp shown, Figure 4B yes Figure 4A A schematic cross section of a suction fixture is shown.

[0067] The suction fixture 41 is similar in construction to the suction fixture 14 ( Figure 3 ), including a suction opening 16 surrounded by a resilient cup 22. For example, the resilient cup 22 can be formed of a flexible and resilient polymer, such as silicone or other resilient materials.

[0068] In one example, the suction fixture 41 can be held in a circular opening on the fixture surface 13. The area of ​​the fixture body 11 below the circular opening can include the suction channel 26. For example, the circular opening can lead to the suction channel 26. The diameter of the circular opening can be smaller than the diameter of the lip 46 but larger than the diameter of the groove 48 between the lip 46 and the elastic cup 22. The lip 46 can also be made of an elastic material. For example, the lip 46 and the elastic cup 22 can be manufactured as (e.g., molded as) a single component.

[0069] For example, to attach the suction fixture 41 to the circular opening in the fixture surface 13, the rod 42 of the suction fixture 41 can be inserted into the opening until the lip 46 passes through the opening (e.g., bends or otherwise twists during insertion). Once the lip 46 passes through the circular opening, the elasticity of the lip 46 can open the lip 46 to prevent the suction fixture 41 from being removed from the circular opening. For example, the proximal outer surface of the lip 46 can taper outwardly and distally toward the elastic cup 22 to facilitate the bending or folding of the lip 46, thereby enabling the lip 46 to be inserted through the circular opening. The tapering can prevent the lip 46 from bending proximally toward the rod 42, thereby preventing the lip 46 from withdrawing from the circular opening.

[0070] In the example shown, the rod 42 can be in the form of a cylinder that is truncated laterally to form a flat side 44. The flow restrictor 24 connects the suction opening 16 at the distal end of the suction fixture 41 to the area between the side 44 of the rod 42 and the cylinder inner surface 50 of the outer member including the elastic cup 22 and the lip 46. Therefore, the cylinder inner surface 50 surrounds at least a portion of the length of the rod 42. The area between the side 44 and the cylinder inner surface 50 forms a fluid connection between the suction opening 16 and the proximal side of the rod 42 (e.g., to the lip 46). In the example shown, the baffle 28 of the flow restrictor 24 is located in the space between the side 42 and the cylinder inner surface 50.

[0071] In this example, when the rod 42 is inserted into the circular opening leading to the suction conduit 26, the inflow may be blocked by the abutting interface between the cylindrical inner surface 50 and the cylindrical outer surface of the rod 42 except along the side 44. The space between the side 44 and the cylindrical inner surface 50 forms a fluid connection between the suction opening 16 and the suction conduit 26. The fluid connection between the suction opening 16 and the suction conduit 26 includes a structure (in the example shown, a baffle 28, or other structure) that forms a flow restrictor 24, so that the inflow through the suction fixture 41 can be limited even when not in contact with the surface of the workpiece 15.

[0072] Other configurations of the suction clamp are possible.

[0073] Alternatively or additionally, one or more suction clamps of the workpiece clamp 10 may extend an adjustable length from the clamp arm 12 toward the workpiece 15. When a warped workpiece is clamped by the plurality of extendable suction clamps and drawn toward the clamp arm 12, some of the extendable suction clamps may extend outward from the clamp arm 12 to maintain clamping while compensating for any warping.

[0074] Figure 5 is a schematic side view of a variation of a suction clamp in which the suction clamp is extendable from a workpiece clamp.

[0075] The extendable suction clamp 30 includes an extension mechanism 32 to extend the distal end of the extendable suction clamp 30 (on which the resilient cup 22 is located in the example shown) a variable distance from the clamp arm 12. Extension and retraction or compression of the extension mechanism 32 to change the variable distance is represented by arrow 34.

[0076] In the example shown, the extendable suction clamp 30 is constructed similarly to the suction clamp 14, as shown in FIG. Figure 3 For example, the extendable suction fixture 30 includes a suction opening 16 (in Figure 5The suction opening 16 is provided with one or more flow restrictors 24 between the suction opening 16 and a connection with a suction source (e.g., a suction connector 18 or the like) that applies suction to the suction opening 16 and the extendable suction fixture 30. For example, the flow restrictor 24 can be located within the extendable suction fixture 30, the fixture arm 12, the fixture base 20, or at other locations within the workpiece fixture 10.

[0077] In one example of the extension mechanism 32, the extension mechanism 32 includes a mechanism configured to fully extend the extendable suction clamp 30 when the extendable suction clamp 30 does not clamp the workpiece. Therefore, the extendable suction clamp 30 is usually extended until the extendable suction clamp 30 clamps a portion of the workpiece surface.

[0078] In one example, the extension mechanism 32 can include one or more resilient mechanical or pneumatic elements that are fully extended when not compressed. For example, the resilient element can include one or more compressible springs or rods that are fully extended when not compressed. The compressible element can extend within the extension mechanism 32 from a point near the distal end of the extension mechanism 32 to a proximal point, such as within the clamp arm 12. When the element is compressed, a portion of the extension mechanism 32 can be pushed into the clamp arm 12, or a telescopic or foldable wall of the extension mechanism 32 can be shortened.

[0079] As another example, the outer wall of the extension mechanism 32 may include resilient accordion folds or otherwise be configured to enable compressive forces to cause the wall of the extension mechanism 32 to crease or crumple while enabling the wall to return to its uncompressed, extended shape when the compressive forces are removed.

[0080] The pneumatic element may include a sealing tube having two or more telescoping sections that enable the sealing tube to shorten when subjected to a compressive force. For example, the sealing tube may extend within the extension mechanism 32 from a point near the distal end of the extension mechanism 32 to a proximal point, such as within the clamp arm 12. Alternatively or additionally, the extension mechanism 32 may include a chamber into which compressed air or other fluid may be introduced. For example, air may be blown into the chamber from an exhaust mechanism of a suction source that applies suction to the suction opening 16.

[0081] With the extendable suction clamps 30 normally extended, the surface of the workpiece can be made to approach (e.g., by a robot or other automated mechanism, or by a manually controlled mechanism, or otherwise) a clamp arm 12 of a workpiece clamp 10 that includes one or more extended extendable suction clamps 30. Typically, as the workpiece 15 approaches the clamp arm 12, suction is applied to the suction opening 16 of each extendable suction clamp 30 of the workpiece clamp 10 (as well as the suction opening 16 of any suction clamp 14 that is not extendable).

[0082] Typically, when a surface area of ​​the workpiece 15 is brought sufficiently close to the distal end of one or more extendable suction fixtures 30, one or more areas of the surface of the workpiece 15 may initially contact a portion of the resilient sealing structure (e.g., a portion of the edge 23 of the resilient cup 22) at the distal end of the extended extendable suction fixture 30. The suction applied to the extendable suction fixture 30 may cause the resilient sealing structure and the surface of the tool 15 to be attracted together. Thus, the resilient sealing structure may form a seal between the workpiece 15 and the extendable suction fixture 30. For example, the entire edge of the resilient sealing structure in the form of the resilient cup 22 may be sucked toward the surface of the workpiece 15 and in physical contact therewith. Thus, the interior of the resilient cup 22 (or other resilient sealing structure) may form a chamber whose only opening is the suction opening 16.

[0083] In this case, continued application of suction to the suction opening 16 can draw fluid out of the chamber formed between the surface of the workpiece 15 and the resilient cup 22 (or other resilient sealing structure). As a result, the suction force can overcome the distal thrust of the extension mechanism 32 and draw the distal end of the extendable suction clamp 30 proximally toward the clamp arm 12 along with the attachment surface of the workpiece 15. The proximal inward movement of the surface of the workpiece 15 can increase the likelihood that the surface of the workpiece 15 will be similarly clamped by other extendable suction clamps 30 or suction clamps 14.

[0084] The presence of the flow restrictor 24 can limit the inflow through any extendable suction fixture 30 or suction fixture 14 that is not in contact with, and therefore not sealed by, the surface of the workpiece 15. The limited inflow can thus ensure that the suction force applied by any extendable suction fixture 30 or suction fixture 14 that is in contact with the surface of the workpiece 15 is able to maintain contact.

[0085] Alternatively or additionally, the extension mechanism 32 may include a controllable motor (e.g., an electric motor having a transmission that converts circular motion of the motor into linear motion of the extension mechanism 32) or an actuator (e.g., a linear actuator, e.g., electrically operated), which may be operated, for example, by a controller of the workpiece clamp 10 to extend or retract the distal end of the extendable suction clamp 30. For example, the clamp arm 12, the extendable suction clamp 30, or the workpiece clamp 10 may be provided with a sensor configured to sense the proximity of a portion of the workpiece 15 proximate to the surface of the extendable suction clamp 30. When the proximity is detected, the extension mechanism 32 may be operated to extend the extendable suction clamp 30 toward the workpiece 15. When contact is sensed (e.g., by a sensor that detects a reduction in inflow through the suction opening 16 of the extendable suction clamp 30), the extension mechanism 32 may be operated to pull the surface of the workpiece 15 toward the clamp arm 12.

[0086] Other types of mechanisms are possible for operation of the extension mechanism 32. The extension mechanism 32 can facilitate the workpiece clamp 10 to clamp a workpiece by positioning the distal end of the extendable suction clamp 30 close enough to the surface of the workpiece 15 to clamp the surface despite the restricted inflow through each suction opening 16 limited by the flow restrictor 24.

[0087] Different embodiments are disclosed herein. Features of certain embodiments may be combined with features of other embodiments; therefore, certain embodiments may be a combination of features of multiple embodiments. The above description of embodiments of the present invention has been given for the purpose of illustration and description. It is not exhaustive, nor is it intended to limit the invention to the precise form disclosed. It will be appreciated by those skilled in the art that many modifications, variations, substitutions, changes, and equivalents are possible in light of the above teachings. Therefore, it will be appreciated that the appended claims are intended to cover all such modifications and changes that fall within the true spirit of the present invention.

[0088] Although certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes and equivalents will now occur to those skilled in the art. It is therefore to be understood that the appended claims are intended to cover all such modifications and changes that fall within the true spirit of the invention.

Claims

1. A fixture for clamping a workpiece, the fixture comprising: a body having a flat clamp surface, the clamp surface comprising a plurality of openings distributed on the clamp surface, each of the openings being connectable to a suction source; as well as at least one flow restrictor located between the plurality of openings and a connector of the clamp to the suction source to restrict inflow through each of the plurality of openings so that when suction is applied to the plurality of openings, a portion of a workpiece surface covers at least one of the plurality of openings and another of the openings remains uncovered, the suction force at the covered opening is strong enough to clamp the workpiece surface, wherein one of the plurality of openings comprises a resilient sealing structure, the resilient sealing structure being configured to form a seal between the opening and the workpiece surface when suction is applied to the opening when the workpiece surface contacts the resilient sealing structure, wherein the elastic sealing structure is connectable to the fixture surface via a rod, the rod being insertable into the opening of the plurality of openings, wherein the rod is in the form of a cylinder which is truncated laterally to form flat sides, Wherein, the at least one flow restrictor is located in the space between the side surface and the cylindrical surface surrounding the rod.

2. The clamp according to claim 1, wherein: The body includes a plurality of arms extending from a single base.

3. The clamp according to claim 2, wherein: A conduit from the connector to one of the plurality of openings extends along one of the plurality of arms.

4. The clamp according to claim 1, wherein: The fixture surface is continuous.

5. The clamp according to claim 1, wherein: The at least one flow restrictor is located between one of the plurality of openings and a conduit that forms a fluid connection between the opening and the connector.

6. The clamp according to claim 1, wherein: The flow restrictor includes a plurality of baffles.

7. The clamp according to claim 6, wherein: The flow restrictor includes an adaptive segmented orifice having staggered opposing fins mounted inside.

8. The clamp according to claim 1, wherein: The flow restrictor includes a constriction.

9. The clamp according to claim 8, wherein: The flow restrictor includes a needle valve.

10. The clamp according to claim 9, wherein: The elastic sealing structure includes an elastic cup.

11. The clamp according to claim 9, wherein: The elastic sealing structure includes a gasket or a washer.

12. The clamp according to claim 1, wherein: The resilient sealing structure includes a polymer.

13. The clamp according to claim 12, wherein: The polymer includes silicone.

14. The clamp according to claim 1, wherein: One of the plurality of openings includes an extension mechanism to extend the opening outwardly from the fixture surface toward the workpiece surface.

15. The clamp according to claim 14, wherein: The extension mechanism is configured to extend the opening outward when the opening is not in contact with the workpiece surface.

16. The clamp according to claim 15, wherein: The extension mechanism is configured so that when suction is applied to the opening and the opening is in contact with the surface of the workpiece, a suction force can be generated to suck the opening toward the fixture surface.

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