EP1655104A2 - Clamping device for clamping pieces - Google Patents

Abstract

The invention relates to a clamping device for clamping objects, in particular workpieces (30), tools or devices, in processing machines, with a base (17) with fastening means (18,35) for securing the clamping device to a machine table of the processing machine and with a for clamping of the object on the base to movable clamps (13). In order to avoid deformations as a result of bending forces introduced into the machine table by the clamping forces, the clamping device is characterized in that the base (17) has a support (20) for the object, such that the object is clamped between the clamping iron (13). and the support (20) is tensioned.

Description

The invention relates to a clamping device for clamping objects, in particular tools, workpieces or devices, in processing machines, with a base with fastening means for securing the clamping device to a machine table of the processing machine and with a for clamping the article on the base to movable clamping iron.

Such clamping devices are well known, for example as a swing clamp. A housing of the swing clamp is bolted to a base on a machine table. In the housing, a piston is hydraulically retractable, which carries at its free end the clamping iron. By pulling the piston into the housing, the piston is first pivoted about its longitudinal axis. Then lowered by further retraction of the piston, the clamping iron on the object, usually a workpiece, from and clamps this on the machine table. The machine table itself serves as an abutment for applying the clamping force. An example of such a swing clamp is known from DE 102 52 549 A1.

A disadvantage of this arrangement is that the machine table itself is integrated into the power flow for clamping the workpiece. The workpiece exerts a compressive force on the machine table while a fixing screw for fastening the housing of the swing clamp on the machine table, which faces the workpiece, exerts a tensile force on the machine table. Attachment sections on the side of the housing facing away from the workpiece in turn exert a compressive force on the machine table. As a result, the machine table is subjected to bending and deformed accordingly. This is undesirable in today often required high-precision machining of workpieces, since it comes at the expense of machining accuracy. Furthermore, due to the deformations, shifts of the workpiece may occur with further deteriorated machining accuracy.

Proceeding from this, the invention is based on the problem, a clamping device of the type mentioned in such a way that the introduction of bending moments in the machine table by clamping forces and the risk of workpiece displacements during clamping is avoided.

To solve this problem, the clamping device according to the invention is characterized in that the base has a support for the object, such that the object is tensioned during clamping between the clamping iron and the support.

According to the invention, the object, ie in general the workpiece, is clamped between the base and the clamping iron. It results in a closed power circuit from the clamping iron on the workpiece in the base, the housing and the piston back into the clamp iron. Force transmission due to the clamping forces in the machine table are completely avoided. Accordingly, no bending stresses and deformations caused thereby occur in the machine table or workpiece displacements. The clamping device according to the invention is therefore also ideal for clamping workpieces for high-precision machining. It is therefore possible to design very simple clamping devices.

According to a development of the invention, the support is adjustable in height, wherein it is preferably fixed in height. This can be done by a screw with self-locking thread or, in fluid-actuated bearing, by means of a clamping piston or the like. In fixtures with such support often the workpiece is first positioned and then brought the support to bear against the workpiece and finally operated, for example, swing clamp. This sequence can be controlled by suitable Zuschaltventile, so that first actuates the support, that is adjusted in height and then fixed in height and finally the actual clamping device, such as the swing clamps, is operated.

In such tensioning devices, a bending moment is exerted on the piston rod as a result of the clamping force. To counteract this, it is advantageous to provide an abutment which counteracts the introduced by the clamping force bending moment. This counter bearing should also be arranged on the base, so that no Beigemomente be introduced into the machine by this counter bearing.

Preferably, the counter bearing exerts at least one force component at right angles to the clamping force, which counteracts the bending moment introduced into the piston by the clamping force. This leads to the force introduced by the counter bearing is not or only partially at the expense of the clamping force. Such an abutment may have a ramp with a sloping slope to the clamping iron, which cooperates with a wedge. This results in a force exerted by the abutment force on the piston, which has both a force component perpendicular to the clamping force, as well as parallel to the clamping force. Additionally or alternatively, the anvil also have a pressure fluid-operated piston, which is directed at right angles to the clamping force. In this case, there is an exclusively perpendicular to the clamping force directed counterforce, so that the clamping force remains unaffected.

There are known pressure-actuated clamping devices, which are acted upon by separate pressure medium lines with pressure medium. Likewise, pressure-medium-operated clamping devices are known, which are supplied via pressure medium supply holes in the example machine table or other device of a machine tool to which they are attached, with pressure medium. This variant has the advantage that no separate, possibly disturbing pressure medium lines are present. In this case, the clamping device is supplied via corresponding passages or couplings the pressure medium. Due to the pressure of the pressure medium acts on the corresponding contact surface between the clamping device and the machine table, for example, a the feedthroughs or clutches apart oppressive, separating force, which can lead to leakage problems. In an independently conceivable development of the tensioning devices, the bushings or couplings are guided in the vicinity of a fastening means, for example screw, for the tensioning device or even through the fastening means. Due to the small or non-existent distance between the bushings or couplings and the fastening means results in a small or no lever arm, so that only small deformations result due to the separating force.

Another aspect of the invention is concerned with the introduction of force of the forces acting on the workpiece machining forces, etc. in the machine table or the like. These forces also lead to elastic deformations on the machine table and thus to higher manufacturing tolerances. This can be minimized by the fastener or one of several fasteners seen in the clamping direction aligned with the support for the workpiece. The forces acting on the workpiece forces are then introduced without lever arm in the machine table or the like and thus also free of bending moment. Where this is not possible for reasons of space, the fastener in question should be herangebaut as close to the edition. Possibly. For example, two or more fasteners may be used tightly around the pad. In this case, the sum of the forces transmitted through the respective fastening means due to machining forces should be as close as possible to the support, as far as possible in the clamping direction, in alignment with it.

Fig. 1

ein erstes Ausführungsbeispiel für eine Spanneinrichtung mit den Erfindungsmerkmalen in Seitenansicht,

Fig. 2

ein zweites Ausführungsbeispiel für eine Spanneinrichtung mit den Erfindungsmerkmalen in perspektivischer Darstellung,

Fig. 3

ein drittes Ausführungsbeispiel für eine Spanneinrichtung mit den Erfindungsmerkmalen in Seitenansicht,

Fig. 4

ein viertes Ausführungsbeispiel für eine Spanneinrichtung mit den Erfindungsmerkmalen in Seitenansicht,

Fig. 5

die Spanneinrichtung gemäß Fig. 4 in Draufsicht,

Fig. 6

ein fünftes Ausführungsbeispiel für eine Spanneinrichtung mit den Erfindungsmerkmalen in Seitenansicht,

Fig. 7

eine Variante zum Ausführungsbeispiel gemäß Fig. 6,

Fig. 8

eine weitere Variante zum Ausführungsbeispiel gemäß Fig. 6,

Fig. 9

die Spanneinrichtung gemäß Fig. 6 in Draufsicht, teilweise geschnitten,

Fig. 10

ein sechstes Ausführungsbeispiel für eine Spanneinrichtung mit den Erfindungsmerkmalen in Seitenansicht, und

Fig. 11

ein weiteres Ausführungsbeispiel für eine Spanneinrichtung mit den Erfindungsmerkmalen in Seitenansicht.

The invention will be explained in more detail with reference to embodiments shown in the drawing. Show it:

Fig. 1

a first embodiment of a clamping device with the features of the invention in side view,

Fig. 2

A second embodiment of a clamping device with the features of the invention in perspective view,

Fig. 3

A third embodiment of a clamping device with the features of the invention in side view,

Fig. 4

A fourth embodiment of a clamping device with the features of the invention in side view,

Fig. 5

the tensioning device according to FIG. 4 in plan view,

Fig. 6

a fifth embodiment of a clamping device with the features of the invention in side view,

Fig. 7

a variant of the embodiment of FIG. 6,

Fig. 8

a further variant of the embodiment of FIG. 6,

Fig. 9

the tensioning device according to FIG. 6 in plan view, partly in section,

Fig. 10

a sixth embodiment of a clamping device with the features of the invention in side view, and

Fig. 11

a further embodiment of a clamping device with the features of the invention in side view.

Fig. 1 shows a swing clamp 10. The swing clamp 10 has a housing 11 and a piston rod 12 which is hydraulically retracted in the housing 11 in a conventional manner. At the free end of the piston rod 12, a clamping arm 13 is attached, which also carries a pressure piece 14 in a conventional manner. In the present case, the pressure member 14 is the crowned head of a screw which is screwed with its threaded bolt 15 in a thread on the clamping iron 13 and secured by a lock nut 16 in a likewise known manner.

On the housing 11, a base 17 is formed, in which, stepped in the present case, holes 18 are recessed. The holes 18 serve to receive fastening screws, by means of which the swing clamp 10 can be screwed to a machine table. The holes 18 are thus at the base arranged as fastening means for the swing clamp 10. In the vicinity of one or more of these holes 18 and the pressure medium supply for the swing clamp 10 is provided.

As can be seen in Fig. 1, the base 17 with respect to the housing 11 loads so far that a web 19 of the base 17 is disposed below the pressure member 14. At the pressure piece 14 facing side of the web 19, a support 20 is arranged for a workpiece. This support 20 is in turn screwed in the present case in the web 19 and secured by a lock nut 21.

In the swing clamp 10 so the workpiece between the pressure pad 14 and the support 20 is stretched. The base 17 thus serves on the support 20 as an abutment for the force exerted by the pressure member 14 on the workpiece clamping forces. Within the swing clamp 10 results in a closed power circuit, as illustrated by the bold circle 22.

• Das Spanneisen 13 ist als zweiarmiger Hebel ausgebildet und mittels eines Gelenks 25 an der Kolbenstange 12 schwenkbar um eine senkrecht zur Kolbenlängsachse verlaufende Schwenkachse gelagert. An seinem einen Ende trägt das Spanneisen 13 das Druckstück 14, welches wiederum in das Spanneisen 13 eingeschraubt und mittels der Kontermutter 16 gesichert ist.

In the case of the pivoting clamp 10 according to FIG. 1, not insignificant bending forces act on the piston 12 during clamping of the workpiece. The swing clamp 23 shown in FIG. 2 therefore has an abutment 24, which is likewise arranged on the base 17. Otherwise, the swing clamp 23 corresponds to FIG. 2 the swing clamp 10 of FIG. 1, so that the same components are designated by the same reference numerals. However, there are the following differences:

• The clamping arm 13 is designed as a two-armed lever and mounted by means of a hinge 25 on the piston rod 12 pivotable about a perpendicular to the piston longitudinal axis pivot axis. At its one end, the clamping arm 13 carries the pressure piece 14, which in turn is screwed into the clamp 13 and secured by means of the lock nut 16.

At its opposite arm, the clamp 13 carries a counter-pressure piece 26, which is also designed as a screw and screwed into the clamp 13 and secured by a lock nut 27. Below the pressure piece 26, a support 28 is screwed onto the base 17, which is adjustable by a screw 29 in height.

A workpiece 30 is in the swing clamp 23 of FIG. 2 directly between the pressure piece 14 and the base 17, by means of which the swing clamp 23 is attached to the machine table 31, tensioned. This results in a closed power circuit, in which, however, the counter bearing 24 is included.

Fig. 3 shows a tensioner 32 analogous to the swing clamp 23 of FIG. 2, so that the same components are again denoted by the same reference numerals. However, the support 20 and / or the abutment 24 are pressure medium-actuated, specifically hydraulically actuated, and put on when clamping a workpiece in the end position. For this purpose, each pressure medium cylinder 33 serve.

Moreover, the tensioner 32 has shown in FIG. 3 on the left in Fig. 3 side as an abutment 24 in its (end) position defined counter-pressure piece 26, while the support 20 has an adjustable end position. For the rest, however, Fig. 3 can be seen that the tensioner 32 is formed very symmetrical. It would therefore also easily possible to provide a pressure piece 14 on both arms of the clamping iron 13 and to arrange a support 20 correspondingly on the base 17 on both sides of the housing 11 so that two workpieces could be clamped simultaneously with the tensioner 32.
As can be clearly seen in FIG. 3, the undersides of the counterpressure piece 26 and the pressure piece 14 are aligned in the direction perpendicular to the piston axis (piston rod 12). This avoids side movements.

In Fig. 4 and 5, a swing clamp 34 is shown, which largely corresponds to the swing clamp 10 of FIG. 1, so that the same components are designated by the same reference numerals. As with the swing clamp 32 As shown in FIG. 3, however, the base 17 is not arranged as a collar on the housing 11. Rather, the housing 11 is arranged standing on the base 17. As a result, and by the closed power flow of the clamping forces within the swing clamp 34, it is possible to attach this swing clamp 34 with clamps 35 on a machine table. The clamps 35 are fixed in a conventional manner in T-slots on the machine table, so that there is a very flexible choice of clamping position.

In Fig. 6 to 9, a swing clamp 36 is shown analogous to the swing clamp 10 of FIG. The support 20 is here but analogous to the support of the tensioner 32 shown in FIG. 3, namely with a pressure cylinder 33. The pressure cylinder 33 is controlled via a Zuschaltventil 37, so that only one pressure medium line, with double-acting elements two lines are required , The connection valve 37 regulates the sequence "applying to the workpiece and clamping the workpiece".

Similarly as in FIG. 6, an intermediate flange 17a (FIG. 7 and FIG. 8) can be used to create a unit which can be installed on or in a device and which does not introduce any deformations into the device itself. It is important that the clamping elements and contactors are attached to the intermediate flange 17a and the intermediate flange 17a in turn in the device.

As already explained in connection with FIG. 1, the pivoting clamp 10 according to FIG. 1, but also the pivoting clamps 34 according to FIGS. 4 and 5 and 36 according to FIGS. 6 to 9, experience bending moments on the piston rod 12, which is the case the swing clamps 23 and 32 shown in FIG. 2 and 3 is avoided by the anvil 24. A disadvantage of the abutment 24, however, is that in this way the force exerted by the piston 12 clamping force is distributed to the pressure member 14 and the anvil 24, so that the available clamping force is reduced. To avoid this disadvantage, horizontally acting abutments 40 and 41 are provided in the pivoting clamps 38 and 39 according to FIG. 10 and FIG. 11, respectively. When swing clamp 38 shown in FIG. 10, the support member 40 is formed as an inclined plane. When lowering the clamping iron 13 for clamping a workpiece, a wedge 42 slides on the clamp 13 on a ramp 43 of the abutment 40. Due to the angular position of the wedge 42 and the ramp 43 results in a horizontal force component, which the bending moment on the piston 12 due to the clamping force counteracts. At the same time arises depending on the angular position and a vertical component, which in the present case, however, is not so strong, so that a much larger proportion in the provided by the piston 12 force can actually be converted into the clamping force.

In the swing clamp 39 shown in FIG. 11, the anvil 41 has a hydraulic piston 44 which is guided in a cylinder bore 45 of the thrust bearing 41. During clamping of the workpiece and the hydraulic piston 44 is acted upon by pressure medium, applies itself to the clamping arm 13 and thus counteracts the introduced by the clamping force in the piston rod 12 bending moment. The pressure medium of the hydraulic piston 44 can be effected via corresponding Zuschaltventile. The vote of the force exerted by the hydraulic piston 44 on the clamping arm 13 counterforce can be controlled by a vote of the piston surfaces of the hydraulic piston 44 and the piston rod 12.
The tensioning devices shown in FIGS. 1 to 11 are pressure-medium-actuated, in particular by means of hydraulic oil. It is also conceivable to actuate the clamping devices electrically, for example via electromagnets. This does not actually happen in practice.

FIGS. 1 to 11 show different variants of the fastening of the tensioning device on a machine table or the like. For the initiation of the working forces acting on the workpiece, it is particularly advantageous if a fastening means is aligned with a line formed by the pressure piece 14 and the support 20 or comes as close as possible. In other words, the fastener in question should be arranged in the clamping direction aligned with the support 20.

S u b e c ia l e s:

10

swing clamps

11

casing

12

piston rod

13

clamps

14

Pressure piece

15

bolt

16

locknut

17

Base

18

drilling

19

web

20

In stock

21

locknut

22

circle

23

swing clamps

24

thrust bearing

25

joint

26

Counterpressure member

27

locknut

28

In stock

29

screw

30

workpiece

31

machine table

32

Stretcher

33

Pressure cylinder

34

swing clamps

35

clamps

36

swing clamps

37

sequence valve

38

swing clamps

39

swing clamps

40

thrust bearing

41

thrust bearing

42

wedge

43

ramp

44

piston

45

bore

Claims (10)

Clamping device for clamping objects, in particular tools, workpieces (30) or devices, in processing machines, having a base (17) with fastening means (18, 35) for attaching the clamping device to a machine table of the processing machine and having one for clamping the article on the Base for movable clamps (13), characterized in that the base (17) has a support (20) for the object, such that the object is tensioned during clamping between the clamping arm (13) and the support (20). Clamping device according to claim 1, characterized in that the support is height adjustable, and preferably fixable, is. Clamping device according to claim 2, characterized in that the pressure-medium-actuated height-adjustable support (20) via a Zuschaltventil (37) can be acted upon with pressure medium, such that the support (20) first applies to the object, the support (20) then locked and Finally, the piston rod (12) is acted upon to build up the clamping force with the pressure medium. Clamping device according to one of claims 1 to 3, characterized by a likewise on the base (17) arranged abutment (24, 40, 41) for the clamping iron (13). Clamping device according to claim 4, characterized in that the anvil (40, 41) exerts a force on the clamping iron (13), which is directed at least with a force component perpendicular to the clamping force. Clamping device according to claim 5, characterized in that the abutment (40) has a ramp (43) with sloping to the clamping iron (13) bevel, which cooperates with a wedge (42) on the clamping iron (13). Clamping device according to claim 5, characterized in that the abutment (41) has a pressure medium-actuated piston (44) which is directed at right angles to the clamping direction. Clamping device according to claim 4, characterized in that the anvil (24) is pressure-medium-actuated. Clamping device according to one of claims 1 to 8, characterized in that bushings or couplings for a pressure means for actuating the tensioning device is guided through a fastening means or arranged in the vicinity of the fastening means for the tensioning device. Clamping device according to one of claims 1 to 9, characterized in that a fastening means for the clamping device in the clamping direction is aligned approximately with a support (20) for the workpiece (30).

Images