Sheet gripping device and sheet gripping method using same

Abstract

Provided are: a sheet gripping device that avoids applying excessive force to a sheet and prevents deformation of the sheet, and that makes it possible to reliably take out one sheet while also withstanding repeated use; and a sheet gripping method.　Provided is a sheet gripping device for gripping an uppermost sheet that is at the top of a sheet group in which a plurality of sheets are stacked, said sheet gripping device comprising: an adhesive body in which an adhesive holding member is provided to one side of a flat plate base material that is in the shape of a flat plate and which adheres to an end part of the uppermost sheet; and a pressing body which presses against the end part of the uppermost sheet adhered to the adhesive body and which grips the uppermost sheet with the adhesive body, wherein after adhering to the end part of the uppermost sheet, the adhesive body rotates so as to stand up starting from one end of the flat plate base material, the end part of the adhered uppermost sheet is turned up, and then the pressing body is pressed thereagainst, thereby making it possible to grip the uppermost sheet. Also provided is a sheet gripping method for using the sheet gripping device to grip a sheet.

Description

Sheet gripping device and method for gripping a sheet using the same

[0001] The present invention relates to a sheet gripping device and a method for gripping a sheet using the same, and more particularly, to a sheet gripping device capable of separating and gripping the uppermost sheet on top of a group of sheets stacked with a plurality of sheets, and a method for gripping a sheet using the same.

[0002] When taking out one sheet from a group of sheets stacked with a plurality of sheets made of paper, cloth, film, etc. and delivering it to the next process or supplying it to a predetermined processing device, a sheet gripping device is used.

[0003] In such a sheet gripping device, in order to separate and grip the uppermost sheet on top of the group of sheets, in addition to methods using vacuum suction or methods using static electricity, there are methods using an adhesive holding material or methods using mechanical means such as needles, etc. that are known.

[0004] Among these, in the method using vacuum suction, there is a risk of deforming or damaging the sheet if it is a thin sheet. Also, in the method using static electricity, there is a risk of so-called double sheet picking due to the sheet becoming charged. Furthermore, in the method using mechanical means such as needles, there is a risk of damaging the sheet itself.

[0005] On the other hand, in the method using an adhesive holding material, it is possible to simply adhesively hold the sheet while avoiding these problems.

[0006] For example, a sheet gripping device is known that includes an adhesive sticking means for sticking the uppermost sheet on top of a group of sheets stacked with a plurality of sheets, and a suction means for sucking the stuck uppermost sheet by suction of air (see Patent Document 1).

[0007] In the sheet gripping device according to this Patent Document 1, after the uppermost sheet is lifted up by the adhesive sticking means, it is sucked by air by the suction means, but if it has air permeability like cloth, the suction by air may be insufficient, and the material, type, shape, etc. of the sheet may be restricted.

[0008] Furthermore, regarding a method for separating and removing a single film bag from a stack of multiple film bags made of resin film, there is a known device in which a film gripper with adhesive tape is brought into contact with the topmost film bag, the film gripper is rotated in this state to lift the edge of the film bag, and gas is blown between the topmost film bag and the film bag below it to completely detach the single film bag and remove it (see Patent Document 2).

[0009] In the apparatus described in Patent Document 2, the adhesive surface of a film gripper with adhesive tape attached is extended toward the bundle of bags by a cylinder, and the bundle of bags is held down by a bar. The film gripper is rotated so that the bar forms a fold, causing the top film bag to spring up. This ensures that one film bag is reliably separated from the bundle of bags. However, because the axis of rotation (center of rotation) when the film gripper is rotated is located away from the film gripper (offset), tension is applied to the top film bag as the film gripper rotates, causing the film bag to stretch. Furthermore, due to the tension applied to the adhesive tape, the adhesive strength of the tape may decrease with repeated use, potentially making it impossible to reliably remove the film bag.

[0010] Japanese Patent Publication No. 2022-59394 Japanese Patent Publication No. 52-129163

[0011] The inventors of the present invention have diligently studied a means to reliably remove a single sheet from a stack of sheets made of paper, cloth, film, etc., regardless of the material, type, or shape of the sheets, without putting stress on the target sheet or the adhesive-holding body to which the adhesive is attached, and using a simple device configuration. As a result, they have found that by providing an adhesive body having a contact surface to which an adhesive-holding material is attached, and a pressing body that grips the top sheet attached to the adhesive body together with the adhesive body, and by rotating the adhesive body so that it stands upright at the lower end of the contact surface, the attached top sheet is rolled up, it is possible to reliably separate and remove (grip) a single sheet while eliminating all the problems of conventional devices such as sheet stretching and decrease in adhesive strength, and have completed the present invention.

[0012] Therefore, the object of the present invention is to provide a sheet gripping device that has a relatively simple configuration, prevents deformation of the sheet without applying excessive force to the sheet, and can reliably dispense a single sheet while withstanding repeated use.

[0013] Another object of the present invention is to provide a method for gripping a sheet that prevents deformation of the sheet without applying excessive force to the sheet, and that can reliably remove one sheet at a time while withstanding repeated use.

[0014] In other words, the present invention is a sheet gripping device for gripping the uppermost sheet from a group of sheets stacked on top of each other, comprising: an adhesive body that adheres to the surface edge of the uppermost sheet with an adhesive holding material attached to the contact surface; and a pressing body that is pressed against the back edge of the uppermost sheet that has been adhered by the adhesive body, thereby gripping the uppermost sheet between itself and the adhesive body, wherein the adhesive body, after adhering to the surface edge of the uppermost sheet, rotates to stand upright starting from its lower end in the height direction of the contact surface, thereby curling up the surface edge of the adhered uppermost sheet, and then pressing the pressing body against the back edge to grip the uppermost sheet.

[0015] Furthermore, the present invention relates to a method for gripping the uppermost sheet from a group of sheets stacked on top of each other, and is characterized by using a sheet gripping device comprising: an adhesive body that adheres to the surface edge of the uppermost sheet with a contact surface having an adhesive holding material attached to it; and a pressing body that is pressed against the back edge of the uppermost sheet that has been adhered with the adhesive body to grip the uppermost sheet between itself and the adhesive body, wherein after the surface edge of the uppermost sheet is adhered with the adhesive body, it is rotated so that it stands upright starting from the lower end in the height direction of the contact surface, the surface edge of the adhered uppermost sheet is rolled up, and then the pressing body is pressed against the back edge to grip the uppermost sheet.

[0016] The sheet gripping device of the present invention is capable of gripping the topmost sheet from a group of sheets stacked on top of each other, and comprises an adhesive body that adheres to the front edge of the topmost sheet with an adhesive holding material attached to the contact surface, and a pressing body that grips the topmost sheet between itself and the adhesive body by pressing against the back edge of the topmost sheet that has been adhered to by the adhesive body.

[0017] In this case, the adhesive body can be used to attach the surface edge of the top sheet, then rotate it so that it stands upright, starting from the lower end in the height direction of the contact surface, thereby curling up the attached top sheet. Then, the pressing body is pressed against the back edge of the top sheet attached by the adhesive body to grip the top sheet. By rotating the adhesive body in this way, starting from the lower end of the contact surface that constitutes the adhesive body, the edge of the attached top sheet can be curled up without applying any extra force that would stretch the sheet. This allows the top sheet to be reliably separated from the sheet group without any load and gripped.

[0018] Here, the adhesive retaining material applied to the contact surface of the adhesive object is not particularly limited, but preferably it is self-adhesive. Unlike commercially available adhesive tapes (adhesive tapes) which have an adhesive applied to a base material such as cellophane, self-adhesive adhesive retaining materials are adhesive themselves (self-adhesive). Therefore, with adhesive tapes, the adhesive strength due to the adhesive decreases when peeled off the object (sheet) after application, and eventually they cannot be reused. In contrast, self-adhesive adhesive retaining materials do not lose their adhesive strength easily and can be reused. In particular, cleaning the surface makes it possible to reuse them even more repeatedly.

[0019] Examples of self-adhesive adhesive holding materials include those made of resins such as silicone rubber, ethylene-propylene-diene rubber (EPDM), butyl rubber, fluororesins, urethane resins, and acrylic resins. In particular, it is preferable that the self-adhesive holding material exhibits van der Waals forces, a type of intermolecular force, at the interface with the protective workpiece to be held.

[0020] Furthermore, in the present invention, the adhesive body is preferably disposed on a frame body having an opening at a position corresponding to at least the contact surface. Specifically, the adhesive body is provided with a follower (paired part) at at least one side end in the width direction relative to the contact surface, and the side surface of the frame body is provided with an arc-shaped guide groove for guiding the follower, and has an opening at least at a position corresponding to the contact surface, so that the lower end of the contact surface of the adhesive body becomes the center of rotation.

[0021] In this case, the adhesive body may be provided with two or more followers at its side ends, and arc-shaped guide grooves for guiding the followers may be provided concentrically on the side surface of the frame body according to the number of followers. Alternatively, the adhesive body may be provided with one or more followers at each of its side ends in the width direction relative to the contact surface, and the frame body may have one or more arc-shaped guide grooves for guiding these followers on both sides. These measures enable the uppermost sheet to be separated and gripped from the sheet group with greater precision and reliability.

[0022] Examples of the follower (paired part) include a pointed follower, a flat-ended follower, a roller follower, a cam follower, and the like. Preferably, it is a point follower with a circular tip, a roller follower, or a cam follower.

[0023] When the sheet gripping device in the present invention has a frame body, when attaching the edge of the uppermost sheet in the sheet group to the adhesive body disposed thereon, the contact surface of the adhesive body should be closed toward the opening of the frame body, and the adhesive holding material should be positioned opposite the uppermost sheet in the sheet group. Furthermore, when curling up the edge of the attached uppermost sheet, as described above, it should be rotated so that it stands upright with the lower end of the contact surface of the adhesive body as the pivot point (center of rotation).

[0024] Furthermore, the sheet gripping device of the present invention may be equipped with a gas blowing nozzle for blowing gas onto the top sheet that has been attached with an adhesive and rolled up. This allows for more reliable separation of the sheet following the top sheet (the sheet below) even if it rolls up together with the top sheet, by blowing gas onto it. When a gas blowing nozzle is provided, gas is blown onto the top sheet that has been rolled up with the adhesive to separate the top sheet from the next sheet, and then the pressing body is pressed against the adhesive to grip the top sheet.

[0025] Furthermore, when using such a sheet gripping device to grip the topmost sheet from a stack of multiple sheets, as described above, first, the surface edge of the topmost sheet is attached with the adhesive holding material on the contact surface of the adhesive body, and then the topmost sheet is rolled up by rotating it so that it stands upright starting from the lower end of the contact surface of the adhesive body. Next, the pressing body is pressed against the back edge of the topmost sheet to grip the topmost sheet between it and the adhesive body.

[0026] In this case, if the sheet gripping device is equipped with a gas nozzle, as mentioned above, gas should be blown onto the top sheet that has been rolled up by the adhesive body, and then the pressing body should be pressed against the adhesive body to grip the top sheet.

[0027] In this invention, a single sheet can be separated and removed (gripped) from a group of sheets stacked on top of each other. The material of such a sheet is not particularly limited, and examples include cloth or paper made of knitted, woven, or nonwoven fabrics, as well as resin films, metal foils, leather, etc. In particular, this invention is suitable for removing sheets such as cloth or paper that are not stiff and are difficult to separate into single sheets (they tend to be divided into two). Furthermore, as long as these are thin sheets, their shape is not limited, and for example, they may have many holes or weaves (gaps between threads) to be breathable, and even if the surface is uneven or bag-shaped, it is possible to separate and remove the top sheet.

[0028] Furthermore, the sheet gripping device of the present invention can be used by attaching it to a robot hand, for example. While not particularly limited to these, it can be suitably used in processes such as sewing machines, heat-sealing machines, adhesive and sealant application machines, and assembly machines, where the topmost sheet from a stack of multiple sheets needs to be gripped and passed on to the next process.

[0029] According to the present invention, a single sheet can be reliably removed from a stack of multiple sheets, despite the relatively simple device configuration. Moreover, since no excessive force is applied to the sheet, deformation of the sheet can be prevented, and the adhesive strength can be maintained, allowing for reliable use over a long period of time.

[0030] Figure 1 is a perspective view (top view) illustrating an embodiment of the sheet gripping device. Figure 2 is a perspective view (bottom view) illustrating an embodiment of the sheet gripping device. Figure 3 is a side view of the frame body showing the state when the top sheet is attached by the sheet gripping device. Figure 4 is another perspective view (bottom view) illustrating an embodiment of the sheet gripping device. Figure 5 is a side view of the frame body showing the state when the top sheet is rolled up by the sheet gripping device. Figure 6 is a schematic partial cross-sectional diagram illustrating how the top sheet is attached by the sheet gripping device. Figure 7 is a schematic partial cross-sectional diagram illustrating how the top sheet that has been attached and rolled up is pressed against and gripped by the pressing body of the sheet gripping device. Figure 9 is a schematic diagram illustrating the state when the top sheet attached with an adhesive is peeled up, with (a) showing the case with the sheet gripping device according to the present invention and (b) showing the case with the prior art.

[0031] The embodiments of the present invention will be described in more detail below with reference to the drawings.

[0032] Figures 1 and 2 show an example of an embodiment of the sheet gripping device according to the present invention. This sheet gripping device X comprises a frame body 1 having frame sides 1a on both the left and right sides and an opening 1b at the bottom, with an adhesive body 5 and a pressing body 6 arranged inside this frame body 1. The approximate dimensions of this frame body 1 are 92 mm wide x 192 mm long x 56 mm high.

[0033] Of these, the adhesive body 5 is formed using a metal base 2 with a roughly fan-shaped cross-section, and an adhesive retaining material 3 is attached to the contact surface 2a to which the uppermost sheet is attached. In this embodiment, preferably, the metal base 2 is made of stainless steel. Furthermore, as mentioned above, the adhesive retaining material 3 is preferably made of silicone rubber or ethylene-propylene-diene rubber (EPDM), and is self-adhesive by exhibiting van der Waals forces. In this embodiment, an adhesive retaining material 3 made of ethylene-propylene-diene rubber with a width of 70 mm x length (height) of 30 mm x thickness of 1 mm is bonded to the contact surface 2a of the metal base 2 with an acrylic adhesive. In addition, the adhesive body 5 is provided with cam followers 4-1 and 4-2 on both sides of the metal base 2 that are in the width direction relative to the contact surface 2a.

[0034] On the other hand, the frame side surface 1a of the frame body 1 is provided with arc-shaped guide grooves 1c and 1d, respectively, which guide the two cam followers 4-1 and 4-2 on the left and right sides of the adhesive body 5, and these guide grooves 1c and 1d are formed in concentric circles. In this embodiment, two cam followers 4-1 are engaged in the guide groove 1c and one cam follower 4-2 is engaged in the guide groove 1d, but it is also possible to use only one of the cam followers 4-1 in the guide groove 1c.

[0035] Furthermore, the adhesive body 5, which is disposed on the frame body 1, is connected to an adhesive body cylinder 7, which is also disposed on the frame body 1. In addition, a tension spring 8 is attached to the frame side surface 1a of the frame body 1, with one end connected to the frame side surface 1a of the frame body 1 and the other end connected to the side end of the adhesive body 5, so that it rotates within the frame body 1 by an operation described later. The adhesive body cylinder 7 may be a hydraulic type, a pneumatic type, or an electric type.

[0036] Furthermore, the pressing body 6 is formed from a flat metal plate and, like the adhesive body 5, is connected to a pressing body cylinder 9 disposed on the frame body 1. Through an operation described later, it can press against the top sheet (not shown here) attached by the adhesive body 5, and grip the top sheet between itself and the adhesive body 5. The pressing body cylinder 9 may be hydraulic, pneumatic, or electrically operated, as described above.

[0037] Here, Figure 2 shows the adhesive body 5 with its contact surface 2a closed toward the opening 1b of the frame body 1 in order to grip the topmost sheet from a stack of sheets. Figure 3 shows a side view of the frame body 1 in this state. At this time, the adhesive body cylinder 7 (not shown) has its piston rod extended, and the adhesive holding material 3 attached to the contact surface 2a of the adhesive body 5 is capable of adhering to the surface edge of the topmost sheet from among the stacked sheets (not shown). Furthermore, of the cam followers provided by the adhesive body 5, two cam followers 4-1 engage with the guide groove 1c, and cam follower 4-2 engages with the guide groove 1d. In addition, the tension spring 8 is in an extended state between one end attached to the frame side surface 1a of the frame body 1 and the other end attached to the side end of the adhesive body 5.

[0038] On the other hand, Figure 4 shows the state in which the topmost sheet (not shown) to which the adhesive body 5 is attached has been rolled up, and Figure 5 is a side view of the frame body 1 at that time. In these, the adhesive body cylinder 7 (not shown) has its piston rod retracted, and the adhesive body 5 has rotated so that it stands upright, starting from the lower end in the height direction of the contact surface. Also, as in the case described above, the cam followers provided by the adhesive body 5 have two cam followers 4-1 engaged with the guide groove 1c, and cam follower 4-2 engaged with the guide groove 1d.

[0039] An example of the procedure for gripping the topmost sheet from a stack of sheets using such a sheet gripping device X will be explained with reference to the drawings. In the above embodiment, the explanation of the gas nozzle for blowing gas onto the topmost sheet attached with an adhesive was omitted, but the following explanation will use a sheet gripping device X equipped with a gas nozzle.

[0040] First, as shown in Figure 6, the adhesive retaining material 3 attached to the contact surface of the adhesive body 5 is closed toward the opening of the frame body 1, and is positioned opposite the topmost sheet 11a of the sheet group 11, which is made up of multiple sheets stacked on top of each other. At this time, the piston rod 7a of the adhesive body cylinder 7 connected to the adhesive body 5 is extended. The piston rod 9a of the presser body cylinder 9 connected to the presser body 6 is also extended. In this state, the distance in the z direction between the sheet gripping device X and the sheet group 11 is brought relatively closer, and the surface edge of the topmost sheet 11a is attached with the adhesive retaining material 3 attached to the adhesive body 5.

[0041] The sheet group 11 may be placed on a sheet supply table or stored in a cassette or the like (neither of which is shown), and brought closer to the sheet gripping device X. Alternatively, the sheet gripping device X may be connected to a robot hand or the like (not shown), and the sheet gripping device X may be brought closer to the sheet group 11. These methods may also be combined.

[0042] After the surface edge of the top sheet 11a is attached with the adhesive holding material 3, as shown in Figure 7, the piston rod 7a of the adhesive cylinder 7 is retracted (the piston rod 7a is stored in the cylinder tube), and the adhesive body 5 is rotated so that it stands upright, starting from the lower end in the height direction of the contact surface on the adhesive body 5. At this time, the center point O of the rotation of the adhesive body 5 remains the same as the position of the lower end of the contact surface (right end in the figure) shown in Figure 6. As a result, the edge of the top sheet 11a attached by the adhesive body 5 is curled up.

[0043] Here, gas is blown from a gas blowing port 10 that is located directly above the standing adherent body 5 and can blow out gas such as air. Thereby, even if the next sheet located under the uppermost sheet 11a is accidentally rolled up together with the uppermost sheet 11a, they can be surely separated by the blowing of the gas. At this time, although it also depends on the thickness and type of the sheet, for example, if it is a cotton cloth with a thickness of about 1 mm, the inner diameter φ of the gas blowing port 10 is approximately 1 mm, and the gas may be blown at a pressure of about 0.5 MPa.

[0044] Next, as shown in FIG. 8, the piston rod 9a of the pressing body cylinder 9 is contracted (the piston rod 7a is stored in the cylinder tube), and the pressing body 6 is pressed against the back end portion of the uppermost sheet 11a, and the uppermost sheet 11a is gripped by the pressing body 6 and the adherent body 5.

[0045] Next, by relatively separating the z-direction distance between the sheet gripping device X and the sheet group 11, the gripped uppermost sheet 11a can be taken out (picked up) from the sheet group 11. At that time, similar to the case of adhering the uppermost sheet 11a with the adherent body 5, the sheet supply table or cassette on which the sheet group 11 is placed may be moved in the z direction, the sheet gripping device X connected to a robot hand or the like may be moved in the z direction, or these may be combined. Also, prior to taking out the uppermost sheet 11a from the sheet group 11 by relatively moving in the z direction like this, the sheet gripping device X to which the uppermost sheet 11a is adhered may be relatively moved in the x direction or the y direction, and then the uppermost sheet 11a may be taken out from the sheet group 11.

[0046] In the present invention, as shown in Figure 9(a), when the top sheet 11a is attached to the contact surface of the adhesive body 5 with the adhesive holding material 3 and then rolled up, the adhesive body 5 rotates to stand upright, starting from the lower end of the contact surface. Therefore, the center of rotation of the adhesive body 5 remains the same at the center point O before and after standing upright. In contrast, in the conventional method, such as that described in Patent Document 2, as shown in Figure 9(b), the axis of rotation (center of rotation O') when the film gripping tool 3' is rotated is located away from the film gripping tool 3' (it is offset). Due to this difference, in the conventional method, problems such as the sheet stretching, the gripping position of the sheet shifting, the adhesive force decreasing due to repeated misalignment between the sheet and the adhesive body, and the attached sheet coming off occur. In the present invention, however, none of these problems occur.

[0047] As described above, according to the present invention, a single sheet can be reliably removed from a stack of multiple sheets. Moreover, since no excessive force is applied to the sheet, deformation of the sheet can be prevented, and the adhesive strength can be maintained, allowing for reliable use over a long period of time.

[0048] X: Sheet gripping device, 1: Frame body, 1a: Frame side, 1b: Opening, 1c, 1d: Guide groove, 2: Metal base, 2a: Contact surface, 3: Adhesive holding material, 4: Follower, 4-1, 4-2: Cam follower, 5: Adhesive body, 6: Pressing body, 7: Cylinder for adhesive body, 8: Tension spring, 9: Cylinder for pressing body, 10: Gas blowing nozzle, 11: Sheet group, 11a: Top sheet.

Claims

1. A sheet gripping device for gripping the uppermost sheet from a group of sheets stacked on top of each other, comprising: an adhesive body that adheres to the surface edge of the uppermost sheet with a contact surface having an adhesive holding material attached; and a pressing body that is pressed against the back edge of the uppermost sheet that has been adhered by the adhesive body, thereby gripping the uppermost sheet between itself and the adhesive body, wherein the adhesive body, after adhering to the surface edge of the uppermost sheet, rotates to stand upright starting from its lower end in the height direction of the contact surface, thereby curling up the surface edge of the adhered uppermost sheet, and then pressing the pressing body against the back edge to grip the uppermost sheet.

2. The sheet gripping device according to claim 1, further comprising a gas blowing nozzle for blowing gas onto the uppermost sheet that has been attached with the adhesive body and rolled up.

3. The sheet gripping device according to claim 1, wherein the adhesive body is provided with a follower at at least one side end in the width direction relative to the contact surface, the adhesive body is disposed within a frame body having an arc-shaped guide groove for guiding the follower and an opening at least corresponding to the contact surface, and when attaching the end of the uppermost sheet, the contact surface of the adhesive body is closed toward the opening of the frame body, and when rolling up the attached end of the uppermost sheet, the adhesive body is rotated with the lower end of the contact surface as the pivot point.

4. The sheet gripping device according to claim 3, wherein the adhesive body is provided with followers at both side ends in the width direction with respect to the contact surface, and the frame body has arc-shaped guide grooves on both sides of the frame body for guiding these followers.

5. A method for gripping the topmost sheet from a group of sheets stacked on top of each other, comprising: a sheet gripping device comprising: an adhesive body that adheres to the surface edge of the topmost sheet with a contact surface having an adhesive holding material attached; and a pressing body that is pressed against the back edge of the topmost sheet that has been adhered by the adhesive body to grip the topmost sheet between itself and the adhesive body; wherein, after the surface edge of the topmost sheet is adhered by the adhesive body, the device rotates the topmost sheet so that it stands upright starting from the lower end in the height direction of the contact surface, the adhered surface edge of the topmost sheet is rolled up, and then the pressing body is pressed against the back edge to grip the topmost sheet.

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