EP3412411A1 - Tensioning system - Google Patents

Abstract

The invention relates to a clamping system (5) for clamping a blank, with an arrangement of at least three clamping elements (13) which are movable by means of an adjusting element (10) between a release position and a clamping position. The clamping elements (13) are in the release position out of engagement and in the clamping position in engagement with a contact surface (16) of a receptacle of the tubular member. The clamping elements (13) are coupled via a spherical compensating element (12) to the adjusting element (10), so that upon movement of the adjusting element (10) in a clamping position, the spherical compensating element (12) performs a compensating movement through which the clamping elements (13) uniformly are guided against the contact surface (16) of the receptacle.

Description

The invention relates to a clamping system for clamping a blank.

Such blanks may in particular be formed by castings 2, which typically consist of metallic materials.

FIG. 1 shows a clamping unit 1 according to the prior art to such a casting 2, in the present case, a die-cast, to fix on a base plate formed by a clamping plate 3. The clamping unit comprises three separate clamping devices 4, which are anchored on the upper side of the clamping plate, wherein these clamping devices are preferably fixed by mechanical means on the clamping plate. Depending on the shape and size of the casting, the jigs must be placed on the top of the chuck by a resource engineer to fix them at appropriate locations on the casting. This process is often cumbersome and time consuming. This is based in particular on the fact that after clamping on the clamping plate, the casting must be processed in predefined steps. The equipment engineer then has to fix the tensioning device in places of the casting that do not need to be machined later.

The invention has for its object to provide a clamping system by means of which a rational and reproducible clamping a blank is possible.

To solve this problem, the features of claim 1 are provided. Advantageous embodiments and expedient developments of the invention are described in the dependent claims.

The invention relates to a clamping system for clamping a blank, with an arrangement of at least three clamping elements which are movable by means of an adjusting element between a release position and a clamping position. The clamping elements are disengaged in the release position and in the clamping position in engagement with a contact surface of a receptacle of the tubular member. The clamping elements are coupled via a spherical compensating element to the adjusting element, so that upon movements of the adjusting element in a clamping position, the spherical compensating element performs a compensating movement through which the clamping elements are uniformly guided against the contact surface of the receptacle.

The clamping system according to the invention can be used for clamping blanks of different types. The blanks are in particular made of castings, which typically consist of metallic materials. Furthermore, the blanks can also be formed by welded structures, Ausbrennteilen and the like.

An essential advantage of the invention is that at least one receptacle is provided on the blank, which is provided on a side wall, in particular on the underside of the blank. Thus, the blank can be placed with this side wall on a base and the clamping system can then be brought from the bottom of the pad to the blank in order to stretch this. Of course, several shots can be provided on the side wall of the blank, so that the blank can be fixed to the pad with several clamping systems. This ensures that the upper side of the blank to be machined remains free, so that no restrictions arise for the machining of the blank due to the clamping system or systems.

Another essential advantage of the invention is that an automated machining of the blank is made possible with the clamping system according to the invention.

Compared with a clamping system known from the prior art eliminates a manual alignment of fixtures on the part to be machined of the blank.

Furthermore, the execution of the clamping operations can be done automatically with the one or more clamping systems themselves. Particularly advantageously, the clamping system is actuated by means of a pneumatic system. Alternatively, electrical or hydraulic actuating means may be provided, in the simplest case mechanical actuating means are provided.

The clamping operation is thus carried out automatically characterized in that the adjusting element is preferably moved with a pneumatic unit in a clamping position, whereby the clamping elements are moved to their clamping position, in which they are in engagement with the contact surface of the receptacle and so hold the blank in its desired position.

Also, the release of the clamping elements of the contact surface is automatic and automatic. For this purpose, the adjusting element is moved from the clamping position to a release position. As a result, the clamping elements are automatically released from the contact surface of the recording. This release operation is preferably supported by spring elements which exert corresponding restoring forces on the clamping elements.

Another significant advantage of the clamping system according to the invention is that with this the blank can be stretched reproducibly, safely and with high accuracy. Such precise clamping is generally not trivial because blanks, especially castings, have significant dimensional tolerances. Of course, this also applies to the inclusion as part of this blank.

In the clamping system according to the invention this fact is taken into account that the individual clamping elements do not perform fixed predetermined relative movements for performing the clamping operation. If this were the case, due to tolerance-related irregularities in the geometry of the receptacle, it could happen that only a few but not all of them are firmly engaged with the contact surface when the clamping elements are moved, and thus not all the clamping elements contribute to the clamping process.

This would lead to incomplete, non-reproducible clamping operations.

According to the invention, this problem is solved in a surprisingly simple manner in that the clamping elements are coupled via a spherical compensating element to the adjusting element, wherein the adjusting element is movably arranged on a support surface of the adjusting element. As a result, the individual clamping elements are no longer rigidly coupled with each other and not rigidly to the adjusting element. Thus, the clamping elements individually perform compensatory movements when this is introduced into the clamping position, which is ensured by these compensatory movements that all clamping elements are uniformly and thus pressed with substantially equal contact forces against the contact surface when the adjustment is retracted into the clamping position and the clamping elements are in their clamping positions. This compensating movement generally takes place in that when a clamping element is guided against the contact surface, the clamping element exerts a counterforce on the spherical compensating element, whereby this is moved in the direction of the other clamping elements, which are not yet in contact with the contact surface. By this compensating movement, the clamping elements are switched in such a way that during the movement of the adjusting the clamping elements are guided with the same contact pressures against the contact surface.

As a result, a precise and reproducible clamping of the blank is obtained, since regardless of tolerances of the contact surface of the receptacle, the clamping elements are always performed with substantially the same contact pressure against the contact surface of the receptacle.

A uniform clamping process can be particularly well realized that the clamping elements are identical.

Particularly advantageously, the clamping elements are mounted on pivot bearings.

In this case, each clamping element has at its front end a tip, which is guided in the clamping position of the clamping element against the contact surface of the receptacle.

This allows a particularly accurate and reproducible clamping of the blank perform, since the pivoting movements of the clamping elements allow a defined movement of the tips of the individual clamping elements against the contact surface, which in a simple manner a secure clamping on the contact surface is effected.

According to a geometrically favorable embodiment, the adjusting element is displaceable in its longitudinal direction.

Furthermore, the axes of the pivot bearing of the clamping elements are oriented perpendicular to the longitudinal axis of the adjusting element.

The linear movement of the adjusting element is thus deflected into the pivoting movement of the clamping elements. This conversion takes place via the spherical compensation element, which is movable on the support surface.

Advantageously, the bearing surface is formed by a front side of the adjusting element.

Suitably, the support surface is a flat surface and the diameter of the support surface is adapted to the diameter of the spherical compensating element.

Particularly advantageously, the pivoting movements of the clamping elements and the geometries of the tips of the clamping elements are adapted and optimized so that the tensioned blank rests against a contact surface, and that a force is exerted on the workpiece in the direction of the contact surface by the retracted into individual clamping positions clamping elements.

As a result, the hold of the blank on the respective pad is further improved.

According to a first variant of the invention, the receptacle is formed by a recess of the workpiece which opens out on a side wall, wherein the traveling segment of the workpiece bounding the recess forms the contact surface.

Advantageously, the recess has a circular cross-section, that is, the receptacle is formed as a hollow cylinder.

In this case, the clamping elements are inserted into the cavity of the receptacle from the inside, in which case the clamping elements are pivoted with their tips to the outside and are thus guided against the contact surface of the receptacle.

In this case, the clamping elements can be coupled via the spherical compensating element directly to the adjusting element.

Advantageously, the outer contours of the clamping elements are adapted to the spherical compensating element, that by the contact of the clamping elements with the spherical compensating element, the clamping elements are transferred upon movement of the adjusting element in the clamping position in its clamping position.

This provides a particularly simple mechanism for actuating the clamping elements.

According to a second variant of the invention, the receptacle is formed by a pin projecting from a side wall of the workpiece, the lateral surface of the pin forming the contact surface.

Advantageously, the pin has a circular cross-section, that is, the pin has a cylindrical shape.

In this case, the clamping elements must be brought from the outside of the recording pin forming.

In this case, each clamping element is coupled via a deflecting element to the spherical compensating element.

Suitably, the outer contours of the deflecting elements are adapted to the spherical compensating element, that a deflection movement is effected by the contact of the spherical compensating element with the deflecting, with which the clamping elements coupled to the deflecting elements are transferred to their clamping position upon movement of the adjusting element in the clamping position.

With the deflection elements is thus carried out in a simple manner, an implementation of the linear movement of the adjusting element in pivotal movements of the clamping elements, so that they are guided from the outside against the lateral surface of the pin.

According to an advantageous embodiment, upon movement of the adjusting element from the clamping position into a release position, the clamping elements are transferred into their release position by a forced guidance of the clamping elements on the adjusting element and by restoring forces exerted by spring elements.

Figur 1:

Spanneinheit zum Spannen eines Rohteils gemäß dem Stand der Technik.

Figur 2:

Schnittdarstellung eines ersten Ausführungsbeispiels der erfindungsgemäßen Spanneinheit mit zwei Spannsystemen.

Figur 3:

Draufsicht auf die Spanneinheit gemäß Figur 2.

Figur 4:

Detaildarstellung eines Spannsystems gemäß Figur 2 im gelösten Zustand.

Figur 5:

Detaildarstellung eines Spannsystems gemäß Figur 2 im gespannten Zustand.

Figur 6:

Schnittdarstellung eines zweiten Ausführungsbeispiels der erfindungsgemäßen Spanneinheit mit zwei Spannsystemen.

Figur 7:

Draufsicht auf die Spanneinheit gemäß Figur 2.

Figur 8:

Detaildarstellung eines Spannsystems gemäß Figur 6 im gelösten Zustand.

Figur 9:

Detaildarstellung eines Spannsystems gemäß Figur 6 im gespannten Zustand.

The invention will be explained below with reference to the drawings. Show it:

FIG. 1:

Clamping unit for clamping a blank according to the prior art.

FIG. 2:

Sectional view of a first embodiment of the clamping unit according to the invention with two clamping systems.

FIG. 3:

Top view of the clamping unit according to FIG. 2 ,

FIG. 4:

Detail representation of a clamping system according to FIG. 2 in the dissolved state.

FIG. 5:

Detail representation of a clamping system according to FIG. 2 in the tensioned state.

FIG. 6:

Sectional view of a second embodiment of the clamping unit according to the invention with two clamping systems.

FIG. 7:

Top view of the clamping unit according to FIG. 2 ,

FIG. 8:

Detail representation of a clamping system according to FIG. 6 in the dissolved state.

FIG. 9:

Detail representation of a clamping system according to FIG. 6 in the tensioned state.

The Figures 2 - 6 show a first embodiment of a clamping unit 1 for clamping a blank, which is formed in the present case of a casting 2. The tensioned with the clamping unit 1 blank can be processed in a suitable manner.

The clamping unit 1 according to the invention has two essentially identical clamping systems 5. Depending on the design of the too exciting casting 2, more than two clamping systems 5 or only one clamping system 5 can be provided.

Clamping of the cast part 2 takes place with the clamping systems 5, with receptacles being provided on the underside of the cast part 2 for this purpose. The tensioning systems 5 themselves are mounted on a support, not shown, e.g. attached to a clamping plate 3. Each clamping system 5 is seated, fastened with screws 6, on a base 5a. By different base 5a or similar compensation segments, a height compensation for adaptation to the contour of the underside of the casting 2 can be done.

Each clamping system 5 has an upper part 7 and a lower part 8, which are fixed with other screws 9 to each other.

To carry out clamping operations, each clamping system 5 has an adjusting element 10 which can be displaced in its longitudinal direction by means of a pneumatic unit, not shown. For connection to the pneumatic unit corresponding pneumatic connections 11 are provided. The adjusting element 10 is formed by an elongated, substantially cylindrical part, wherein the adjusting element 10 is mounted displaced along its longitudinal axis.

The upper end face 10a of the adjusting element 10 forms a flat bearing surface. On this support surface a spherical compensating element 12 is movably mounted. The spherical compensation element 12 consists of a solid ball whose diameter is adapted to the diameter of the adjusting element 10.

The adjusting element 10 and the spherical compensating element 12 are assigned three identically designed clamping elements 13. On opposite side surfaces of each clamping element 13 open out cylindrical shaft segments 14 which form a pivot axis to which the clamping element 13 is pivotally mounted. The shaft segments 14 of the clamping elements 13 are each mounted in corresponding rotary bearings, which are each formed in half by a segment of the upper part 7 and a segment of the lower part 8, as from the FIGS. 4 and 5 seen. The pivot axes of the clamping elements 13 extend perpendicular to the longitudinal axis of the adjusting element 10.

At the upper end of a clamping element 13 a transversely of the main body protruding tip 13 a is provided. The tip 13 a is used for fixing in the receptacle of the casting 2.

In the embodiment of the FIGS. 2 to 5 the receptacles consist of recesses 15, which open at the bottom of the casting 2. The recesses 15 have a circular cross-section which is constant over the entire height of the respective recess 15. Alternatively, the recess 15 may also be slightly conical. Also, it is not mandatory to provide a circular cross-section. The recesses 15 are bounded by a cylindrical base surface of the casting 2, which form a contact surface 16.

As in particular from the FIGS. 4 and 5 can be seen, the lower sides of each clamping element 13 are supported on a spring element 17 which is mounted in the lower part 8.

Like from the FIGS. 4 and 5 further seen, each clamping element 13 on a side facing the adjusting element 10 has a curvature. The adjusting element 10 has a notch 10 b, which forms a stop for the lower edge of the respective clamping element 13.

For clamping the casting 2, this is placed on the clamping systems 5 so that the upper part 7 of the respective clamping system 5 projects into the associated recess 15 of the casting 2. The casting 2 is then on an upper contact surface of the respective clamping system 5, as in particular from FIG. 2 seen.

To carry out the tensioning operation of each clamping system 5, the adjusting element 10 is moved along its longitudinal direction out of its in. By means of the pneumatic unit FIG. 4 shown release position in his in FIG. 5 Retracted shown clamping position.

In the release position of the adjusting element 10, the clamping elements 13 are pivoted by the restoring forces of the spring elements 17 in their release position. In the release positions, the clamping elements 13 are pivoted in the direction of the adjusting element 10 such that their tips 13a do not protrude beyond the side surface of the upper part 7. In this position, the clamping elements 13, the upper part 7 of the clamping system 5 can be easily inserted into the recess 15.

The further the adjusting element 10 is moved upwards at the release position, the more the segments of the clamping elements 13 with the tips 13a are pivoted outward by the contact of the spherical compensation element 12, so that the tips 13a are guided in the direction of the contact surface 16. The pivoting movements of the clamping elements 13 are predetermined by the curvatures of the individual clamping elements 13.

With an ideal cylindrical geometry of the recess 15, the tips 13a of all the clamping elements 13 come into contact with the contact surface 16 simultaneously. Tolerance-related deviations from this ideal geometry of the recess 15 typically only the tip 13a of a clamping element 13 come into contact with the contact surface 16 , These tolerance-related asymmetries of the supply of the tips 13a of the clamping elements 13 are balanced by a compensating movement of the spherical compensating element 12. Since the spherical compensating element 12 is freely movable on the support surface of the adjusting element 10 and the spherical compensating element 12 is coupled to the clamping element 13 only by contact with the curved or inclined side surfaces, the spherical compensating element 12 oriented in a direction perpendicular to the longitudinal axis of the adjusting element 10 Level on the support surface perform a corresponding compensation movement. Then comes a clamping element 13 with a tip 13a in contact with the contact surface 16, the ball-shaped compensating element 12 is moved in opposite directions by the opposing force exerted thereby, whereby the other clamping elements 13 are performed with their tips 13a reinforced against the contact surface 16. Thus, as a result, the tips 13a of all the clamping elements 13 are guided uniformly against the contact surface 16, so that all clamping elements 13 exert approximately the same clamping forces on the contact surface 16, whereby a reproducible clamping operation is obtained. FIG. 5 shows the clamping element 13 in its clamping position and the adjusting element 10 in its clamping position. In this clamping position, the front edge of a clamping element 13 bears against the stop formed by the notch 10b of the adjusting elements 10.

The tips 13a of the clamping elements 13 are advantageously designed such that upon pressing the syringes of the contact surface 16 a force is applied downward and thus against the contact surface of the clamping system 5, whereby the hold of the casting 2 is further improved by the clamping system 5.

To release the casting 2, the adjusting element 10 is moved safely with the pneumatic unit in the release position, so that they 13a of the clamping elements 13 are pivoted by the restoring forces of the spring elements 17 and also by a forced operation of the clamping elements 13 on the adjusting element 10 in the upper part 7, to the clamping elements 13 in the in FIG. 4 shown release position lie. Thus, the casting 2 can be released from the clamping system 5.

The FIGS. 6 to 9 show a second embodiment of the clamping unit 1 according to the invention. In this case, the receptacles of the casting 2 consist of pins 18 which project from the underside thereof. The pins 18 have a constant over their height circular cross-section. In general, other cross-sectional shapes are possible, wherein the cross-section generally does not have to be constant even over the height. The cylindrical outer surface of a pin 18 forms the contact surface 16th

The pins 18 serve as receptacles only for fastening the casting 2 and can be removed from the cast part 2 after it has been machined.

According to the difference in the formation of the receptacles as pin 18 compared to recesses 15, the embodiment differs FIGS. 6 to 9 from the embodiment of the FIGS. 2 to 5 by the implementation of the translational movement of the adjusting element 10 in the pivoting movements of the clamping elements 13, which in turn are pivotable with respect to the pivot axes defined by the shaft segments 14.

In the embodiment according to the FIGS. 6 to 9 is in turn on the plane bearing surface forming front end face 10a of the adjusting element 10, the spherical compensating element 12 movably mounted. In contrast to the embodiment according to the FIGS. 2 to 5 However, in the embodiment of the FIGS. 6 to 9 the adjusting element 10 is not in contact with deflecting elements 19 via the spherical compensating element 12, wherein in each case a deflecting element 19 is connected to a clamping element 13. Each deflecting element 19 is displaceably mounted in the lower part 8 in the horizontal direction, that is, the deflecting elements 19 can perform translational movements perpendicular to the longitudinal axis of the adjusting element 10.

The first longitudinal end of a deflecting element 19 is bounded by an inclined surface 19 a, which bears against the spherical compensating element 12. The other longitudinal end is located in the region below the pivot axis laterally on the clamping element 13.

The curved lower edge of each clamping element 13 abuts against a ball element 20, which rests on the spring element 17 performing the restoring force, the spring element 17 being positively guided in a recess of the lower part 8.

FIG. 8 shows the adjustment 10 in its release position, that is in its lower limit position. In this release position, the spherical compensation element 12 has moved downwards so far that it rests in the lower region of the inclined surface 19a of the deflection elements 19. As a result, the clamping elements 13 are pivoted back into the region of the upper part 7 and held there with the restoring forces of the spring elements 17. In these release positions of the clamping elements 13, the pin 18 can be inserted in the area of the upper part 7 with the clamping elements 13, this area being in the form of a recess which opens out at the upper side of the upper part 7. The diameter of this recess is adapted to the outer diameter of the pin 18, so that the pin 18 is located with a small clearance in the recess of the upper part 7.

For clamping the casting 2, the adjusting element 10 is moved from the release position to the clamping position in each clamping system 5 by the pneumatic unit. As a result, the spherical compensating element 12 is pushed upwards and slides along the inclined surfaces 19a of the deflecting elements 19. By means of the contact pressure exerted by the adjusting element 10 via the spherical compensating element 12, the deflecting elements 19 are moved outwardly. As a result, the clamping elements 13 are pivoted against the restoring forces of the spring elements 17 and the tips 13 a of the clamping elements 13 are guided against the contact surface 16 of the pin 18. This pivoting movement of Clamping elements 13 is continued until the adjusting element 10 is retracted into its clamping position and thus the clamping elements 13 are transferred to their clamping position, in which the tips 13 a of the clamping elements 13 are guided with contact pressure against the contact surface 16 of the pin 18 and the casting 2 clamped tight is ( FIG. 9 ).

In the clamping positions, the tips 13a of the clamping elements 13 again point slightly downwards, so that the casting 2 with the respective pin 18 is guided into the recess of the upper part 7 of the clamping system 5 by the clamping operation, whereby the grip of the casting 2 on the clamping system 5 further improved becomes.

To release the pin 18 of the casting 2 from the clamping system 5, the adjusting element 10 is retracted by the pneumatic unit back into the release position, whereby the clamping elements 13 are transferred to their release position and held there with the spring elements 17 ( FIG. 8 ). In this release position of the clamping elements 13, the pin 18 of the casting 2 can be pulled out of the recess of the upper part 7 of the clamping system 5.

LIST OF REFERENCE NUMBERS

(1)

clamping unit

(2)

casting

(3)

chipboard

(4)

jig

(5)

clamping system

(5a)

base

(6)

screw

(7)

top

(8th)

lower part

(9)

screw

(10)

adjustment

(10a)

front

(10b)

notch

(11)

pneumatic connection

(12)

spherical compensating element

(13)

clamping element

(13a)

top

(14)

wave segment

(15)

recess

(16)

contact area

(17)

spring element

(18)

spigot

(19)

deflecting

(19a)

sloping surface

(20)

ball element

Claims (15)

Clamping system (5) for clamping a blank, with an arrangement of at least three clamping elements (13) which are movable by means of an adjusting element (10) between a release position and a clamping position, wherein the clamping elements (13) in the release position disengaged and in the Clamping position in engagement with a contact surface (16) of a receptacle of the blank, wherein the clamping elements (13) via a spherical compensating element (12) is coupled to the adjusting element (10) and the spherical compensating element (12) on a bearing surface of the adjusting element (10 ) is movably mounted so that upon movement of the adjusting element (10) in a clamping position, the spherical compensating element (12) performs a compensating movement through which the clamping elements (13) are uniformly guided against the contact surface (16) of the receptacle. Clamping system (5) according to claim 1, characterized in that the clamping elements (13) are identical. Clamping system (5) according to claim 1 or 2, characterized in that the clamping elements (13) are mounted on pivot bearings. Clamping system (5) according to any one of claims 1-3, characterized in that each clamping element (13) has at its front end a tip (13a) which guided in the clamping position of the clamping element (13) against the contact surface (16) of the receptacle is. Clamping system (5) according to one of claims 1 - 4, characterized in that the bearing surface is formed by an end face (10a) of the adjusting element (10). Clamping system (5) according to claim 5, characterized in that the diameter of the support surface is adapted to the diameter of the spherical compensating element (12). Clamping system (5) according to any one of claims 1-6, characterized in that the adjusting element (10) is displaceable in its longitudinal direction. Clamping system (5) according to claim 7, characterized in that the axes of the pivot bearing of the clamping elements (13) are oriented perpendicular to the longitudinal axis of the adjusting element (10). Clamping system (5) according to any one of claims 1-8, characterized in that the tensioned blank rests against a contact surface, and that a force is exerted on the workpiece in the direction of the contact surface by the retracted into its clamping position clamping elements (13). Clamping system (5) according to any one of claims 1-9, characterized in that the adjusting element (10) is pneumatically, mechanically, hydraulically or electrically driven. Clamping system (5) according to any one of claims 1-10, characterized in that upon movement of the adjusting element (10) from the clamping position to a release position, the clamping elements (13) by a forced operation of the clamping elements (13) on the adjusting element (10) and by Spring elements (17) exerted restoring forces are transferred to their release position. Clamping system (5) according to any one of claims 1-11, characterized in that the receptacle is formed by a recess (15) of the workpiece which opens out on a side wall, wherein the wall segment of the workpiece delimiting the recess (15) forms the contact surface (16) , Clamping system (5) according to claim 12, characterized in that the clamping elements (13) via the spherical compensating element (12) are coupled directly to the adjusting element (10), wherein the outer contours of the clamping elements (13) to the spherical compensating element (12). is adapted, that by the contact of the clamping elements (13) with the spherical compensating element (12), the clamping elements (13) are transferred to their clamping position upon movement of the adjusting element (10) in the clamping position. Clamping system (5) according to any one of claims 1-11, characterized in that the receptacle is formed by a protruding from a side wall of the workpiece pin (18), wherein the lateral surface of the pin (18) forms the contact surface (16). Clamping system (5) according to claim 14, characterized in that each clamping element (13) via a deflecting element (19) is coupled to the spherical compensating element (12), wherein the outer contours of the deflecting elements (19) adapted to the spherical compensating element (12) are that by the contact of the spherical compensating element (12) with the deflecting element (19) causes a deflection, with which the deflecting elements (19) coupled clamping elements (13) upon movement of the adjusting element (10) in the clamping position in its clamping position are transferred.

Images