Workpiece gripping device

Abstract

Provided is a workpiece gripping device that realizes highly reliable workpiece gripping and efficient workpiece gripping even in a case where a workpiece having a three-dimensional shape is included.　This workpiece gripping device for gripping a workpiece is characterized by having: a frame-like support part; a flexible and airtight hollow bag-like body which is attached to one surface of the frame-like support part and in which a substance that undergoes a change of state due to a jamming transition is accommodated; an electrostatic clamping means which is provided on a workpiece contacting surface of the hollow bag-like body, and which electrostatically clamps the workpiece; and a shape-retaining means which deforms and retains the shape of the hollow bag-like body in accordance with the shape of the workpiece. The workpiece gripping device is characterized in that: the frame-like support part and the hollow bag-like body respectively have at least a non-contact region in which the frame-like support part and the hollow bag-like body do not contact each other, and the hollow bag-like body is attached to one surface of the frame-like support part; and, when in use, the workpiece is pushed against the workpiece contacting surface of the hollow bag-like body and is gripped and clamped, by utilizing the shape retention by the jamming transition, and the electrostatic clamping.

Description

Workpiece gripping device

[0001] The present invention relates to a workpiece gripping device for gripping a workpiece (hereinafter simply referred to as a "workpiece") that is an object to be gripped.

[0002] Conventionally, when transferring or transporting objects in assembly plants, manufacturing plants, etc., robots (also called robot arms or robot manipulators) equipped with robotic hands (also called end effectors) equipped with mechanically operated gripping mechanisms have been used to grasp and lift objects. End effectors such as robotic hands have mainly adopted methods of grasping objects with mechanical mechanisms that mimic the movements of claws or fingers, depending on the actual task to be performed and the shape, hardness, material, etc. of the workpiece.

[0003] Recently, there has been a demand for the same end effector to be able to grip, transfer, or transport not only nearly identical items but also a wide variety of items of various materials, sizes, shapes, or weights, one by one. Even within the same production line, there is a demand for efficient gripping of such items without the hassle and time loss of sorting or the need to change equipment.

[0004] To meet these demands, particularly in order to improve the ability to fit to the three-dimensional shape of an object, methods have been developed to equip end effectors with mechanisms that can change the rigidity of the part that grips the workpiece. To achieve this, a gripper device utilizing jamming transition has been adopted. This gripper device uses a bag containing sealed powder and granular material, which is pressed against the workpiece while still in a soft state, to conform to the shape. Then, while in this state, the bag's jamming transition is used to harden the interior, and the workpiece is gripped by maintaining the enveloping shape of the bag.

[0005] For example, in Patent Document 1, in response to the problems with conventional suction-type robot hands and configurable airbags, or the problems with conventional grippers that utilize jamming transfer, an suction gripper that also utilizes jamming transfer is proposed in which the hollow bag that comes into contact with the workpiece is made hemispherical, thereby eliminating parts that are not involved in gripping and resulting in an improved, more efficient structure.

[0006] 3, for example, Patent Document 2 proposes an adhesive gripper that includes a fixing member 1 having a hole 7, a gripping unit 2 that includes a plurality of flexible and airtight bag-shaped portions 2 a, 2 b that are arranged on either side of the hole 7 so that the interiors of the bag-shaped portions are connected in the central axial direction of the hole 7 and that are filled with powder or granules 8 and a fluid, and a hardening means 3 that hardens the plurality of bag-shaped portions 2 a, 2 b, and that is used by pressing one of the plurality of bag-shaped portions 2 a, 2 b against a workpiece. The adhesive gripper of Patent Document 2 is said to be able to grip a variety of objects by having a gripping unit 2 that includes a plurality of bag-shaped portions 2 a, 2 b, which increases the deformable capacity of the bag-shaped portions.

[0007] Furthermore, Patent Document 3 discloses a shape-conforming electroadhesive gripper for picking up irregular objects. For example, as shown in Figures 3 and 4, the gripper includes a main body 110 and an electroadhesive module 120. The main body 110 has a base 111 with a port 115 and a flexible film 113 attached thereto. The flexible film 113 changes its rigidity to deform to fit the shape of the target workpiece, and then fixes the deformed shape. The flexible film 113 may be filled with a filler such as small particles. Furthermore, the electroadhesive module 120 is formed from an electrorheological elastomer containing a polarizable dielectric material within the elastomer material. When an electric field is applied, the electroadhesive module 120 changes its rigidity to deform to fit the shape of the workpiece, and the electrostatic force generated is utilized to pick up the workpiece.

[0008] JP 2012-236240 A JP 2021-065977 A U.S. Patent Application Publication No. 2020 / 0023527

[0009] As described above, the method described in Patent Document 1 has several advantages over conventional gripper devices that utilize jamming transition, in that the hollow bag is made hemispherical, thereby providing an efficient structure in which inefficient parts that are not involved in gripping are eliminated. However, the method has the following problems.

[0010] That is, in the gripper device of Patent Document 1, as can be seen from FIG. 3(B) and other figures, the upper end of the gripping portion (reference numeral: 12) including the hollow bag is attached in close contact with the fixed member (reference numeral: 11) over its entire surface in order to effectively apply a pressing force against the pressure-receiving surface and allow the hollow bag to conform to the shape of the workpiece. If the gripping portion (hollow bag) is attached to the fixed member over its entire surface in this manner, when the pressure inside the bag is reduced (suctioned) to cause jamming transition, the upper part of the bag is pulled and contracted, which may cause the bag to separate from the workpiece or may impair the close contact (fit) between the bag and the workpiece. Furthermore, since the fixed member is located over the entire surface of the hollow bag, when the hollow bag is pressed against the workpiece, deformation (movement) of the bag, particularly on the fixed member side, is limited, which may reduce the amount of deformation of the bag (the amount of sinking or wrapping around the workpiece) and reduce the close contact (fit) between the bag and the workpiece. This may result in a loss of secure grip of the workpiece.

[0011] Furthermore, the suction gripper of Patent Document 2 is said to have a gripping portion 2 including multiple bag-shaped portions 2 a, 2 b sandwiched between holes 7 in a fixing member 1, thereby increasing the deformable capacity of the bag-shaped portion. However, because the fixing member 1 is provided so as to contact the side of the bag-shaped portion, there is a concern that the pressing force of the bag-shaped portion against the workpiece may be insufficient, and the degree of deformation and adhesion (fit) of the bag-shaped portion to the workpiece may be insufficient. Furthermore, there is a concern that the amount of powder or the like filled inside the bag-shaped portion may suppress deformation of the bag-shaped portion relative to the workpiece. However, the larger the holes 7, the more likely the filler material is to accumulate at the bottom of the bag-shaped portion, which makes the suppression of deformation more pronounced, and similarly, there is a concern that the bag-shaped portion may not be able to deform properly relative to the workpiece.

[0012] Furthermore, in the shape-conforming electric adhesive gripper of Patent Document 3, as can be seen from FIG. 3 and the like, the flexible film 113 is attached to the entire surface of the base 111, and therefore, as in the case of Patent Document 1, when the gripper is pressed against the workpiece, the deformation (movement) of the flexible film 113 is restricted, which raises concerns that the amount of deformation of the film relative to the workpiece (the amount of sinking into the workpiece, the amount of wrapping) will be reduced. Furthermore, similarly, the electric adhesive module 120 is in contact with the flexible film 113 over its entire surface, which raises concerns that when the gripper is pressed against the workpiece, the deformation (movement) of the electric adhesive module 120 relative to the workpiece will be restricted. In addition to these points, the electrorheological elastomer used for the electric adhesive module 120 is BaTiO ３ However, because the electrical adhesive module 120 uses specific inorganic materials such as acrylic resin, it is expensive and impractical. Furthermore, in terms of usage and characteristics, the elastomer material used in the electrical adhesive module 120 is a polymer material, such as natural rubber or silicone, which has a relatively low dielectric constant and is less likely to generate static electricity, and therefore the generation of electrostatic force is likely to be hindered. Furthermore, in order to generate a strong electrostatic force, a large amount of inorganic material must be dispersed, which increases the hardness of the electrical adhesive module 120 and makes it prone to losing its ability to fit and pick up the workpiece. Furthermore, when using such inorganic materials, simply mixing them as powder leaves them in an amorphous state and does not exhibit sufficient dielectric properties, so they usually need to be sintered to crystallize them. The use of crystallized inorganic materials also increases the hardness of the electrical adhesive module 120, raising concerns that it may also lose its ability to fit and pick up the workpiece. Furthermore, because the electrical adhesive module 120 has this configuration, a fairly high voltage is required to generate a high electrostatic force, making it difficult to adjust the electrostatic force.

[0013] Therefore, the inventors of the present application, while taking into consideration the mechanisms described in the above Patent Documents 1 to 3, conducted extensive research into a workpiece gripping device that can achieve highly reliable gripping of a workpiece without the above-mentioned concerns, and came up with the idea of ​​improving the shape of the support part corresponding to the fixing member and utilizing electrostatic attraction together with jamming transfer, thereby completing the present invention. Furthermore, they also came up with the idea of ​​optimizing the degree of contact between the hollow bag-shaped body, which is the contact part with the workpiece, and the support part, optimizing the material of the hollow bag-shaped body, and more preferably optimizing the configuration of the electrostatic attraction means.

[0014] Therefore, the object of the present invention is to provide a workpiece gripping device that can grip workpieces with high reliability, even when the workpieces have three-dimensional shapes, and that enables efficient workpiece gripping, such as by reducing the need for device modifications.

[0015] That is, the gist of the present invention is as follows: (1) A workpiece gripping device for gripping a workpiece, comprising: a frame-shaped support part, a flexible and airtight hollow bag-like body attached to one surface of the frame-shaped support part and containing a substance whose state changes due to jamming transition, electrostatic attraction means provided on the surface of the hollow bag-like body that comes into contact with the workpiece and electrostatically attracts the workpiece, and shape retention means that deforms the shape of the hollow bag-like body to match the shape of the workpiece and retains it, the frame-shaped support part and the hollow bag-like body each having at least a non-contact area where the frame-shaped support part and the hollow bag-like body do not come into contact with each other, and the hollow bag-like body is attached to one surface of the frame-shaped support part, and in use, the workpiece is pressed against the surface of the hollow bag-like body that comes into contact with the workpiece to grip and attract it, utilizing the retention of the shape due to jamming transition and the electrostatic attraction. (2) The workpiece gripping device according to (1), characterized in that the area of ​​the non-contact region is 30 to 85% of the total area of ​​the frame-shaped support portion including the non-contact region. (3) The workpiece gripping device according to (1), characterized in that at least the surface of the hollow bag-shaped body that comes into contact with the workpiece is made of a material having a thickness of 10 to 150 μm, a tensile modulus of elasticity of 10 to 50 MPa, and a tensile elongation of 100 to 1000%. (4) The workpiece gripping device according to (1), characterized in that at least the surface of the hollow bag-shaped body that comes into contact with the workpiece is made of one or more materials selected from the group consisting of polyurethane, polyurethane elastomer, soft vinyl chloride, polyvinylidene chloride, polyolefin, and polyolefin copolymer. (5) The workpiece gripping device according to (1), characterized in that the substance that changes state due to jamming transition is one or more materials selected from the group consisting of powder, granules, and fluid. (6) The workpiece gripping device according to (1), characterized in that the shape maintaining means is a pressure adjusting means for adjusting the pressure inside the hollow bag-shaped body, and the pressure inside the hollow bag-shaped body is reduced by the pressure adjusting means to maintain the shape. (7) The workpiece gripping device according to (6), characterized in that an air vent is attached to the hollow bag-shaped body, and the pressure is adjusted by letting in and out gas through the air vent.(8) The workpiece gripping device according to any one of (1) to (7), wherein the hollow bag-shaped body is composed of an upper sheet attached to one surface of the frame-shaped support part and a lower sheet attached by fusion or adhesive to the surface of the upper sheet opposite the attached surface, the lower sheet having a surface that contacts the workpiece and also having the electrostatic attraction means. (9) The workpiece gripping device according to (8), wherein the electrostatic attraction means is an electrostatic chuck, and the lower sheet is an electrostatic chuck sheet having an electrode therein, the electrostatic chuck sheet being constructed by sequentially laminating and fusion-bonding or bonding a first resin film on the inside side of the hollow bag-shaped body, an electrode, and a second resin film on the outside side of the hollow bag-shaped body, the second resin film having a surface that contacts the workpiece. (10) The workpiece gripping device according to (9), wherein the first resin film and / or the second resin film has a thickness of 10 to 150 μm, a tensile modulus of elasticity of 10 to 50 MPa, and a tensile elongation of 100 to 1000%. (11) The workpiece gripping device according to (9), wherein the first resin film and / or the second resin film is made of one or more materials selected from the group consisting of polyurethane, polyurethane elastomer, soft vinyl chloride, polyvinylidene chloride, polyolefin, and polyolefin copolymer. (12) The workpiece gripping device according to (9), wherein the electrode is a bipolar electrode having a positive electrode and a negative electrode, is formed from a cured product of a conductive paint, and is an electrode sheet having a thickness of 30 to 100 μm. (13) The workpiece gripping device according to (12), wherein the bipolar electrode is an electrode formed by a pair of comb-shaped electrodes, the comb teeth of which are interdigitated with each other on the same plane while maintaining a constant distance from each other. (14) The workpiece gripping device according to (9), wherein the electrostatic chuck sheet has a thickness of 90 to 350 μm, a tensile modulus of elasticity of 10 to 50 MPa, and a tensile elongation of 100 to 1000%.

[0016] The workpiece gripping device of the present invention can grip a workpiece with high reliability even when the workpiece has a three-dimensional shape. Furthermore, it can grip a workpiece efficiently by reducing the need for device modifications.

[0017] FIG. 1 is a schematic diagram showing the top view of an example of a workpiece gripping device of the present invention. FIG. 2 is a cross-sectional view of the workpiece gripping device shown in FIG. 1 along the line A-A. FIG. 3 is a schematic diagram illustrating an example of a series of operations when gripping a workpiece using the workpiece gripping device of the present invention. (I) shows the state before gripping the workpiece, (II) shows the state after gripping the workpiece, and (III) shows the state after gripping and lifting the workpiece. FIG. 4 is a cross-sectional view of another example of a workpiece gripping device of the present invention. FIG. 5 is a schematic diagram showing an electrostatic chuck sheet, which is an example of the electrostatic adsorption means of the workpiece gripping device of the present invention. (FIG. 5A) is a plan view, and (FIG. 5B) is a cross-sectional view of the line B-B in (FIG. 5A).

[0018] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The present invention is not limited to the following embodiments, and various modifications and combinations of the following embodiments are possible without departing from the spirit of the present invention. In this specification and drawings, components having substantially the same functions are designated by the same reference numerals, and redundant description may be omitted.

[0019] An example of a workpiece gripping device of the present invention is shown in Figures 1 and 2. The workpiece gripping device of the present invention (reference numeral 1; hereinafter, only numerals are shown, and the same applies to other numerals) comprises a frame-shaped support portion 2, a flexible and airtight hollow bag-like body 3 attached to one surface of the frame-shaped support portion 2 and containing a substance 4 whose state changes due to jamming transition, electrostatic attraction means (not shown) provided on a contact surface 3b of the hollow bag-like body 3 with the workpiece and electrostatically attracting the workpiece, and shape retention means (not shown) that deforms the shape of the hollow bag-like body to match the shape of the workpiece and retains it.

[0020] Here, the hollow bag-shaped body 3 has at least a non-contact area 14 that does not come into contact with the frame-shaped support part 2 and is attached to the support part.

[0021] Furthermore, according to the workpiece gripping device of the present invention, when in use, the shape is maintained by jamming transfer and electrostatic adsorption is utilized to press the workpiece against the contact surface 3b of the hollow bag-shaped body with the workpiece, thereby gripping and adsorbing it.

[0022] <Frame-shaped support part> The frame-shaped support part 2 (hereinafter, may be simply referred to as "support part") is attached in close contact with a part of the hollow bag-like body 3 described below, and during use, has the role of pressing the hollow bag-like body 3 (transmitting the pressing force) and of fixing the hollow bag-like body 3 so that it does not sag due to gravity when suspended in the air (preventing deformation of the hollow bag-like body 3 during transportation). Furthermore, via this support part 2, it can also serve as a connecting device for attaching the workpiece gripping device 1 to other equipment or devices that perform the operation of a robot arm or the like.

[0023] 1 and 2, the frame-shaped support part 2 literally has a frame-like shape, and because it is open inside, it has a non-contact area that does not come into contact with the hollow bag-shaped body 3 described below. That is, at least a non-contact area 14 where the frame-shaped support part 2 and the hollow bag-shaped body 3 do not come into contact with each other is formed in the frame-shaped support part 2 and the hollow bag-shaped body 3. Specifically, as shown in FIGS. 1 and 2, at least a non-contact area 14 that does not come into contact with the frame-shaped support part 2 is formed on the upper surface side (support part side) 3a of the hollow bag-shaped body 3.

[0024] The formation of such a non-contact region 14 between the frame-shaped support portion 2 and the hollow bag-like body 3 prevents the hollow bag-like body 3 from being pulled upward, even when, for example, the interior of the bag is depressurized (suctioned) as a means for causing jamming transfer, and allows the bag to contract while fitting to the workpiece. In other words, even when the interior of the bag is depressurized (suctioned), the force that causes the bag to contract can be sufficiently applied to the workpiece. Furthermore, the presence of the non-contact region 14 reduces restrictions on the movement and deformation of the bag even when the hollow bag-like body 3 is pressed against the workpiece, ensuring a sufficient amount of deformation of the bag (the amount of sinking and wrapping around the workpiece) that follows the shape of the workpiece, thereby improving adhesion (fit) to the workpiece.

[0025] The size (area) of the non-contact region 14 is not limited as long as it can achieve the above-described functions and effects. However, it is preferable to set it so that the hollow bag-shaped body 3 deforms and sinks into or envelops the workpiece during use. Specifically, the area of ​​the open portion of the frame-shaped support part 2 is preferably 30 to 85%, and more preferably 50 to 85%, of the total area of ​​the frame-shaped support part 2 assuming there is no open portion inside. Alternatively, from another perspective, the frame-shaped support part 2 is preferably designed so that 30 to 85% of the total area of ​​the frame-shaped support part 2 on the upper surface side (support part side) 3a of the hollow bag-shaped body 3 constitutes the non-contact region 14. A more preferable area ratio of the non-contact region 14 of the hollow bag-shaped body 3 (3a) is 50 to 85%. If the non-contact region 14 is larger than this range, the contact area will be reduced, which may impair the adhesion between the frame-shaped support part 2 and the hollow bag-shaped body 3. Furthermore, there is a concern that the bag portion may move too much when ascending or moving at high speed. That is, this may cause the hollow bag-like body 3 to come off or fall from the frame-shaped support portion 2 during use, or the movement of the bag portion may cause the workpiece to come off the hollow bag-like body 3. On the other hand, if the non-contact region 14 is too small, the area of ​​close contact between the frame-shaped support portion 2 and the hollow bag-like body 3 increases, improving stability. However, as described above, there is a risk that the deformation and movement of the hollow bag-like body 3 may be excessively restricted during use, which may impair the close contact (fit) with the workpiece and impair the workpiece gripping function.

[0026] The shape of the frame-shaped support part 2 is sufficient as long as the non-contact area 14 is formed at least on the inside, and it is sufficient as long as it is literally frame-shaped. Furthermore, the outer shape is not limited to a square, and the frame may have a circular, elliptical, polygonal, or other shape. Furthermore, as long as the frame can sufficiently adhere to the hollow bag-shaped body 3, the shape does not have to be uniform in the thickness direction, and may even vary in shape in the thickness direction. These shapes can be appropriately set depending on the shape of the workpiece to be gripped and the shape of the attachment part to other equipment or devices, such as a robot arm, as long as the function of the frame-shaped support part 2 can be exhibited.

[0027] There are no limitations on the material of the frame-shaped support part 2, and it can be selected appropriately depending on the application. It is preferable that the material has at least a degree of rigidity that allows it to support the hollow bag-shaped body 3 and stabilize it during use. For example, it can be appropriately selected from metal, resin molded body, and composite members thereof. From the viewpoint of weight, it is preferable that it is made of a resin material. The frame-shaped support part 2 may be made of a laminate of one material or a laminate of multiple materials, or may be made of a single material or multiple materials connected together. There are also no limitations on its thickness, and from the viewpoint of stability, it is usually preferable to use one that is 3 mm to 10 mm.

[0028] <Adhesion Layer> As can be seen from FIG. 2 , the frame-shaped support 2 and the hollow bag-like body 3 are preferably adhered to each other via an adhesion layer 5 for the purpose of enhancing adhesion and stability. That is, the adhesion layer 5 is preferably disposed between the frame-shaped support 2 and the hollow bag-like body 3. The adhesion layer 5 is not limited as long as it can enhance adhesion and stability between the frame-shaped support 2 and the hollow bag-like body 3, and may be any layer capable of fixing the two together. For example, it may be an adhesion layer (e.g., an elastic material) made of a known resin material or an adhesive layer made of a known adhesive. More simply, it may be an adhesive sheet or tape such as double-sided tape. The thickness of the adhesion layer 5 is not limited, but is typically preferably in the range of 0.01 mm to 2 mm, more preferably 0.1 mm to 1 mm.

[0029] <Hollow bag-like body> The hollow bag-like body 3 contains a substance 4 whose state changes due to jamming transition, and is a bag-like body capable of forming a space for containing such a substance. The hollow bag-like body 3 may be made of a single material, or may be made of a combination of multiple materials. One method for combining multiple materials is, for example, using an upper sheet and a lower sheet, as described below. Furthermore, the bag portion does not need to be made of a single layer of the same material, and may be made of a laminate of a single material or multiple materials, or may be made of a single material or multiple materials connected together, depending on the application or purpose, or may be made of an appropriate combination of these.

[0030] As described above, the hollow bag-shaped body 3 has a non-contact region 14, and a portion of the upper surface side (support portion side) 3a is attached in close contact with one surface of the frame-shaped support portion 2. Here, "one surface" refers to the surface that serves as the pressing surface when the frame-shaped support portion 2 is pressed against the hollow bag-shaped body 3, specifically, the surface (bottom surface) of the frame-shaped support portion 2 shown in FIG. 2 that contacts the adhesive layer 5. The shape of the contact surface can be changed depending on the shape of the frame-shaped support portion 2. Here, it is preferable that the hollow bag-shaped body 3 is not attached to the other surface of the frame-shaped support portion 2. Although it depends on the use of the workpiece gripping device, it is usually practically preferable to attach, for example, an attachment for attaching to a robot or a frame for transmitting a pressing force to the other surface of the frame-shaped support portion 2 (the surface opposite the pressing surface (bottom surface)). Also, it is usually preferable that nothing be attached to the side surfaces (surfaces excluding the bottom and top surfaces) of the frame-shaped support portion 2 .

[0031] The hollow bag-like body 3 also has a side 3b on which the workpiece comes into contact. These 3a and 3b are not clearly distinguished, and they may exist to the extent that the roles of the support side 3a of the hollow bag-like body 3 on the frame-shaped support part 2 and the workpiece contact side 3b are roughly divided. In this regard, although the hollow bag-like body 3 is shown in Figure 2 as being made entirely of the same material, it may be made of two or more types of material, or 3a and 3b may be made of different materials.

[0032] As shown in FIG. 2 , the shape of the hollow bag-like body 3 is preferably a substantially hemispherical bag-like shape, taking into consideration the formation of an internal storage space and contact with the workpiece, but is not limited thereto. As long as an internal storage space can be formed, the hollow bag-like body 3 does not need to be bulged only on the lower side (the workpiece contact surface side). For example, the hollow bag-like body 3 may have a certain degree of bulge on the upper side (the bottom side of the frame-shaped support portion 2) as well, like a cushion or a floor cushion. However, as described above, a preferred embodiment is one in which the hollow bag-like body 3 is not provided on any surface other than the pressing surface (bottom surface) of the frame-shaped support portion 2. It may also have a shape with a horizontal bulge. Even if the hollow bag-like body 3 does not have the shape described above before use, it may have the shape described above during use. The shape of the hollow bag-like body 3 may be determined appropriately, taking into consideration the adhesion to the frame-shaped support portion 2, or the adhesion and fit to the workpiece. The extent to which the internal storage space is formed (internal volume) may also be determined appropriately based on the same viewpoint. From the viewpoint of contact with the workpiece and the contact area, it is preferable that the area of ​​the lower side (workpiece contact surface side) 3b of the hollow bag-like body 3 is larger than the workpiece.

[0033] The hollow bag-like body 3 must be flexible enough to change shape to fit the surface and three-dimensional shape of the workpiece, and must be made of an airtight material that does not allow gas to pass through, so that the shape can be changed even by pressure adjustment means (pressurization, depressurization) among the shape-retaining means described below. Since the workpiece can be gripped using jamming transition, it is particularly preferable for the hollow bag-like body 3 to be flexible, and it is preferably made of a relatively flexible and stretchable material that can easily follow the shape of the workpiece. It is also preferable for the hollow bag-like body 3 to be configured to have a thickness that does not impair this flexibility or stretchability.

[0034] In order to achieve such properties, the hollow bag-shaped body 3 is preferably made of a material having a tensile modulus of elasticity of 10 to 50 MPa and a tensile elongation of 100 to 1000%, and the thickness is preferably 10 to 150 μm.

[0035] A more preferable upper limit of the tensile modulus is 48 MPa, and an even more preferable upper limit is 46 MPa.

[0036] A more preferred lower limit of the tensile elongation is 200%, an even more preferred lower limit is 300%, and an even more preferred lower limit is 500%. On the other hand, a more preferred upper limit of the tensile elongation is 900%.

[0037] A more preferable upper limit of the thickness is 140 μm, and an even more preferable upper limit is 130 μm. If the thickness is too small, durability tends to be weakened, leading to damage due to external force during use or discharge in the electrostatic chuck sheet embodiment described below. Also, if the thickness is too large, the amount of deformation tends to be small, and the ability to conform to the workpiece tends to be poor.

[0038] There are no limitations on the material of the hollow bag-shaped body 3, but as described above, it is preferable that the material be relatively flexible and stretchable and have the above-mentioned preferred tensile modulus, tensile elongation, and thickness, and it is preferable that the material be appropriately selected from those that satisfy such preferred properties. A preferred material is resin.

[0039] Preferred resins include, for example, polyurethane, polyurethane elastomer, soft vinyl chloride, polyvinylidene chloride, polyolefin, polyolefin copolymer, etc. These resins can be selected from one type or a mixture of two or more types. Among these, it is more preferable to use polyurethane, polyurethane elastomer, and / or polyolefin copolymer from the viewpoint of having the above-mentioned tensile modulus and tensile elongation, or the predetermined dielectric constant and volume resistivity properties related to electrostatic adsorption characteristics.

[0040] Polyurethane elastomers are generally obtained by reacting a long-chain polyol, a chain extender, and a diisocyanate, and are composed of a soft segment having a structural unit derived from the long-chain polyol and a hard segment having a polyurethane structure obtained by reacting the chain extender with a diisocyanate. Polyurethane elastomers can be classified according to the type of long-chain polyol used as the soft segment component, and include polyester-based polyurethane elastomers, polyether-based polyurethane elastomers, and polycarbonate-based polyurethane elastomers. In this embodiment, polyester-based polyurethane elastomers are more preferred because they facilitate achieving the above-described physical properties. Commercially available polyurethane elastomers include the Higress series (Seedom Co., Ltd.), represented by Higress DUS202-CDR 6HF and Higress DUS605-CDR 6HI, the Silklon series (Okura Kogyo Co., Ltd.), and the Unigrand XN series (Nippon Unipolymer Co., Ltd.).

[0041] The polyolefin may be, for example, a polyethylene film made from ethylene, or a polyolefin resin made from an olefin monomer such as propylene, butene, pentene, hexene, heptene, or octene, or may be a film containing such a polyolefin resin as the main component (e.g., 80% by mass or more). Polyolefin copolymers obtained by copolymerizing two or more of these olefin monomers may also be used. Examples of such copolymers include ethylene and the above-mentioned olefin monomers other than ethylene. Commercially available polyolefin copolymers include Polygrace (Takeda Sangyo Co., Ltd.) and Artply (Diaplus Film Co., Ltd.).

[0042] As described below, the resin is preferably one that can be used to form the hollow bag-shaped body 3 in the form of a laminate of multiple resin sheets, and is preferably a resin that can be fused with heat and pressure, or that can be adhesive or bonded. More preferably, it is a resin that can be fused (thermally laminated) because this eliminates the need for an adhesive or pressure-sensitive adhesive layer. Examples of such resins include polyurethane elastomers and soft vinyl chloride, among the resins mentioned above.

[0043] Furthermore, in order to more effectively grip the workpiece on the contact surface 3b of the hollow bag-shaped body 3, it is preferable that the surface roughness be relatively small. To provide such roughness, a material having such roughness itself may be used, a commercially available surface adjusted to such roughness (sometimes called a mirror surface) may be used, or the surface may be appropriately processed and adjusted by a known method such as mirror finishing.

[0044] <Substance that changes state due to jamming transition, shape retention means> The hollow bag-like body 3 contains a substance 4 (hereinafter, sometimes simply referred to as "jamming substance 4") that changes state due to jamming transition. Here, jamming transition refers to a state change in which a powder consisting of a large number of particles of different sizes, such as sand or powder, behaves like a fluid when the density of the particles contained therein is below a certain threshold, but behaves like a solid when the density is above that threshold. The workpiece gripping device of the present invention can grasp or hold a workpiece by utilizing the jamming transition of this jamming substance 4 to deform and retain the shape of the hollow bag-like body 3. Then, in combination with adhesion by the electrostatic adhesion means described below, the workpiece is gripped by the hollow bag-like body 3.

[0045] The jamming substance 4 can be appropriately selected depending on the shape-retaining means for deforming and maintaining the shape of the hollow bag-shaped body 3. For example, if the shape-retaining means is a pressure-regulating means for adjusting (decompressing or compressing) the pressure inside the hollow bag-shaped body 3, a powder or granules made of one or more materials selected from the group consisting of general inorganic materials, organic materials, and metal materials can be used. Such powders or granules are not limited, and examples include beads made of natural mica, talc, aluminum, copper, or glass; beads made of resins such as rubber or polystyrene; and food powders such as coffee powder or wheat flour. The size (particle size) of the powder or granules is not limited, but typically, those with a median particle size of 10 μm to 500 μm can be widely used. From the viewpoint of usability, a median particle size of 50 μm to 200 μm is preferred.

[0046] When such powder or granules are used as the jamming material 4, the shape-maintaining means is a pressure-regulating means, which reduces the pressure inside the bag while the hollow bag 3 conforms to the shape of the workpiece, thereby maintaining the shape of the hollow bag 3 while gripping or embracing the workpiece. The workpiece can be gripped and lifted in this state. A typical pressure-reducing device (e.g., a vacuum pump or vacuum ejector) can be used as the pressure-regulating means. In this case, as shown in FIGS. 1 and 2 , a vent hole 6, a venting means such as a tube 8 connected to the vent hole 6, and a connecting part 7 are provided on the upper surface 3a of the hollow bag 3. The vent hole 6 is preferably provided in advance during the preparation of the hollow bag 3. A pressure-reducing device (not shown) is provided at the end of the tube 8. In other words, the pressure inside the hollow bag 3 is adjusted by introducing and evacuating gas such as air through the vent hole 6.

[0047] On the other hand, the jamming substance 4 may be a fluid, such as water or oil, and in this case, a liquid pump or the like capable of sucking such a fluid is used as the shape-maintaining means.

[0048] Furthermore, examples of the special jamming substance 4 include magnetic fluids (MR fluids) in which magnetic particles (granules) are dispersed in a liquid (fluid), and electrorheological fluids (ER fluids) in which insulating microparticles (granules) are dispersed in an insulating liquid (fluid). For these particles (granules), the shape-retaining means is, in the case of magnetic fluids, applying a magnetic field to the magnetic fluid using a permanent magnet or electromagnet to increase the viscosity of the magnetic fluid, and in the case of electrorheological fluids, applying an electric field to the electrorheological fluid using an electric field application unit to increase the viscosity of the electrorheological fluid. As long as the characteristics of the jamming substance 4 can be utilized to deform and retain the shape of the hollow bag-shaped body 3 to match the shape of the workpiece, any method can be used, without being limited to the jamming substance 4 or shape-retaining means described above. Among these, from the standpoints of ease of use and simplicity, it is preferable that the shape-retaining means be a pressure-regulating means that allows air or other gases to be introduced or released through the air vent 6. When the shape-retaining means is the pressure-adjusting means, it is preferable that the jamming substance 4 be a powder or granules made of one or more materials selected from the group consisting of the above-mentioned general inorganic materials, organic materials, and metal materials.

[0049] 3 is a schematic diagram showing an example of a series of operations performed when the workpiece gripping device 1 grips a workpiece 13 when a pressure adjusting means is used as the shape maintaining means. In this Fig. 3, the workpiece gripping device 1 is shown in a simplified manner, but it is assumed that it is provided with the aforementioned components that are not shown, and that the workpiece contact surface 3b of the hollow bag-shaped body 3 is provided with electrostatic adsorption means, which will be described later.

[0050] 3(I) shows the state immediately before the workpiece contact surface 3b of the hollow bag-like body 3 is about to be pressed against the workpiece 13. In this state, the pressure of the hollow bag-like body 3 has not been reduced to an extent that would cause it to deform or maintain its shape, and it is in a state where the shape of the hollow bag-like body 3 can be deformed when pressed against the workpiece. Note that in this state, the hollow bag-like body 3 may be pressurized or depressurized to a certain extent as long as the purpose is not impaired.

[0051] Next, FIG. 3 (II) shows a state in which the workpiece gripping device 1 is lowered from the state shown in FIG. 3 (I) to press the hollow bag-like body 3 (3b) against the workpiece 13. The arrow α in the figure indicates the pressing force at this time. As a result, the hollow bag-like body 3 deforms (elastically deforms) to conform to the shape of the workpiece 13. In this state, the shape of the hollow bag-like body 3 is maintained by utilizing jamming transfer and a shape-maintaining means. In FIG. 3 , the shape-maintaining means is a pressure-regulating means. Therefore, when a vacuum pump or the like (not shown) is activated, a suction force is applied as indicated by the arrow β in the figure. This causes the gas inside the hollow bag-like body 3 to be sucked through the tube 8, reducing the pressure and shrinking the bag. At this time, a contraction force is applied to the workpiece 13 as indicated by the arrow γ in the figure. As a result, the hollow bag-like body 3 closely fits the shape of the workpiece 13, maintaining its shape. In other words, the workpiece 13 is grasped (embraced) by the hollow bag-like body 3.

[0052] In the workpiece gripping device of the present invention, as described above, there is no contact between the frame-shaped support portion 2 and a portion of the upper surface 3a (support portion side) of the hollow bag-like body 3 (i.e., there is a non-contact region 14), so even when the hollow bag-like body 3 is decompressed, the amount of the bag pulled toward the frame-shaped support portion 2 can be greatly reduced. Therefore, in the workpiece gripping device of the present invention, the hollow bag-like body 3 (3b) can remain in close contact (fit) with the workpiece 13, and the contraction force γ can be fully exerted, which is preferable.

[0053] Furthermore, in this state (II), an electrostatic attraction force is applied between the hollow bag-like body 3 (3b) and the workpiece 13 by the electrostatic attraction means provided on the workpiece contact surface 3b of the hollow bag-like body 3, further improving the adhesion (fit) between the hollow bag-like body 3 (3b) and the workpiece 13. The electrostatic attraction force is generated, for example, by applying a voltage (not shown) to the electrostatic attraction means.

[0054] 3 (III) shows a state in which the workpiece 13 gripped (embraced) by the hollow bag-like body 3 in the state (II) is lifted. That is, by operating a means (equipment, device) not shown in the figure to raise the workpiece gripping device 1 while the state (II) is maintained, the workpiece 13 is lifted while gripped (embraced) by the hollow bag-like body 3.

[0055] Thereafter, when the shape holding means and the electrostatic adsorption means are stopped or released, the workpiece 13 is released from the workpiece gripping device 1 .

[0056] <Electrostatic Adsorption Means> As described above, electrostatic adsorption means is provided on the workpiece contact surface side 3b of the hollow bag-shaped body 3. By providing the electrostatic adsorption means, the gripping of the workpiece using the jamming transfer described above is reinforced by adsorption by electrostatic force, so that the workpiece can be gripped more reliably.

[0057] The electrostatic attraction means is not limited, and known means may be used as is, or known means may be improved or modified. For example, a general electrostatic chuck device in which an electrode is disposed inside a dielectric body and a voltage is applied to the electrode to charge the surface of the dielectric body with static electricity is preferably used. The electrostatic attraction means is provided on a part or the entire workpiece contact surface 3b of the hollow bag-shaped body 3, and the installation range can be determined appropriately depending on the size and type of the workpiece.

[0058] As a specific example of the electrostatic adsorption means, for example, an electrostatic chuck device (e.g., an electrostatic chuck sheet) may be externally attached to a part or the entire workpiece contact surface 3b of the hollow bag-shaped body 3 that does not have an electrostatic adsorption means, or the workpiece contact surface 3b of the hollow bag-shaped body 3 itself may be configured with an electrostatic adsorption means such as an electrostatic chuck device. Preferably, the workpiece contact surface 3b of the hollow bag-shaped body 3 itself is configured with an electrostatic adsorption means such as an electrostatic chuck device.

[0059] For example, the hollow bag-like body 3 may be preferably configured as follows. That is, the support side 3a of the hollow bag-like body 3 may be configured as an upper sheet, and the surface of the upper sheet opposite the support side 3a (i.e., the workpiece contact side 3b) may be configured as a lower sheet separate from the upper sheet. In this case, the lower sheet has the workpiece contact side 3b and also has electrostatic adsorption means. That is, in this preferred embodiment, the lower sheet itself is part of the hollow bag-like body 3 (the lower side 3b) and also serves as the electrostatic adsorption means. In this way, by configuring the lower sheet with the electrostatic adsorption means separately from the upper sheet, it is possible to prevent, for example, arcing due to insulation breakdown caused by contact between the upper sheet and the lower sheet. Furthermore, for example, when electrodes are made of conductive paint, as described below, their strength tends to be relatively weak. Therefore, it is possible to provide electrodes only in necessary areas.

[0060] In this case, the upper sheet and the lower sheet are preferably attached by joining, adhering, fusing, etc. the materials used in each sheet. Among these, taking into consideration the characteristics of the hollow bag-like body 3 described above (flexibility, softness, stretchability, airtightness, etc.), it is preferable to form the upper sheet and the lower sheet as resin sheets and fuse these resin sheets with heat and pressure, or to stick or adhere them, but more preferably, as described above, fusing the resin sheets together (thermal lamination) is used.

[0061] <Electrostatic Chuck Sheet> In a preferred embodiment when the lower sheet itself is the electrostatic chucking means, the lower sheet is an electrostatic chuck sheet having an electrode therein. Specifically, the electrostatic chuck sheet is preferably configured such that the electrode is disposed inside a resin sheet. An example of a workpiece gripping device in which the lower sheet is configured with such an electrostatic chuck sheet is shown in FIG. 4. In FIG. 4, the hollow bag-like body 3 is configured with an upper sheet 3c and a lower sheet 3d. The lower sheet 3d is also configured with a first resin film 3d which is on the inner side of the bag of the hollow bag-like body 3 (the side facing the jamming material 4). １ and a second resin film 3d which becomes the outer side (work contact surface side) 3b of the bag of the hollow bag-shaped body 3. ２The first resin film 3d is preferably configured by fusion or adhesion of these resin films, with an electrode 9 (preferably a relatively thin electrode sheet) disposed between the first resin film 3d and the second resin film 3d. １ , the electrode 9, and the second resin film 3d ２ Preferably, the sheet is made of a laminated sheet in which resin films are fused or adhered together, and more preferably, it is a laminated sheet in which resin films are fused together (thermally laminated).

[0062] FIG. 4 shows a power supply member 12 such as a conductive tape that is provided on the electrode 9 in order to apply a voltage to the electrode 9 of the electrostatic chuck sheet during use, and a power supply cable 11 that supplies power to the electrode 9, and the power supply cable 11 is connected to a power supply device (not shown).

[0063] Here, it is preferable to use a resin film used for the electrostatic chuck sheet that has the above-mentioned properties (tensile modulus of elasticity, tensile elongation, thickness, etc.) in order to satisfy the properties of the hollow bag-shaped body 3. In other words, it is also preferable to use the resins exemplified above. Note that the first resin film 3d １ and the second resin film 3d ２ The first resin film 3d and the second resin film 4d may be made of different resins, or may be made of the same resin, as long as the object of the present invention is not impaired. １ and second resin film 3d ２ Each of the first resin film 3d may be formed of a plurality of layers of the same or different kinds. １ and second resin film 3d ２ Other layers such as films or sheets made of resin may be provided separately.

[0064] In addition, at least the second resin film 3d on the contact surface side of the workpiece ２ For the volume resistivity of ９ Ω cm to 10 １４ It is preferable that the dielectric constant is 2 F / m or more. More preferably, the volume resistivity is 10 １０ Ω cm to 10１２ Ω·cm. It is preferable to use a resin having such properties as at least the resin film on the side that comes into contact with the workpiece, since this allows for sufficient electrostatic chucking force to be exerted. The use of a material having such properties as the first resin film 3b that comes into contact with the workpiece of the hollow bag-shaped body 3 is not limited to the embodiment of the electrostatic chuck sheet, and is also preferably adopted in the above-mentioned description. Note that the first resin film 3d, which is not on the side that comes into contact with the workpiece, １ Regarding the second resin film 3d, its volume resistivity and dielectric constant are ２ The second resin film 3d on the workpiece contact surface side may be different from the first resin film 3d. ２ The current that should flow between the workpiece and the first resin film 3d is passed through the first resin film 3d on the opposite side of the contact surface. １ Therefore, the first resin film 3d １ The volume resistivity of the second resin film 3d ２ It is preferable that the value is equal to or larger than the value.

[0065] <Electrode> The electrode used in the electrostatic adsorption means of the workpiece gripping device of the present invention can be either monopolar or bipolar, but bipolar electrodes are preferred. A monopolar electrode may require special consideration, such as arranging the electrode closer to the workpiece. In other words, a bipolar electrode having a positive and negative electrode is preferred. The material, shape, and pattern of the electrode are not limited, and known electrodes or improved or modified known electrodes can be used. For example, metal foil can be used as is, or a metal film formed by sputtering, ion plating, or other methods can be etched into a predetermined shape. Alternatively, a metal material can be sprayed onto the electrode, or a conductive paint can be applied or printed onto the electrode to form a predetermined shape. The thickness of the electrode can be, for example, 1 to 100 μm.

[0066] Here, taking into consideration the characteristics of the hollow bag-shaped body 3 described above (flexibility, flexibility, stretchability, airtightness, etc.), the electrode is preferably flexible and pliable. To achieve flexibility and pliability, methods for optimizing the material, shape, thickness, etc. described above can be used. Among these, in order to achieve flexibility and pliability, it is preferable that part or all of the electrode is made of a conductive paint. More preferably, the electrode is made only of a cured product of the conductive paint (conductive coating film). In this case, a preferred embodiment is an electrode sheet with a thickness of 30 to 100 μm to ensure sufficient conductivity. Since too large a thickness tends to impair flexibility and pliability, a more preferred upper limit of the thickness is 80 μm, and an even more preferred upper limit is 70 μm. Furthermore, it is more preferable that the flexibility and pliability be adjusted so that cracking or loss of conductivity does not occur even when the electrode stretches and contracts during use. For example, as confirmed in the examples described below, it is preferable that the conductive coating film be formed so that the "sheet with electrodes" obtained by applying a conductive paint to the first resin film or the second resin film and drying and curing the paint has a tensile modulus of 10 to 50 MPa and / or a tensile modulus of 100 to 1000%.

[0067] Known conductive paints can be used as the conductive paint. For example, the conductive paint may be a conductive paint in which particles of a conductive material are held in a binder resin, or a conductive paint containing conductive metal particles. Examples of such conductive paints include polyester-based AgCu conductive paints in which AgCu is held in a polyester resin, carbon-based conductive paints in which carbon black or the like is held in various resins, zinc-based paints, and nickel-based paints. These conductive paints can be used in any form, such as organic solvent-based, water-based, or powder-based.

[0068] The conductive paint can be applied, for example, by immersing the substrate in the conductive paint to form a conductive coating on the surface, or by application using a brush or spray. The amount of conductive paint applied is preferably adjusted appropriately to achieve the desired thickness of the conductive coating after drying. When forming an electrode by applying the conductive paint to the first or second resin film, it is preferable to make the conductive paint more easily absorbed, and it is preferable to adjust the roughness of the resin film surface to which the paint is applied. In this case, it is preferable to make the resin film have a relatively large roughness. To achieve this roughness, the material itself can be made to have this roughness, a commercially available surface (sometimes referred to as a matte surface) can be used, or the surface can be processed appropriately using known methods such as roughening using plasma treatment with a plasma generator.

[0069] The shape of the bipolar electrode can be selected as appropriate, for example, from a flat, semicircular, comb-like, or mesh-like pattern. Preferably, a pair of comb-like electrodes is used, and more preferably, as shown in Figs. 5A and 5B of Fig. 5, the comb teeth of a pair of comb-like electrodes are interdigitated on the same plane while maintaining a fixed distance from each other. Such a pattern tends to enhance the electrostatic attraction force to the workpiece. While the detailed principles are unclear, such a pattern can generate a gradient force between the workpiece and an insulator, even if it is not a conductor or semiconductor, thereby enabling the generation of a stronger electrostatic attraction force than other bipolar electrodes.

[0070] When the bipolar electrode is formed by interdigitating the teeth of a pair of comb-shaped electrodes on the same plane while maintaining a constant distance between them, the width of each comb tooth (electrode width) is preferably 0.5 to 20 mm, and the spacing (pitch) between the teeth is preferably 0.5 to 10 mm. More preferably, the width of each comb tooth (electrode width) is 1 to 10 mm, and the spacing (pitch) between the teeth is 1 to 3 mm. Setting the width of each comb tooth (electrode width) to 1 mm or more improves the workability of the electrode, while setting the width to 10 mm or less is preferable because it can suppress a decrease in the adsorptive force. Setting the spacing (pitch) between the comb teeth to 1 mm or more contributes to suppressing discharge between the electrodes, while setting the spacing to 3 mm or less is preferable because it can suppress a decrease in the adsorptive force. In other words, forming the comb teeth with such a width (electrode width) and spacing (pitch) between the comb teeth is preferable because it can ensure the adsorptive force, the workability of the electrode, and safety during use.

[0071] At least the first resin film 3d as described above １ , the electrode 9, and the second resin film 3d ２ and are laminated to form a laminated sheet. There are no limitations on the method for manufacturing the laminated sheet, but the method described in the Examples below can be preferably employed. The electrodes 9 must be sandwiched between the resin films so as not to be exposed. Specifically, as described above, the electrodes are sandwiched between the resin films, and then fused by applying heat and pressure. If necessary, bonding may be performed using a bonding sheet, adhesive, or pressure-sensitive adhesive. However, when the electrostatic chuck sheet (hollow bag-shaped body 3) is pressed against a workpiece or deformed and stretched during use to maintain its shape, this may hinder deformation and stretching, or peeling of the adhesive surfaces may occur. Therefore, a method of fusing the resin films by utilizing their thermoplasticity is more preferred.

[0072] The electrostatic chuck sheet thus obtained preferably has a thickness of 90 to 350 μm, a tensile modulus of elasticity of 10 to 50 MPa, and a tensile elongation of 100 to 1000%.

[0073] The upper limit of the tensile elastic modulus of the electrostatic chuck sheet is more preferably 48 MPa, and even more preferably 46 MPa.

[0074] The lower limit of the tensile elongation of the electrostatic chuck sheet is more preferably 200%, and even more preferably 300%. On the other hand, the upper limit of the tensile elongation is more preferably 900%.

[0075] The lower limit of the thickness of the electrostatic chuck sheet is more preferably 100 μm, and even more preferably 130 μm. On the other hand, the upper limit of the thickness is more preferably 230 μm, and even more preferably 180 μm. If the thickness is too small, the durability tends to be weak, leading to breakage due to external force or discharge during use. On the other hand, if the thickness is too large, the amount of deformation tends to be small, and the ability to conform to the workpiece tends to be poor.

[0076] When the obtained electrostatic chuck sheet is used as the lower sheet 3d of the hollow bag-shaped body 3, it is preferable to use a method of fusing and bonding the upper sheet 3c and the lower sheet 3d together using heat and pressure, similar to the case of preparing the laminated sheet. In this case, since it is necessary to secure a space for accommodating the jamming substance 4 inside, it is preferable to limit the fused portion to a range that takes into consideration the accommodating space. For example, it is sufficient to fused a certain range of the outer peripheral edges of the upper sheet 3c and the lower sheet 3d. As long as airtightness can be secured, the entire outer peripheral edges do not need to be fused. For example, as can be seen from the enlarged portion of Figure 4, at the outer peripheral edges of the upper sheet 3c and the lower sheet 3d, the lower surface of the upper sheet 3c and the first resin film 3d of the lower sheet 3d are fused. １ It is preferable that the upper surface of the lower sheet 3d is fused to the upper surface of the resin sheet 3. Although the electrode 9 is shown in the enlarged portion, it is not essential that the electrode 9 be disposed up to the end of the resin sheet. The electrode 9 may be of a size that allows it to come into contact with the workpiece of the lower sheet 3d.

[0077] <Method of Manufacturing Workpiece Gripping Device> The method described in the examples below can be preferably used as a method of manufacturing the workpiece gripping device. That is, regardless of whether the hollow bag-like body 3 is made of the same material or whether it is made of an upper sheet 3c and a lower sheet 3d, the hollow bag-like body 3 is prepared by an appropriate method. Note that when the shape-retaining means is a pressure adjusting means, it is preferable to provide an air vent 6 in advance in the upper sheet 3c. To form the air vent 6, a general drilling tool or instrument can be used.

[0078] Here, the jamming material 4 to be contained in the hollow bag-like body 3 may be contained during the preparation process of the hollow bag-like body 3, regardless of whether the hollow bag-like body 3 is composed of an upper sheet 3c and a lower sheet 3d, or may be contained after the preparation of the hollow bag-like body 3 is completed, for example, by being placed through the above-mentioned ventilation hole 6. The amount of jamming material 4 contained is not limited, but it is preferable that it occupies approximately 60 to 90 volume % of the internal volume of the bag, and more preferably 70 to 80 volume %. If there is too much jamming material 4, the bag may not deform sufficiently when gripping the workpiece, which may result in insufficient gripping (embracing) of the workpiece. On the other hand, if there is too little jamming material 4, there will be less jamming material to grip (embrace) the workpiece, which may also impair gripping of the workpiece.

[0079] After preparing the hollow bag-shaped body 3 containing the jamming material 4, other necessary parts (for example, the connecting parts 7 of the vent hole 6, the tubes 8, and other necessary parts related thereto) are prepared or installed, and the frame-shaped support part 2 is attached to the support part side (3a or 3c) of the hollow bag-shaped body 3. As described above, an adhesive layer 5 is disposed between the frame-shaped support part 2 and the hollow bag-shaped body 3 as needed. In this manner, the workpiece gripping device of the present invention can be manufactured.

[0080] <Power Supply> In the workpiece gripping device of the present invention, if an external voltage needs to be applied to the electrostatic chucking means, a power supply is provided. The power supply can be similar to those used in general electrostatic chucking devices, as long as it is capable of generating a high DC voltage. The generated potential difference can be approximately ±100 to ±5000 V. If necessary, a boost circuit (high voltage generating circuit) can be provided to boost the voltage to the required level. One method of applying voltage to the electrostatic chucking means is to use a power supply member 12, such as a conductive tape, attached to the electrode 9 of the electrostatic chucking means, and a power supply cable 11 that supplies power to the member, as shown in FIG. 4.

[0081] In the workpiece gripping device of the present invention, if necessary, additional tools or devices such as sensors, controllers, image processing systems, etc. may be provided depending on the purpose of gripping, transferring, transporting, etc. Furthermore, the shape, size, material, etc. of each part may be changed or added within the scope of the object of the present invention.

[0082] The workpiece gripping device of the present invention may be used by itself or as an end effector of a robot.

[0083] The workpiece to be gripped in the present invention is not limited, and is particularly suitable for use with a three-dimensional shape, with three-dimensional conductors (metallic three-dimensional objects, mechanical parts, etc.) being more preferred. Furthermore, the present invention is not limited to conductors, and may also be applicable to semi-conductors or insulating materials that require a gradient force. The shape of the workpiece is also not limited to three-dimensional objects, and may also include relatively thin, non-three-dimensional objects such as flat or sheet-shaped plates, paper, cloth, resin films, metal foils, and metal plates.

[0084] Preferred embodiments of the present invention will be specifically described below based on examples and comparative examples, but the present invention should not be construed as being limited to the following embodiments.

[0085] [Example 1] <Production of workpiece holding device> The workpiece holding device shown in Fig. 4 was produced by the following procedure. (1) First, the first resin film 3d １ and second resin film 3d ２(2) Two identical polyester-based polyurethane elastomer films (manufactured by Seedum Corporation, product name: Hygress DUS202-CDR 6HF, 170 mm x 150 mm, thickness: 50 μm) were prepared as the electrode mask. One of the films was used to bond a masking film (Masking SM Cutting Sticker Sheet SM-01) to its matte surface. (3) Next, the masking film alone was cut using a cutting plotter to form an electrode mask. Unnecessary portions of the cut electrode mask were removed, and a conductive paint (manufactured by Plascoat Co., Ltd., product name: Polycarm PCS-S2117) was applied to a thickness of 30 μm after drying. (4) After the conductive paint dried and hardened, the unnecessary masking portions were removed, and a bipolar electrode 9 (electrode sheet) with the pattern shown in Figs. 5A and 5B was formed on the matte surface of the polyurethane film (electrode sheet). The bipolar electrode was formed by a pair of comb-shaped electrodes, with the teeth of each electrode meshing on the same plane while maintaining a constant distance between them. The width of each comb (electrode width) was 10 mm, and the distance (pitch) between the teeth was 3 mm. (4) Copper foil tape (product name: Electrical Tape CU-35C, manufactured by 3M Limited) was attached as a power supply member 12 to each of the positive and negative electrodes of the formed electrodes 9 (9a, 9b), and a silicone-coated cable (power supply cable 11, product name: Flame-retardant Silicone Rubber Insulated Wire RSU-26, manufactured by Nissei Electric Co., Ltd.) was attached to the copper foil tape with solder. (5) The matte side of another polyurethane film was placed on top of the electrode-formed side of the electrode-attached sheet, and the entire surface was fused together by pressing with an iron or laminator at a temperature of approximately 120°C. This was used as the electrostatic chuck sheet 10 (lower sheet 3d). (6) Separately from the electrostatic chuck sheet 10 (lower sheet 3d), another sheet of the same polyurethane film was prepared as the upper sheet 3c, and a hole (vent hole 6) was opened in one location on the upper sheet 3c using a hole punch. After the hole was opened, the matte surface of the polyurethane film was placed on one of the surfaces (mirror surface) of the electrostatic chuck sheet 10 obtained above, and about 10 mm of the outer peripheral edge was heat-sealed by applying a temperature of 120°C using an iron or laminator. This was used as a hollow bag-like body 3. The internal volume of the hollow bag-like body 3 was 240,000 mm ３(7) Powder (glass beads (median particle size: 106-90 μm) manufactured by Fuji Manufacturing Co., Ltd.) was placed through the hole (vent hole 6) formed in the hollow bag-shaped body 3. The volume of the powder was approximately 70-80% by volume of the bag's volume. (8) Next, a cloth filter (polyester smooth) was placed on the surface side of the hole formed on the upper sheet 3c side. Then, a 3 cm square plate and a one-touch joint (corresponding to connecting part 7) were attached to the side where the filter was installed, and an air tube 8 (outer diameter: φ6 mm, inner diameter: φ4 mm) made of soft polyurethane material was attached to this joint. (9) Finally, a double-sided tape (width: approximately 15 mm) was attached in a frame shape as an adhesive layer to the upper sheet 3c side of the hollow bag-shaped body 3, and a frame-shaped support part (120 mm x 100 mm (including an inner space part corresponding to the non-contact area 14 of 90 mm x 70 mm), thickness: 5 mm) made of polylactic acid resin material was attached to it, thereby obtaining a workpiece gripping device 1 according to Example 1 of the present invention.

[0086] Example 2 A workpiece gripping device 1 according to Example 2 was produced in the same manner as in Example 1, except that a polyester polyurethane elastomer film having a thickness of 100 μm was used.

[0087] <Measurement of tensile modulus and tensile elongation> The tensile modulus and tensile elongation of the following Samples A to C, which were made using the resin and electrodes used in Example 1, were measured by the following procedure. (Samples) Sample A: Polyester-based polyurethane elastomer film used in Example 1 (manufactured by Seedum Co., Ltd., product name: Hygress DUS202-CDR 6HF, thickness: 50 μm) Sample B: Electrostatic chuck sheet produced in the middle of Example 1 (total thickness of 130 μm, consisting of 2 Samples A and 30 μm electrodes made of conductive paint) Sample C: Sheet with electrodes produced in the middle of Example 1 (total thickness of 80 μm, consisting of Sample A and 30 μm electrodes made of conductive paint)

[0088] <Measurement of sheet longitudinal modulus (tensile modulus)> Equipment used: (Materials testing machine) Precision universal testing machine Autograph, Shimadzu Corporation, AGX-50kNV Test piece size: Length 150 mm x Width 25 mm Number of tests: Two sheets of each sample Test method: Refer to JIS K 7127 Measurement procedure: The upper and lower ends of the test piece were fixed to the device, and the test piece was pulled at a speed of 1 mm / min to measure the tensile modulus. The results are shown in Table 1.

[0089]

[0090] <Measuring Tensile Elongation of Sheets> - Equipment Used: (Materials Testing Machine) Precision Universal Testing Machine Autograph, Shimadzu Corporation, AGX-50kNV, Video Non-Contact Extensometer, Shimadzu Corporation, TRViewX500D - Test Piece Size: Length 150 mm x Width 25 mm - Number of Tests: Two of Each Sample - Test Method: Refer to JIS K 7127 - Measurement Procedure: The above materials testing machine and video non-contact extensometer were used. The upper and lower ends of the test piece were fixed to the device and pulled at a speed of 100 mm / min until the test piece broke. The video non-contact extensometer was used to film the test piece being pulled until it broke, and the tensile elongation was measured. The results are shown in Table 2.

[0091]

[0092] A workpiece gripping device according to Comparative Example 1 was produced using the same procedure as in Example 1, except that a frame-shaped support part was used that did not have an inner space portion corresponding to the non-contact area 14. In Comparative Example 1, the frame-shaped support part 2 and the upper sheet of the hollow bag-like body 3 are bonded together over their entire surfaces via the adhesive layer 5.

[0093] <Evaluation of the amount of deformation of the hollow bag-shaped body (amount of sinking into the workpiece)> Using the workpiece gripping devices of Example 1 and Comparative Example 1 prepared above, the amount of deformation (amount of sinking into the workpiece) when pressed against the workpiece was measured. A graduated aluminum cylinder (diameter 15 mm, height 50 mm) was used as the workpiece. The lower sheet 3d side (workpiece contact surface side) of each workpiece gripping device of Example 1 and Comparative Example 1 was pressed vertically against the bottom surface of the workpiece until sinking no longer progressed, and the degree of deformation of the lower sheet 3d side (amount of sinking) was measured from the scale attached to the workpiece. The evaluation results were as follows. Amount of sinking of the workpiece gripping device of Example 1: 2 cm Amount of sinking of the workpiece gripping device of Comparative Example 1: 1 cm

[0094] <Gripping Force Evaluation 1> Using the workpiece gripping device of Example 1 prepared above, a power supply (CTPS-3KV2AF electrostatic chuck power supply manufactured by Aid Giken Co., Ltd., maximum 3 kV output) was prepared at the end of the power supply cable 11. First, the frame-shaped support portion 2 of the workpiece gripping device 1 was attached to a robot arm (COBOTTA manufactured by Denso Wave Inc.) and lifted. The power supply was turned on, and a 2 cm square silicon wafer with a string was attached to the center of the lower sheet 3d of the lifted workpiece gripping device. Next, with the silicon wafer attached to the workpiece gripping device, a weight was attached to the string attached to the silicon wafer to confirm the maximum weight that could be gripped. The weight at which the wafer fell was used to evaluate gripping ability (repeated 10 times). The weight was held for 10 seconds or more. The results are shown in Table 3 below.

[0095]

[0096] <Gripping Force Evaluation 2> In the above <Gripping Force Evaluation 1>, a metal fork, knife, or pen weighing approximately 50 g was used instead of the silicon wafer. Specifically, first, the air tube 8 of the workpiece gripping device 1 according to Example 1 was connected to a vacuum pump (manufactured by Nitto Kohki Co., Ltd.). Next, with the lower sheet 3d side of the workpiece gripping device 1 sufficiently pressed against the fork, knife, or pen, the vacuum pump was turned on to suction the inside of the hollow bag-like body 3, causing jamming transition. As a result, the hollow bag-like body 3 contracted to conform to the shape of the fork, knife, or pen, and was held in that shape. The power supply was also turned on as in <Gripping Force Evaluation 1>. In this state, the robot arm was moved so as to lift the workpiece gripping device 1 upward. In each case, the fork, knife, or pen was lifted while still gripped by the hollow bag-like body 3 of the workpiece gripping device 1. When the power supply was then turned off, the fork, knife or pen that was being held fell in all cases, and the holding and suction state could not be maintained.

[0097] Furthermore, when a similar evaluation was performed using the workpiece gripping device 1 according to Example 2, the results were similar to those of the workpiece gripping device according to Example 1. That is, it was confirmed that the workpiece gripping device according to Example 2 was also able to grip a fork, knife, or pen, which have a three-dimensional shape, by using both the action of jamming transfer and the electrostatic attraction force, but the results showed that the gripping / attraction state could not be maintained when the electrostatic attraction force was turned off.

[0098] <Grip Force Evaluation 3> (Sample Preparation) A hollow bag-shaped body 3 was prepared using the same procedures as steps (1) to (8) of <Preparation of Workpiece Grip Device> in Example 1. Next, four types of frame-shaped support members made of polylactic acid resin material, each with a different size corresponding to the non-contact area 14, were prepared (Samples D to G). Samples D to G were produced using a 3D printer (Ultimaker, product name: Ultimaker S5 Pro Bundle). Four hollow bag-shaped bodies 3 were then prepared, with double-sided tape attached as an adhesive layer to the upper sheet 3c side of the hollow bag-shaped body 3, matching the width of the frame members of Samples D to G. Each of the frame-shaped support members (Samples D to G) was attached to each of the four hollow bag-shaped body 3 to obtain the workpiece gripping devices D to G for evaluation. The sizes of the four frame-shaped support members (Samples D to G) prepared are as follows. The noted area ratios are calculated as follows:

[0099] (Samples D to G) Sample D: 170 mm x 100 mm (of which the inner space portion corresponding to the non-contact area 14 is 150 mm x 80 mm (area ratio: 70%)), thickness: 8 mm Sample E: 170 mm x 100 mm (of which the inner space portion corresponding to the non-contact area 14 is 130 mm x 66 mm (area ratio: 50%)), thickness: 8 mm Sample F: 170 mm x 100 mm (of which the inner space portion corresponding to the non-contact area 14 is 110 mm x 46 mm (area ratio: 30%)), thickness: 8 mm Sample G: 170 mm x 100 mm (of which the inner space portion corresponding to the non-contact area 14 is 40 mm x 44 mm (area ratio: 10%)), thickness: 8 mm Area ratio (%) = 100 x (area of ​​the inner space portion) / (total area of ​​the frame-shaped support portion assuming that the non-contact area 14 does not exist)

[0100] (Evaluation of Gripping Force) The workpiece gripping devices D to G prepared for evaluation were used, and a power supply (CTPS-3KV2AF electrostatic chuck power supply, manufactured by Aid Giken Co., Ltd., maximum 3 kV output) was attached to the end of the power supply cable 11. Furthermore, an aluminum alloy (A5052) pipe with an outer diameter of φ50 mm and a mass of 80 g was used as the workpiece, and the side of the pipe was used as the gripping surface. First, each of the workpiece gripping devices D to G for evaluation was placed on the top surface of the workpiece (the side of the pipe) from the side of the lower sheet 3d of the hollow bag-like body 3. Next, as in the above-mentioned <Evaluation of Gripping Force 2>, the air tube 8 was connected to a vacuum pump (manufactured by Nitto Kohki Co., Ltd.), and the vacuum pump was turned on to suction the inside of each hollow bag-like body 3, causing jamming transfer. As in the above-mentioned <Evaluation of Gripping Force 1>, the power supply was turned on and voltage was applied to each workpiece gripping device. The voltage was applied under two conditions: ±500 V and ±1000 V. In this state, each of the evaluation workpiece gripping devices D to G was moved upward so as to be lifted. In both cases, the workpiece was lifted while still held by the hollow bag-shaped body 3. Then, with the workpiece held by each of the workpiece gripping devices D to G, a weight was added to the workpiece's pipe to increase its weight, and the maximum weight that could be held was confirmed. The weight was held for 10 seconds, and the weight that could be held for 10 seconds was measured (repeated 3 times). The results are shown in Table 4 below.

[0101]

[0102] As shown in the results in Table 4 above, for the evaluation workpiece gripping devices D to G, the larger the area ratio of the inner space portion of the frame-shaped support parts D to G, the heavier the weight that could be gripped, and the improvement in the gripping force of the workpiece gripping device was observed. In addition, differences were observed in the amount of deformation of the hollow bag-like body (the amount of sinking into the workpiece) when each workpiece gripping device D to G was pressed against the workpiece, and it was confirmed that the largest deformation was observed when sample D was used, and compared to when sample G was used, the amount of deformation of the hollow bag-like body (the amount of sinking into the workpiece) was about 8 mm larger.

[0103] REFERENCE SIGNS LIST 1... workpiece gripping device, 2... frame-shaped support part, 3... hollow bag-like body, 3a... hollow bag-like body (support part side), 3b... hollow bag-like body (workpiece contact surface side), 3c... upper sheet, 3d... lower sheet, 3d １ ...first resin film, 3d ２ ...second resin film, 4...substance whose state changes due to jamming transition, 5...adhesion layer, 6...ventilation hole, 7...connection part, 8...tube, 9...electrode, 9a, 9b...positive electrode or negative electrode, 10...electrostatic chuck sheet, 11...power supply cable, 12...power supply member, 13...work, 14...non-contact area

Claims

1. A workpiece gripping device for gripping a workpiece, comprising: a frame-shaped support part; a flexible and airtight hollow bag-like body attached to one surface of the frame-shaped support part and containing a substance whose state changes due to jamming transition; electrostatic adsorption means provided on the contact surface of the hollow bag-like body with the workpiece and electrostatically adsorbing the workpiece; and shape retention means for deforming the shape of the hollow bag-like body to match the shape of the workpiece and retaining it, wherein the frame-shaped support part and the hollow bag-like body each have at least a non-contact area where the frame-shaped support part and the hollow bag-like body do not come into contact with each other, and the hollow bag-like body is attached to one surface of the frame-shaped support part, and in use, the workpiece is pressed against the contact surface of the hollow bag-like body with the workpiece to grip and adsorb it, utilizing the retention of the shape due to jamming transition and the electrostatic adsorption.

2. A workpiece gripping device as described in claim 1, characterized in that the area of ​​the non-contact region is 30 to 85% of the total area of ​​the frame-shaped support portion, including the non-contact region.

3. A workpiece gripping device as described in claim 1, characterized in that at least the contact surface of the hollow bag-shaped body with the workpiece is made of a material having a thickness of 10 to 150 μm, a tensile modulus of elasticity of 10 to 50 MPa, and a tensile elongation of 100 to 1000%.

4. A workpiece gripping device as described in claim 1, characterized in that at least the contact surface of the hollow bag-shaped body with the workpiece is made of one or more materials selected from the group consisting of polyurethane, polyurethane elastomer, soft polyvinyl chloride, polyvinylidene chloride, polyolefin and polyolefin copolymer.

5. A workpiece gripping device as described in claim 1, characterized in that the substance whose state changes due to the jamming transition is one or more types selected from the group consisting of powders, granules and fluids.

6. A workpiece gripping device as described in claim 1, characterized in that the shape maintaining means is a pressure adjustment means for adjusting the pressure inside the hollow bag-like body, and the pressure inside the hollow bag-like body is reduced by the pressure adjustment means to maintain the shape.

7. A workpiece gripping device as described in claim 6, characterized in that the hollow bag-shaped body is provided with an air vent, and the pressure is adjusted by letting in and out gas through the air vent.

8. A workpiece gripping device as described in any one of claims 1 to 7, characterized in that the hollow bag-shaped body is composed of an upper sheet attached to one side of the frame-shaped support part, and a lower sheet attached by fusion or adhesion to the side of the upper sheet opposite the attachment surface, the lower sheet having a contact surface with the workpiece and also having the electrostatic adsorption means.

9. A workpiece gripping device as described in claim 8, characterized in that the electrostatic adsorption means is an electrostatic chuck, the lower sheet is an electrostatic chuck sheet having an electrode therein, the electrostatic chuck sheet being constructed by sequentially laminating and fusing or bonding a first resin film on the inside side of a hollow bag-like body, an electrode, and a second resin film on the outside side of the hollow bag-like body, the second resin film having a contact surface with the workpiece.

10. A workpiece gripping device as described in claim 9, characterized in that the first resin film and / or the second resin film have a thickness of 10 to 150 μm, a tensile modulus of elasticity of 10 to 50 MPa, and a tensile elongation of 100 to 1000%.

11. The workpiece gripping device described in claim 9, characterized in that the first resin film and / or the second resin film are made of one or more materials selected from the group consisting of polyurethane, polyurethane elastomer, soft polyvinyl chloride, polyvinylidene chloride, polyolefin, and polyolefin copolymer.

12. The workpiece gripping device according to claim 9, characterized in that the electrode is a bipolar electrode having a positive electrode and a negative electrode, is formed from a cured conductive paint, and is an electrode sheet having a thickness of 30 to 100 μm.

13. The workpiece gripping device according to claim 12, characterized in that the bipolar electrode is an electrode formed by a pair of comb-shaped electrodes whose teeth mesh with each other on the same plane while maintaining a constant distance from each other.

14. The workpiece gripping device according to claim 9, characterized in that the electrostatic chuck sheet has a thickness of 90 to 350 μm, a tensile modulus of elasticity of 10 to 50 MPa, and a tensile elongation of 100 to 1000%.

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