Clamp device

The present invention relates to a clamp device. The clamp device is provided with a driving force transmission mechanism, which transmits driving force from a drive unit to clamp arms. The driving force transmission mechanism converts the rectilinear movement of a piston rod of the drive unit into: a first operation, in which the clamp arms rotate while moving in directions toward or away from each other; and a second operation, in which the clamp arms move in parallel in directions toward or away from each other with gripping surfaces in a mutually parallel state.

TECHNICAL FIELD

The present invention relates to a clamp device for clamping a workpiece with a plurality of clamp arms.

BACKGROUND ART

The clamp device is widely used in a welding process of an automatic assembly line of the machine industry and the like. A clamp device of this type generally has a pair of clamp arms rotatably mounted on a clamp body via pins. By applying a driving force of a cylinder to one end portion of each clamp arm, these clamp arms are rotated about the pins, and a workpiece is clamped and positioned from the left and right sides by a gripping surface provided at the other end portion of each clamp arm. Then, the workpiece is subjected to necessary processing and a transportation process (see, for example, Japanese Patent No. 4950123).

Among those clamp devices, for example, Japanese Laid-Open Patent Publication No. 2015-037829 discloses a clamp device in which a pair of clamp arms having attachments attached to the gripping surfaces and a pair of clamp arms having no attachment attached to the gripping surfaces are selectively rotated.

In addition, Japanese Laid-Open Patent Publication No. 2009-012138 discloses a clamp device that clamps a workpiece by translating a pair of clamp arms in a direction to approach or separate from each other.

SUMMARY OF INVENTION

The clamp device disclosed in above-mentioned Japanese Patent No. 4950123 has a constant gap (hereinafter referred to as a clamp distance) between the gripping faces at a clamping position where the gripping faces of a pair of clamp arms are parallel to each other. Therefore, in the case where the clamp distance and the width dimension of the workpiece (the distance between the portions of the workpiece in contact with the gripping surface of each clamp arm) are different, it is not easy to apply a uniform clamping force to plural types of workpieces having different width dimensions. Therefore, it is sometimes impossible to clamp reliably such plural types of workpieces.

Therefore, when conveying plural types of workpieces having different width sizes to an automatic assembly line, it is necessary to prepare plural types of clamp devices with different clamp distances according to the types of workpieces.

On the other hand, in the technique disclosed in Japanese Laid-Open Patent Publication No. 2015-037829, one clamp device can clamp plural types of workpieces having different widths. However, because a plurality of clamp arms corresponding to the types of workpieces is required, the clamp device becomes complicated and large in size.

Further, when a pair of clamp arms are rotated about the pins, one end portions of the pair of clamp arms limit the maximum opening angle of the other end portions (gripping surfaces) of the pair of clamp arms to such an extent that the one end portions of the pair of clamp arms do not interfere with each other. That is, the gap between the pair of gripping surfaces in the unclamping state becomes comparatively narrow. In this case, it is necessary to avoid contact between the workpiece and the clamp arms, so that the supply direction and the discharge direction of the workpieces with respect to the clamp device may be restricted.

Furthermore, in the technique disclosed in Japanese Laid-Open Patent Publication No. 2009-012138, since the pair of clamp arms are merely translated, the degree of freedom in the supply direction and the discharge direction of the workpiece with respect to the clamp device is greatly restricted.

The present invention has been made in consideration of such a problem. It is an object of the present invention to clamp plural types of workpieces having different widths reliably and stably while suppressing upsizing of the device with a simple structure. It is also possible to increase the degree of freedom of the supply direction and the discharge direction of the workpieces.

A clamp device according to the present invention is to clamp a workpiece among a plurality of clamp arms. The clamp device comprises: a clamp body; a plurality of clamp arms supported movably with respect to the clamp body; a driving unit having a displacement body for linear reciprocating motion and provided on the clamp body; and a driving force transmission mechanism configured to transmit a driving force of the driving unit to each of the clamp arms, wherein the driving force transmission mechanism is configured to convert the linear motion of the displacement body into a first motion for moving and rotating the plurality of clamp arms in a direction toward or away from each other, and into a second motion for translating the plurality of clamp arms in a direction toward or away from each other in a state where gripping surfaces of the respective clamp arms to contact the workpiece are in parallel.

According to this configuration, since the clamp distance can be changed, it is possible to reliably and stably clamp plural types of workpieces having different widths while suppressing upsizing of the clamp device with a simple configuration. Also, as the clamp arms rotate, the distance between the gripping surfaces in the unclamping state can be made relatively wide, so that the degree of freedom in the supply direction and the discharge direction of the workpieces can be increased.

In the above-described clamp device, the driving force transmission mechanism may include a movable part provided on the displacement body, a first cam hole being formed in the movable part, a fixed part provided on the clamp body, a second cam hole being formed in the fixed part, a first shaft and a second shaft provided with respect to each of the clamp arms, a first roller rotatably provided on the first shaft and movable in the first cam hole, a second roller rotatably provided on the first shaft and movable in the second cam hole, and a third roller rotatably provided on the second shaft and movable in the second cam hole, wherein the movable part and the fixed part may be arranged so that the first cam hole and the second cam hole at least partially overlap each other in plan view.

According to such a configuration, as the movable part linearly moves with respect to the clamp body in accordance with the linear motion of the displacement body, the first roller moves in the first cam hole and the second and third rollers move in the second cam hole. Thus, the linear motion of the displacement body can be converted into the first motion and the second motion with a simple configuration.

In the above clamp device, the plurality of clamp arms may be provided as one pair. The pair of clamp arms include a pair of the first cam holes may be provided substantially in a laterally symmetrical manner, and a pair of the second cam holes may be provided substantially in a laterally symmetrical manner. Each of the first cam holes may be formed of a first hole portion and a second hole portion. The first hope portion extends toward a first axis of symmetry of the pair of first cam holes while inclining toward one side of a moving direction of the movable part. The second hole portion extends from the first hole portion toward the one side of a moving direction of the movable part while inclining toward the first axis of symmetry. Each of the second cam holes may be formed of a third hole portion and a fourth hole portion. The third hole portion extends toward a second axis of symmetry of the pair of the second cam holes while inclining toward the one side of a moving direction of the movable part. The fourth hole portion extends from the third hole portion toward the second axis of symmetry.

According to such a configuration, as the first roller moves within the first hole portion, each clamp arm is made to perform the first motion, and as the first roller moves within the second hole portion, each clamp arm is made to perform the second motion. Further, because the second hole portion is inclined in the direction toward the position of the first axis of symmetry with respect to the moving direction of the movable part, as the first roller moves in the second hole portion toward the one side in the direction along which the movable part moves, the clamping force exerted on the workpiece can be increased by the wedge action at the inclined surface angle (θ).

In the clamp device described above, the first shaft and the second shaft may be provided at an end of each of the clamp arms opposite to a side on which the gripping surface is located.

According to such a configuration, it is possible to prevent the end portions of the clamp arms on the side opposite to the side on which the gripping surfaces are located from interfering with each other in the unclamping state, so that the maximum opening angle of the clamp arm can be set relatively large. Thereby, the degree of freedom in the supply direction and the discharge direction of the workpieces can be further enhanced.

In the above clamp device, a pair of the movable parts, the fixed parts, the first rollers, the second rollers, and the third rollers may be disposed on both sides of the clamp arm in pairs.

According to such a configuration, it is possible to smoothly and stably perform the first motion and the second motion of the pair of clamp arms.

In the above-described clamp device, the movable part may be provided with a slide portion, and the clamp body may be provided with a guide portion for guiding the slide portion along the moving direction of the displacement body.

According to such a configuration, since the movable part can smoothly move linearly, the first motion and the second motion of the pair of clamp arms can be performed more smoothly and stably.

The clamp device may further include a workpiece disposing portion in which the workpiece is placed, and each of the clamp arms is arranged so as not to protrude from the workpiece disposing surface of the workpiece disposing portion to a side where the workpiece is located in the unclamping state.

According to such a configuration, interference between the workpiece and the clamp arm can be effectively suppressed, so that the degree of freedom in the supply direction and the discharge direction of the workpieces can be further enhanced.

According to the present invention, it is possible to reliably and stably clamp plural types of workpieces having different width dimensions while suppressing upsizing of the device with a simple structure, and to increase the degree of freedom of the supply direction and discharge direction of the workpieces.

DESCRIPTION OF EMBODIMENTS

Preferred embodiments of the clamp device according to the present invention will be described below with reference to the accompanying drawings.

The clamp device10according to the present embodiment clamps workpieces W1and W2between a pair (plurality) of clamp arms16a,16b, and is applied to, for example, a welding process of an automatic assembly line of the machine industry or the like.

As shown inFIGS. 1 to 3, the clamp device10includes a clamp body12, a driving unit14provided on the clamp body12, a pair of right and left clamp arms16a,16bmovably provided on the clamp body12, and a driving force transmission mechanism18that transmits a driving force of the driving unit14to the respective clamp arms16a,16b.

In the following description, it is assumed that the width direction of the clamp device10(the direction in which the clamp arms16a,16bare arranged) is the X direction, the direction perpendicular to the X direction and the longitudinal direction of the clamp device10is the Y direction, and the direction perpendicular to the X direction and the Y direction is taken as the Z direction. Further, in the Y direction, the downward direction inFIG. 1is defined as the Y1direction, and the upward direction inFIG. 1is defined as the Y2direction.

The clamp body12includes a pair of T-shaped plate bodies20,22arranged substantially parallel to each other, while being spaced apart from each other by a predetermined distance; a base portion24connecting the narrow end portions of the plate bodies20,22; a pair of right and left connecting portions26a,26bfor connecting the side portions of the plate bodies20,22to each other; and a workpiece placement part28for connecting wide other ends of the plate bodies20,22to each other.

Elongated holes (guide portions)30,32are formed along the longitudinal direction (Y direction) at substantially the center in the width direction (X direction) of the plate bodies20,22. The base portion24is formed in a flat plate shape, one side surface of which is fastened to the substantially central portion in the width direction of a narrow portion34of the plate body20by screws36, and the other side surface is fastened to the substantially central portion in the width direction of a narrow portion38of the plate body22by screws40. Further, the base portion24is fixed to a floor surface or the like, for example, by unillustrated bolts or the like.

One side surface of each of the connecting portions26a,26bis fastened to a substantially central portion of a wide portion42of the plate body20in the Y direction by screws44. The other side surface is fastened to the center portion in the Y direction of a wide portion46of the plate body22by screws48. That is, the connecting portion26aand the connecting portion26bare opposed to each other in the X direction.

As shown inFIG. 3, on the inner surfaces of the connecting portion26a(the surface facing the coupling portion26b), at the approximate center in the arrangement direction (Z direction) of the pair of plate bodies20,22, a projecting portion50ais formed along the entire length in the Y direction. An inclined surface52athat is inclined to the outer surface side of the connecting portion26atoward the Y2direction is formed at an end of the distal end surfaces of the projecting portion50ain the Y2direction.

The connecting portion26bhas the same structure as the connecting portion26a, and the projecting portion50band the inclined surface52bare formed. As shown inFIGS. 1 and 2, the workpiece placement part28is a flat plate body on which the workpiece W1is placed, and is fastened to the wide portions42,46substantially at the center thereof in the X direction by screws54.

The driving unit14is configured as a fluid pressure cylinder (actuator). As shown inFIG. 5, the driving unit14includes a cylinder tube56, an end block58that closes an opening in one end side (Y1direction) of the cylinder tube56, a piston60displaceably arranged along the axial direction inside the cylinder tube56, a piston rod (displacement body)62connected to the piston60, and a rod cover64supporting the piston rod62displaceably while blocking an opening in the other end side (Y2direction) of the cylinder tube56. The structure of the driving unit14is not particularly limited, and various mechanisms capable of linearly displacing the displacement body may be applied. For example, a linear electric actuator including a ball screw actuator or the like can be adopted as the driving unit.

The cylinder tube56is disposed between the narrow portions34,38of the pair of plate bodies20,22(seeFIG. 1). A first port and a second port (not shown) for supplying and discharging compressed fluid (driving fluid) are formed in the cylinder tube56.

As shown inFIGS. 1 and 2, the pair of clamp arms16a,16bare located between the pair of connecting portions26a,26band are spaced apart from each other by a predetermined distance in the X direction. The clamp arm16ais formed in a quadrangular prism shape. One end portion of the clamp arm16abulges to both sides in the X direction. On the other end portion of the clamp arm16a, a gripping surface66acontacting the workpieces W1, W2is formed. The clamp arm16bis configured similarly to the clamp arm16a, and a gripping surface66bis formed at the other end portion thereof.

The driving force transmission mechanism18includes a pair of movable plates (movable parts)68,70arranged to be spaced apart from each other in the Z direction, a first connecting portion72connecting ends of the pair of movable plates68,70in the Y1direction in a state of being connected to the piston rod62, a second connecting portion74connecting ends of the pair of movable plates68,70in the Y2direction, and a pair of fixed plates (fixed parts)76,78which are arranged inward of the pair of movable plates68,70in the Z direction with a gap between the fixed plates76,78.

The movable plate68and the fixed plate76are disposed between the pair of clamp arms16a,16band the wide portion42, and the movable plate70and the fixed plate78are disposed between the pair of clamp arms16a,16band the wide portion46. Further, the movable plates68,70and the fixed plates76,78extend in the X direction in a state parallel to the wide portions42,46. The movable plate68is configured in the same manner as the movable plate70, and the fixed plate76is configured in the same manner as the fixed plate78. Therefore, in the following, the configurations of the movable plate68and the fixed plate76will be described, and the description of the configurations of the movable plate70and the fixed plate78will be omitted.

At the approximate center in the X direction of the movable plate68, a first arrangement portion80recessed so as to arrange the first connection portion72and a second arrangement portion82recessed so as to arrange the second connection portion74are formed. A slide portion84extending along the Y direction is fastened by screws86to the surface of the movable plate68facing the wide portion42. The slide portion84is disposed slidably in the elongated hole30of the plate body20along the Y direction. As a result, the movable plate68can slide smoothly along the Y direction under the guiding action of the elongated hole30of the plate body20.

As shown inFIG. 4A, the movable plate68has a pair of first cam holes88a,88bformed substantially symmetrically with respect to the centerline (first axis of symmetry) CL1in the X direction thereof. The first cam hole88ais formed of a first hole portion90ahaving an end portion91ain the vicinity of the outer corner portion of the movable plate68in the Y1direction and extending from the end portion91atoward the inner side in the X direction (toward the centerline CL1) and inclined in the Y2direction, and a second hole portion92aextending from the innermost position of the first hole portion90ain the X direction in the Y2direction and inclined toward the inner side in the X direction. The first hole portion90ais formed to be shorter than the second hole portion92a. The inner surface93aon the outer side of the second hole portion92ais inclined at a predetermined inclined surface angle θ with respect to the imaginary line IL in the Y direction and functions as a wedge working surface for guiding the first roller116adescribed later. The first cam hole88bis configured similarly to the first cam hole88aand includes a first hole portion90bhaving an end portion91band a second hole portion92bhaving an inner surface93b.

Returning toFIG. 2, the first connecting portion72is a flat plate member extending in the Z direction, and the piston rod62is fastened to the substantially center in the Z direction by a screw94. Both end portions of the first connecting portion72are formed to be narrower than the central portion thereof and are fastened by screws96in a state of being disposed in the first arrangement portions80of the movable plates68,70.

The second connecting portion74is a flat plate-shaped member extending along the Z direction. Both end portions of the second connecting portion74are formed to be narrower than the central portion thereof and fastened by screws98in a state of being disposed on the second arrangement portion82of the movable plates68,70.

Both ends of the fixed plates76,78in the X direction are fastened to the projecting portions50a,50bby screws100, so that the fixed plates76,78are fixed to the clamp body12. A first recessed portion102into which the first connecting portion72can be inserted and a second recessed portion104into which the second connecting portion74can be inserted are formed substantially in the center in the X direction of the fixed plates76,78. This prevents the first connecting portion72and the second connecting portion74from interfering with the fixed plates76,78when the movable plates68,70are displaced in the Y direction with respect to the fixed plates76,78.

As shown inFIG. 4B, the fixed plate76has a pair of second cam holes106a,106bformed substantially symmetrically with respect to the centerline (second axis of symmetry) CL2in the X direction. A part of the second cam hole106ais formed so as to overlap a part of the first cam hole88ain plan view (front view) from the Z direction (seeFIGS. 5 to 7). The same applies to the second cam hole106b.

The second cam hole106ais formed of a third hole portion108aextending from the vicinity of the outer corner portion of the fixed plate76in the Y1direction toward the inner side in the X direction (toward the centerline CL2) and inclined in the Y2direction, and a fourth hole portion110aextending along the X direction from the innermost position of the three hole portion108ain the X direction inside. The third hole portion108ais set to be substantially the same length as the fourth hole portion110a. The second cam hole106bis configured similarly to the second cam hole106a, and has a third hole portion108band a fourth hole portion110b.

As shown inFIG. 2, the driving force transmission mechanism18includes a first shaft112aand a second shaft114aprovided (fixed) so as to penetrate through one end of the clamp arm16ain the Z direction, a first roller116arotatably provided on the first shaft112aand moving in the first cam holes88aof the movable plates68,70, a second roller118arotatably provided on the first shaft112aand moving in the second cam holes106aof the fixed plates76,78, and a third roller120arotatably provided on the second shaft114aand moving in the second cam holes106aof the fixed plates76,78.

The first shaft112ais located on the inner side in the X direction (the side on which the clamp arm16bis positioned) than the second shaft114aand is longer than the second shaft114a. The first shaft112aextends at both sides of the clamp arm16ain the Z direction in a state of being provided at one end portion of the clamp arm16a, and the first roller116aand the second roller118aare provided on the first shaft112aat each side of the portions extending. The second shaft114aextends at both sides of the clamp arm16ain the Z direction in a state of being provided at one end portion of the clamp arm16a, and the third roller120ais provided on the second shaft114aat each side of the portions extending. The first shaft112aand the second shaft114aare provided with holding members122a(seeFIG. 3) for holding the axial positions of the first to third rollers116a,118a, and120a.

Further, the driving force transmission mechanism18includes a first shaft112band a second shaft114b(fixed) provided so as to penetrate through one end portion of the clamp arm16bin the Z direction, a first roller116brotatably provided on the first shaft112band moving in the first cam holes88bof the movable plate68,70, a second roller118brotatably provided on the first shaft112band moving in the second cam holes106bof the fixed plates76,78, and a third roller120brotatably provided on the second shaft114band moving in the second cam holes106bof the fixed plates76,78.

The first shaft112b, the second shaft114b, the first to third rollers116b,118b, and120bare similar in structure to those provided on the clamp arm16a, and therefore description thereof is omitted. Note that holding members122b(seeFIG. 3) is provided on the first shaft112band the second shaft114b.

The clamp device10according to the present embodiment is basically configured as described above. Next, the operation and effects thereof will be described. In the following description, the unclamping state in which the gripping surfaces66a,66bof the pair of clamp arms16a,16bshown inFIG. 5are maximally separated from each other will be described as an initial position.

In this initial state, the first rollers116a,116bare positioned on the outermost side in the X direction in the first hole portions90a,90b. Further, the second rollers118a,118bare positioned at the boundaries between the third hole portions108a,108band the fourth hole portions110a,110b, and the third rollers120a,120bare positioned at the fourth hole portions110a,110b.

Here, the workpiece W1clamped by the above-described clamp device10will be briefly described. This workpiece W1is composed of a first frame200having a U-shaped cross section and a second frame202having a U-shaped cross section combined with the first frame200. The first frame200opens toward the Y2direction, and both sidewalls204are inclined so as to gradually widen outward in the X direction toward the Y2direction. On the other hand, the second frame202is disposed in the opening of the first frame200in a state of being open toward the Y1direction.

The workpiece W1is supplied (conveyed) to the workpiece placement part28of the clamp device10by a conveying device or the like of the automatic assembly line. At this time, the distance between the gripping surface66aof the clamp arm16aand the gripping surface66bof the clamp arm16bis considerably larger than the width dimension of the workpiece placement part28, and the clamp arms16a,16bare advanced in the Y1direction than the workpiece placement surface of the workpiece placement part28. In other words, the clamp arms16a,16bdo not protrude from the workpiece placement surface of the workpiece placement part28in the Y2direction. Therefore, it is possible to smoothly supply the workpiece W1to the workpiece placement part28without interfering with the clamp arms16a,16b.

That is, in the present embodiment, in order to supply and discharge the workpiece W1not only from the Z direction (the direction orthogonal to the page ofFIG. 5) and the Y2direction but also from the X direction in the unclamping state of the clamp device10. Therefore, the degree of freedom in the supply direction and the discharge direction of the workpiece W1can be increased.

When the workpiece W1is set in the workpiece placement part28, the piston60is displaced toward the end block58under the action of the compressed fluid. Then, since the piston rod62is displaced in the Y1direction, the movable plates68,70are displaced in the Y1direction while the slide portions84provided on the respective movable plates68,70are guided by the elongated holes30,32. At this time, the first roller116arolls (runs) on the wall surface constituting the first hole portion90atoward the second hole portion92a, the second roller118arolls on the wall surface constituting the fourth hole portion110ainward in the X direction, and the third roller120arolls on the wall surface constituting the third hole portion108atoward the fourth hole portion110a.

Basically, the operations of the first to third rollers116a,118a, and120aand the operations of the first to third rollers116b,118b, and120bare the same as the movements of the movable plates68,70. Therefore, here, the operation of the first to third rollers116a,118a, and120awill be mainly described, and the explanation of the operation of the first to third rollers116b,118band120bwill be omitted.

As a result, the pair of clamp arms16a,16bmove inward in the X direction (in directions approaching each other), and the gripping surfaces66a,66bare rotated so as to be parallel to the Y direction (seeFIG. 6). InFIGS. 5 and 6, the clamp arm16arotates in the counterclockwise direction while moving to the side where the clamp arm16bis located, and the clamp arm16brotates in the clockwise direction while moving to the side where the clamp arm16ais located.

When the gripping surface66aand the gripping surface66bare parallel to each other, the first roller116ais positioned at the boundary between the first hole portion90aand the second hole portion92a, the second roller118ais positioned slightly inward from the center of the fourth hole portion110ain the X direction, and the third roller120ais positioned at the boundary between the third hole portion108aand the fourth hole portion110a. In the embodiment shown inFIG. 6, in this state, the gripping surfaces66a,66bcontact the sidewalls204of the first frame200.

When the piston60is further displaced toward the end block58under the action of the compressed fluid, the piston rod62and the movable plates68,70are further displaced in the Y1direction. Then, the first roller116arolls on the wall surface forming the second hole portion92ain the Y2direction, and the second roller118aand the third roller120aroll on the wall surface forming the fourth hole portion110ainward in the X direction.

As a result, the pair of clamp arms16a,16bmove in parallel in the X direction while pressing the sidewalls204of the first frame200. That is, while maintaining the parallel state of the gripping surface66aand the gripping surface66b, the gap (clamp distance) between the gripping surface66aand the gripping surface66bis narrowed. At this time, the inner surfaces93a,93boutside the second hole portions92a,92bare inclined at the inclined surface angle θ (seeFIG. 4A). Therefore, as the first rollers116a,116bmove along the second hole portions92a,92balong the Y2direction, the clamping force (gripping force) of the clamp arms16a,16bagainst the workpiece W1increases due to the wedging action. Thereby, even when the restoring force accompanying the deformation of the both sidewalls204of the first frame200acts on the clamp arms16a,16bwhen gripping the workpiece W1, the workpiece W1is surely and stably clamped.

Then, as the sidewalls204of the first frame200contact the second frame202, clamping of the workpiece W1is completed (seeFIG. 7). In this state, the workpiece W1is to be welded or treated.

In such a clamp device10, the clamping interval can be changed within a predetermined range while holding the parallel state of the gripping surface66aand the gripping surface66b. Therefore, for example, even in the case of clamping the workpiece W2having the width dimension L2larger than the width dimension L1of the workpiece W1shown inFIG. 7, the gripping surfaces66a,66breliably and stably clamp the workpiece W2(seeFIG. 8), avoiding one side abutment. In particular, as the first rollers116a,116bare pressed against the inner faces93a,93bof the second hole portions92a,92bpositioned outward, the clamp arms16a,16bpress and grasp the workpiece W2by a wedge action in which the clamp arms16a,16bare translated in a direction to approach each other.

On the other hand, when releasing (unclamping) the clamp of the workpiece W1, the piston60is displaced toward the rod cover64under the action of the compressed fluid. Then, since the piston rod62and the movable plates68,70are displaced in the Y2direction, the pair of clamp arms16a,16bare translated in a direction to separate from each other (outward in the X direction) while maintaining the parallel state (seeFIG. 6). As the piston60is further displaced toward the rod cover64, the pair of clamp arms16a,16bmove outward in the X direction and rotate so that the gripping surfaces66a,66bare apart from each other (seeFIG. 5).

Then, as the clamp arm16acontacts the inclined surface52aand the clamp arm16bcontacts the inclined surface52b, the rotation of these clamp arms16a,16bis stopped. The rotation of the clamp arms16a,16bmay be stopped such that, for example, in a state where they are not in contact with the inclined surfaces52aand52b, the first rollers116aand116bcontact the wall surfaces constituting the first cam holes88a,88b(the end portions91aand91bof the first hole portions90aand90b).

In the present embodiment, the driving force transmission mechanism18converts the linear motion of the piston60and the piston rod62into a first motion in which the pair of claim arms16a,16brotate while moving toward and away from each other, and into a second motion in which the pair of clamp arms16a,16bare translated toward and away from each other in a state where the gripping surfaces66a,66bare parallel to each other.

Thus, since the clamp distance can be changed, it is possible to reliably and stably clamp plural types of workpieces W1, W2having different widths while suppressing upsizing of the clamp device10with a simple configuration. Further, as the clamp arms16a,16brotate, the distance between the gripping faces66a,66bin the unclamping state can be made relatively wide, so that the degree of freedom of the supply direction of the workpiece W1can be increased.

According to the present embodiment, the first shaft112aand the second shaft114aare provided at one end portion of the clamp arm16a, and the first shaft112band the second shaft114bare provided at one end portion of the clamp arm16b. Therefore, it is possible to prevent the end portions of the clamp arms16a,16bfrom interfering with each other in the unclamping state. Accordingly, since the maximum opening angle of the clamp arms16a,16bcan be set relatively large, the degree of freedom in the supply direction and discharge direction of the workpieces W1, W2can further be enhanced.

In this embodiment, the movable plate68(the movable plate70), the fixed plate76(the fixed plate78), the first rollers116a,116b, the second rollers118a,118b, and the third rollers120a,120bare provided on both sides in the Z direction of the clamp arms16a,16bin pairs. Thus, the first motion and the second motion of the clamp arms16a,16bcan be performed more smoothly and stably.

Further, the slide portion84is guided by the elongated holes30,32formed in the plate bodies20,22, so that the respective movable plates68,70can be linearly moved smoothly. Therefore, the first motion and the second motion of the pair of clamp arms16a,16bcan be performed more smoothly and stably.

The present embodiment is not limited to the above-described configuration. For example, the clamp device10may have a plurality of clamp arms16a,16baccording to the shape of the workpiece to be clamped or the like. In this case, the number of the clamp arms16aand the number of the clamp arms16bmay be the same or different.

Further, the driving force transmission mechanism18can be dispensed with the movable plate70, the fixed plate78, the first roller116a,116b, the second roller118a,118b, and the third rollers120a,120bthat are disposed between the clamp arms16a,16band the plate body22. Even in this case, the same action and effect as those of the above-described embodiment can be obtained.