Opening / closing chuck and method of manufacturing finger thereof

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 an open-close 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 slidably in a direction in which they approach and move away from each other. For example, Patent Document 1 describes a parallel gripper in which a wedge-shaped hook transmission part is provided for moving two base jaws movably guided in a housing toward or away from each other, and the wedge-shaped hook transmission part 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 to form 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 by a pair of slidably supported fingers, a load acts on the fingers in a predetermined direction (vertical or horizontal) due to a reaction force from the workpiece, and a moment acts on the fingers to rotate the fingers around various axes in three dimensions. The load and moment acting on the fingers become larger as the gripping force of the workpiece is increased. Also, the moment acting on the fingers becomes larger as the distance between the gripping position of the workpiece in the gripping member (attachment) extended from the fingers and the support position of the fingers becomes longer. If the load and moment acting on the fingers are large, stress concentration occurs on 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 occurring 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 to open at an angle, and in preventing excessive surface pressure, but does not take into consideration the moments acting 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 the 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 at the contact surface between the fingers and the body due to loads in the vertical direction, etc., acting on the fingers and moments around various three-dimensional axes. [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 approaching and separating from each other, 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, including 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] According to the above-described open-close chuck, it is possible to reduce the concentration of stress on the fingers caused by the load acting on the fingers in the vertical direction and the moment about three axes, and to lower the maximum surface pressure.

[0010] In addition, a first manufacturing method for 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 protruding laterally from a main body, and the outer peripheral surface of the protrusions consists of five surfaces, namely 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] In addition, a second manufacturing method for a finger according to the present invention relates to a finger that slides within a guide groove of 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 protruding laterally from a main body, and the outer peripheral surface of the protrusions consists of five surfaces, namely an upper surface, a side surface, a lower surface, a first end surface and a second end surface, and the upper surface and lower surface are tapered surfaces that approach each other toward the side surface, and includes a step of simultaneously grinding the side surface and the upper surface and lower surface using a single processing tool, thereby applying crowning to the intersections of the above five surfaces.

[0012] According to the above-mentioned first and second manufacturing methods, crowning processing for relieving stress concentration occurring in the fingers and body due to loads in the vertical direction and moments about three axes acting on the fingers can be easily performed with fewer steps. Effect of the Invention

[0013] The open-close chuck of the present invention has crowning applied to the intersections of five surfaces that constitute 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 reduce stress concentration when a moment about 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 surfaces 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 crown the intersections between the five surfaces of the protrusion, thereby making it possible to easily perform the crowning process 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 in even fewer steps. [Brief description of the drawings]

[0016] [Figure 1] 1 is an external perspective view of an open-close chuck according to a first embodiment of the present invention; [Diagram 2] 2 is a cross-sectional view taken along line II-II of the open-close chuck of FIG. 1. [Diagram 3] FIG. 2 is a front view of the open-close chuck of FIG. [Figure 4] FIG. 2 is an external perspective view of a finger of the open-close chuck of FIG. [Diagram 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. [Figure 6] 6A is an enlarged view of a portion A in FIG. 3, and FIG. 6B is an enlarged view of a portion B in FIG. [Figure 7] 5 is a diagram showing a schematic diagram of a method for providing crowning to the finger of FIG. 4. FIG. [Figure 8] 5 is a diagram showing a schematic diagram of a path along which a first processing tool is moved when crowning is performed on the finger in FIG. 4. FIG. [Figure 9] 5 is a diagram showing a schematic diagram of a path along which a second processing tool is moved when crowning is performed on the finger in FIG. 4. FIG. [Figure 10] FIG. 6 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 a portion C in FIG. 10, and FIG. 11B is an enlarged view of a portion 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 showing a schematic view of 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. 11 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 showing a schematic diagram of a path along which a third processing tool is moved when crowning is performed on the finger in FIG. 14. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The present invention relates to a method for manufacturing an open-close chuck and its fingers, and will be described with reference to the accompanying drawings, showing preferred embodiments thereof. In the following description, when words related 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 member.

[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 longitudinal direction of the body 12, and a guide groove 22 extending in the longitudinal direction of the body 12 and opening at both ends to the end faces of the body 12 is provided in a portion above the cylinder chamber 24. A piston 26 capable of sliding in the vertical 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. An upper portion of the piston rod 28 faces the inside of the guide groove 22 and serves as 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 the piston rod 28 move upward, and the pair of fingers 14 slide in a direction 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 the piston rod 28 move downward, and the pair of fingers 14 slide in a direction toward each other.

[0021] 3 and 4, each finger 14 is a member having 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 enable the fingers 14 to slide, the upper surfaces 16a, 18a, the side surfaces 16b, 18b and the lower surfaces 16c, 18c of the projections 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 portion 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 projections 16, 18 of the finger 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 projections 16, 18 are perpendicular to the side surfaces 20a, 20b of the main body 20, and are also perpendicular to the side surfaces 16b, 18b of the projections 16, 18.

[0025] The intersections of the above five faces are crowned. Specifically, the intersections of the upper faces 16a, 18a and the first end faces 16d, 18d, the intersections of the side faces 16b, 18b and the first end faces 16d, 18d, and the intersections of the lower faces 16c, 18c and the first end faces 16d, 18d are crowned. Similarly, the intersections of the upper faces 16a, 18a and the second end faces 16e, 18e, the intersections of the side faces 16b, 18b and the second end faces 16e, 18e, and the intersections of the lower faces 16c, 18c and the second end faces 16e, 18e are crowned. In addition, the intersections of the upper faces 16a, 18a and the side faces 16b, 18b, and the intersections of the lower faces 16c, 18c and the side faces 16b, 18b are also crowned.

[0026] These crownings are formed between the overhanging parts 16, 18 of the finger 14 and the wall surface of the guide groove 22 so that a gap is formed between the contact parts between the two and gradually expands. Here, the meaning of "a gap is formed between the contact parts between the two and gradually expands" will be explained (as in other similar descriptions in this specification). When the finger contacts the body with a strong pressure, one or both of the finger and the body are elastically deformed, and the boundary between the contact area and the non-contact area between the two moves. The crowning is applied to the area including the start point of this boundary to the conceivable end point, and is formed to draw a gentle curve in the entire area. In other words, it is intended to prevent the occurrence of a corner in the area where the finger contacts the body. FIG. 5 shows the crowning applied to the intersection of the lower surface 16c and the first end surface 16d of the overhanging part 16. FIG. 6A shows the crowning applied to the intersection of the upper surface 16a and the side surface 16b of the overhanging part 16. FIG. 6B shows a crowning provided at the intersection between the lower surface 16c and the side surface 16b of the overhanging 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 formed so that a gap is formed between the overhanging portions 16, 18 of the finger 14 and the wall surface of the guide groove 22, which gradually widens from the contact point between the two. Fig. 6A shows the crowning applied to the intersection between the wall surface of the guide groove 22 facing the upper surface 16a of the overhanging portion 16 and the wall surface of the guide groove 22 facing the side surface 20a of the main body portion 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 gripping a workpiece using the open-close chuck 10, in addition to a pitch moment (moment about the Y-axis) acting on the fingers 14, a vertical load (Z direction), a lateral load (Y direction), a roll moment (moment about the X-axis), and a yaw moment (moment about the Z-axis) may also act on the fingers 14.

[0030] The crownings provided at the intersections of the upper faces 16a, 18a and the first end faces 16d, 18d, the intersections of the lower faces 16c, 18c and the first end faces 16d, 18d, the intersections of the upper faces 16a, 18a and the second end faces 16e, 18e, and the intersections of the lower faces 16c, 18c and the second end faces 16e, 18e mainly mitigate stress concentration when a pitch moment acts on the finger 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 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 mainly relieve stress concentration when a roll moment acts on the finger 14. If the radius of curvature of these crownings is R2 and the length of the projections 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 applied to the guide grooves 22 of the body 12 also relieve stress concentration when a roll moment acts on the finger 14.

[0032] The crownings at the intersections of the side surfaces 16b, 18b and the first end faces 16d, 18d and the intersections of the side surfaces 16b, 18b and the second end faces 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 is in the range of 0.1 to 27.

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

[0034] The crownings applied to the intersections of the side surfaces 16b, 18b and the first end faces 16d, 18d, the intersections of the side surfaces 16b, 18b and the second end faces 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 reduce 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, namely, 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, and crowning is applied to predetermined locations in the guide groove 22 of the body 12, so that stress concentration can be alleviated when a moment about three axes or a vertical load acts 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 process) 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 parts 16, 18 with grinding of the upper surfaces 16a, 18a and the lower surfaces 16c, 18c of the pair of overhanging parts 16, 18. Grinding of the side surfaces 16b, 18b of the pair of overhanging parts 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 parts 16, 18 is performed using a second processing tool 36 made of a grindstone or an end mill.

[0038] As shown in Fig. 7, the first processing tool 34, which is a rotating body, is made 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 parts 34a on both ends. The first processing tool 34 is disposed so that its axis faces the Z direction, and can be rotated around the axis. The first processing tool 34 can also be freely moved in the X direction and the Y direction. For convenience, Fig. 7 shows the finger 14 having the shape after crowning processing.

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

[0040] In the crowning process, 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 in 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 in 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 causes the side surface 16b of one of the overhanging portions 16 to be ground 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 so as to circle 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 one of the overhanging portions 16 until it returns to its original position.

[0043] During the movement of the first processing tool 34, in order to perform crowning at 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 drive in and grind at the intersection, and in order to perform crowning at 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 drive in and grind at the intersection. Similarly, to apply crowning to the intersection between the side surface 18b and the second end face 18e of the other protrusion 18, the first processing tool 34 is ground while being driven in by controlling the amount of movement in the X2 direction and the Y1 direction at the intersection, and to apply crowning to the intersection between the side surface 16b and the second end face 16e of one protrusion 16, the first processing tool 34 is ground while being driven in by controlling the amount of movement in the X1 direction and the Y1 direction at the intersection.

[0044] When grinding of the side surfaces 16b, 18b of the pair of protrusions 16, 18 is completed by making the first processing tool 34 rotate 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 retreated.

[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 causes the underside 18c of the other overhanging portion 18 at the location where the second processing tool 36 comes into contact to be ground. 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 so as to circle around the outside of these surfaces.

[0046] 9, the other protruding portion 18 is moved in the X1 direction along the lower surface 18c 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 other protruding portion 18 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 perform crowning at the intersection between the lower surface 18c and the first end surface 18d, the second processing tool 36 is driven in by controlling the X1-direction movement amount and the Z1-direction movement amount at the intersection, and in order to perform crowning at the intersection between the upper surface 18a and the first end surface 18d, the second processing tool 36 is driven in by controlling the X2-direction movement amount and the Z1-direction movement amount at the intersection. In addition, in order to perform crowning at the intersection between the upper surface 18a and the second end surface 18e, the second processing tool 36 is driven in by controlling the X2-direction movement amount and the Z2-direction movement amount at the intersection, and in order to perform crowning at the intersection between the lower surface 18c and the second end surface 18e, the second processing tool 36 is driven in by controlling the X1-direction movement amount and the Z2-direction movement amount at the intersection.

[0048] When grinding of the upper surface 18a and the lower surface 18c of the other protrusion 18 is completed by making the second processing tool 36 rotate once around the other protrusion 18, 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 withdrawn.

[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 lower surface 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 lower surface 16c of one of the overhanging portions 16 and contact the lower surface 16c with a predetermined pressure. This causes the lower surface 16c of one of the overhanging portions 16 at the portion where the second processing tool 36 comes into contact to be ground. 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 so as to circle around the outside of these surfaces.

[0050] Specifically, it is moved in the X2 direction along the underside 16c of one of the overhanging 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 keeping a distance 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, it is moved in the Z2 direction to the vicinity of the underside 16c while keeping a distance from the finger 14, and then moved in the X2 direction along the underside 16c until it returns to its original position.

[0051] When the second processing tool 36 moves, the amount of movement in the X direction and the amount of movement in the Z direction 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 manner 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 overhanging portion 16 is completed by making the second processing tool 36 go around the one overhanging portion 16 once, the rotation of the second processing tool 36 is stopped and the second processing tool 36 is moved away from and retracted from the lower surface 16c of the one overhanging portion 16. By the above process, it is possible to perform crowning on the intersections of the five surfaces that constitute the outer circumferential surfaces of the pair of overhanging portions 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 Fig. 10 to Fig. 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 parts in the fingers and the shape of a guide groove provided in the body.

[0054] As shown in Figs. 10 and 12, the finger 42 has a pair of trapezoidal overhangs 44, 46 that overhang the entire length of the finger 42. The upper surfaces 44a, 46a and the lower surfaces 44c, 46c of the overhangs 44, 46 are tapered surfaces that are inclined toward each other toward the side surfaces 44b, 46b. The guide groove 50 of the body 12 has a cross-sectional shape that follows the cross-sectional shape of the finger 42. To enable the finger 42 to slide, the upper surfaces 44a, 46a, the side surfaces 44b, 46b and the lower surfaces 44c, 46c of the overhangs 44, 46 face the wall surface of the guide groove 50 with a small gap therebetween, and the bottom surface 48c of the body 48 also faces the wall surface of the guide groove 50 with a small gap therebetween.

[0055] Crowning is applied to the intersections of five surfaces, namely, 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, which constitute the outer peripheral surface of each of the protruding portions 44, 46. 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 faces 44a, 46a and the second end faces 44e, 46e, the intersections of the side faces 44b, 46b and the second end faces 44e, 46e, and the intersections of the lower faces 44c, 46c and the second end faces 44e, 46e. Crowning is also applied to the intersections of the upper faces 44a, 46a and the side faces 44b, 46b, and the intersections of the lower faces 44c, 46c and the side faces 44b, 46b.

[0056] These crownings are provided so that a gap is formed between the projections 44, 46 of the finger 42 and the wall surface of the guide groove 50, the gap gradually expanding from the contact point between the projections 44, 46 and the wall surface of the guide groove 50. Fig. 11A shows the crowning provided at the intersection between the upper surface 44a and the side surface 44b of the projection 44. Fig. 11B shows the crowning provided at the intersection between the lower surface 44c and the side surface 44b of the projection 44.

[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 portion 48, and is 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 formed so that a gap is formed between the overhanging portions 44, 46 of the finger 42 and the wall surface of the guide groove 50, which gradually widens from the contact point between the two. 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 / closing chuck 40 of this embodiment, crowning is applied to the intersections of 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 faces 44d, 46d and the second end faces 44e, 46e, and crowning is applied to specified locations in the guide groove 50 of the body 12, thereby making it possible to alleviate stress concentration when a moment about three axes or a vertical load acts on the fingers.

[0060] Next, a method of applying the crowning to the finger 42 (crowning) will be described with reference to Figures 12 and 13. This crowning is performed by simultaneously grinding the side surfaces 44b, 46b of the pair of protruding parts 44, 46 and grinding the upper surfaces 44a, 46a and the lower surfaces 44c, 46c of the pair of protruding parts 44, 46 using a third processing tool 52 (single processing tool) made of a grindstone or an end mill, thereby applying all of the crowning described above.

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

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

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

[0064] Next, while rotating the third processing tool 52 about its axis, it is moved in the Y2 direction to approach one of the overhanging portions 44 and contact the upper surface 44a, the side surface 44b, and the lower surface 44c with a predetermined pressure. As a result, the upper surface 44a, the side surface 44b, and the lower surface 44c of one of the overhanging portions 44 at the portion where the third processing tool 52 comes into contact are simultaneously ground. To perform this grinding over the entire one of the overhanging portions 44 and the entire other overhanging portion 46, the third processing tool 52 is moved so as to circle around the outsides 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] During the movement of the third processing tool 52, in order to perform crowning at the intersections of 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 for one of the protrusions 44, the movement amounts of the third processing tool 52 in the X1 direction and the Y2 direction are controlled to drive in and grind at the intersections, and in order to perform crowning at the intersections of 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 for the other protrusion 46, the movement amounts of the third processing tool 52 in the X2 direction and the Y2 direction are controlled to drive in and grind at the intersections.

[0067] Regarding the other protrusion 46, in order to apply crowning 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, the X2-directional movement amount and the Y1-directional movement amount of the third processing tool 52 are controlled at the intersections while being driven in, and regarding the one protrusion 44, in order to apply crowning 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, the X1-directional movement amount and the Y1-directional movement amount of the third processing tool 52 are controlled at the intersections while being driven in.

[0068] In this manner, by simply moving the third processing tool 52 once, it is possible to provide crowning to the intersections between the five faces that form the outer circumferential surfaces of the pair of overhanging 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 Fig. 14 and Fig. 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 each protruding portion is provided with a recess and a grease reservoir.

[0070] 14, a recess 72 is provided in the longitudinal center of the upper surface 64a, the side surface 64b, and the 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 is also provided in the other overhanging portion 66 with a similar configuration. Grease stored in the grease reservoir 70 is supplied to the sliding surfaces of the overhanging portions 64, 66, maintaining the lubricating function.

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

[0072] Crowning is applied to the intersections of five surfaces constituting the outer peripheral surface of each of the projections 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, in the guide groove of the body 12, crowning is applied to the intersections of the wall surfaces facing the upper surfaces 64a, 66a of the projections 64, 66 and the wall surfaces facing the side surfaces 68a, 68b of the main body 68, and crowning is applied to the portions where the stepped portions of the guide grooves face the lower surfaces 64c, 66c of the projections 64, 66.

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

[0074] While rotating the third processing tool 52 about its axis, it is brought into contact with the upper surface 64a, the side surface 64b, and the 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. In order 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 outsides 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. and the first end face 64d of one protrusion 64, the intersection of the side surface 66b etc. and the first end face 66d of the other protrusion 66, the intersection of the side surface 66b etc. and the second end face 66e of the other protrusion 66, and the intersection of the side surface 64b etc. and the second end face 64e of one protrusion 64.

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

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

[0078] The method of 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 without departing from the gist of the present invention. [Explanation of symbols]

[0079] 10, 40...Opening and closing chuck 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... Sides of 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: Recess CR1, CR2: Crowning area

Claims

1. A method for manufacturing a pair of fingers that slide within guide grooves in a body of an open-close chuck and are supported so as to be slidable in directions approaching and separating from each other, comprising the steps of: the finger has a pair of protruding portions protruding laterally from a main body portion, the outer peripheral surface of the protruding portion is made up of five surfaces, including an upper surface, a side surface, a lower surface, a first end surface, and a second end surface, the upper surface and the lower surface being perpendicular to the side surfaces, The method for manufacturing a finger includes a step of crowning the intersections between the 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, and the 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.

2. A method for manufacturing a pair of fingers that slide within guide grooves in a body of an open-close chuck and are supported so as to be slidable in directions approaching and separating from each other, comprising the steps of: the finger has a pair of protruding portions protruding laterally from a main body portion, the outer peripheral surface of the protruding portion is made up of five surfaces, namely, an upper surface, a side surface, a lower surface, a first end surface, and a second end surface, the upper surface and the lower surface being tapered surfaces that approach each other toward the side surface, The method for manufacturing a finger includes a step of using a single processing tool to simultaneously grind the side surfaces and grind the upper and lower surfaces, thereby crowning the intersections between the five surfaces, and the crowning forms a gap between the protrusion and the wall surface of the guide groove that gradually widens from the point of contact between the two.

3. 3. A method for manufacturing a finger according to claim 2, comprising the steps of: A recess is provided at 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 recess. A grease reservoir is provided at the bottom surface of the recess provided on the upper surface, the recess being open to the bottom surface. The method for manufacturing a finger, wherein the crowning region is crowned by the above process.

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