CN107009160B

CN107009160B - Drive device and workpiece clamping unit equipped with the same

Info

Publication number: CN107009160B
Application number: CN201610833849.6A
Authority: CN
Inventors: 马里奥·鲍尔
Original assignee: Festo SE and Co KG
Current assignee: Festo SE and Co KG
Priority date: 2015-09-23
Filing date: 2016-09-20
Publication date: 2020-07-31
Anticipated expiration: 2036-09-20
Also published as: CN107009160A; DE102015218245A1

Abstract

The invention relates to a drive device and a workpiece clamping unit (1) equipped with the drive device, wherein the drive device (3) has a base body (7) on which articulated parallelogram elements (28) are arranged. The main arm (32) of the articulated parallelogram (28) forms a follower (4) connected to the clamping element (5) which can be displaced between a raised release position and a lowered clamping position by the pivoting movement of a first secondary arm (33) of the articulated parallelogram (28) which acts as a force introduction. A clamping groove surface (54) is formed on the force introduction element (42) and cooperates with a drive element (43) which can be driven for a clamping drive movement (47 a). In the clamping drive movement (47a), the drive element (43) moves along the clamping groove surface (54), so that the force introduction element (42) is loaded with a torque which causes the driven element (4) to be displaced into the clamping position.

Description

Drive device and workpiece clamping unit equipped with the same

Technical Field

The invention relates to a drive device for a workpiece clamping unit, comprising:

-a base body,

a follower which is or can be connected to the clamping element and which is supported such that it can carry out a clamping working movement and an opposite release working movement in the working plane relative to the base body from a raised release position into a lowered clamping position, wherein the clamping working movement and the release working movement are each composed of a lifting movement oriented in the direction of the axis of the vertical axis and a lateral movement superimposed thereto oriented in the direction of the axis perpendicular to the horizontal axis,

-a force introduction member (bewegungsgekoppelt) associated with the driven member, and

a drive element which can be driven for a linear overall drive movement to and fro, by means of which drive element the force introduction element can be acted upon with a drive force which at least causes the clamping working movement.

The invention further relates to a workpiece clamping unit equipped with such a drive device.

Background

A workpiece clamping unit suitable for releasably clamping a workpiece is known from EP 1586498B 1, which is equipped with a drive device of the type mentioned above. The known workpiece clamping unit has a base body from which a hollow centering bit projects upward, the side walls of which have through-openings for hook-shaped clamping elements projecting into the centering bit. The clamping element is connected in one piece to a driven part which can be displaced in the axial direction of the vertical axis and can be pivoted transversely to the axial direction of the vertical axis, the driven part itself is connected in one piece to a force introduction part, on which a drive part of the linear drive, which can be displaced in a linear manner in the axial direction of the vertical axis, acts. When the drive element of the linear drive executes a clamping drive movement, the assembly of force introduction element, driven element and clamping element is moved along, so that the driven element is displaced from the raised release position into the lowered clamping position when executing a clamping working movement, wherein the driven element is laterally displaced from the centering ram by a lateral inclination with a hook-shaped clamping section and acts from above on a workpiece previously inserted onto the centering ram, and the workpiece is thus locked with the workpiece contact surface. Due to the direct connection between the drive element and the driven element, the clamping force that can be applied by the clamping element to the workpiece corresponds substantially to the drive force of the linear drive, so that high clamping forces can only be achieved with very large linear drives and thus very large drive devices.

EP 1702719B 1 discloses a workpiece clamping unit which likewise has hook-shaped clamping elements which can be driven for a clamping working movement which is composed of a vertical lifting movement and a lateral movement perpendicular thereto. The clamping element is connected integrally to a follower, which has two arcuate recesses, by means of which the follower can move with the guide pin when the follower is displaced between a raised release position and a lowered clamping position. A force introduction part which is pivotably supported on the base body acts in an articulated manner on the output part and is furthermore connected in an articulated manner to the output part of the linear drive.

Disclosure of Invention

The object on which the invention is based is to provide a drive device and a workpiece clamping unit equipped with the drive device, which enable high clamping forces to be generated along a comparatively large stroke range in combination with compact dimensions, so that workpieces of different thicknesses can be clamped reliably.

In order to solve this problem, provision is made in a drive device of the type mentioned at the outset for the driven part to be formed by a main arm of the articulated parallelogram, which main arm is in each case rotatably mounted via a first main pivot joint on a first secondary arm of the articulated parallelogram and via a second main pivot joint spaced apart from the first main pivot joint on a second secondary arm of the articulated parallelogram, wherein the first secondary arm is pivotably mounted on the base body via a first secondary pivot joint spaced apart from the first main pivot joint associated with the first secondary arm and the second secondary arm is pivotably mounted on the base body via a second secondary pivot joint spaced apart from the second main pivot joint associated with the second secondary arm, wherein the force introduction part is formed by the first secondary arm and has a clamping groove face, during the clamping drive movement of the overall drive movement of the drive element, the drive element is moved along the clamping groove surface with an increasing distance from the first secondary rotary joint of the first secondary arm when the drive force is applied, as a result of which a first pivoting movement of the force application element about the first secondary rotary joint, from which a clamping working movement of the driven element is obtained, can be generated.

The object is also achieved by a workpiece clamping unit for releasably clamping a workpiece, which is equipped with such a drive device.

In the drive device according to the invention, the follower is formed by the main arm of the articulated parallelogram and is arranged hingedly on the base body via the two secondary arms of the articulated parallelogram in such a way that the follower keeps its spatial orientation constant in its clamping working movement and in its opposite release working movement. Accordingly, the clamping and release actuating movements are each composed of a linear lifting movement in the axial direction of the vertical axis and a superimposed lateral movement perpendicular thereto. In the clamping operation movement, a clamping element arranged on the driven part and, in particular, connected integrally to the driven part, can execute a movement in order to clamp a workpiece previously placed in the region of the base body for enabling the machining. The clamping working movement is generated at least in the presence of a force introduction part of the drive device, which is formed directly by one of the two secondary arms of the articulated parallelogram and on which a clamping groove surface is formed, along which the drive part can be moved in the course of the clamping drive movement under simultaneous application of a torque-generating drive force. The clamping slot surface is in particular designed in such a way that it extends in its longitudinal direction away from the secondary pivot joint of the first secondary arm of the articulated parallelogram, which forms the force introduction part, so that the force introduction point, at which the front drive part introduces the drive force into the force introduction part, is increasingly further away from the mentioned secondary joint in the clamping drive movement. This results in a stroke ratio and a force ratio which particularly favorably influence the clamping result. In the first phase of the clamping operation movement, the pivot angle of the force introduction element due to the lifting of the drive element is relatively large, so that the driven element and therefore the clamping element cooperating with the driven element approach the lowered clamping position relatively quickly from the release position. The further the force introduction point is from the secondary pivot joint of the force introduction part, the larger the lever arm and the greater the clamping force which pulls the driven part and thus also the clamping element into the clamping position. Thus, it is also possible to generate a driving force which causes a high clamping force over a relatively wide lift range with a relatively small-sized linear drive. Accordingly, workpieces with thicknesses that differ from one another within a certain range can be reliably clamped by means of a workpiece clamping unit equipped with a drive device without any adjustment or modification measures having to be carried out on the drive device or the workpiece clamping unit. The following workpieces can be clamped in a smooth and alternative manner: their thickness within the clamping area deviates from the specified nominal dimension by +/-0.5 mm.

The invention has an advantageous development.

The clamping slot surface is preferably designed in such a way that it has an outer end section along which the drive element moves when the driven element executes the final phase of the clamping operating movement, and that the outer end section is designed in its longitudinal direction in such a way that the drive element introduces an at least approximately constant torque into the force introduction element. For this purpose, the outer end section of the clamping groove surface has a non-linear longitudinal profile, which preferably relates to a concavely curved longitudinal profile. The concave curvature of the longitudinal extent results in the increased length of the effective lever arm at the force introduction point being compensated for by the changing force introduction direction. Thus, a pivoting movement of the force introduction part with constant mechanical advantage occurs, which is transmitted via the parallelogram support to the clamping element mounted on the driven part.

The longitudinal section of the clamping groove surface in front of the outer end section, which is referred to as the initial longitudinal section for better differentiation, preferably has a longitudinal course such that the drive part moving along the initial longitudinal section during the clamping drive movement brings about a greater mechanical advantage of the rotary movement with respect to the force introduction part (drehbeweegungs ü bersetzeng) than in the outer end section following the initial longitudinal section.

The first secondary arm of the articulated parallelogram forming the force introduction part has a connecting section which extends between the first secondary rotary joint and the first main rotary joint associated with the driven part. The clamping link surface can in principle be arranged on the connecting section, but is expediently located on an actuating section which projects from the connecting section transversely to the hinge axis of the first main pivot joint in a free-end manner. The force introduction means in this way represents a two-armed lever, wherein the connecting section is one of the lever arms and the actuating section is the other lever arm. The length of the lever arm formed by the actuating section, which is effective in terms of actuation, is determined by the distance between the first secondary pivot joint and the current force introduction point, i.e. the point of action of the drive element on the clamping groove surface.

The articulated parallelogram is preferably designed in such a way that both main pivot joints lie on a joint line which is always oriented parallel to the vertical axis.

The release drive movement may be generated by any mechanism in which the follower moves back from the lowered gripping position to the raised release position. For example, a spring mechanism can be used which acts on the force introduction element or on another point of the articulated parallelogram. However, it is considered to be particularly advantageous if the drive element responsible for generating the clamping working movement also causes the opposite release working movement. If this is the case, the force introduction part, in addition to the clamping groove surface, also has a release groove surface, which likewise has a longitudinal course that extends along the working plane and in particular approaches the first secondary articulation of the first secondary arm. If the drive element executes a release drive movement opposite to its clamping operating movement, the drive element is displaced along the release groove surface and presses the force introduction element against the release groove surface, so that the force introduction element executes a second pivoting movement opposite to the first pivoting movement, which causes the driven element, which is coupled in an articulated manner to the force introduction element, to move from the lowered clamping position back into the raised release position.

Preferably, the force introduction element is provided with a slotted guide recess into which the drive element engages, and the slotted guide recess has recess flanks which are arranged opposite one another at a distance, wherein one recess flank forms a clamping slotted guide surface and the other recess flank forms a release slotted guide surface. The chute recess may be circumferentially annularly closed. However, an embodiment in which the runner recess is open at one end side is considered more suitable. On the opposite closed end side, the gate recess preferably has a concavely curved wall surface in this case. The open end face is expediently directed downward, but can also be directed upward.

The drive device is preferably designed in such a way that the linear overall drive movement of the drive element is oriented in the axial direction of the vertical axis. In general, the drive device or the workpiece clamping unit is oriented in the case of its conventional use in such a way that the vertical axis extends vertically. However, the drive device can also expediently be operated in any other spatial orientation, for example in a horizontally oriented vertical axis.

In order to provide a precise overall drive movement and to laterally support the drive element, it is advantageous if a linear guide is arranged on the base body, which defines the direction of movement of the overall drive movement and at the same time supports the drive element in the lateral direction in the working plane.

The linear guide device is expediently provided with at least one guide recess extending in the direction of movement of the total drive movement, into which a guide piece connected to the drive piece projects, so that the guide piece is supported by the sides of the guide recess. Preferably, one of the two mutually parallel guide recesses is located on the opposite side of the drive member on each wing, and the drive member is provided with two guides which each project into one of the guide recesses.

The drive is preferably roller-shaped. The guide elements which are also present are expediently also designed in the form of rollers.

The drive element is preferably a component of a linear drive arranged on the base body. Here, an electromotive linear drive is possible. However, the linear drive is preferably of a fluid-operated construction type.

A preferred embodiment of the workpiece clamping unit equipped with the drive device has a hollow centering head arranged on the base body so as to project upward, which is surrounded by an upwardly directed workpiece contact surface. A clamping element, which is preferably connected in one piece with the driven part, protrudes from below into the hollow centering head, the clamping element having a laterally protruding hook-shaped clamping section. The side wall of the hollow centering head has a through-opening which allows the hook-shaped clamping section to pass through from the inside. In the raised release position of the drive element, the hook-shaped clamping section is located in the raised position in the hollow centering bit, so that there is the possibility of a smooth insertion of the workpiece to be clamped onto the centering bit from above. During the clamping operation, the hook-shaped clamping section approaches the workpiece contact surface and is simultaneously moved laterally out of the centering head, so that the clamping section can be inserted into the workpiece on the centering head before being loaded from above and locked with the workpiece contact surface.

Drawings

The invention is explained in detail below with the aid of the figures. Wherein:

fig. 1 shows a preferred first embodiment of a drive device according to the invention and a workpiece clamping unit according to the invention with the drive device in a longitudinal section according to section I-I of fig. 6, wherein the constituent parts of the articulated parallelogram are depicted in an unbroken manner and wherein the follower is in the lifted release position;

FIG. 2 shows the same illustration as in FIG. 1, however with the hinged parallelogram sectioned;

fig. 3 shows a sectional view corresponding to fig. 1 in the state of the displacement of the follower into the lowered clamping position;

FIG. 4 shows the same illustration as in FIG. 3, however with the hinged parallelogram sectioned;

fig. 5 shows, in a sectional view corresponding to fig. 2 or 4, the drive device and the workpiece clamping unit with the follower in an intermediate position between a raised release position and a lowered clamping position;

fig. 6 shows the device of fig. 1 to 5 in a longitudinal section rotated by 90 ° with respect to fig. 1 to 5, according to section VI-VI of fig. 1;

fig. 7 shows an enlarged fragmentary view of the drive device in the region of cooperation between the drive element and the force introduction element.

Detailed Description

In the drawing, a workpiece clamping unit 1 is shown, indicated as a whole by reference numeral 1, which can be used for releasably clamping a workpiece 2 shown in dash-dot lines and which is equipped with a drive device 3.

The drive device 3 comprises a driven part 4, on which a clamping element 5 is arranged in a detachable or non-detachable manner. Illustratively, the follower 4 and the clamping element 5 are integrally connected to each other. The clamping element 5 mounted on the driven part 4 moves directly together with the driven part 4, so that the two components can always jointly execute an operating movement 6, indicated by the double arrow, which is composed of two movement components, namely a clamping operating movement 6a and a release operating movement 6b, which is oriented opposite thereto.

When subsequently referring to the movement of the driven member 4 or the clamping element 5, a corresponding movement of the respective other component is therefore also meant.

The drive device 3 comprises a rigid base body 7, which is preferably of block-shaped design. Inside the base body 7, a base body interior 8 is present, in which further components of the drive device 3 are accommodated. The base body 7 is formed, for example, from two

base body halves

7a, 7b which are placed laterally together and are connected to one another by means of screw connections or other fastening means, the base body halves preferably being embodied in the form of half shells.

The workpiece clamping unit 1 and the drive device 3 have an imaginary vertical axis 12 and are oriented in common use with a vertical axis 12. With reference to the vertical orientation of the vertical axis 12, the base body 7 has an upper side 13 and a lower side 14. The base body interior 8 opens out at the top 13 with a recess 15, through which recess 15 a clamping element 5 partially arranged in the base body interior 8 protrudes upward from the base body 7.

On the base body 7, a centering device 16 is arranged on the upper side 13. It has a cavity 17 aligned with the recess 15, which also extends into an upwardly projecting centering head 18 of the centering device 16. The side wall of the centering bit 18 surrounding the cavity 17 has a window-like passage opening 22 at its circumferential point.

In the bottom region of the centering bit 18, a workpiece contact surface 23 is formed on the centering device 16, which faces upward in the axial direction of the vertical axis 12, around the centering bit 18. Alternatively, the workpiece contact surface can also be arranged directly on the base body 7.

The workpiece 2 to be clamped has a centering opening, with which the workpiece is inserted onto the centering head 18, so that the workpiece lies on the workpiece contact surface 23.

In its region inside the cavity 17, the clamping element 5 has a preferably hook-shaped clamping section 24 with a clamping projection 25 projecting transversely to the vertical axis 12. In the lowered clamping position, which is visible in fig. 3 and 4, the clamping section 24 extends through the through-opening 22 laterally from the centering bit 18 and presses the workpiece 2 lying on the workpiece contact surface 23 from above, so that it is clamped securely in a detachable manner between the clamping bead 25 and the workpiece contact surface 23.

The follower 4 and the clamping element 5 can also assume a raised release position, visible in fig. 1 and 2, in which the clamping section 24 is positioned in the axial direction of the vertical axis 12 upwards away from the height assumed in the clamping position and at the same time assumes a position completely moved into the cavity 17. In the raised release position, the workpiece 2 can be inserted onto the centering bit 18 in the manner already described and can also be removed again from the centering bit 18 after the machining has taken place.

The movement between the release position and the clamping position is the already mentioned working movement 6. This occurs only in a single plane, which is referred to as the working plane 26 and is located in the drawing plane in fig. 1 to 5. The working plane is spanned by the vertical axis 12 and a transverse axis 27 perpendicular thereto.

The working movement 6 has an arcuate course. The working movement is composed of a movement component, which is also referred to as a lifting movement, extending in the axial direction of the vertical axis 12 and, superimposed on it, a movement component, which is also referred to as a lateral movement, in the axial direction of the transverse axis 27.

The possibility for carrying out the working movement 6 results from the fact that the driven element 4 is a component of a transmission designed as an articulated parallelogram 28.

The articulated parallelogram 28 has a rigid arm, referred to as the main arm 32, which forms the follower 4. Furthermore, two further arms are subordinate to the articulated parallelogram 28, these two further arms being referred to for better distinction as a first secondary arm 33 and a second secondary arm 34. The main arm 32 is connected to the first secondary arm 33 in an articulated manner via a first swivel joint, which for better distinction is referred to as a first main swivel joint 35. Furthermore, the main arm 32 is connected to the second sub-arm 34 in an articulated manner via a further swivel joint, which for better distinction is referred to as a second main swivel joint 36.

The first secondary arm 33 is mounted on the base body 7 in a rotatable manner by means of a further rotary joint, which for better distinction is referred to as a first secondary rotary joint 37. The second secondary arm 34 is likewise mounted on the base body 7 in a rotatable manner via a rotary joint, referred to for better distinction as the second secondary rotary joint 38.

Each of the four

rotating hinges

35, 36, 37, 38 defines a hinge axis perpendicular to the working plane 26, which hinge axes are marked by a cross in the figures. The hinge axis forms the center of the relative rotational movement between the two components which are respectively hinged to one another.

The distance between the two primary pivot joints 35, 36 is as large as the distance between the two secondary pivot joints 37, 38. Furthermore, the spacing between the first main turning hinge 35 and the first secondary turning hinge 37 is as large as the spacing between the second main turning hinge 36 and the second secondary turning hinge 38. However, this distance is preferably smaller than the distance between the two main pivot joints 35, 36.

The articulated parallelogram 28 thus formed makes it possible for the main arm 32 and thus the follower 4 formed by the main arm 32 to realize the above-mentioned working movement 6 extending along an arc, wherein the spatial orientation of the follower 4 with respect to the base body 7 is always kept constant. In the working movement 6, the two secondary arms 33, 34 are each pivoted about the associated secondary pivot joint 37, 38 relative to the base body 7.

A main arm 32 and two secondary arms 33, 34 are arranged in the interior space 8 of the basic body. In order to form the two secondary pivot joints 37, 38, the base body interior 8 is expediently passed through transversely to the working plane 26 by cylindrical bearing pins 37a, 38a, respectively, which are fixed at the end in one of the two

base body halves

7a, 7b and which pass through the associated secondary arms 33, 34, so that the pivotable mobility of the respective secondary arm 33, 34 is ensured. To accommodate high loads, rolling bearing mechanisms may be used.

At least the clamping working movement 6a, but preferably also the release working movement 6b, can be generated in the drive device 3 in such a way that the force introduction element 42, which is coupled to the driven element 4, cooperates in terms of drive with the drive element 43 of the linear drive 44.

The linear drive 44 is mounted on the base body 7 and has a drive housing 45 fastened to the base body 7 and a drive unit 46 which can be moved linearly with respect to the drive housing and to which the drive element 43 is assigned. By means of an external energy input, for example electrical or fluid energy, the drive unit 46 can be driven for a reciprocating linear movement, which is subsequently referred to for better differentiation as a total drive movement 47 and is illustrated by a double arrow.

Preferably, the linear drive 44 is a fluid-operated, in particular pneumatically operated, linear drive, wherein the drive unit 46 has a drive piston arranged in a slidable manner in a drive housing 45, which is connected to a drive rod 48 which projects at the end from the drive housing 45 and carries the drive element 43 outside the drive housing 45. The drive element 43 is preferably mounted on the end face on the drive rod 48. By the controlled supply of fluid into the drive housing 45, the drive piston, not illustrated in more detail, is acted upon by fluid force, so that the entire drive unit 46 and thus also the drive element 43 can be driven for the overall drive movement 47.

The drive rod 48 expediently protrudes from the drive housing 45 on the upper side and sinks from the underside 14 into the base body 7 and the base body interior 8 formed therein. The drive element 43 is thus located inside the base body interior space 8.

The linear drive 44 is designed and arranged in such a way that the overall drive movement 47 extends in the axial direction of the vertical axis 12. In the preferred position of use, which can be seen from the drawing, the drive element 43 is either moved vertically upward or vertically downward depending on the current direction of movement of the overall drive movement 47.

The total drive movement 47 thus has two possible directions of movement. The movement phase of the overall drive movement 47, which is directed upwards in the preferred use orientation, is referred to as the clamping drive movement 47a, while the opposite and exemplary downwardly directed movement phase is referred to as the release drive movement 47 b. The two

movement phases

47a, 47b are indicated in the drawing by arrows.

The force introduction member 42, which cooperates with the drive member 43, is formed directly by the first secondary arm 33 of the articulated parallelogram 28. The force introduction element can thus be pivoted relative to the base body 7 about the first secondary pivot joint 37, the pivot plane lying in the working plane 26. The pivoting movement 52 of the force introduction element 42, which is possible here to reciprocate, is illustrated by a double arrow.

The reciprocating pivoting movement 52 of the force introduction element 42 is composed of two mutually opposite first and

second pivoting movements

52a, 52b, which are indicated by arrows. In the first pivoting movement 52a, the first main pivot joint 35, which is arranged at a distance from the first secondary pivot joint 37, is displaced in the direction of the lower side 14, wherein the follower 4 follows, so that it executes the clamping working movement 6 a. In the second pivoting movement 52b of the force introduction element 42, the first main pivot joint 35 is moved upwards, so that the driven element 4 is driven for releasing the working movement 6 b.

To generate the pivoting movement 52, the force introduction element 42 has a sliding groove recess 53, into which the drive element 43 engages. The gate recess 53 has two first and

second recess sides

53a, 53b facing one another and lying opposite one another at a distance from one another, which each form a gate surface, which in the case of the first recess side 53a is referred to as a clamping gate surface 54 and in the case of the second recess side 53b as a release gate surface 55.

The gate recess 53 is expediently formed in an actuating section 56 of the force introduction part 42, which projects away from a connecting section 57 of the force introduction part 42 in the circumferential region of the first secondary rotating hinge 37, which connecting section extends between the first secondary rotating hinge 37 and the first main rotating hinge 35.

The force introduction means 42 is therefore designed in the manner of a two-arm lever, wherein the first lever arm is formed by the connecting section 57 and the second lever arm is formed by the actuating section 56.

The clamping slot surface 54 is directed in the direction of the second pivoting movement 52b, while the release slot surface 55 is directed in the direction of the first pivoting movement 52 a.

The gate recess 53 expediently has a downwardly directed open end face 58, through which the drive element 43 is recessed into the gate recess. The operating section 56 therefore expediently has a U-shaped profile. Opposite the open end face 58, the gate recess 53 is expediently delimited by a concavely curved wall surface 59, which connects the two

recess flanks

53a, 53b to one another.

In an embodiment that is not shown, the one-sided open gate recess 53 is oriented in such a way that the open end side 58 points upward. In a further embodiment, which is likewise not shown, the gate recess 53 is closed circumferentially in a ring shape, so that the drive element 43 engages laterally in the gate recess.

The articulated parallelogram 28 is designed in such a way that the virtual joint connecting line 62, which connects the two main pivot joints 35, 36 to one another, is always oriented parallel to the vertical axis 12. A parallel displacement of the joint connection line 62 in the axial direction of the transverse axis 27 takes place in the working movement 6.

The drive element 43 which is sunk into the gate recess 53 is in contact with the clamping gate surface 54 on the one hand and the release gate surface 55 on the other hand. The driver 43 has two

force transmission areas

43a, 43b on the periphery, wherein the driver rests with a first force introduction area 43a on the clamping groove surface 54 and with a further second force introduction area 43b on the release groove surface 55. The contact areas between the respective

force introduction areas

43a, 43b and the associated link surfaces 54, 55 mark force introduction points, at which the drive force exerted by the drive element 43 is introduced into the force introduction element 42.

The drive element 43 can be a sliding body which bears in a slidable manner against the two

recess flanks

53a, 53 b. However, it is preferably designed as a rolling body 63 which can rotate on the drive rod 48 about an axis of rotation 64 perpendicular to the working plane 26, so that it can roll on the two

recess sides

53a, 53 b. In this case, the

force introduction regions

43a, 43b are formed by the circumferential regions of the rolling elements 63 which are currently in contact with the associated

recess flanks

53a, 53 b. Preferably, the gate recess 53 is slightly wider than the diameter of the drive element 43, so that the drive element can perform a smooth rolling movement.

The clamping groove surface 54 has a longitudinal extent in the working plane 26 such that the longitudinal course of the clamping groove surface is inclined relative to a movement axis 65, which movement axis 65 extends in the movement direction of the overall drive movement 47. Preferably, the movement axis 65 has the same orientation as the vertical axis 12. The release chute face 55, which is preferably present, also has a corresponding oblique orientation with respect to the movement axis 65.

The clamping slot face 54 is remote in its longitudinal direction from the region of the first secondary pivoting hinge 37. In this case, the clamping link faces upward closer and closer to the movement axis 65. The same applies to the preferably present release gate surface 55, which is, however, further away from the first secondary pivot joint 37 due to the distance from the clamping gate surface 54.

The angle of inclination 66 between the clamping groove face 54 and the axis of movement 65 has a maximum value visible from fig. 1 and 2 when the follower 4 is in the raised release position. The force introduction point between the drive element 43 and the clamping groove surface 54 is here close to the first secondary pivoting joint 37. If, starting from this point, the linear drive 44 is actuated such that the drive element 43 executes the clamping drive movement 47a, the drive element 43 moves with constant contact along the clamping groove surface 54, with the force introduction point being increasingly distant from the first secondary pivoting joint 37.

Due to the offset between the longitudinal orientation of the clamping groove surface 54 and the movement axis 65, the clamping drive movement 47a therefore leads to a drive force being introduced into the force introduction piece 42 in the respective force introduction point, as a result of which a torque is obtained, as a result of which the force introduction piece 42 pivots about the first secondary pivot joint 37 while carrying out the first pivoting movement 52 a. This results in a clamping working movement 6a of the driven member 4. The clamping work movement is ended when the workpiece 2 is clamped and further movement of the clamping element 5 is prevented.

In order to then displace the driven element 4 again from the lowered gripping position into the raised release position, the linear drive 44 is operated such that the drive element 43 executes a release drive movement 47 b. The driver 43 is thereby pressed against the release groove surface 55 and moves back to the initial point along the release groove surface 55 with continuous contact. This results in the driver 43 introducing a drive force into the force introduction piece 42 on the release groove surface 55, from which drive force a torque is obtained which causes the second pivoting movement 52b of the force introduction piece 42.

The driver 43 is located in the region of the open end face 58 of the gate recess 53 in the release position of the driven element 4, while the driver is positioned in the region of a concave wall 59 of the gate recess 53, against which the driver can also rest completely, in the clamping position of the driven element 4 visible from fig. 3 and 4.

The slotted link recess 53 expediently has a longitudinal axis 67 which runs at a distance from the center of the first secondary pivoting joint 37. In the release position of the driven member 4, the longitudinal axis 67 extends more steeply with respect to the movement axis 65 than in the clamping position of the driven member 4.

The clamping groove surface 54 preferably has a non-linear longitudinal course. The clamping link surface is preferably divided into an initial longitudinal section 68 starting near the first secondary pivot joint 37 and an immediately subsequent outer end section 69. The transition between the initial longitudinal section 68 and the outer end section 69 is particularly smooth.

The initial longitudinal section 68 preferably has a rectilinear extension, while the outer end section 69 is preferably concavely curved.

When the driven member 4 is in the release position, the driving member 43 occupies a basic position close to the first secondary pivoting hinge 37, in which it abuts against the initial longitudinal section 68. In a subsequent first movement phase of the clamping drive movement 47a, the force introduction point first moves along the initial longitudinal section 68, with a greater mechanical advantage of the rotary movement than in the subsequent passage through the outer end section 69. The force introduction means 42 pivots relatively quickly at the beginning of the first pivoting movement 52a, so that the driven part 4 and the clamping element 5 move at a relatively high speed from the release position in the direction of the clamping position.

As soon as the force introduction point reaches the outer end section 69, a second movement phase of the first pivoting movement 52a with constant mechanical advantage ensues. This is associated with the fact that, although the lever arm with respect to the first secondary pivot joint 37 is further enlarged, at the same time, due to the curvature of the clamping groove surface 54, the force introduction direction in the force introduction point, which is responsible for the torque, changes, so that the force perpendicular to the lever arm is reduced. The pivoting movement of the force introduction piece 42 is also smaller during the second movement phase than during the first pivoting movement phase.

During the second movement phase, the constant torque causes a constant downwardly directed clamping force on the driven part 4 or the clamping element 5 when the drive part 43 is moved with its force introduction point along the outer end section 69 of the clamping groove surface 54. The constant clamping force is present over a relatively large stroke range, so that workpieces 2 of different thicknesses can be clamped with the same clamping force by means of one and the same workpiece clamping unit 1. This is also advantageous with respect to force transmission systems working according to the toggle principle.

To cause the release working movement 6b of the driven member 6, the drive member 43 is driven for the release drive movement 47 b. The drive element 43 moves along the release groove surface 55 and, with respect to the force introduction element 42, generates a torque which generates the second pivoting movement 52 b.

The release chute face 55 suitably has a linear extension over its entire length. The longitudinal axis of the release groove surface 55 preferably runs parallel to the longitudinal axis of an initial longitudinal section 68 of the clamping groove surface 54, which likewise expediently has a linear longitudinal extent. The longitudinal orientation is parallel to the longitudinal axis 67 of the gate recesses 53.

The release groove surface 55 can be dispensed with if the second pivot movement 52b of the force introduction part 42, which is responsible for the release of the working movement 6b, is not to be actively triggered by the drive part 43. The runner recess 53 is then also superfluous. The clamping groove surface 54 can in this case be arranged directly on the outer surface of the edge side of the correspondingly shaped operating section 56. The second return pivot movement 52b can be generated here, for example, by a spring mechanism which acts between the base body 7 and the force introduction element 42 and, when the drive element executes the release drive movement 47b, causes the drive element 43 to follow the clamping groove surface 54.

In order to be able to apply high torques to the force introduction part 42 without damaging the linear drive 44, it is advantageous if a linear guide 72 is arranged on the base body 7, which guides the drive part 43 in the direction of its overall drive movement 47 and in this case supports the drive part 43 in the axial direction of the transverse axis 27 in the working plane 26.

The embodiment of the drive device 3 is equipped with such a linear guide 72, which is expediently composed of two guide recesses 73, which are formed in the inner face of the base body 7 delimiting the base body interior 8 and are arranged perpendicularly opposite the working plane 26. The guide recess 73 extends in the axial direction of the movement axis 65 and preferably in the axial direction of the vertical axis 12. Each guide recess 73 is formed, for example, on the inner face of one of the two

base body halves

7a, 7 b.

The drive unit 46 has two guide elements 74 flanking the drive element 43, wherein these preferably relate to rotatably mounted guide rollers and engage in one of the guide recesses 73. Each guide 74 is supported on both recess sides of the associated guide recess 73. The guide recess 73 is preferably formed by a groove-like depression.

The guide element 74 is supported on both recess sides, not only in the case of the clamping drive movement 47a, but also in the case of the release drive movement 47b, along which it moves in the associated guide recess 73 and in the axial direction of the transverse axis 27.

Claims

1. A drive apparatus for a workpiece clamping unit, the drive apparatus having:

-a base body (7),

-a follower (4) which is connected or connectable to a clamping element (5) and which is supported such that it can carry out a clamping working movement (6a) and an opposite release working movement (6b) in a working plane (26) relative to the base body (7) from a raised release position into a lowered clamping position, wherein the clamping working movement (6a) and the release working movement (6b) are each composed of a lifting movement oriented in the axial direction of a vertical axis (12) and a lateral movement superimposed thereto, oriented in the axial direction of a transverse axis (27) perpendicular to the vertical axis (12),

-a force introduction member (42) linked with the driven member (4), and

a drive element (43) which can be driven for a linear overall drive movement (47) to and fro and by means of which the force introduction element (42) can be acted upon to cause at least the drive force of the clamping working movement (6a),

it is characterized in that the preparation method is characterized in that,

the driven part (4) is formed by a main arm (32) of the articulated parallelogram (28), which is rotatably supported on a first secondary arm (33) of the articulated parallelogram (28) via a first main pivot joint (35) and on a second secondary arm (34) of the articulated parallelogram (28) via a second main pivot joint (36) spaced apart from the first main pivot joint (35), wherein the first secondary arm (33) is pivotably supported on the base body (7) via a first secondary pivot joint (37) spaced apart from the first main pivot joint (35) associated with the first secondary arm and the second secondary arm (34) is pivotably supported on the base body (7) via a second secondary pivot joint (38) spaced apart from the second main pivot joint (36) associated with the second secondary arm, wherein the force introduction part (42) is formed by the first secondary arm (33) and has a clamping groove surface (54) along which the drive part (43) is moved with increasing distance from the first secondary rotary joint (37) of the first secondary arm (33) upon introduction of a driving force during a clamping drive movement (47a) of the overall drive movement (47) of the drive part, as a result of which a first pivoting movement (52a) of the force introduction part (42) about the first secondary rotary joint (37) can be generated, along which a clamping working movement (6a) of the driven part (4) results, wherein the clamping groove surface (54) has an outer end section (69) along which the drive part (43) is moved when the driven part (4) executes a final phase of the clamping working movement (6a), and the outer end section has a longitudinal course such that, by means of a drive element (43) which moves along the outer end section during the clamping drive movement (47a), an at least approximately constant torque is introduced into the force introduction element (42) in relation to the first secondary pivot joint (37) of the first secondary arm (33), wherein the outer end section (69) of the clamping groove surface (54) has a concavely curved longitudinal course.

2. The drive apparatus as claimed in claim 1, characterized in that an initial longitudinal section (68) of the clamping groove surface (54) which precedes an outer end section (69) of the clamping groove surface (54) has a longitudinal course such that a drive element (43) which moves along the initial longitudinal section of the clamping groove surface (54) during the clamping drive movement (47a) brings about a greater mechanical advantage of the rotary movement with respect to the force introduction element (42) than in the outer end section (69) of the clamping groove surface (54) which follows the initial longitudinal section.

3. The drive device according to claim 1 or 2, characterized in that the force introduction piece (42) has a connecting section (57) which extends between the first secondary rotary joint (37) and the first main rotary joint (35), and an operating section (56) which projects in a free-end manner from the connecting section (57) transversely to the joint axis of the first secondary rotary joint (37) in the working plane (26) and has the clamping slot surface (54).

4. Drive device according to claim 1 or 2, characterized in that both main turning hinges (35, 36) are located on a hinge connection line (62) which is always parallel to the vertical axis (12).

5. The drive apparatus according to claim 1 or 2, characterized in that the force introduction piece (42) has, in addition to the clamping groove surface (54), a release groove surface (55) along which the drive piece (43) moves in a release drive movement (47b) of the total drive movement (47) of the drive piece opposite the clamping drive movement (47a), whereby a second pivot movement (52b) of the force introduction piece (42) opposite the first pivot movement (52a) can be generated, from which the release working movement (6b) of the driven piece (4) results.

6. The drive device according to claim 5, characterized in that the force introduction piece (42) has a slotted guide recess (53) in which the drive piece (43) engages and which has oppositely disposed recess flanks (53a, 53b) at a distance, wherein one recess flank (53a) forms the clamping slot face and the other recess flank (53b) forms the release slot face (55).

7. The drive apparatus according to claim 6, characterized in that the gate recess (53) is open on one end side and expediently has a concavely curved wall surface (59) on the closed end side opposite the open end side (58).

8. The drive apparatus according to claim 1 or 2, characterized in that the linear total drive movement (47) is oriented in the axial direction of the vertical axis (12).

9. The drive apparatus as claimed in claim 1 or 2, characterized in that a linear guide (72) which specifies the direction of movement of the total drive movement (47) of the drive element (43) and supports the drive element (43) in the direction of the axis of the transverse axis (27) is arranged on the base body (7).

10. The drive apparatus as claimed in claim 9, characterized in that the linear guide device (72) has at least one guide recess (73) which extends in the direction of movement of the total drive movement (47), into which a guide piece (74) connected to the drive piece (43) projects, which guide piece is supported by the side of the guide recess (73).

11. The drive device according to claim 1 or 2, characterized in that the drive element (43) is an integral part of a linear drive (44) arranged on the base body (7).

12. A workpiece clamping unit for releasably clamping a workpiece, characterized in that the workpiece clamping unit is equipped with at least one drive device (3) according to any one of claims 1 to 11.

13. Workpiece clamping unit according to claim 12, characterised in that a hollow centering head (18) which is oriented in the axial direction of the vertical axis (12) and is surrounded by an upwardly directed workpiece contact surface (23) is arranged on the base body (7), into which hollow centering head the clamping element (5) projecting away from the driven part (4) projects, and the side wall of the hollow centering bit has a through-opening (22) for the passage of a hook-shaped clamping section (24) of the clamping element (5), the hook-shaped clamping section is located inside the hollow centering head (18) in the release position of the driven element (4), and laterally projects from the centering plug (18) in the clamping position of the follower, so as to load the workpiece (2) inserted on the centering plug (18) and lock the workpiece with the workpiece contact surface (23).