WO1999046089A2

WO1999046089A2 - Method for assembling heat exchanger plates to be clamped together

Info

Publication number: WO1999046089A2
Application number: PCT/DE1999/000626
Authority: WO
Inventors: Hans-Wilhelm Beissner
Original assignee: Carl Walter Schraubwerkzeug-Fabrik Gmbh & Co. Kg
Priority date: 1998-03-09
Filing date: 1999-03-09
Publication date: 1999-09-16
Also published as: EP1062076A2; DE19810039C2; DE19810039A1; WO1999046089A3

Abstract

The invention relates to a method for assembling stacked plates (1) which are to be assembled on or by means of a bolt (2) and hereby axially clamped with considerable force. According to said method, hydraulic force (30a, 30, F1) is applied first in order to push the plates (1) together. Said hydraulic force runs parallel to the direction of the axis (100) of the bolt (2), which is provided with a thread. A clamping nut (4, 4a) is then screwed onto the bolt (2) by turning in the direction of the hydraulically clamped plates. As the clamping nut (4, 4a) is turned, only enough force is applied to move said nut forwards, turning, on the thread of the bolt (2) until it meets the stacked plates (1; 1a). No significant counter- or clamping forces are exerted on the nut (4, 4a) by the plates (1; 1a), said plates having already been prestressed by the hydraulic device (30, 30a). The invention enables a greater clamping force to be exerted more easily and more rapidly by the hydraulic device in order to clamp the plates whilst reducing the burden on the nut, which no longer has to provide this additional force when it is screwed down onto the plates. The nut can however secure the plates in the position brought about by the hydraulic clamping device, by means of the thread and by means of its advancing movement. The nut is therefore only responsible for fixing the position of the plates.

Description

Assembly method for plates of a heat exchanger to be clamped together

The invention relates to a method with which the plates of a plate heat exchanger can be clamped specifically, the forces being divided. On the one hand, a force is applied hydraulically in order to first compress and clamp the plates, on the other hand, a screw is then rotated on a bolt with thread, whereby only the force for the rotational movement has to be applied and no axially directed force in the bolt direction, the previously has already been applied by the hydraulic tensioning device.

US-A 4,150,477 (Willis P. Orr) describes a method and an apparatus for prestressing flanges to be connected. A uniform pressure is applied to the flanges to a predetermined, measurable compression, and then the nuts and bolts are used to secure the flanges. Screwing is done "hand tight" while the hydraulic cylinders apply pressure to the flanges. If the first screws and bolts are hand-tight, the hydraulic clamping devices referred to as "clamp units" can be removed, and further bolts and screws are inserted at the locations where the clamping devices previously had their place. After loosening the clamping devices, the screws / bolts already fastened by hand or with a key bear the clamping forces, cf. there column 3, lines 15 to 41, and column 4, lines 5 to 10, as well as claim 6 there. Also with the application of separate hydraulic pressure before loosening or tensioning boiler screws in power plants DE-A 22 43 045 (Klöckner- Works). Two (divided) coupling jaws (there 18) are engaged on an overhead groove system (there 19), the coupling jaws being designed radially on the inside to complement the groove system of the pin there. After engaging the coupling jaws, a hydraulic force is applied by the lifting cylinders there to expand the bolt and to loosen a 50 to 80 kg boiler nut located further down on the bolt by means of a tooth meshing from the outside (see page 3, second paragraph there) , Page 5, penultimate paragraph, and page 7, penultimate paragraph). The arrangement is arranged coaxially around the bolt and applies a hydraulic force to the boiler flange before screwing movements take place on the boiler nut; this procedure is described for both unscrewing and unscrewing the boiler nuts. If all boiler nuts are turned off, a lifting movement is carried out by a support ring (there 14.15) with laterally offset spindle drives (there 26.27.28) which raises all loosened boiler nuts at the same time, which presupposes that before the start the lifting movement, the coupling jaws have been moved radially out of the complementary groove system at the upper end of the pin there.

With the invention, a higher clamping force is to be made easier and faster for clamping elastically flexible packaged plates - for example a heat exchanger - by the hydraulic device and at the same time relieving the strain on the nut element which no longer has this force when it moves against the plates should also apply.

The solution can be found in claim 1 or claim 10 or claim 13.

The nut, as a "tensioning and fixing element with thread", can secure the positioning of the plates generated by the hydraulic tensioning device due to its internal thread and its backward movement and thus essentially (only) receives the position fixation as a task. The forces for compressing the elastically resiliently stacked plates do not strain the nut during its rotational movement.

The coaxial counter bearing uses the invention to support the hydraulic pressure. Especially when used in plate heat exchangers, which allow a considerable path for the flexibly packaged plates, it is advantageous to be able to move the coaxial counter bearing upwards, whereby - after the hydraulic force has been switched off - the hydraulic device in the direction of a rotating action (by hand or by machine) the plates to be clamped is adjusted, if necessary retracts again (claim 1). After reaching a predetermined position, the hydraulic pressure can be applied again, so that a further tensioning of the resiliently packaged plates is possible. This is followed - in particular iteratively - by one or more of these method steps in order to be able to gradually cover the full stroke of the plates to be tensioned even when using small or short-stroke hydraulic devices (claim 10, claim 12).

The coaxial counter bearing can be designed as a split nut or a split nut element in order to be able to release it directly from the thread after the clamping process has ended, without first having to screw the counter bearing back to the end of the threaded bolt (after it has been described in the above) Has been moved forward on the same bolt). Depending on the length of the hydraulic device, the coaxial counter bearing can be screwed further forwards or further back, for a long clamping distance corresponding to the axial length of the hydraulic device.

After the hydraulic pressure has been switched off or at least the hydraulic pressure has been largely reduced, the counter bearing can also serve to screw the hydraulic cylinder, which in particular has a single action, back into its rest position.

The smaller the maximum stroke of the hydraulic device, the more often the pressure is switched off for a given total clamping path and the coaxial counter bearing is adjusted.

The nut that moves up to hold the spring assembly already compressed by the hydraulic cylinders can be a polygonal nut, a toothed ring can be attached to it (claim 4), or the nut can be specially designed with a rear toothing area that is in diameter is reduced compared to the front investment area (claim 4). By reducing the diameter of the rear tooth area of the nut, a key which is sleeve-shaped at its front and has internal teeth can grip over this nut section without increasing the diameter of the two-area nut as a whole, and there is the possibility of obtaining a slim design that is radial Enables the nut to be moved in and tightened in a confined space by iterative turning, axial removal and new engagement of the internal teeth of the key on the nut and turning again. The cylinder head wrench and nut are located in an equally slim housing, which is the hollow body

The task is to apply the hydraulically applied force past the nut directly to the flange or plates to be clamped.

The hydraulic cylinder can be designed as a short-stroke cylinder, in particular in the case of the attachment variant of the flanges, or as a long-stroke cylinder for the spring assemblies to be tensioned over a larger axial stroke; they rest on the power coupling housing at the rear and are supported on a counter bearing, that is screwed onto the bolt directly or onto an anchor piece screwed onto the end of the bolt with a front internal thread and a rear external thread (claim 8).

The tensioning cylinder can be designed as a single-acting hydraulic cylinder, then it can be retracted by hand after the action of the tensioning force F1 and extension by switching off the hydraulic pressure and screwing the hydraulic cylinder back to its rest position with the counter bearing. The counter bearing can be specially designed, it can be designed as a split nut which, after removing a sleeve piece connecting the two half-shells and gripping over a cylindrically tapered collar, can be radially disassembled in order to loosen them directly from the thread without first removing the counter bearing End of the bolt. If the sleeve piece is placed on the split nut, it is a thrust bearing that can only be moved in the axial direction by turning, if the sleeve is removed, the thrust bearing breaks down into two parts, which can be removed radially from the thread.

The force coupling housing, which extends over the nut as a force bypass, has a window or hatch through which a key can reach to actuate the nut in a rotating manner. Instead of a key, a pinion can also be attached to the polygonal shape of the nut, which works as a ring gear with a drive pinion swung in from outside through the hatch. For the variant of the two-range nut, the ring gear is arranged directly on it. Attaching the ring gear means that it can be gripped from the outside with a pinion or gear in the power coupling housing and the nut is actuated in a rotating manner. If no sprocket is provided, then an open polygon ring spanner can engage the nut in a form-fitting manner and move it forward in angular segments without a practically significant force acting on it, rather only the fixing force F2 has to be applied by the spanner, the clamping force F1 is already originated from the hydraulic cylinder via the power coupling housing.

The fixing force F2 can also be greater in the end area of the clamping movement, i.e. shortly before the spring assembly is fully tensioned - up to the specified distance of the individual plates - or the flange is fully applied, so that the final one together with the hydraulically acting cylinder and the main force F1 , only a small stroke has to be carried out manually, e.g. only half or a full turn of the nut, which here, however, exerts part of the clamping force itself. Manual dosing and positioning can be carried out more precisely, and this manual adjustment at the end of the clamping movement can be set by the predetermined maximum pressure of the clamping cylinder - when this pressure is slightly below the pressure required for the complete clamping of the plates or the flange . The difference in pressure between the hydraulically applied pressure F1 of the tensioning cylinder, which presses even when the nut itself exerts an additional force F2 in the axial direction, and the necessary pressure lies, which is to be referred to here as FO, in order to maintain the full tension, is then applied by the nut, so that a sum of forces is formed, F1 + F2 = FO, which sum of forces is sufficient to press the flange completely or the packaged plates like this to tension that their specified distances are within tolerance.

Examples of the areas in which the force F1 alone, in which the force F2 alone and in which both forces act together can be easily understood if it is assumed that a stroke of 200 mm is required for tensioning a spring assembly and on about 195 mm the hydraulic cylinder exerts the force F1 for tensioning. Only the last 5 mm, for example, can be covered with the application of both forces F1 and F2, the force F1 taking on the lion's share and the force component F2 only additionally applying the force which has to be supplemented for complete tensioning. In the assumed example, a hydraulic pressure of, for example, 710 bar may be required for the cylinder to fully tension the package, so that the use of 700 bar generates the force F1 and with the force component F2 (only) an additional pressure of 10 bar to end the tensioning must be applied.

Will the mother only move up over the long way described

Applying screwing forces, i.e. without the force component F2 required, an accelerated rotation can take place by engaging a pinion in the window of the force coupling housing, the pinion being rotated mechanically or by hand from the outside and the drive pressing on a parallel axis to follow the forward movement of the nut, since the pinion that is put on the nut is only thin, that is, it occupies only a narrow axial area, while the stroke that is overcome is many times greater.

The invention (s) are explained and supplemented below using several exemplary embodiments.

Figure 1 is a side view of a first embodiment. FIG. 1a is a view in the axial direction with respect to the axis 100, two of the devices from FIG. 1 acting simultaneously on a spring assembly 1. Figure 2, Figure 3,

FIG. 4 are enlarged sections, partly in section, of the device according to FIG. 1. The sectional planes A-A, B-B and C-C are each drawn in and are self-explanatory for the person skilled in the art. Figure 5 is a second embodiment with a shortened bolt 2 and a slim support housing 31a, for fixing a flange 1a. Figure 6 is an axial view, partly in section, of the second embodiment shown in Figure 5.

The first exemplary embodiment is based on a main axis 100 shown in the figure, which is the central axis of an elongated bolt 2, which extends from the left to the right edge of the figure in FIG. This long bolt 2 has an external thread 2 *, and at the left end a nut can be seen, which forms the stop point for a spring assembly 1, which consists of several packaged plates and must be clamped together (for example a heat exchanger). A nut 4, which is also screwed onto the bolt 2, takes over this function, however, before tensioning the spring assembly, this must be compressed, for which purpose not only the nut 4 is screwed onto the bolt (to the left in the picture), but uses a hydraulic tensioning device is, which starts from a clamping cylinder 30, which (right in the picture) is supported on a counter bearing 20 which is screwed onto the other end of the bolt 2. Depending on the length of the clamping cylinder, the counter bearing can be screwed further forwards or further back, for a long clamping path of approximately 100 mm or 200 mm, corresponding to the length of the (not extended) clamping cylinder 30. Between the clamping cylinder 30 and the right surface of the spring assembly 1 a force coupling housing 31 is provided, here as a larger diameter cylindrical coupling piece with a radially (here to the front) window 32 through which the aforementioned retaining nut 4 is visible. The size of the window 32 is such that a spanner can reach through the window and can be rotated through an angular segment in order to move the nut 4 forward. At the same time, the window must not be too large to the main force F1 of the hydraulic clamping cylinder 30 over the hollow cylindrical Housing and its cylindrical walls past the nut safely on the end face of the spring assembly.

The function of this basic structure of the tensioning device becomes clear when the tensioning cylinder 30 - supported on the counterbearing - extends under the action of hydraulic pressure and the force F1 is applied to the spring assembly via the force coupling housing 31 for tensioning the spring assembly 1 - past the nut , so that it is stretched between the front end of the power coupling housing 31 and the nut shown on the left and move its plates closer together, up to a predetermined distance. In accordance with the predetermined hydraulic pressure, the spring assembly reaches a tensioned position, and the nut 4 can be easily moved forward with no key being exerted by axial pressure, which reaches through the window 32. If the mother then lies against the end face of the spring assembly 1, it only needs a short distance to apply a force component F2 in order to secure the pressure exerted by the hydraulic cylinder 30 and, after loosening the tensioning cylinder 30, the axial position of the outermost plate - and thus all of them other plates - to be determined. You can see the small amount of work, the low effort with the spanner and the high speed and the simplicity with which the clamping cylinder 30 takes over the largest stroke and only the last end, e.g. a thread pitch, must be taken from the nut 4.

If the tensioning cylinder 30 is only subjected to such a pressure that is just not sufficient to fully tension the spring assembly 1 as the packaged plates to the predetermined extent, a differential force F2 will be applied by the nut 4, but only in a short time Path section, the thread pitch previously described, for example, and only with the differential force F2, which the clamping cylinder (still) lacks, in order to arrive at the slightly higher force F0, which is sufficient for complete clamping.

After tensioning and subsequent fixing by the nut 4, the tensioning cylinder 30 can be loosened again, for this its hydraulic pressure is switched off, and with the nut acting as the counter bearing 20 the cylinder, if it is a single-acting cylinder, can be screwed back into its rest position, which can be done manually. Likewise, the counter bearing 20 on the

Plates 1 or the flange 1a are screwed on in order to carry out a further (or more) clamping processes in at least one further hydraulic thrust until the package of plates is firmly clamped together. Then the counter bearing 20 either screwed back or removed from the thread if, as will be explained later, it is designed as a split nut with a connecting sleeve.

A preferred drive mode, which makes the use of a hand-operated key superfluous, is a pinion 6 which engages in the window 32 and which engages on a pinion 5 placed on the nut and can be driven by a cord wheel 7 by hand or by a mechanical drive. Due to the low force required to move the nut 4, the knurled wheel 7, which can be better seen in supervision in Figure 1a or in section in Figure 3, can take over the forward movement of the nut, and the cooperating elements of the cord wheel 7 and the Pinions 6 are movable together on an L-shaped plate carrier 43 along an axis 40 with the axial forward movement of the nut 4, which sliding axis 40 lies in a center 102, which is arranged above and laterally offset from the previously described main axis 100 on the power coupling housing is. This driving of the drive 7, 6 can be seen more clearly in FIG. 4 in the upper area, which figure shows an enlarged detail of the power coupling housing.

The described device and the possible way of working with it runs through the further description and the further figures. It should be emphasized that, according to FIG. 1a, two (or more) of the devices described, jointly, synchronously or asynchronously, can take over clamping tasks on a spring assembly 1 if axial synchronization without tilting the plates is important or if higher forces have to be applied. Then several axes 100, 101 run parallel to one another, and several long bolts 2, 2 'are provided, which serve as connecting bolts between retaining nuts. The operation of the knurled drive 7,6 - here mechanically with a corded wheel - which can be pivoted about the axis 102 and is mounted on an L-shaped holding plate in such a way that it folds into the window 32 can be seen in FIG can and along the slide shaft 40 can move with the movement of the nut 4 (is slidable with sliding). After the end of the movement, it can be folded upwards again about the axis 102.

Figures 2, 3 and 4 are to be described together, since they are all closely related and each show different cuts. The cutout shows the force coupling housing 31 most clearly in FIG. 4, how it engages over the nut 4 and forms an interior space that gives the nut 4 sufficient leeway, and additionally allows a pinion 5 to be attached to the nut, which is better seen in Figure 2. The polygonal shape of the nut receives the correspondingly shaped inner recess 5a of the pinion 5 in a form-fitting manner, and with the schematically shown pinion 6 the drive described above engages in the window 32 in order to fit the pinion 5 attached to the nut and thus the nut in the axial direction To move axis 100 forward. During the forward movement, the force F2 is practically zero, while the main force F1 exerts from the pressurized hydraulic cylinder 30 in the axial direction 100 onto the outer plate of the plate pack 1 - coupled via the housing 31. Above the coupling housing, a shaft 40 can be seen on a support piece 42, which can be pulled out of the support piece 42 in its axial direction 102 on a handle 41 and the drive 6, 7, which is closer in FIG. 2 in an end view with the L-shaped plate 43 can be seen. On this axis 40, the drive 43, 6, 7 is longitudinally displaceable in the direction of the axis 100 and it can follow the movement of the nut 4. At the same time, pivoting about axis 102 is possible.

So that the power coupling housing 31 does not slope downwards on one side, a centering ring 33 is provided which lies near the contact surface of the clamping cylinder 30 which engages in a cup-shaped recess on the housing in such a way that the power coupling housing 31 fits tightly against the bolt 2 Tilting is protected.

If the bolt 2 is only short, a tie rod 2a screwed onto the thread 2 ^* can be used, as shown in FIG. In addition, the variant of Figure 5 is advantageous in terms of a slim design of the power coupling housing 31a, which in this embodiment has a different geometric shape and is elongated and closely adapted to the dimension of the nut 4a lying in it. This force coupling housing 31a has an elongated cylinder section, but with a reduced diameter compared to FIG. 1, and a rear holding section 34, which is held together by a cylinder screw 33. The clamping cylinder 30a is larger in diameter here, but greatly shortened, and in the variant of FIG. 5, it only has a small stroke, for which it is supported on the counter bearing 20 of the same design.

The main force F1 is transmitted from the tensioning cylinder via the slim support housing 31a to the flange 1a, also past the nut 4a and independently of the movement of the nut. Here too, the clamping force F1, which is independent of the mother force, is the main part of the force required for flange mounting, while the Force component F2 can only enter at the last moment of tensioning and is only a fraction of the force applied by tensioning cylinder 30a.

The tie rod 2a, which is attached to the end of the short bolt 2 in FIG. 5, forms the extension to which the counter bearing 20 is screwed. The tie rod has a front screw section 2b with an internal thread in order to be screwed onto the bolt 2 with its thread 2 ^* , and a rear bolt section 2c with an external thread 2 ^* *, for fixing the counter bearing 20. Its length is measured by the length of the clamping cylinder 30a and this on the necessary stroke for clamping the flange 1a.

In the front area of the slim power coupling housing 31, the specially designed two-area nut 4a is to be explained, which has a front pressure section 4c, which is cylindrical here, and a rear pinion section 4b, which is reduced in diameter and is also cylindrical. In between there is a slightly throaty transition area. The rear sprocket section, which has a reduced diameter, has radially outwardly projecting teeth into which a sleeve head wrench 50, which consists of a front sleeve section 52 and a projecting handle 51, engages. The cylinder sleeve has a diameter which, together with the diameter of the rear pinion section 4b of the two-range nut 4a, does not form a larger overall diameter than the front pressure section 4c of the nut 4a, so that the slim support housing over the joined cylinder areas of the nut and key can fit tightly. Bolts which are close together can be machined in this way, and the key can be moved with a slight axial backward movement and then pushed back onto the toothing of the tooth area 4b of the nut and turned further by a further angular segment. The nut 4a is thus moved forward, while the device operates as described in FIG. 1.

The window 32 is also provided in this power coupling case 31a; the handle 51 of the sleeve key 50 reaches through this window, as can be seen from FIG.

The assembly of the device according to FIG. 5 takes place in such a way that the two-range nut 4a is first screwed onto the short bolt 2 and is loosely moved against the flange 1a. Then the force coupling housing 31a, already assembled with the key 50, is put over the nut 4a and with a screw 33, which extends transversely to the axis 100, fixes the housing 31a, for example also with a centering ring 33, as was explained in FIG. 4. The tie rod 2a is then inserted through the rear axial opening of the force coupling housing 31 and screwed onto the end of the bolt 2a. This screwing can also take place before the force coupling housing 31a is plugged on. Then the clamping cylinder 30a is threaded and the nut 20 is fixed as a counter bearing behind the clamping cylinder. The device is then ready for operation and the flange 1a is tensioned by applying hydraulic pressure to the clamping cylinder. With the key 50 the mother can be moved up.

The coaxial counter bearing 20 will be explained with reference to FIG. 5. A sleeve-like union piece 20a is provided, which holds together in the rear region a section of the diameter 21, which is reduced in diameter, of the nut 21a, 21b, which is divided into two or more parts. If the sleeve piece 20a is pushed over the reduced-diameter holding section, the nut cannot be disassembled into its parts and can only be rotated on the thread 2 * of the bolt 2 with its internal thread. However, if the sleeve piece 20a is removed (removed axially backwards), the nut breaks down into its two or more elements and can be removed in the radial direction from the thread of the bolt 2 without the counter bearing 20 having to be screwed back all the way. This configuration of the counter bearing is particularly advantageous if the stroke distance of the tensioning cylinder 30 or 30 a is to be retracted or moved in with the counter bearing 20. With single-acting hydraulic cylinders, retraction corresponds to the (manual) reset of the cylinder.

Claims

Expectations:

1. Assembly method for resiliently packaged plates (1) which are to be mounted on or via a bolt (2 *, 2 **) provided with an external thread and are axially, especially against one another, tensioned with high force what procedure

(a) a pressure force (F1) is applied by a hydraulic device (30, 30a) to compress the plates (1), which force runs parallel to the axial direction (100) of the bolt (2); (b) a clamping element (4,4a) screwing on the bolt (2) through a

Rotational movement is moved in the direction of the clamped plates, in which rotating movement practically only the forces are applied to the tensioning element (4,4a) in order to rotate it forward on the external thread of the bolt (2) and to the packaged plates (1). to be applied without any significant counter or clamping forces - from the plates (1) already preloaded by the hydraulic device (30, 30a) - acting on the clamping member (4,4a); (c) wherein a hollow body (31, 31a) placed over the tensioning member (4,4a) transmits the hydraulic pressure force (F1) to the packaged plates (1) without loading the tensioning member, which hollow body is over the

Hydraulic device (30, 30a) is axially supported on a coaxial counter bearing (20) with an internal thread and is moved in the axial direction in engagement with the external thread (2 *, 2 **) of the bolt (2) when the hydraulic pressure force is switched off.

2. The method according to claim 1, wherein the hollow body (31, 31a) is sleeve-shaped and - in particular radially closely adjacent - is put over a nut (4,4a) for the axial transmission of the hydraulic pressure forces (F1).

3. The method of claim 1, wherein the coaxial counter bearing (20) has a split nut (21a, 21b).

4. The method according to claim 1, wherein

(a) a toothed ring with an outward-facing uniform tooth profile and an internal cutout (5a) matching the polygon of a nut (4) as a clamping element is positively fitted onto the nut and forces for rotating the nut by means of a manually or mechanically operated pinion (7) (6) applied to the ring gear; or

(b) a two-range nut (4a) has a front bearing area (4c), in particular a cylindrical sleeve, and a slimmer toothing area (4b) adjoining it to the rear, the toothing of which protrudes radially outward and concentric to the axis (100) of the bolt ( 2) extends to receive a sleeve-shaped end (52) of an actuating key (50) with which the nut is moved in an axially screwing manner, the outer dimensions of the front contact area (4c) and the outer dimensions of the sleeve end (52) of the key (50) in are essentially the same.

5. The method according to claim 1, wherein the hollow body (31, 31a) has a radially directed window (32) into which a rotatable pinion (6) or an open-end wrench or a sleeve wrench (50; 51, 52) engages and a rotary movement on the clamping element (4,4a) without influencing the hydraulic

Transfers axial clamping forces (F1).

6. The method according to claim 5, wherein the rotatable pinion (6,7) is tilted about a second axis (102, 40) which is arranged laterally on the hollow body (31, 31a) (42) and parallel to the pin axis (100) runs to release the pinion from its engagement with a ring gear (5) of the clamping member (4, 4a).

7. The method according to claim 1, wherein two or more clamping devices on two or more axes (100, 101) of bolts (2,2 ') are operated simultaneously and clamping forces and advancing retaining screws (4) work synchronously, thereby causing the plates (1 ) is largely avoided from a plane perpendicular to the axes.

8. The method according to any preceding claim, in which on the bolt (2) a cylindrical anchor piece (2a) with the same axis is screwed around the

Extend the bolt backwards and mount the counter bearing (20) for the hydraulic tensioning device (30, 30a) on the extension.

9. The method according to any preceding claim, wherein the plates are flat, a drive device (7) along a shaft (40) is axially moved in a second axis (102) and the forward movement of the tensioning member (4) is tracked without toothing engagement a pinion on the drive (7) and on the tensioning element (4) is lost.

10. A method for assembling (resiliently) flexibly packaged plates (1) which are to be mounted via a bolt (2 *, 2 **) provided with an external thread and are axially, especially against one another, clamped together with high force in what procedure

(a) a pressure force (F1) is applied by a hydraulic device (30, 30a) to compress the plates (1), which force runs parallel to the axial direction (100) of the bolt (2);

(b) a clamping member (4,4a) is screwed on the bolt (2) by a rotational movement in the direction of the clamped plates, in which rotating movement on the clamping member (4,4a) practically only the forces are applied to rotate it to move forward on the external thread of the bolt (2) and to apply it to the packaged plates (1) without any significant counter or clamping forces - from the plates (1) already preloaded by the hydraulic device (30, 30a) - on the clamping element ( 4,4a) act; (d) wherein a body (31, 31a) placed over the tensioning member (4,4a) is axially supported via the hydraulic device (30,30a) on a coaxial counter bearing (20) provided with an internal thread; (c2) the hydraulic pressure force (F1) is switched on and the packaged

Plates (1) a first piece can be clamped together, according to. Characteristic (a) without loading the tensioning element; (c3) the hydraulic pressure force (F1) after the forward movement of the tensioning element (4,4a), according to feature (b), is substantially switched off; (c4) the coaxial counter bearing (20) is moved axially onto the packaged plates (1).

11. The method according to claim 10, wherein the hydraulic cylinder (30,30a) with the coaxial counter bearing (20) - in constant engagement of the thread - on the external thread of the bolt (2) is moved.

12. The method according to claim 10, wherein

(a) the hydraulic pressure force (F1) is switched on again and the packaged plates (1) are clamped together a second piece, according to Characteristic (a) without loading the tensioning element; (b) the hydraulic pressure force (F1) after moving the tensioning member forward

(4, 4a), according to feature (b), is essentially switched off again;

13. Device for performing the method according to one of the preceding claims, in which - at the front end of a hydraulic cylinder (30, 30a), in particular a single-acting hydraulic cylinder, on a - on a bolt (2) screwably movable - nut element (4,4a ) passing coupling housing (31, 31a) abuts, for transmitting hydraulic clamping forces (F1) past the nut element (4,4a) and directly onto the resilient plate pack (1) of a heat exchanger;

- The hydraulic cylinder (30, 30a) with a rear one

Thrust bearing provided with an internal thread (20; 20a, 21a, 21b) on a long bolt (2) or anchor piece (2a) provided with an external thread (2 *), which is screwed on to a short bolt and is axially fixable and movable.

14. The apparatus of claim 13, wherein the power coupling housing (31, 31a) has a radially open hatch (32) for engaging an actuating device (6, 50), such as pinion, spanner or cylinder head wrench, for rotating tracking, Fixing or adjusting the nut element (4,4a) on the spring assembly (1, 1a).

15. The apparatus of claim 13, wherein the hydraulic cylinder (30,30a) in the direction of the plate pack - in the constant engagement of the thread - is movable after substantially lowering or switching off the hydraulic clamping force (F1).