Open-close chuck and method for manufacturing the same

Abstract

To provide an opening / closing chuck that improves the gripping force of work and enables the gripping of work at a position further separated from a supporting position of a finger, by easing stress concentration generated in the finger due to a load acting on the finger and three-dimensional various axial moment.SOLUTION: A finger 14 has a pair of bulging portions 16 and 18 projecting out from a body portion 20 to a side part. Outer peripheral surfaces of the bulging portions are composed of upper surfaces 16a and 18a, side surfaces 16b and 18b, lower surfaces 16c and 18c, first end surfaces 16d and 18d, and second end surfaces 16e and 18e. Crowning is performed at intersecting portions of those surfaces.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a chuck having a pair of fingers for gripping a workpiece, and a method for manufacturing the fingers. [Background technology]

[0002] Conventionally, there has been known an open-close chuck in which a pair of fingers for gripping a workpiece are supported so as to slide toward and away from each other. For example, Patent Document 1 describes a parallel gripper in which a wedge-shaped hook transmission unit is provided that moves two base jaws movably guided in a housing toward and away from each other, and the wedge-shaped hook transmission unit is adjusted by a piston.

[0003] Furthermore, Patent Document 2 describes a gripping device having a pair of slides, in which a ramp is provided on the guide flank of each slide, thereby forming a wedge gap that widens toward the end face of the slide. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2003-526528 [Patent Document 2] European Patent Application Publication No. 3563989 Summary of the Invention [Problem to be solved by the invention]

[0005] When a workpiece is gripped using a pair of slidably supported fingers, a load acts on the fingers in a predetermined direction (vertical or horizontal) due to the reaction force from the workpiece, and moments act on the fingers to rotate the fingers around various axes in three dimensions. The load and moment acting on the fingers increase as the gripping force of the workpiece increases. Furthermore, the moment acting on the fingers increases as the distance between the gripping position of the workpiece on the gripping member (attachment) extended from the fingers and the support position of the fingers increases. If the load and moment acting on the fingers are large, stress concentration occurs at the contact surface between the fingers and the body, generating excessive surface pressure and damaging the sliding surfaces of the fingers and the body.

[0006] However, technology that takes into consideration the stress concentration that occurs in the fingers and body has not yet been fully developed. The technology described in Patent Document 2 is effective to some extent in mitigating the stress concentration that occurs when the opposing ends of a pair of slides rotate so as to open at an angle, and in preventing excessive surface pressure, but does not take into consideration the moments that act on the slides around various three-dimensional axes.

[0007] The present invention has been made in consideration of the above circumstances, and aims to provide an open-close chuck and a method for manufacturing the fingers thereof, which increase the gripping force of a workpiece and enable the workpiece to be gripped at a position farther away from the support position of the fingers by alleviating stress concentration that occurs on the contact surface between the fingers and the body due to loads in the vertical direction and moments around various three-dimensional axes acting on the fingers. [Means for solving the problem]

[0008] The open-close chuck of the present invention includes a pair of fingers that slide within a guide groove in the body and are supported so as to be able to slide freely in directions that move toward and away from each other, and the fingers have a pair of protrusions that protrude laterally from the main body, and the outer peripheral surface of the protrusions consists of five surfaces: an upper surface, a side surface, a lower surface, a first end surface, and a second end surface, and the intersections of these surfaces are crowned.

[0009] The above-described open-close chuck can alleviate stress concentration on the fingers due to loads acting on the fingers in the vertical direction and moments around three axes, thereby reducing the maximum surface pressure.

[0010] Furthermore, a first manufacturing method of a finger according to the present invention relates to a finger that slides within a guide groove in the body of an open-close chuck, is supported so as to be able to slide freely in directions approaching and separating from each other, has a pair of protrusions that protrude laterally from the main body, and the outer surface of the protrusions consists of five surfaces: an upper surface, a side surface, a lower surface, a first end surface, and a second end surface, and the upper and lower surfaces are perpendicular to the side surfaces, and includes a step of crowning the intersections of the above five surfaces by combining grinding of the side surfaces with a first processing tool and grinding of the upper and lower surfaces with a second processing tool.

[0011] Furthermore, a second manufacturing method of a finger according to the present invention relates to a finger that slides within a guide groove in the body of an open-close chuck, is supported so as to be able to slide freely in directions that move toward and away from each other, has a pair of protruding portions that protrude laterally from the main body, and the outer surface of the protruding portions consists of five surfaces: an upper surface, a side surface, a lower surface, a first end surface, and a second end surface, and the upper and lower surfaces are tapered surfaces that approach each other toward the side surfaces, and includes a step of simultaneously grinding the side surfaces and the upper and lower surfaces using a single processing tool, thereby providing crowning at the intersections of the above five surfaces.

[0012] According to the first and second manufacturing methods, crowning processing for alleviating stress concentrations that occur in the fingers and body due to loads acting on the fingers in the vertical direction and moments around three axes can be easily performed with fewer steps. [Effects of the Invention]

[0013] The open-close chuck of the present invention has crowning applied to the intersections of the five surfaces that make up the outer peripheral surface of the protruding portion of the finger, namely the upper surface, side surface, lower surface, first end surface, and second end surface, thereby making it possible to alleviate stress concentration when a moment around three axes or a vertical load acts on the finger.

[0014] In addition, the first manufacturing method of the finger according to the present invention combines grinding of the side surface of the protrusion with a first processing tool and grinding of the upper and lower surfaces of the protrusion with a second processing tool to apply crowning to the intersections between the five surfaces of the protrusion, thereby enabling the crowning process to be easily performed with fewer steps.

[0015] In addition, the second manufacturing method of the finger according to the present invention uses a single tool to simultaneously grind the side surfaces of the protrusion and grind the upper and lower surfaces of the protrusion, and crowns the intersections between the five surfaces of the protrusion, thereby making it easier to perform the crowning process with even fewer steps. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a perspective view showing the appearance of an open-close chuck according to a first embodiment of the present invention; [Figure 2] 2 is a cross-sectional view of the open-close chuck taken along line II-II of FIG. 1. [Figure 3] FIG. 2 is a front view of the open-close chuck of FIG. [Figure 4] FIG. 2 is a perspective view showing the appearance of a finger of the open-close chuck of FIG. 1; [Figure 5] 4 is a diagram showing a part of a cross section of the finger and the body taken along line VV in FIG. 3. FIG. [Figure 6] 6A is an enlarged view of part A in FIG. 3, and FIG. 6B is an enlarged view of part B in FIG. [Figure 7] 5 is a diagram showing a schematic diagram of a method for crowning the finger of FIG. 4. FIG. [Figure 8] 5 is a diagram schematically showing a path along which a first processing tool is moved when crowning is performed on the finger of FIG. 4. FIG. [Figure 9] 5 is a diagram schematically showing a path along which a second processing tool is moved when crowning is performed on the finger of FIG. 4. FIG. [Figure 10] FIG. 10 is a front view of an open-close chuck according to a second embodiment of the present invention. [Figure 11] 11A is an enlarged view of part C in FIG. 10, and FIG. 11B is an enlarged view of part D in FIG. [Figure 12] 11A to 11C are diagrams illustrating a method of crowning the fingers of the open-close chuck of FIG. 10. [Figure 13] 11 is a diagram schematically showing a path along which a third processing tool is moved when crowning is performed on a finger of the open-close chuck of FIG. 10. FIG. [Figure 14] FIG. 10 is a perspective view of a finger of an open-close chuck according to a third embodiment of the present invention. [Figure 15] 15 is a diagram schematically showing a path along which a third processing tool is moved when crowning is performed on the finger of FIG. 14. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention relates to a method for manufacturing an open-close chuck and its fingers, and a method for manufacturing the same, and will be described with reference to the accompanying drawings. In the following description, when terms relating to directions such as up, down, left, and right are used, they refer to directions on the drawings for convenience, and do not limit the actual arrangement of each component.

[0018] (First embodiment) An open-close chuck 10 according to a first embodiment of the present invention will be described with reference to Figs. 1 to 6. As shown in Figs. 1 and 2, the open-close chuck 10 includes a rectangular parallelepiped body 12 and a pair of fingers 14 supported so as to be slidable in the longitudinal direction (X direction) of the body 12. The open-close chuck 10 is used with an attachment (not shown) for gripping a workpiece connected to the fingers 14. Reference numeral 14a denotes a screw hole for connecting the attachment.

[0019] A cylinder chamber 24 is provided in the lower center of the body 12 in the longitudinal direction, and a guide groove 22 is provided above the cylinder chamber 24, extending in the longitudinal direction of the body 12 and opening at both ends to the end faces of the body 12. A piston 26 that is slidable in the up and down direction (Z direction) is disposed in the cylinder chamber 24. The cylinder chamber 24 is divided into a first pressure chamber 24a formed below the piston 26 and a second pressure chamber 24b formed above the piston 26. The first pressure chamber 24a is closed by a cap 30.

[0020] A piston rod 28 connected to the piston 26 by a bolt 32 extends further upward through the second pressure chamber 24b. The upper part of the piston rod 28 faces the inside of the guide groove 22 and forms a cam portion 28a having a known structure for driving the fingers 14. When air is supplied to the first pressure chamber 24a and air is exhausted from the second pressure chamber 24b, the piston 26 and piston rod 28 move upward, and the pair of fingers 14 slide away from each other. When air is supplied to the second pressure chamber 24b and air is exhausted from the first pressure chamber 24a, the piston 26 and piston rod 28 move downward, and the pair of fingers 14 slide toward each other.

[0021] 3 and 4, each finger 14 is a member with an inverted T-shaped cross section, and has a pair of overhanging portions 16, 18 that protrude laterally from a main body portion 20 over the entire length of the finger 14 in the longitudinal direction (X direction). The guide groove 22 of the body 12 has an inverted T-shaped cross section that follows the cross-sectional shape of the finger 14. The finger 14 slides within the guide groove 22 of the body 12.

[0022] To allow the fingers 14 to slide, the upper surfaces 16a, 18a, side surfaces 16b, 18b, and lower surfaces 16c, 18c of the protrusions 16, 18 face the wall surfaces of the guide groove 22 with a small gap between them. A larger gap exists between the side surfaces 20a, 20b of the main body 20 and the wall surfaces of the guide groove 22.

[0023] The bottom surface 20c of the main body 20 is substantially flush with the lower surfaces 16c, 18c of the overhanging portions 16, 18. A step 22a is provided between the wall surface of the guide groove 22 facing the bottom surface 20c of the main body 20 and the wall surface of the guide groove 22 facing the lower surfaces 16c, 18c of the overhanging portions 16, 18 (see FIG. 6B).

[0024] The outer peripheral surface of each of the protruding portions 16, 18 of the fingers 14 is made up of five surfaces: upper surfaces 16a, 18a, side surfaces 16b, 18b, lower surfaces 16c, 18c, first end surfaces (end surfaces in the X1 direction) 16d, 18d, and second end surfaces (end surfaces in the X2 direction) 16e, 18e. The upper surfaces 16a, 18a and lower surfaces 16c, 18c of each of the protruding portions 16, 18 are perpendicular to the side surfaces 20a, 20b of the main body 20 and also perpendicular to the side surfaces 16b, 18b of the protruding portions 16, 18.

[0025] Crowning is applied to the intersections of the five surfaces. Specifically, crowning is applied to the intersections of the upper surfaces 16a, 18a and the first end surfaces 16d, 18d, the intersections of the side surfaces 16b, 18b and the first end surfaces 16d, 18d, and the intersections of the lower surfaces 16c, 18c and the first end surfaces 16d, 18d. Similarly, crowning is applied to the intersections of the upper surfaces 16a, 18a and the second end surfaces 16e, 18e, the intersections of the side surfaces 16b, 18b and the second end surfaces 16e, 18e, and the intersections of the lower surfaces 16c, 18c and the second end surfaces 16e, 18e. Crowning is also applied to the intersections of the upper surfaces 16a, 18a and the side surfaces 16b, 18b, and the intersections of the lower surfaces 16c, 18c and the side surfaces 16b, 18b.

[0026] These crownings are intended to form a gap between the protruding portions 16, 18 of the finger 14 and the wall surface of the guide groove 22, gradually expanding from the contact point between the two. Here, we will explain the meaning of "a gap gradually expanding from the contact point between the two" (as well as other similar descriptions in this specification). When the finger contacts the body with strong pressure, one or both of the finger and the body elastically deform, causing the boundary between the contact area and the non-contact area to move. The crowning is applied to the area from the start point of this boundary to the conceivable end point, forming a gentle curve throughout the entire area. In other words, it prevents the creation of sharp corners in the area where the finger contacts the body. Figure 5 shows the crowning applied to the intersection of the lower surface 16c and the first end surface 16d of the protruding portion 16. Figure 6A shows the crowning applied to the intersection of the upper surface 16a and the side surface 16b of the protruding portion 16. FIG. 6B shows a crowning provided at the intersection between the lower surface 16c and the side surface 16b of the protruding portion 16.

[0027] In addition, the guide groove 22 of the body 12 is crowned at the intersection between the wall surface facing the upper surfaces 16a, 18a of the protrusions 16, 18 and the wall surface facing the side surfaces 20a, 20b of the main body 20, and is also crowned at the point where the step portion 22a faces the lower surfaces 16c, 18c of the protrusions 16, 18.

[0028] These crownings are also designed to form a gap that gradually widens from the contact point between the overhanging portions 16, 18 of the finger 14 and the wall surface of the guide groove 22. Fig. 6A shows the crowning applied to the intersection between the wall surface of the guide groove 22 that faces the upper surface 16a of the overhanging portion 16 and the wall surface of the guide groove 22 that faces the side surface 20a of the main body 20. Fig. 6B shows the crowning applied to the location where the step portion 22a faces the lower surface 16c of the overhanging portion 16.

[0029] When a workpiece is gripped using the open-close chuck 10, in addition to a pitch moment (moment around the Y axis), a vertical load (Z direction), a lateral load (Y direction), a roll moment (moment around the X axis), and a yaw moment (moment around the Z axis) may act on the fingers 14.

[0030] The crownings provided at the intersections of the upper surfaces 16a, 18a and the first end surfaces 16d, 18d, the intersections of the lower surfaces 16c, 18c and the first end surfaces 16d, 18d, the intersections of the upper surfaces 16a, 18a and the second end surfaces 16e, 18e, and the intersections of the lower surfaces 16c, 18c and the second end surfaces 16e, 18e mainly mitigate stress concentration when a pitch moment acts on the fingers 14. When the radius of curvature of these crownings is R1 and the length of the protrusions 16, 18 in the longitudinal direction (X direction) is L, the value of R1 / L is preferably in the range of 0.1 to 27.

[0031] The crownings provided at the intersections between the upper surfaces 16a, 18a and the side surfaces 16b, 18b and the intersections between the lower surfaces 16c, 18c and the side surfaces 16b, 18b mainly mitigate stress concentration when a roll moment acts on the fingers 14. When the radius of curvature of these crownings is R2 and the length of the protrusions 16, 18 in the width direction (Y direction) is W, it is preferable that the value of R2 / W is in the range of 0.1 to 27. The crownings provided on the guide grooves 22 of the body 12 also mitigate stress concentration when a roll moment acts on the fingers 14.

[0032] The crownings at the intersections of the side surfaces 16b, 18b and the first end surfaces 16d, 18d and the intersections of the side surfaces 16b, 18b and the second end surfaces 16e, 18e mainly mitigate stress concentration when a yaw moment acts on the finger 14. When the radius of curvature of these crownings is R3 and the longitudinal length of the protrusions 16, 18 is L, it is preferable that the value of R3 / L be in the range of 0.1 to 27.

[0033] The crownings applied to the intersections of the lower surfaces 16c, 18c and the first end surfaces 16d, 18d, the intersections of the lower surfaces 16c, 18c and the second end surfaces 16e, 18e, and the intersections of the lower surfaces 16c, 18c and the side surfaces 16b, 18b alleviate stress concentration when a vertical load acts on the fingers 14. Of the crownings applied to the guide grooves 22 of the body 12, the crownings applied at the locations where the step portions 22a face the lower surfaces 16c, 18c of the protruding portions 16, 18 also alleviate stress concentration when a vertical load acts on the fingers 14.

[0034] The crownings applied to the intersections of the side surfaces 16b, 18b and the first end surfaces 16d, 18d, the intersections of the side surfaces 16b, 18b and the second end surfaces 16e, 18e, the intersections of the upper surfaces 16a, 18a and the side surfaces 16b, 18b, and the intersections of the lower surfaces 16c, 18c and the side surfaces 16b, 18b alleviate stress concentration when a lateral load acts on the finger 14.

[0035] According to the open-close chuck 10 of this embodiment, crowning is applied to the intersections of five surfaces that constitute the outer peripheral surface of the protrusions 16, 18 of the fingers 14: the upper surfaces 16a, 18a, the side surfaces 16b, 18b, the lower surfaces 16c, 18c, the first end surfaces 16d, 18d, and the second end surfaces 16e, 18e. In addition, crowning is applied to predetermined locations in the guide groove 22 of the body 12, so that stress concentration can be alleviated when moments around three axes or vertical loads act on the fingers 14.

[0036] Next, a method for manufacturing the fingers 14 of the open-close chuck 10, specifically a method for providing the above-mentioned crowning to the fingers 14 (crowning processing) will be described with reference to FIGS.

[0037] This crowning process can perform all of the crowning described above by combining grinding of the side surfaces 16b, 18b of the pair of overhanging portions 16, 18 with grinding of the upper surfaces 16a, 18a and the lower surfaces 16c, 18c of the pair of overhanging portions 16, 18. Grinding of the side surfaces 16b, 18b of the pair of overhanging portions 16, 18 is performed using a first processing tool 34 made of a grindstone or an end mill, and grinding of the upper surfaces 16a, 18a and the lower surfaces 16c, 18c of the pair of overhanging portions 16, 18 is performed using a second processing tool 36 made of a grindstone or an end mill.

[0038] As shown in Figure 7, the first processing tool 34, which is a rotating body, is designed so that the shape of the surface that comes into contact with the workpiece matches the shape of the side surfaces 16b, 18b of the desired protrusions 16, 18, and has crowning processing portions 34a on both ends. The first processing tool 34 is disposed so that its axis faces the Z direction and can be driven to rotate about this axis. The first processing tool 34 can also be moved freely in the X and Y directions. For convenience, Figure 7 shows the finger 14 in the shape after crowning processing.

[0039] The second processing tool 36, which is also a rotating body, is designed so that the shape of the surface that comes into contact with the workpiece matches the desired shapes of the upper surfaces 16a, 18a and lower surfaces 16c, 18c of the protrusions 16, 18, and has a crowning processing portion 36a at one end. The second processing tool 36 is positioned so that its axis faces the Y direction, and can be driven to rotate about that axis. The second processing tool 36 can also be moved freely in the X and Z directions.

[0040] During crowning, first, the finger 14 is fixed to the clamp table 38 with the pair of overhanging portions 16, 18 facing upward. At this time, the first processing tool 34 is in a retracted position at a predetermined distance from the side surface 16b of one of the overhanging portions 16, midway along the longitudinal direction (X direction) of the side surface 16b, and the second processing tool 36 is in a retracted position at a predetermined distance from the undersurface 18c of the other overhanging portion 18, midway along the longitudinal direction (X direction) of the undersurface 18c.

[0041] Next, while rotating the first processing tool 34 about its axis, it is moved in the Y2 direction to approach the side surface 16b of one of the overhanging portions 16 and contact the side surface 16b with a predetermined pressure. This grinds the side surface 16b of one of the overhanging portions 16 at the location where the first processing tool 34 comes into contact. To perform this grinding over the entire side surface 16b of one of the overhanging portions 16 and the entire side surface 18b of the other overhanging portion 18, the first processing tool 34 is moved in a circular motion around the outside of these.

[0042] 8, the finger 14 is moved in the X1 direction along the side surface 16b of one of the overhanging portions 16 to the vicinity of the first end surface 16d, and then moved in the Y2 direction to the vicinity of the side surface 18b of the other overhanging portion 18 while keeping a distance from the finger 14, and further moved in the X2 direction to the vicinity of the second end surface 18e along the side surface 18b of the other overhanging portion 18. Next, the finger 14 is moved in the Y1 direction to the vicinity of the side surface 16b of one of the overhanging portions 16 while keeping a distance from the finger 14, and then moved in the X1 direction along the side surface 16b of the one overhanging portion 16 until it returns to its original position.

[0043] When the first processing tool 34 moves, in order to apply crowning to the intersection between the side surface 16b and the first end face 16d of one of the protrusions 16, the amount of movement of the first processing tool 34 in the X1 direction and the Y2 direction is controlled to grind the intersection while forcing it in, and in order to apply crowning to the intersection between the side surface 18b and the first end face 18d of the other protrusion 18, the amount of movement of the first processing tool 34 in the X2 direction and the Y2 direction is controlled to grind the intersection while forcing it in. Similarly, in order to apply crowning to the intersection between the side surface 18b and the second end face 18e of the other protrusion 18, the X2-direction movement amount and Y1-direction movement amount of the first processing tool 34 are controlled at the intersection while grinding, and in order to apply crowning to the intersection between the side surface 16b and the second end face 16e of one protrusion 16, the X1-direction movement amount and Y1-direction movement amount of the first processing tool 34 are controlled at the intersection while grinding.

[0044] When grinding of the side surfaces 16b, 18b of the pair of protrusions 16, 18 is completed by rotating the first processing tool 34 once, the rotation of the first processing tool 34 is stopped and the first processing tool 34 is moved away from the side surface 16b of one of the protrusions 16 and retracted.

[0045] Next, while rotating the second processing tool 36 about its axis, it is moved in the Z1 direction to approach the underside 18c of the other overhanging portion 18 and contact the underside 18c with a predetermined pressure. This grinds the underside 18c of the other overhanging portion 18 at the location where the second processing tool 36 comes into contact. To perform this grinding over the entire underside 18c and the entire upper surface 18a of the other overhanging portion 18, the second processing tool 36 is moved in a circular motion around the outside of these surfaces.

[0046] 9, the finger 14 is moved in the X1 direction along the lower surface 18c of the other protruding portion 18 to the vicinity of the first end surface 18d, then moved in the Z1 direction to the vicinity of the upper surface 18a while keeping a distance from the finger 14, and further moved in the X2 direction along the upper surface 18a to the vicinity of the second end surface 18e. Next, the finger 14 is moved in the Z2 direction to the vicinity of the lower surface 18c while keeping a distance from the finger 14, and then moved in the X1 direction along the lower surface 18c until it returns to its original position.

[0047] During the movement of the second processing tool 36, in order to provide crowning at the intersection between the lower surface 18c and the first end surface 18d, the amount of movement of the second processing tool 36 in the X1 direction and the Z1 direction is controlled to grind the intersection while driving in, and in order to provide crowning at the intersection between the upper surface 18a and the first end surface 18d, the amount of movement of the second processing tool 36 in the X2 direction and the Z1 direction is controlled to grind the intersection while driving in. Also, in order to provide crowning at the intersection between the upper surface 18a and the second end surface 18e, the amount of movement of the second processing tool 36 in the X2 direction and the Z2 direction is controlled to grind the intersection while driving in, and in order to provide crowning at the intersection between the lower surface 18c and the second end surface 18e, the amount of movement of the second processing tool 36 in the X1 direction and the Z2 direction is controlled to grind the intersection while driving in.

[0048] By making the second processing tool 36 circle around the other protrusion 18, grinding of the upper surface 18a and the lower surface 18c of the other protrusion 18 is completed, and then the rotation of the second processing tool 36 is stopped, and the second processing tool 36 is moved away from the lower surface 18c of the other protrusion 18 and temporarily retracted.

[0049] Next, the clamp table 38 is rotated 180 degrees in a horizontal plane so that the second processing tool 36 is positioned opposite the underside 16c of one of the overhanging portions 16. Then, while rotating the second processing tool 36 about its axis again, it is moved in the Z1 direction to approach the underside 16c of one of the overhanging portions 16 and contact the underside 16c with a predetermined pressure. This grinds the underside 16c of one of the overhanging portions 16 at the location where the second processing tool 36 comes into contact. To perform this grinding over the entire upper surface 16a and the entire lower surface 16c of one of the overhanging portions 16, the second processing tool 36 is moved in a circular motion around the outside of these surfaces.

[0050] Specifically, the finger 14 is moved in the X2 direction along the lower surface 16c of one of the protruding portions 16 to the vicinity of the second end surface 16e, then moved in the Z1 direction to the vicinity of the upper surface 16a while distancing itself from the finger 14, and further moved in the X1 direction along the upper surface 16a to the vicinity of the first end surface 16d. Next, the finger 14 is moved in the Z2 direction to the vicinity of the lower surface 16c while distancing itself from the finger 14, and then moved in the X2 direction along the lower surface 16c until it returns to its original position.

[0051] When the second processing tool 36 moves, the X-direction movement amount and the Z-direction movement amount are controlled at the intersection of the lower surface 16c and the second end surface 16e, the intersection of the upper surface 16a and the second end surface 16e, the intersection of the upper surface 16a and the first end surface 16d, and the intersection of the lower surface 16c and the first end surface 16d, in the same way as in the case of the other protrusion 18.

[0052] When grinding of the upper surface 16a and the lower surface 16c of the one protrusion 16 is completed by making the second processing tool 36 go around the one protrusion 16, the rotation of the second processing tool 36 is stopped and the second processing tool 36 is moved away from the lower surface 16c of the one protrusion 16. By the above process, crowning can be applied to the intersections of the five surfaces that make up the outer circumferential surfaces of the pair of protrusions 16, 18 of the finger 14.

[0053] (Second embodiment) Next, a method for manufacturing an open / close chuck 40 and its fingers 42 according to a second embodiment of the present invention will be described with reference to Figures 10 to 13. The open / close chuck 40 according to the second embodiment differs from the open / close chuck 10 according to the first embodiment in the shape of a pair of protruding portions on the fingers and the shape of the guide grooves provided in the body.

[0054] As shown in Figures 10 and 12, the finger 42 has a pair of trapezoidal overhangs 44, 46 that protrude laterally from the main body 48 along its entire longitudinal length. The upper surfaces 44a, 46a and lower surfaces 44c, 46c of the overhangs 44, 46 are tapered, sloping closer to each other as they approach the side surfaces 44b, 46b. The guide groove 50 of the body 12 has a cross-sectional shape that conforms to the cross-sectional shape of the finger 42. To enable sliding of the finger 42, the upper surfaces 44a, 46a, side surfaces 44b, 46b, and lower surfaces 44c, 46c of the overhangs 44, 46 face the wall surfaces of the guide groove 50 across a small gap, and the bottom surface 48c of the main body 48 also faces the wall surfaces of the guide groove 50 across a small gap.

[0055] Crowning is applied to the intersections of five surfaces that constitute the outer peripheral surface of each protrusion 44, 46: the upper surface 44a, 46a, the side surface 44b, 46b, the lower surface 44c, 46c, the first end surface 44d, 46d, and the second end surface 44e, 46e. Specifically, crowning is applied to the intersections of the upper surface 44a, 46a and the first end surface 44d, 46d, the intersections of the side surface 44b, 46b and the first end surface 44d, 46d, and the intersections of the lower surface 44c, 46c and the first end surface 44d, 46d. Similarly, crowning is applied to the intersections of the upper surfaces 44a, 46a and the second end surfaces 44e, 46e, the intersections of the side surfaces 44b, 46b and the second end surfaces 44e, 46e, and the intersections of the lower surfaces 44c, 46c and the second end surfaces 44e, 46e. Crowning is also applied to the intersections of the upper surfaces 44a, 46a and the side surfaces 44b, 46b, and the intersections of the lower surfaces 44c, 46c and the side surfaces 44b, 46b.

[0056] These crownings are intended to form a gap that gradually widens from the contact point between the protrusions 44, 46 of the finger 42 and the wall surface of the guide groove 50. Fig. 11A shows the crowning applied to the intersection of the upper surface 44a and the side surface 44b of the protrusion 44. Fig. 11B shows the crowning applied to the intersection of the lower surface 44c of the protrusion 44 and the side surface 44b.

[0057] In addition, the guide groove 50 of the body 12 is crowned at the intersection between the wall surface facing the upper surfaces 44a, 46a of the protrusions 44, 46 and the wall surface facing the side surfaces 48a, 48b of the main body 48, and is also crowned at the location where the step portion 50a faces the lower surfaces 44c, 46c of the protrusions 44, 46.

[0058] These crownings are also designed to form a gap that gradually widens from the contact point between the overhanging portions 44, 46 of the finger 42 and the wall surface of the guide groove 50. Fig. 11A shows the crowning applied to the intersection between the wall surface of the guide groove 50 facing the upper surface 44a of the overhanging portion 44 and the wall surface of the guide groove 50 facing the side surface 48a of the main body portion 48. Fig. 11B shows the crowning applied to the location where the step portion 50a faces the lower surface 44c of the overhanging portion 44.

[0059] According to the opening and closing chuck 40 of this embodiment, crowning is applied to the intersections of the five surfaces that constitute the outer peripheral surface of the protrusions 44, 46 of the fingers 42, namely the upper surfaces 44a, 46a, the side surfaces 44b, 46b, the lower surfaces 44c, 46c, the first end surfaces 44d, 46d, and the second end surfaces 44e, 46e, and further, crowning is applied to predetermined locations in the guide groove 50 of the body 12, thereby making it possible to alleviate stress concentration when moments around three axes or vertical loads act on the fingers.

[0060] Next, a method of crowning the finger 42 (crowning process) will be described with reference to Figures 12 and 13. This crowning process uses a third processing tool 52 (a single processing tool) made of a grinding stone or an end mill to simultaneously grind the side surfaces 44b, 46b of the pair of overhanging portions 44, 46 and grind the upper surfaces 44a, 46a and the lower surfaces 44c, 46c of the pair of overhanging portions 44, 46, thereby performing all of the crowning described above.

[0061] As shown in Figure 12, the third processing tool 52, which is a rotating body, is designed so that the shape of the surface that comes into contact with the workpiece matches the shapes of the upper surfaces 44a, 46a, side surfaces 44b, 46b, and lower surfaces 44c, 46c of the intended protrusions 44, 46. The third processing tool 52 is disposed with its axis oriented in the Z direction and can be driven to rotate about this axis. The third processing tool 52 can also be moved freely in the X and Y directions.

[0062] The third processing tool 52 is provided with a first crowning portion 52a and a second crowning portion 52b. The first crowning portion 52a is for applying crowning to the intersections between the upper surfaces 44a, 46a and the side surfaces 44b, 46b of the protrusions 44, 46, and the second crowning portion 52b is for applying crowning to the intersections between the lower surfaces 44c, 46c and the side surfaces 44b, 46b of the protrusions 44, 46.

[0063] In the crowning process, first, the finger 42 is fixed to the clamp table 38 with the pair of protruding portions 44, 46 facing upward. At this time, the third processing tool 52 is positioned facing one of the protruding portions 44 midway in the longitudinal direction (X direction) of the protruding portion 44.

[0064] Next, while rotating the third processing tool 52 about its axis, it is moved in the Y2 direction to approach one of the protruding portions 44 and bring it into contact with the upper surface 44a, side surface 44b, and lower surface 44c with a predetermined pressure. This simultaneously grinds the upper surface 44a, side surface 44b, and lower surface 44c of one of the protruding portions 44 at the locations where the third processing tool 52 comes into contact. To perform this grinding over the entire one of the protruding portions 44 and the entire other of the protruding portions 46, the third processing tool 52 is moved in a manner that circles around the outside of these portions.

[0065] 13, the finger 42 is moved in the X1 direction along the side surface 44b of one of the overhanging portions 44 to the vicinity of the first end surface 44d, and then moved in the Y2 direction to the vicinity of the side surface 46b of the other overhanging portion 46 while keeping a distance from the finger 42, and further moved in the X2 direction to the vicinity of the second end surface 46e along the side surface 46b of the other overhanging portion 46. Next, the finger 42 is moved in the Y1 direction to the vicinity of the side surface 44b of one of the overhanging portions 44 while keeping a distance from the finger 42, and then moved in the X1 direction along the side surface 44b of the one overhanging portion 44 until it returns to its original position.

[0066] When the third processing tool 52 moves, in order to apply crowning to the intersections of one protrusion 44 between the upper surface 44a and the first end surface 44d, the intersections of the side surface 44b and the first end surface 44d, and the intersections of the lower surface 44c and the first end surface 44d, the X1-directional movement amount and the Y2-directional movement amount of the third processing tool 52 are controlled to grind the intersections, and in order to apply crowning to the intersections of the other protrusion 46 between the upper surface 46a and the first end surface 46d, the intersections of the side surface 46b and the first end surface 46d, and the intersections of the lower surface 46c and the first end surface 46d, the X2-directional movement amount and the Y2-directional movement amount of the third processing tool 52 are controlled to grind the intersections.

[0067] For the other protrusion 46, crowning is applied to the intersections between the upper surface 46a and the second end surface 46e, the intersections between the side surface 46b and the second end surface 46e, and the intersections between the lower surface 46c and the second end surface 46e, and at these intersections, the movement amount of the third processing tool 52 in the X2 direction and the Y1 direction is controlled to grind while driving in; and for the one protrusion 44, crowning is applied to the intersections between the upper surface 44a and the second end surface 44e, the intersections between the side surface 44b and the second end surface 44e, and the intersections between the lower surface 44c and the second end surface 44e, and at these intersections, the movement amount of the third processing tool 52 in the X1 direction and the Y1 direction is controlled to grind while driving in.

[0068] In this way, by simply moving the third processing tool 52 around once, it is possible to apply crowning to the intersections of the five surfaces that form the outer peripheral surfaces of the pair of protruding portions 44, 46 of the finger 42.

[0069] (Third embodiment) Next, a finger 62 of an open / close chuck according to a third embodiment of the present invention and a manufacturing method thereof will be described with reference to Figures 14 and 15. The finger 62 according to the third embodiment differs from the finger 42 of the open / close chuck according to the second embodiment in that a recess and a grease reservoir are provided in each protruding portion.

[0070] 14, a recess 72 is provided in the longitudinal center of the upper surface 64a, side surface 64b, and lower surface 64c of one of the overhanging portions 64, and crowning regions CR1, CR2 are provided at both ends of the recess 72. A grease reservoir 70 is provided that opens to the bottom surface of the recess 72 formed in the upper surface 64a. A grease reservoir 70 with a similar configuration is also provided in the other overhanging portion 66. Grease stored in the grease reservoir 70 is supplied to the sliding surfaces of the overhanging portions 64, 66, maintaining the lubricating function.

[0071] Grease reservoir 70 opens to the bottom surface of recess 72, so its edge does not come into contact with the wall surfaces of the guide groove, causing stress concentration. In addition, recess 72 connects to the sliding surfaces (surfaces that come into contact with the wall surfaces of the guide groove) on upper surface 64a, side surface 64b, and lower surface 64c via crowned crowning regions CR1 and CR2, so the provision of recess 72 does not cause stress concentration between the guide groove and recess 72.

[0072] Crowning is applied to the intersections of five surfaces that constitute the outer peripheral surface of each of the protrusions 64, 66: the upper surfaces 64a, 66a, the side surfaces 64b, 66b, the lower surfaces 64c, 66c, the first end surfaces 64d, 66d, and the second end surfaces 64e, 66e. In addition, the guide groove of the body 12 is crowned at the intersections of the wall surfaces facing the upper surfaces 64a, 66a of the protrusions 64, 66 and the wall surfaces facing the side surfaces 68a, 68b of the main body 68, and the stepped portions of the guide groove are crowned at the locations where they face the lower surfaces 64c, 66c of the protrusions 64, 66.

[0073] Next, a method of crowning the finger 62 (crowning process) will be described with reference to Fig. 15. This crowning process uses the same third processing tool (single processing tool) 52 as in the second embodiment to simultaneously grind the side surfaces 64b, 66b of the pair of overhanging portions 64, 66 and grind the upper surfaces 64a, 66a and the lower surfaces 64c, 66c of the pair of overhanging portions 64, 66, thereby performing all of the crowning described above.

[0074] While rotating the third processing tool 52 around its axis, it is brought into contact with the upper surface 64a, side surface 64b, and lower surface 64c of one of the overhanging portions 64 at a predetermined position in the longitudinal direction (X direction) of the one of the overhanging portions 64, and grinds them simultaneously. To perform this grinding over the entire one of the overhanging portions 64 and the entire other of the overhanging portions 66, the third processing tool 52 is moved so as to circle around the outside of these portions.

[0075] When the third processing tool 52 moves, the X-direction movement amount and Y-direction movement amount of the third processing tool 52 are controlled to grind while being driven in, as in the second embodiment, at the intersection of the side surface 64b, etc. of one of the protruding portions 64 and the first end face 64d, the intersection of the side surface 66b, etc. of the other protruding portion 66 and the first end face 66d, the intersection of the side surface 66b, etc. of the other protruding portion 66 and the second end face 66e, and the intersection of the side surface 64b, etc. of one of the protruding portions 64 and the second end face 64e.

[0076] Furthermore, in order to form the crowning regions CR1, CR2 and the recess 72 for one of the protruding portions 64, the amount of movement of the third processing tool 52 in the Y1 direction or the Y2 direction is controlled to grind the protruding portion 64 near the center in the longitudinal direction of the one of the protruding portions 64. Similarly, the amount of movement of the third processing tool 52 in the Y1 direction or the Y2 direction is controlled to grind the protruding portion 66 near the center in the longitudinal direction of the other of the protruding portions 66.

[0077] In this way, by simply rotating the third processing tool 52 once, crowning can be applied to the intersections of the five surfaces that make up the outer peripheral surfaces of the pair of protrusions 64, 66, and crowning areas CR1, CR2 and recesses 72 can be formed in the pair of protrusions 64, 66.

[0078] The method for manufacturing the open-close chuck and its fingers according to the present invention is not limited to the above-described embodiment, and it goes without saying that various configurations can be adopted within the scope of the gist of the present invention. [Explanation of symbols]

[0079] 10, 40...Open and close zipper 12...Body 14, 42, 62...Fingers 16, 18, 44, 46, 64, 66...Protrusion 16a, 18a, 44a, 46a, 64a, 66a...Top surface 16b, 18b, 44b, 46b, 64b, 66b...side 16c, 18c, 44c, 46c, 64c, 66c...Bottom side 16d, 18d, 44d, 46d, 64d, 66d...first end surface 16e, 18e, 44e, 46e, 64e, 66e...2nd end surface 20, 48, 68...Main body 20a, 20b, 48a, 48b, 68a, 68b...side surfaces of the main body 20c, 48c...Bottom of main body 22, 50... Guide groove 22a, 50a... Step portion 34...First processing tool 36...Second processing tool 52...Third processing tool (single processing tool) 70...Grease reservoir 72...Concave portion CR1, CR2...Crowning area

Claims

1. An open-close chuck including a pair of fingers that slide within a guide groove of a body and are supported so as to be slidable in directions approaching and separating from each other, The fingers have a pair of protruding portions that protrude laterally from the main body portion, and the outer peripheral surface of the protruding portions consists of five surfaces: an upper surface, a side surface, a lower surface, a first end surface, and a second end surface. Crowning is applied to the intersections of these surfaces, and this crowning forms a gap between the protruding portions and the wall surface of the guide groove that gradually widens continuously from the contact point between the two.

2. The open-close chuck according to claim 1, The upper surface and the lower surface are perpendicular to the side surface of the chuck.

3. The open-close chuck according to claim 1, The upper surface and the lower surface are tapered surfaces that approach each other toward the side surfaces.

4. The open-close chuck according to claim 1, The guide groove of the body is crowned at the intersection between the wall surface facing the top surface and the wall surface facing the side surface of the main body, and this crowning forms a gap between the protrusion and the wall surface of the guide groove that gradually widens from the contact point between the two.

5. The open-close chuck according to claim 1, The opening and closing chuck has a crowning at the point where the step portion provided in the guide groove of the body faces the underside, and this crowning forms a gap between the protrusion portion and the wall surface of the guide groove that gradually widens from the contact point between the two.

6. The open-close chuck according to claim 3, a recessed portion is provided in the longitudinal center of the upper surface, the side surface, and the lower surface, and a crowning region is provided at both ends of the recessed portion, and a grease reservoir is provided that opens to a bottom surface of the recessed portion provided in the upper surface.

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