Clamping sets

Locking assemblies are used in mechanical engineering to create a friction-locked shaft-hub connection. The clamping set connects the hub of a gearwheel, for example, to a shaft by means of a frictional connection. This backlash-free connection between shaft and hub allows torques and axial forces to be transmitted reliably. Depending on the design of the clamping set, high bending moments can also be transmitted with this type of connection.

Functional principle of clamping sets

Clamping sets (also known as ‘conical clamping elements’ or ‘internal clamping elements’) consist of one or two conical thrust rings and a conical clamping sleeve, depending on the design. By tightening the clamping screws to the specified tightening torque, the conical thrust rings are pulled onto the conical surface of the clamping sleeve. This process generates a radial force both inwards and outwards. While the outer diameter increases, the diameter inside the clamping set is reduced. This creates a frictional connection between the clamping set (cone clamping element) and the shaft and hub.

In contrast to a keyway in conventional parallel key connections, the stresses in the shaft are distributed evenly over the entire contact surface when using a clamping set. The even distribution of tension creates a reliable, freely positionable and, above all, wear-free connection. The shaft can also often be made smaller, which can lead to a reduction in the weight of the design.

Types of clamping sets

Clamping sets are available in a wide variety of designs and types. In addition to the torsional or bending moments to be transmitted, the available installation spaces and loads also play a key role in selecting the right product. Whether self-centring, low surface pressure, high speeds or stainless versions for the food and chemical industries – the product portfolio of TAS Schäfer GmbH offers a suitable solution for all areas.

Clamping sets are divided into two groups: The more compliant cone clamping elements and the rigid cone clamping elements.

Compliant cone clamping elements

The flexible cone clamping elements have a total of four conical functional surfaces and several individual components. Due to the design and the resulting larger cone angle, the more flexible clamping sets are not self-locking. This means that it is not necessary to press off the thrust rings during disassembly. As the thrust rings are not moved axially on the shaft during assembly, there is no axial displacement between the shaft and hub.

Rigid cone clamping elements

Rigid cone clamping elements only have one or two conical functional surfaces. This results in different technical properties than the more flexible cone clamping elements. Due to their design, rigid Cone Clamping Elements can transmit higher bending moments. In addition, this design has the property of better self-centring and self-locking. A further characteristic is that the clamping screws are not subjected to any further loads from forces during operation after installation. This increases the safety and service life of the rigid cone clamping elements.

Examples of rigid cone clamping elements are series 3012 and 3006

In general, the various clamping sets can be categorised according to the type of application and the available installation space. Short clamping sets are usually able to absorb low to medium torsional and bending moments. Wide clamping sets, on the other hand, are used for high to very high torsional and bending moments. The properties of individual clamping sets, the transmittable torsional and bending moments and their installation length can be found in the product overview below. Further properties, such as self-locking, self-centring or the possible bending moment component of the clamping set, can be found on the respective product pages in the catalogue.

Advantages of clamping sets

The performance of individual components, cost benefits, reduced assembly times or increased service life play an important role for industry when fastening components on rotating shafts.

A conventional method in the past was the connection via a keyway. With this type of connection, a keyway is milled into the shaft. This is also done in the hub. However, milling these grooves is costly and time-consuming. Another disadvantage is the reduction in the transmittable torque due to the weakening of the shaft. A grooved connection often results in movement and ultimately play, which can affect the accuracy of a machine system and create the risk of failure.

This risk can be avoided with a friction-locked shaft-hub connection with a clamping set, as there is no play. The use of a clamping set therefore ensures precision and safety. In addition, costly manufacturing processes, such as milling or shaping the grooves, can be avoided.

Another advantage of using a TAS Schäfer clamping set is the positioning on the shaft. Unlike with a keyway, the clamping set can be moved freely on the shaft.

TAS Schäfer Spannsätze können ebenfalls für bestehende Wellen mit einer Nut verwendet werden, so dass eine Optimierung bestehender Systeme ermöglicht wird.

Baureihen wie bspw. des Spannsatzes TAS 3015 DK verhindern im Zuge der Montage direkte Bewegungen auf der Welle. Dies vermeidet kostspielige Beschädigungen der Welle bei der Montage.

Montage von Spannsätzen

Die Montage erfolgt durch Einsetzen des Spannsatzes zwischen die Bauteile und dem anschließenden Anziehen der Spannschrauben. Die Schrauben müssen in einer vorgegebenen Reihenfolge und identischem Anzugsmoment angezogen werden. Durch die Verwendung konischer Flächen vergrößert sich der Außendurchmesser und verringert sich der Innendurchmesser des Spannsatzes. Radiale Pressung wird aufgebaut.

Die Spannkräfte werden über die Schrauben bereitgestellt (Kraft gesteuert). Dies ermöglicht den direkten Ausgleich des Spiels zwischen Welle und Nabe. Die Spannsätze der TAS Schäfer GmbH werden einbaufertig geliefert. Für eine einwandfreie Funktion und um einen ausreichenden und gleichmäßigen Reibwert zu erreichen, müssen die Kontaktflächen von Welle und Nabe sauber und mit einem Ölfilm versehen sein.

Entsprechende Montageanleitungen der Spannsätze werden über die Online-Plattform der TAS Schäfer GmbH zur Verfügung gestellt: TAS Schäfer Montageanleitungen

Typische Anwendungsbeispiele von Spannsätzen

Der Einsatz von Spannsätzen ist vielfältig und umfasst viele verschiedene Industriebereiche. Vom klassischen Maschinenbau, sowie der Förder- und Antriebstechnik bis hin zur Verpackungs- und Nahrungsmittelindustrie, um nur einige Beispiele zu nennen. Schlussendlich ermöglicht der Spannsatz eine präzise Befestigung von Nabenköpern auf Wellen oder Achsen, wie zum Beispiel bei der Fixierung von Zahn- und Kettenrädern. Darüber hinaus finden unsere Spannsätze Anwendungen in Förderbandtrommeln oder Brechern. In der Nahrungsmittel- und Petrochemischen Industrie werden rostfreie Ausführungen der Spannsätze häufig in Abfüll- oder Rühranlagen eingesetzt. Zur Befestigung von Riemenscheiben sowie zur Beförderung von Gegenständen innerhalb der Maschine werden Spannsätze in der Verpackungsindustrie genutzt.