EP0894573B1 - Workpiece clamp - Google Patents

Description

Component clamps are used in a wide variety of technical areas current fixation of workpieces used. You need to be quick and work reliably and maintenance-free multiples over long periods of use Ensure load changes.

In this context, DE 35 28 337 C2 counts a component clamp to the prior art, in which a tie rod is part of a acted upon by a pressure fluid such as air or hydraulic fluid and forms axially displaceable piston in a cylinder. That turned away from the piston The end of the tension rod is connected with a bolt, the two Carrying pairs of roles. The rollers of the outer pair of rollers run in a straight line Slits that extend parallel to the longitudinal axis of the tension rod. The Rollers of the inner pair of rollers circulate in arcuate slots an axis swiveling clamping arm. The guide slot can also be curved in an arc.

With this design, uncontrollably high clamping forces are to be achieved with self-locking be avoided in the end position. However, this design requires a complicated mechanism with consequent elaborate production. The component clamp builds wide through the guide slot. Because of the direct leverage is a long piston travel and therefore inevitably one elongated design given. The toggle principle is used here applied in a modified form.

To hold on to a component clamp based on the toggle principle to come, it is necessary to use a component of the toggle assembly driving tab over top dead center. The force increases in theory the tab to infinity. In practice, the force limited by elastic deformations in the entire system. this means however wear and tear. Furthermore, it cannot be guaranteed that the Clamping arm with high clamping forces is actually pivoted over the dead center becomes. The maximum clamping force is determined by the one available Energy, especially compressed air. Is this in a compressed air cylinder prevailing cylinder force is not large enough to the required Applying clamping forces to the clamping arm does not move the tab over the Dead center and therefore not in self-retention.

DE 31 30 942 A1 discloses a component tensioner based on the toggle principle. At the free end of a piston with a pressure medium connected piston rod is articulated a resiliently designed tab, which is also connected to a rigid toggle lever that is at 90 ° Dislocation is coupled with a tension arm. The tab is designed that the distance between the coupling joints with the piston rod and the lever is changeable.

The resilient tab should prevent infinitely large clamping forces become. With this, however, only the clamping force can be limited, but not Self-locking can be achieved. In addition, the fatigue strength and Durability of the tab can be problematic. Their production is also complex. In addition, the force limit is from the spring constant as well depends on the travel.

In the component clamp of EP 0 370 914 A1, the pivoting of the Clamping organ from a clamping position to a release position and vice versa accomplished by means of a drive element that is linear in a housing is movable. A lever arm is articulated to the drive element, which in turn is articulated with a rod. On the other hand, it is Rod articulated to a crankshaft, which rotates with the Clamping element is connected.

In the joint area between the lever arm and the rod there is a Wheel that can roll on a wedge surface that is part of one Axis swiveling profile part forms. The profile part is in turn under the influence of a compression spring, which strives to keep the profile part in the direction to press the wheel.

There is a recess in the vicinity of the axis for the profile part Wedge surface. The recess forms in connection with the wheel and the Compression spring a locking means that the moving parts crankshaft, drive element, Lock the rod and lever arm in the clamped position. Due to the elastic locking of this special component assignment but no precisely definable dead center position of the clamping member with a perfect one Self-locking achievable.

This component clamp has a larger number of individual parts Commitment. An additional lever arm is also integrated. There is one additional articulation point required with the corresponding manufacturing effort. In addition, this joint area forms a wear area, which one increased maintenance is required.

Furthermore, the wedge surface forms part of the known component clamp of the profile part pivotable about the axis. Here too is not only an additional component is present, but another wear point in Shape of the axis.

In addition, the profile part is under the influence of a compression spring. Herewith is not only involves an increased effort, but also an additional one Storage of the compression spring. Another negative in the known case is that Springs are subject to undesired wear.

In the context of the multi-head clamping device of DE 36 86 385 T2, each An elastically deformable element is provided in the clamping head Moment of locking the clamping arm in the clamping position itself resiliently compliant. Accordingly, none can with this proposal precisely definable dead center realized with perfect self-locking become.

US Pat. No. 4,921,233 discloses a component tensioner according to the preamble of independent claim 1, in which one with the tension arm connected role on a positive guide, the one has concave area over the roll from several lengths. Each individual section of this concave area has a radius with a center of curvature between the hinge axis of the tension arm and the articulated axis connecting the tension arm to the roller Tab lies. In this way, e.g. self-locking in the event of a power failure be avoided. This endeavor is further supported by that the angle between a plane through the two hinge axes the tab runs, and the plane that the hinge axis of the tension arm and the hinge axis between the tension arm and the bracket cuts less than 90 ° should be.

Based on the prior art, the invention is based on the object to create a component tensioner that is simple to use the toggle principle allows a limitation of the increase in force and it still ensures that in the clamping position even if the Clamping energy the clamping position is guaranteed by self-locking.

The solution to this problem is in the features listed in claim 1 seen.

The essence of the invention is the fact that the positive control for at least one roller arranged at the end of the tension rod with a to the first coupling joint between the lever and the lug in its dead center concave end portion is provided. This concave end section begins in front of the side facing the standby position by the Dead center second coupling joint extending to the longitudinal axis the tension rod in the standby position vertically extending plane and ends on the side facing away from this standby position Plane at an end point at which the roller after passing over the dead center, to reach a self-locking state. The concave End section is curved in a circular arc. It has a radius which is the length of the tab between the first and second coupling joints plus the radius of the roller.

Reaches the second coupling joint between the bracket and the tension rod the beginning of the concave end section before this level is the Clamping arm in the clamping position. The maximum clamping force is built up. It there is no further increase in force. By continuing on the tie rod the existing clamping force becomes the second coupling joint between the bracket and tension rod moved across the plane until this second Coupling the end of the concave end section lying behind the plane has reached. The maximum tension remains during this movement always received. Behind the level is the tab in the self-locking area. If the clamping energy disappears in this position, the full one remains Preserve resilience without loss.

The particular advantage of the invention is therefore to ensure the force limitation easily through the concave end portion with a very specific radius. Only with this radius is a constant force over the course of the piston travel possible. This will make a flawless Guaranteed self-locking after passing dead center. The Component clamp also has a very compact design, because of the inventive Path translation between the lever and the tab only one small stroke of the tension rod is required.

The invention also allows the pivoting angle of the tension arm between set up the standby position and the clamping position as desired can. Only by using stroke-limiting pieces or by replacing the tension rod opening angles of in particular 45 °, 60 °, 90 ° and 115 ° up to a maximum opening angle of 135 ° can be provided. Furthermore, the component clamp can easily an integrated position query can be assigned.

The housing for mounting the tension arm, lever, bracket and tension rod is also designed so that a cooperating with the tension arm Abutment for fixing the position of the workpieces to be machined to the housing can be releasably assigned.

A particularly expedient embodiment of the invention consists in the Features of claim 2. Thereafter, the concave end portion extends of forced guidance over a length that takes you through the plane first coupling joint between the lever and the tab across dead center Swivel angle of the bracket from 6 ° to 10 °, but preferably 8 °, equivalent. This means that the tab is self-locking at 4 ° above the level guaranteed.

According to the features of claim 3, the positive guidance, the lever, the tab and the roller in one with the guide for the tension rod connectable two-part housing arranged. That way these parts are well protected against external influences even in rough operation. The two-piece nature of the housing allows for easy manufacture as well easy assembly. The tour is guided in particular by a Cylinder formed when according to a preferred embodiment Tension rod as a compressed air or also with a Piston rod connected to hydraulically actuated pistons is. The necessary deflection of the tension rod when the roller comes into contact with the concave end section is through the seals on the cylinder for the tension rod.

Uniform tilt-free power transmission from the tension rod on the tension arm is achieved with the features of claim 4.

It is particularly useful if the pivot shaft in accordance with claim 5 the end sections carrying the articulated arms is of polygonal design. In this case, the pivot shaft can be designed, in particular, as a square. The Articulated arms are then with corresponding recesses and / or clamping pieces provided, through which the articulated arms perfectly on the Swivel shaft can be set. The pivot shaft and the lever are preferably a component that is manufactured by turning and milling operations can be.

Figur 1

einen Bauteilspanner in schematischer Seitenansicht;

Figur 2

den Bauteilspanner der Figur 1 in der Draufsicht;

Figuren 3 bis 6

in vergrößerter Darstellung einen vertikalen Längsschnitt durch die Figur 2 entlang der Linie A-A entsprechend dem Ausschnitt B der Figur 1 in vier verschiedenen Betriebsstellungen;

Figuren 7 bis 10

die Darstellungen der Figuren 3 bis 6 im Schema und

Figur 11

in nochmals vergrößertem Maßstab die Darstellung der Figur 9.

The invention is explained in more detail below on the basis of an exemplary embodiment illustrated in the drawings. Show it:

Figure 1

a component clamp in a schematic side view;

Figure 2

the component clamp of Figure 1 in plan view;

Figures 3 to 6

in an enlarged representation a vertical longitudinal section through FIG. 2 along line AA corresponding to section B of FIG. 1 in four different operating positions;

Figures 7 to 10

the representations of Figures 3 to 6 in the scheme and

Figure 11

on a further enlarged scale the illustration of FIG. 9.

1 in FIGS. 1 and 2 is a component clamp operated with compressed air designated. The component clamp 1 comprises a pressurized air Cylinder 2 for guiding a piston, not shown in detail Piston rod, a two-part housing 3 connected to the cylinder 2 with an integrated toggle lever system, not shown in more detail to transfer the force exerted by the compressed air on the piston a pivotable clamping arm 4. The clamping arm 4 has a U-shaped configuration two articulated arms 5, which on clamping pieces 6 at one of the the housing 3 leads out four-sided pivot shaft 7 are releasably attached. In the illustrated in Figures 1 and 2 Clamping position ST, the longitudinal axis 8 of the clamping arm 4 runs perpendicular to Longitudinal axis 9 of the cylinder 2. The compressed air connection of the annular space 2a with 10 and that of the piston chamber 2b with 10a.

As can be seen in FIGS. 3 to 6, the tensioning arm 4 in FIG Inside the housing 3, a rigid lever 11 connected in 90 ° displacement. The lever 11 forms an integral part of the pivot shaft 7.

At the end facing away from the pivot shaft 7, the lever 11 is over a first coupling joint 12 connected to a rigid bracket 13, which in turn again via a second coupling joint 14 with one end 15 one Tension rod 16 is connected (Figure 3). The second coupling joint 14 supports on a roller 17, which on a positive guide 18 in the housing 3 rolls. A recess 19 in the halves 20, 21 of the housing 3 is on adjusted the size of the pivoting movements of the lever 11 and the tab 13.

As can be seen more clearly in FIG. 11, the Positive guidance 18 for the roller 17 from a straight line Length section 22 and an arcuate curved end section 23 together. The length L of the straight length section 22 corresponds to that Size of the pivot angle α of the tension arm 4 between the standby position BP and the clamping position ST. It runs in a straight line parallel to Longitudinal axis 9 of the cylinder 2. The end section 23 is to the first coupling joint 12 between the lever 11 and the tab 13 in its dead center (Clamping position ST of 4) curved concavely. It starts at 24 before the standby position (BP) facing the side through which is in the dead center located first coupling joint 12 extending to the longitudinal axis 9 of the Cylinder 2 perpendicular plane E-E and ends at 25 on this Standby position (BP) facing away from this level E-E. His Arc length L3 corresponds to the angle 2β between points 24 and 25. The angle β between the plane E-E and the points 24, 25 of the concave End section 23 is 4 ° in each case.

FIG. 11 also shows that the length L1 of the tab 13 between the first coupling joint 12 and the second coupling joint 14 larger than the distance A between the first coupling joint 12 and the coaxial to Longitudinal axis 9 of the cylinder 2 extending longitudinal axis 27 of the tension rod 18 is dimensioned.

The mode of operation of the component clamp 1 is shown below with reference to the figures 3 to 11 explained in more detail.

FIGS. 3 and 7 show the standby position BP of the tension arm 4. The opening angle α is 135 °. The component clamp 1 is complete open. There is 10 compressed air in the annulus via the compressed air connection 2a of the cylinder 2.

By acting on the piston 28 in the piston chamber 2b of the cylinder 2 this is moved in the longitudinal direction of the cylinder 2 (Figures 4 and 8). in this connection rolls the roller 17 on the longitudinal section 22 of the positive guide 18. The roller 17 has the lower end 24 of the concave in the plane of the drawing End section 23 reached (Figures 4 and 8), the tension arm 4 by 135 ° have been pivoted into the clamping position ST. The opening angle is 0 °. The maximum clamping force has been reached.

By further loading the piston 28 with compressed air via the compressed air connection 10a of the piston chamber 2b extends the tension rod 16 further and pivots the tab 13 about the now fixed first coupling joint 12 between the lever 11 and the tab 13 into the plane E-E, which extends through the first coupling joint 12 and perpendicular to Longitudinal axis 9 of the cylinder 2 runs. Here, the roller 17 rolls on the concave End section 23 without increasing the already achieved clamping force (Figures 5, 9 and 11).

By continuing to pressurize the piston 28 with compressed air Tab 13 according to Figures 6 and 10 also beyond this level E-E moved further until the roller 17 the upper in the plane of the drawing End 25 of the concave end portion 23 has reached.

If compressed air now drops, the full clamping force would be retained remain because the tab 13 - based on the drawing level - with 4 ° over level E-E and is therefore in the area of self-locking.

REFERENCE NUMBERS

1 6

tensioner component

2 6

cylinder

2a -

Annulus v. 2

2 B -

Piston chamber v. 2

3 -

casing

4 -

clamping arm

5 -

Articulated arms 4

6 -

Clamps

7 -

pivot shaft

8th -

Longitudinal axis v. 4

9 -

Longitudinal axis v. 2

10 -

Compressed air connection

10a -

Compressed air connection

11 -

lever

12 -

first coupling joint f. 11 u. 13

13 -

flap

14 -

second coupling joint between 13 u. 16

15 -

End of v. 16

16 -

tension rod

17 -

caster

18 -

forced control

19 -

Recess in 20, 21

20 -

Half of v. 3

21 -

Half of v. 3

22 -

Longitudinal section v. 18

23 -

End section v. 18

24 -

Beginning of 23

25 -

End of v. 23

26 -

Axis v. 7

27 -

Longitudinal axis v. 16

28 -

Piston in 2nd

A -

Distance between 12 u. 27

BP -

stand-by position

E-E-

Level through 12

L -

Length of 22

L1 -

Length of 13

L2 -

Length of 11

L3 -

Arc length of 23

R -

Radius of 23

r -

Radius of 17

ST -

Clamping position v. 4

α -

Swivel angle v. 4

β -

Angle between E-E and 24 or 25

Claims (5)

1. A component clamp comprising a clamping bar (16) movable by pneumatic, hydraulic of electric emergy, a clamping arm (4) pivotable out of its clamping position (ST) into a standby position (BP) and vice-versa, a rigid lever (11) connected non-rotatably to the clamping arm (4) via a pivot (7), and a rigid link (13) coupled for rotation both with the lever (11) and with the end (15) of the clamping bar (16), the length (L1) of said link between a first joint (12) and a second joint (14) being greater than the distance (A) between the first joint (12) of the link (13) to the lever (11) and the longitudinal axis (27) of the clamping bar (16) in the standby position (BP), wherein the second joint (14) is supported, between the link (13) and the end (15) of the clamping bar (16), against at least one roller (17) which rolls on a positive guide (18) which has a length portion (L) corresponding to the angle of pivoting (α) of the clamping arm (4) between the standby position (BP) and the clamping position (ST), said length portion extending rectilinearly in parallel relationship to the longitudinal axis (27) of the clamping bar (16) in the standby position (BP), and which is provided with an end portion (23) which, in relation to the first joint (12) between the lever (11) and the link (13), is concave in the dead centre position of said joint, said end portion (23) starting in front of that side of the plane (E-E) extending through the first joint (12) in the dead-centre position and perpendicularly to the longitudinal axis (27) of the clamping bar (16) in the standby position (BP) that faces the standby position (BP), characterised in that the end portion (23) on the side of said plane (E-E) remote from said standby position (BP) ends at an end point (25) at which the roller (17) arrives after traversing the dead-centre position to reach a self-locking state, the concave end portion (23) having a radius (R) which corresponds to the length (L1) of the link (13) between the first joint (12) and the second joint (13) plus the radius (r) of the roller (17).
2. A component clamp according to claim 1, wherein the concave end portion (23) of the positive guide (18) extends over an arc length (L3) corresponding to an angle of pivoting (2β) of 6° to 10°, preferably 8°, of the link (13) spanning the plane (E-E).
3. A component clamp according to claim 1 or 2, wherein the positive guide (18), the lever (11), the link (13) and the roller (17) are disposed in a two-part housing (3) which is adapted to be connected to the guide (2) for the clamping bar (16).
4. A component clamp according to any one of claims 1 to 3, wherein the clamping arm (4) laterally encloses the housing (3) by two joint arms (5) and is non-rotatably connected via the joint arms (5) to the ends of the pivot (7) made in one piece with the lever (11), said ends being taken out of the housing (3).
5. A component clamp according to claim 4, wherein the pivot (7) is of polygonal construction in the end portions bearing the joint arms (5).

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