DE9011970U1 - Clamping device - Google Patents

Description

Clamping device

The invention relates to a tensioning device 05 for circulating endless chains, belts, straps or ropes with an axially adjustable tensioning member arranged in a holder.

Tensioning devices of the type mentioned are known in many different variations and are used to tension endless drive or conveyor elements either by deflection devices or by units attached tangentially to the endless loop in such a way that they rotate without slipping. It is important that automatic re-tensioning takes place, i.e. that the tensioning element, which is axially adjustable in the holder, adjusts when the drive or conveyor element is extended. This is achieved in known tensioning devices by the tensioning element being tensioned under the effect of a

Telephone: (02 21) 131041 Telex; 888 2307 dopa d Fax: (02 21)134297 (0221)134881 Telegram: Dompalent Cologne

Accounts:

SaI. Oppenheim jr. &Cie.. Cologne (bank code 370 302 00) Account no. 10 Deutsche Bank AG. Cologne (bank code 370 700 60) Account no. 1165018 Postgiro Cologne (bank code 370100 50) Account no. 654-500

Pressure device that is made up of at least one pre-tensioned mechanical compression spring or hydraulic or pneumatic pressure devices. The latter cannot be used without restrictions due to space and cost reasons, and mechanical compression springs have the disadvantage that they spring back elastically, i.e. they can move in the opposite direction to the tensioning direction and start to vibrate. This effect occurs, for example, when starting or stopping or when the speed of the rotating drive or conveyor element changes. When the compression springs spring back, the tensioning element moves accordingly, with the result that the endless drive or conveyor element starts moving transversely to its direction of travel, which reduces the drive transmission power in endless drive elements and can lead to loads being shifted until they are dropped in loaded conveyor elements, or to tilting of the load units or damage to the endless conveyor elements, which are generally chains, in the case of circulating conveyors equipped with attached support units (horizontal or vertical lifts). In order to suppress the spring back effect as much as possible, the tensioning devices have so far always been provided in the loose chain strand. In reversing operation, in which the slack strand alternately becomes the load strand, two of the known tensioning devices are therefore required. This not only increases the costs of the system, but also creates space problems when accommodating the two tensioning devices in or on the loop of the endless element.

The invention is based on the object of designing a tensioning device for general use with loaded or unloaded rotating endless chains, belts, straps or ropes in such a way that it ensures uniform tension and re-tensioning of the endless drive or conveyor element without kickback or vibration in critical operating phases.

This object is achieved according to the invention in that the adjustable tendon has a wedge-shaped external profile which widens in the tensioning direction of the tendon and which interacts with a counter-wedge device which is loosely attached against its wedge surface and can be axially displaced in the holder.

The interaction of the wedge surface of the tendon and the counter wedge device, which can be moved axially in the bracket, means that the tendon can move freely in the clamping direction to adjust its respective clamping position, but its movement in the opposite direction is blocked by the form-fitting of the inclined surfaces and the outward pressure of the counter wedge device against the bracket.

Tensioning element moves when the endless drive is extended-25

or conveyor element and is fixed in the respective position by the wedge effect, so that tearing or hitting of chains, belts, straps or ropes is prevented, especially in the critical start-up phase or when stopping. The constant tension of the drive or conveyor element in every operating situation has a positive effect on the service life of the endless element, the bearings at the deflection points and the deflection wheels, as well as the drives. Loads are

continuously promoted and experienced on their Trans-35

portweg no impairments. Since the wedge lock reliably prevents the tendon from being pushed back or knocked back, the tensioning device is also effective on the load strand and in the case of drive or conveyor elements in reversing operation, only a single ^y

Clamping device required.

Depending on the type of application and installation of the tensioning device according to the invention, its tensioning element can function with or without a pressure device. If, for example, a tensioning device of small dimensions is installed in a small drive or conveyor element so that the tensioning direction of its tensioning element points downwards, gravity can be sufficient to advance the tensioning element when the drive or conveyor element is extended. The counter-wedge device then falls automatically and secures the position of the tensioning element by securing itself to the bracket through outward pressure. As soon as further advancement of the tensioning element is required, 20

the counter wedge device allows this and then pushes forward. For larger units or when the tendon is horizontal or directed upwards, it must be equipped with a pressure device. Coil springs are used. When using the tensioning device in this way, it is necessary that the tendon carries counter bearings for pressure springs that load the counter wedge device in the tensioning direction. Regardless of the position of the tensioning device, the pressure device acting on the tendon and the pressure springs of the counter wedge device guarantee that when the drive or conveyor elements are extended, the tendon pushes forward to safely absorb the loosening and that the return prevention

ing arrangement, i.e. the counter wedge device, automatically follows up.

To ensure that the tensioning device can be adapted to different applications, the tensioning element must be 05

The pressure device preferably has an adjustable pressure force. A threaded spindle with a slider on which the inner end of the compression spring is supported can be used for adjustment.

In a clamping device with a shaft that can be moved axially in a parallel-walled cavity of a housing, the outer end of which carries a sliding element, the invention provides that the wedge-shaped external profile is provided at the inner end of the shaft and that the counter-wedge device can be moved along the cavity wall with the back surface opposite its inclined surface. The shaft can be designed as a rectangular hollow profile that has a wedge surface on each of its opposite narrow sides. The counter-wedge device preferably consists of two matching wedge pieces. The sliding element can be designed as a plate made of wear-resistant material. The head surface of the sliding element advantageously forms

usually an arc whose radius is adapted to the intended use for larger or smaller wrap angles.

Alternatively, the shaft can be designed as a circular cylindrical hollow profile with a tapered inner end. The counter wedge device can consist of a closed or segmented wedge ring with an inner inclined surface. A circular cylindrical

The design of the tensioning device can be useful when wide endless bands or belts are to be tensioned, to which the tensioning element must engage with an enlarged contact surface of the sliding element and which require increased stability of the housing and shaft.

The counter wedge device can be manually reset using extensions that protrude outwards through longitudinal slots in the wall of the housing. The resettability of the counter wedge device enables the tensioning device to be readjusted when the tendon reaches its maximum extension position. When the counter wedge device is pushed back into the housing, the tendon can be easily pushed forward by applying pressure against its sliding element.
15

In a further advantageous embodiment of the invention, it is provided that the tensioning member is a trapezoidal bearing block for a deflection element, which is arranged between two parallel guides and that the inclined surface of a wedge piece is loosely attached to each wedge surface of the bearing block, the opposite back surface of which can be slid along the respective guide.

The bearing block with tensioning function provided at one of the deflection points of a chain, band, belt or rope has the same effect as the previously explained design of a tensioning device, which it replaces. The bearing block can also be

The bearing block can work with or without a pressure device, depending on the type of installation. For example, if it is installed at the bottom of a vertical conveyor, which can be a carousel system, the bearing block sinks under its own weight and under

the weight of the load carried by the chain downwards when the chain elongates, and the counter wedge device immediately follows suit under its own weight or under the effect of associated compression springs. The parallel guides between which the bearing block is provided can each consist of a U-profile rail, against whose closed straight web the back surface of the respective wedge piece is pressed.

The drawing shows embodiments of the invention schematically. It shows:

Figure 1 shows a longitudinal section through the first embodiment of a clamping device in the middle clamping position,

Figure 2 shows a longitudinal section through the second embodiment of a clamping device in the basic position,

Figure 3 shows a longitudinal section through the clamping device according to Figure 2 in the extreme clamping position and

Figure 4 shows a partial section through a bearing block serving as a clamping device.

The tensioning device 10, which can be attached to the loop of an endless drive or conveyor element, which is referred to as a "chain" below, consists of a flat housing 11 with a rectangular cross-section, which is enclosed by four pairs of parallel side walls 12 and a base 13, opposite which is an upper wall 14 with a central opening 15. In the two

A straight longitudinal slot 16 is formed in the middle of each of the narrower side walls 12 shown. Both longitudinal slots 16 are diametrically opposite one another and the shape and size of the two longitudinal slots 16 correspond. A tensioning member 20 is housed in the rectangular cavity 19 of the housing 11. The tensioning member 20 consists of a straight shaft 21 with a rectangular cross-section that acts as a pressure piston and has a sliding element 22 with a convexly curved head surface 23 on its closed outer end. The sliding element 22 consists of wear-resistant material. Its surface can be equipped with track profiles for one or more chains running next to one another. The shaft 21 of the tensioning device 10 is hollow and open at the lower end. A threaded spindle 25 extends through the opening into the shaft 21, the lower end of which is guided outwards through a hole in the base 13 of the housing 11 and is rotatably mounted in this hole by means of a bushing 26 made of wear-resistant plastic material. The threaded spindle 25 can be rotated using a hexagon head 27 over a square; a plate-like runner 28, which is screwed onto the threaded spindle 25 and cannot be rotated in the hollow space 19 of the housing 11 due to its cross-section adjustment, is pushed upwards or downwards.

downwards. Wear-resistant guide parts 29 secure the runner 28 against tilting. The inner end of a helical spring 31, which surrounds the threaded spindle 25, rests on the surface 30 of the runner 28 and whose other end rests against a sleeve 32. The sleeve 32 is preferably also made of wear-resistant plastic and sits on an inward-facing shoulder 33 of the shaft 21. The threaded spindle 25 is threadless from the sleeve 32 onwards.

and is mounted with a central pin in a plastic ring 34 which is fastened in the region of the upper opening 15 of the housing 11.

The opposing narrower surfaces 21a of the shaft 21 are parallel to each other in the area between the sliding element 22 and the shoulder 33. These surfaces then run downwards at an angle to each other, and

the tapered wedge surfaces 21b. The two wedge surfaces 10

21b are smooth and inclined at the same angle. A flat ring plate 35 is attached to the inner end of the wedge surfaces 21b of the shaft 21 in such a way that its inner hole 24 is aligned with the opening of the shaft

21 is flush and its outer part has a 15

The circumference of the end of the shaft 21 forms a flange protruding from it. On the flange of the ring plate 35 there are bolts 36 which are surrounded by compression springs 37 with an axial projection.

A wedge piece 40 interacts with each wedge surface 21b of the shaft 21. Each wedge piece 40 has an axial length approximately corresponding to the wedge surfaces 21b and the same angle of inclination of the inclination surface 40b. The back surface 40a of each wedge piece 40 runs parallel to

IeI to the inner surface of the wall 12 of the housing 11, i.e.

the back surfaces 40a of the two wedge pieces 40 are parallel to each other and to the cavity wall and press against it. Each wedge piece 40 is provided with an axially directed blind hole in its straight base surface, into which the compression spring 37 projects, which is supported on the flange of the ring plate 35. A transverse extension 42 projects outwards from the upper end of each wedge piece 40, which extends through the

Longitudinal slots 16 and serves as a handle for manual adjustment of the wedge pieces 4 0.

The helical spring 31 surrounding the threaded spindle 25 prestresses the clamping member 20 in the tensioning direction (arrow A). The pressure force of the helical spring 31 can be adjusted within certain limits. For this purpose, the hexagon head 27 is rotated so that the threaded spindle 25 firmly connected to it rotates and the

Rotor 28 is adjusted axially.
10

If the tensioning device 10 is either placed tangentially against a revolving endless chain or the like or is installed in the loop instead of a second deflection part, the sliding element 22 presses against the chain with pre-tension and re-tensions it under the influence of the coil spring 31 when it elongates. In this case, the wedge pieces 40 are immediately repositioned by the compression springs 37 and clamped to the housing wall, so that the tensioning element 2 0 cannot be moved back.

opposite to the direction of arrow A due to wedging becomes impossible. This ensures that the optimum tensioning position for the chain is maintained. The service life of the chain is extended and the power of the drive unit is fully utilized. When

For reversing operations, only one clamping device 10 is required.

To adjust the tensioning device 10 when the tendon 20 is fully extended, the wedge pieces 40 are pushed back by hand using the extensions 42, whereupon the tendon 20 can be pushed back.

Figures 2 and 3 show a clamping device 100 of a slightly modified embodiment. The parts that correspond to the example in Figure 1 are designated with the same reference numbers, supplemented by "100".

The clamping member 120 in this clamping device 100 is equipped with a shaft 121 with parallel walls from one end to the other, which is closed at the outer end by a wall 50 and whose

lower end is open and has a sideways outward 10

directed flange 51. In the projection-free, elongated cavity 52 of the shaft 121 there is a coaxial threaded spindle 125, which can be set in rotation outside the housing 111 via a hexagon head 127 firmly connected to it. The threaded spindle 125 is surrounded by a helical spring 131, which is supported between the upper wall 50 of the shaft 121 and a runner 128, which can be moved upwards or downwards when the threaded spindle 125 rotates.

is to reduce the tension of the coil spring 131-20

Figure 2 shows the runner 128 in the lowest position and the tensioning member 120 is in the basic position with the coil spring 131 fully tensioned. Figure 3 shows the runner 128 turned up on the threaded spindle 125. The tensioning member 120 is fully extended with approx. 50% spring tension. By further turning the runner 128, the spring tension can be set to 100% if the application requires this.

At the inner end of the shaft 121, at its one-30

Wedges 53 are formed or attached to the opposite narrow sides, the wider end of which points in the clamping direction A and the continuously tapering wedge

surface 121b points outwards to the side. Two wedge pieces 140, which are also opposite one another, work together with the wedges, the wedge surfaces 140d of which fit together with the wedge surfaces 121b and are arranged in a complementary manner. Straight back surfaces 140a of each wedge piece 140 press against the cavity wall 112. Each wedge piece 140 is under the effect of a helical spring 137, which surrounds a bolt 136 standing on the flange 51 and is inserted into a blind hole in the wedge piece 140 that is open at the bottom. The ver-10

The young end of each wedge piece 140 has a sideways outward-facing extension 142 which serves to manually return the clamping member 120 from the position shown in Figure 3 to the position shown in Figure 2. The extensions 142 protrude outward through longitudinal slots 116 of the housing 111.

The clamping device 100, whose sliding element 122 is made of wear-resistant plastic with sliding properties

is either tangentially connected to an endless Ket-20

te or is located in one of the deflection points of an endless loop. The design of the clamping device 100 is shorter than that of the clamping device 10 (Figure 1). This is not only due to the axially shorter length of the wedges 53 and the wedge pieces 140, but also to the fact that the rotor 128 fits into the cavity 52 of the shaft 121 and no additional housing space is required for it.

The components not explained in detail in the description of the example in Figures 2 and 3 are identical to those of the example in Figure 1.

In the tensioning device 60 according to Figure 4, the tensioning member 61 is a trapezoidal bearing block for an axis 55 of a deflection element of an endless chain or the like. The bearing block is designed as a stable metal plate and its two stepless wedge surfaces 62, 63 converge opposite to the tensioning direction A. The tensioning device 60 shown is located at the lower end of a chain loop, e.g. for a vertically conveying carousel system. The tensioning member 61 hangs between two vertical, mutually parallel guides 64 with a U-profile cross-section. A plate 66 is screwed to the upper narrow side 65 of the tensioning member 61 by means of bolts 67, which is longer than the narrow side 65. Bolts 68 directed towards the tensioning member 61, which are surrounded by coil springs 69, are screwed through holes in the overhanging ends of the plate 66. The coil springs 69 are located in blind holes 70 of each wedge piece 71 and press against the bottom of the blind holes in such a way that the wedge pieces 71 are pushed downwards. Each wedge piece 71 has a straight back surface 72 opposite its inclined surface 74, which slides without hindrance on the vertical straight surface 73 of the respective guide 64. The angle of inclination of the inclined inclined surfaces 74 corresponds to the angle of inclination of the wedge surfaces 62, 63 of the clamping member 61.

Against the narrow side 65 of the tendon 61 acts

a pressure medium-loaded piston-cylinder unit 30

75, which is attached to a frame 76 of the chain device. The piston-cylinder unit 75 can work hydraulically or pneumatically. Spiral or disc springs or

Gas springs can be used.
35

The coil springs 69 of the wedge pieces 71 are not required if the tensioning member 61 slides downwards by itself under the weight of the bearing block and/or the weight of loads carried by the chain. In any case, both the pressure device 75 and the compression springs 70 are necessary if the tensioning device 60 is oriented horizontally or vice versa as shown in Figure 4 and is attached to the upper end of a chain loop.

When the chain, which runs around the deflection device mounted on the axle 55, elongates, the pressure device 75 presses the tensioning member 61 downwards by a corresponding amount, and immediately the two

Wedge pieces 71 and block the tendon 61 in 15

the set clamping position by pressing against the wedge surfaces 62, 63 and the surfaces 73 of the guides 64, so that it cannot slide back.

A limit switch 77 indicates when the permissible length 20

tension of the chain or the like is reached or exceeded.

Claims (8)

EXPECTATIONS 1. Tensioning device for circulating endless chains, belts, straps or ropes with an axially adjustable tensioning element arranged in a holder, characterized,
that the adjustable tensioning member (20; 120; 61) has a wedge-shaped external profile which widens in the tensioning direction (A) of the tensioning member (20; 120; 61) and which cooperates with a counter-wedge device (40; 140; 71) which is loosely attached against its wedge surface (21b; 121b; 62, 63) and can be axially displaced in the holder. 2. Clamping device according to claim 1,
characterized, that the tensioning member (2 0; 120; 61) carries counter bearings for compression springs (37; 137; 69) which load the counter wedge device (4 0; 140; 71) in the tensioning direction. 3. Clamping device according to claim 1 or 2,
characterized, that the tensioning member (2 0; 120; 61) is loaded by a pressure device (45; 131; 75) with adjustable pressure force in the tensioning direction (A). 4. Clamping device according to one of claims 1-3 with a shaft (21; 121) which is axially displaceable in a parallel-walled cavity of a housing (11; Hl), the outer end of which carries a sliding element (22; 122), characterized,
that the wedge-shaped external profiling (21b; 121b) is provided at the inner end of the shaft (21; 121) and that the counter-wedge device (40; 140) can be slid along the cavity wall (12; 112) with the back surface (40a; 140a) opposite its inclined surface (40b; 140b). 5. Clamping device according to claim 4
characterized, that the shaft (21; 121) is designed as a rectangular hollow profile which has a wedge surface (21b; 121b) on each of its opposite narrow sides and that the counter-wedge device consists of two matching wedge pieces (40; 140). 6. Clamping device according to claim 4
characterized, that the shaft is designed as a circular cylindrical hollow profile with a tapered inner end and that the counter wedge device consists of a closed or segmented wedge ring with an inner inclined surface. 7. Clamping device according to one of claims 2-6,
characterized, that the counter wedge device (40; 140) can be manually reset by means of extensions (42; 142) projecting outwards through longitudinal slots (16; 116) in the wall (12; 112) of the housing (11; 111). 8. Clamping device according to one of claims 1-3,
characterized, that the clamping member (61) is a trapezoidal bearing block for a deflection element, which is arranged between two mutually parallel guides (64) and that the inclined surface (74) of a wedge piece (71) is loosely attached against each wedge surface (62, 63) of the bearing block, the opposite back surface (72) of which can be slid along the respective guide (64).