GB2109904A - Safety coupling for rolling mill driving gear - Google Patents

Abstract

The invention relates to a safety coupling for rolling mill driving gear with a small spindle clearance in which carrier tongues inter-connecting a pair of coupling halves 1 with prestressed local link elements. In order to obtain an uncoupling at an accurately adjustable overload moment, a small cut-off interval and fatigue resistant construction even with a small space requirement in relation to the extent of the operating moments, the invention proposes a coupling comprising two polygonal (normally triangular) bodies (1), arranged on the respective shaft ends (4), and which form the coupling halves. The bodies are connected through three carrier tongues (2) under pretension via a piston cylinder arrangement (5). <IMAGE>

Description

SPECIFICATION Safety coupling for rolling mill driving gear This invention relates to a safety coupling for rolling mill driving gear with a small spindle clearance.

Such couplings are known in rolling mill driving gear, which disenage on overloading, in order to avoid greater damage to other parts of the total installation. Simple overload safety devices have shearing pins.

Overload safety devices are known which disengage through failure under tensile or compressive stress of carrier members interconnecting a pair of coupling valves. Such devices are disclosed in German published Application Nos. 2640989 and 29 01 572. Annular carrier members are also known from German Patent No. 24 30 541. Further, a safety coupling is known which with a small cut-off interval achieves a high fatigue strength, see German Application No. P 3043744.

Known safety couplings for rolling mills with greatly variable operating moments require a large amount of space. The aim of the present invention is to create a safety coupling against overloading for rolling mill driving gear with a small spindle clearance which uses carrier tongues and pre-stressed internal transmission elements, in which the advantages of the disengagement at a precisely adjustable overload moment, a small cut-off interval and fatigue resistant construction are available despite the relatively small space requirement in relation to the extent of the operating moments.

To the above end, according to the invention a safety coupling comprises a pair of polygonal bodies for arrangement on respective shaft ends to be coupled, the apices of the respective bodies being connected by three carrier tongues, each capable of being maintained under pretension via a piston cylinder mechanism.

Each polygonal body is normally triangular but in any event will usually comprise a plurality of radius arms, the distal end of which defines a said apex.

Safety couplings according to the invention have advantages particularly in those rolling mills in which the shafts driving the rolls lie parallel or substantially parallel to each other, and only have a slight clearance from each other. A high degree of operating reliability of the entire driving line can be achieved directly in front of the rolls embracing the rolling material. The drive shafts and the pinion gear connected in front of these shafts are durably protected by the fatigue strength of the safety coupling, and the periods of interference through prematurely broken safety elements are eliminated.

The invention will now be described by way of example and with reference to the accompanying diagrammatic drawings wherein: Figure 7 shows a perspective general view of a safety coupling according to the invention; Figure 2 shows a longitudinal section through a carrier tongue on the coupling of Figure 1; and Figure 3 shows a partial section through one of the two coupling halves.

As shown in Figure 1, two identical triangular bodies 1 are arranged on the shaft 4, which are connected with each other through three carrier tongues 2, which are under pretension through an additional cylinder/piston arrangement. As can be seen from Figure 2, the carrier tongues 2 are equipped with a piston cylinder arrangement 3.

In the half section shown in Figure 3 it can be seen that one of the two triangular bodies is provided with a pin 6 which is supported in the second triangular body. This pin is upset at its end such that it is held in position by a holding disc 7 when the safety coupling has been broken through overloading.

The torque transmission from one half, of the coupling to the other takes place through a common hydraulic pre-stressing 5 of the carrier tongues 2 and by a common hydraulic pre-stressing 3, independent of this, of the inner connection elements to equal and narrowly defined proportions for the individual transmission members. The positive direction of the forces between the attachments of the carrier tongues 2 onto the triangular body 1 runs obliquely to the axis of rotation. Through the common hydraulic prestressing 5 of the connection elements, an assembly free from play is ensured.

The axial force resulting from the operating moment is taken up in the central bearing 6,7,8 and 9.

As soon as a moment of rotation occurs, which is greater around the release interval than the nominal moment, the coupling is separated through breaking of the inner connection elements. The central bearing ensures that during the releasing process the spindle halves are carried on further and can only carry out a limited axial displacement.

1. A safety coupling for rolling mill driving gear with a small spindle clearance, comprising a pair of polygonal bodies for arrangement on respective shaft ends to be coupled, the apices of the respective bodies being connected by three carrier tongues, each capable of being maintained under pretension via a piston cylinder mechanism.

2. A safety coupling according to Claim 1 wherein each body is triangular.

3. A safety coupling according to Claim 1 or Claim 2 wherein each body comprises a plurality of radius arms, the distal end of which defines a said apex.

4. A safety coupling according to any preceding Claim wherein one of the bodies is formed with a central pin and the other of the bodies has a central recess for the receipt and support of the pin.

5. A safety coupling according to Claim 4 wherein the pin is formed with a relief turn for engaging a holding disc to retain the pin the recess.

6. A safety coupling substantially as described herein with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Safety coupling for rolling mill driving gear This invention relates to a safety coupling for rolling mill driving gear with a small spindle clearance. Such couplings are known in rolling mill driving gear, which disenage on overloading, in order to avoid greater damage to other parts of the total installation. Simple overload safety devices have shearing pins. Overload safety devices are known which disengage through failure under tensile or compressive stress of carrier members interconnecting a pair of coupling valves. Such devices are disclosed in German published Application Nos. 2640989 and 29 01 572. Annular carrier members are also known from German Patent No. 24 30 541. Further, a safety coupling is known which with a small cut-off interval achieves a high fatigue strength, see German Application No. P 3043744. Known safety couplings for rolling mills with greatly variable operating moments require a large amount of space. The aim of the present invention is to create a safety coupling against overloading for rolling mill driving gear with a small spindle clearance which uses carrier tongues and pre-stressed internal transmission elements, in which the advantages of the disengagement at a precisely adjustable overload moment, a small cut-off interval and fatigue resistant construction are available despite the relatively small space requirement in relation to the extent of the operating moments. To the above end, according to the invention a safety coupling comprises a pair of polygonal bodies for arrangement on respective shaft ends to be coupled, the apices of the respective bodies being connected by three carrier tongues, each capable of being maintained under pretension via a piston cylinder mechanism. Each polygonal body is normally triangular but in any event will usually comprise a plurality of radius arms, the distal end of which defines a said apex. Safety couplings according to the invention have advantages particularly in those rolling mills in which the shafts driving the rolls lie parallel or substantially parallel to each other, and only have a slight clearance from each other. A high degree of operating reliability of the entire driving line can be achieved directly in front of the rolls embracing the rolling material. The drive shafts and the pinion gear connected in front of these shafts are durably protected by the fatigue strength of the safety coupling, and the periods of interference through prematurely broken safety elements are eliminated. The invention will now be described by way of example and with reference to the accompanying diagrammatic drawings wherein: Figure 7 shows a perspective general view of a safety coupling according to the invention; Figure 2 shows a longitudinal section through a carrier tongue on the coupling of Figure 1; and Figure 3 shows a partial section through one of the two coupling halves. As shown in Figure 1, two identical triangular bodies 1 are arranged on the shaft 4, which are connected with each other through three carrier tongues 2, which are under pretension through an additional cylinder/piston arrangement. As can be seen from Figure 2, the carrier tongues 2 are equipped with a piston cylinder arrangement 3. In the half section shown in Figure 3 it can be seen that one of the two triangular bodies is provided with a pin 6 which is supported in the second triangular body. This pin is upset at its end such that it is held in position by a holding disc 7 when the safety coupling has been broken through overloading. The torque transmission from one half, of the coupling to the other takes place through a common hydraulic pre-stressing 5 of the carrier tongues 2 and by a common hydraulic pre-stressing 3, independent of this, of the inner connection elements to equal and narrowly defined proportions for the individual transmission members. The positive direction of the forces between the attachments of the carrier tongues 2 onto the triangular body 1 runs obliquely to the axis of rotation. Through the common hydraulic prestressing 5 of the connection elements, an assembly free from play is ensured. The axial force resulting from the operating moment is taken up in the central bearing 6,7,8 and 9. As soon as a moment of rotation occurs, which is greater around the release interval than the nominal moment, the coupling is separated through breaking of the inner connection elements. The central bearing ensures that during the releasing process the spindle halves are carried on further and can only carry out a limited axial displacement. CLAIMS

1. A safety coupling for rolling mill driving gear with a small spindle clearance, comprising a pair of polygonal bodies for arrangement on respective shaft ends to be coupled, the apices of the respective bodies being connected by three carrier tongues, each capable of being maintained under pretension via a piston cylinder mechanism.

2. A safety coupling according to Claim 1 wherein each body is triangular.

3. A safety coupling according to Claim 1 or Claim 2 wherein each body comprises a plurality of radius arms, the distal end of which defines a said apex.

4. A safety coupling according to any preceding Claim wherein one of the bodies is formed with a central pin and the other of the bodies has a central recess for the receipt and support of the pin.

5. A safety coupling according to Claim 4 wherein the pin is formed with a relief turn for engaging a holding disc to retain the pin the recess.

6. A safety coupling substantially as described herein with reference to the accompanying drawings.