EP3393689B1 - Cold-pilger rolling mill - Google Patents

Description

The present invention relates to a pilger rolling mill for forming a billet into a tube with a first roll stand which is mounted so as to be linearly movable in a direction of movement, two rolls for forming the billet into the tube being rotatably mounted on shafts on the roll stand, one of the rolls having a drive gear is arranged on a shaft and wherein the drive gear engages in a fixed rack which is fastened to a rack holder in such a way that a translational movement of the roll stand causes a rotational movement of the drive gear and the roll, and a crank drive connected to the roll stand, which is in operation during the pilger rolling mill converts a rotary movement of a drive motor via an push rod into an oscillating translational movement of the roll stand.

For the production of precise metal pipes, in particular from steel, an extensive hollow cylindrical blank is reduced by compressive stresses. The blank is formed into a tube with a defined reduced outside diameter and a defined wall thickness.

The most common reduction method for pipes is known as cold pilgrims, the blank being called Luppe. During rolling, the billet is pushed over a calibrated rolling mandrel that defines the inner diameter of the finished tube and is surrounded from the outside by two likewise calibrated rollers that define the outer diameter of the finished tube and is rolled out in the longitudinal direction over the rolling mandrel.

During the cold pilgrimage, the blanks undergo a gradual advance in the direction of the rolling mandrel or over it, while the rollers are rotated horizontally back and forth over the mandrel and thus the blanks. The horizontal movement of the rolls is predetermined by a roll stand on which the rolls are rotatably mounted. In known cold pilger rolling mills, the roll stand is moved back and forth in a direction parallel to the rolling mandrel with the aid of a crank drive.

DE 6752062 U and DE10 2012 112398 A1 disclose examples of such pilgrim rolling mills. DE 6752062 U discloses a pilger rolling mill for forming a billet into a tube with a first rolling stand which is mounted so as to be linearly movable in a direction of movement, two rolls for shaping the billet into the tube being rotatably mounted on shafts, one of the rolls having a drive gear (1) is arranged on a shaft and wherein the drive gear (1) engages in a fixed rack (2) which is fastened to a rack holder (3) in such a way that a translational movement of the roll stand causes a rotational movement of the drive gear (1) and the roller, and a crank drive connected to the roll stand, which during operation of the pilger rolling mill converts a rotary movement of a drive motor via a push rod into an oscillating translational movement of the roll stand, the rack holder (2) being designed such that the first roll stand against a second roll stand with one of the first Dimension different second dimension a is interchangeable. DE 10 2012 112396 discloses a pilger rolling mill which has two toothed rack holders arranged in mirror symmetry to a reference plane running perpendicular to the shafts of the rolls, with toothed racks attached thereto, the shaft of one of the two rolls, preferably the lower roll, carrying a drive gear on both sides of the reference plane, the two Drive gearwheels each engage in one of the toothed racks and a cylinder axis of the blank to be accommodated between the rollers lies in the reference plane.

In one embodiment, the crank mechanism is connected to a torque and mass balancing system, which stores the kinetic energy released at the reversal points during the back and forth movement of the roll stand and this for subsequent acceleration of the mill stand after reversing the direction of movement. The rollers themselves, on the other hand, receive their rotary movement through a toothed rack which is fixed relative to the roll stand and into which toothed wheels which are firmly connected to the roller axes engage.

The feed clamping slide with the blank is moved in the so-called feed direction over the mandrel. The conically calibrated rollers, which are arranged vertically one above the other in the roll stand, rotate at the same angular speed in opposite directions to one another while the feed clamping carriage holds the blank. The two rollers each roll in the same direction parallel to the cylinder axis of the blank and counter to the direction of advance on the surface of the blank.

The caliber shape of the essentially circularly calibrated rolls is always reduced until the diameter of the finished tube is reached in the last cross section of the caliber. In general, the cross-section of the caliber shape consists of a working caliber, which comprises a conical pilgrim's mouth, a constant circular smoothing caliber and a subsequent, slightly larger spout, and an idling caliber with a larger opening. The pilgrim's mouth, which is formed by the rollers, detects the shell and the rollers press a small material wave from the outside, which is stretched by the smoothing caliber of the rollers and the mandrel to the intended wall thickness until the idling caliber of the rollers releases the finished tube. During rolling, the roll stand with the rollers attached to it moves against the feed direction of the blank. With the help of the feed clamping carriage, after reaching the idle caliber of the rolls, the slug is pushed a further step towards the rolling mandrel, while the rolls with the roll stand return to their horizontal starting position. At the same time, the blanks undergo a rotation about their axis in order to achieve a uniform shape of the finished tube also in the circumferential direction. By rolling over each pipe section several times, a uniform wall thickness and roundness of the pipe as well as uniform inside and outside diameters are achieved.

A state-of-the-art pilger rolling mill is limited to the production of finished tubes with a narrow range of inside and outside diameters of the finished tubes, since the rolling stand used in the respective pilger rolling mill is only ever designed for a narrow range of inside and outside diameters of the tube to be processed is. In order to serve the corresponding sales market with the greatest possible variety of inside and outside diameters of the finished tubes, a large number of pilger rolling mills with different rolling stands must also be kept available. Here, the roll stands must be selected for the respective requirements for the diameter of the pipes to be processed.

Larger roll stands are also required for the production of finished pipes with a larger diameter with regard to the width of the roll stand and the diameter of the rolls used therein. As the size of the roll stand increases, the mass of the roll stand also increases.

A mill stand with a certain size is designed for a special parameter range of the diameter of the pipes to be manufactured, in which the billet is as good as possible, i. H. is processed as evenly as possible. Rolling of billets outside of this parameter range is possible, but the rolls work outside their optimal range. As a result, the precision of the machining process decreases and the finished tubes are of poorer quality compared to the finished tubes, which were processed in the optimal parameter range.

According to the prior art, only a specific inside and outside diameter of the pipes to be processed in a pilger rolling mill can be produced with a specific roll stand and a set of rolls attached to it. The value of the outside diameter of the finished tube can only be expanded to a narrow range of values by exchanging the rolls of the roll stand with a second pair of rolls. The rollers of the second pair of rollers differ from the rollers of the first pair of rollers in terms of their caliber shape. The caliber shape of the rolls of the second roll stand has a different configuration in the circumferential direction of the rolls from the caliber form of the rolls of the first roll stand, so that loops with a slightly different diameter are grasped by the pilgrim mouth of the second pair of rolls, shaped in the smooth caliber and via the outlet to the Idle calibers can be passed to release the finished tube. The outside diameter of the finished pipe can thus be changed within a narrow range of values.

The expanded limits of the pipe diameter that can be machined result from the fact that the rolls of the second pair of rolls must still be able to be installed in the roll stand of the pilger rolling mill. On the one hand, this requirement necessitates an adaptation of the rolls of the second pair of rolls with respect to their expansion parallel to their cylinder axis to the width of the roll stand. On the other hand, it presupposes identical diameters of the rolls of the second pair of rolls to the rolls of the first pair of rolls, so that the position of the axes of rotation of the rolls remains unchanged.

However, changing the rolls takes a lot of time and leads to longer downtimes of the pilger rolling mill and to higher costs.

Against this background, the present invention is based on the object of providing a pilger rolling mill which, in the same pilger rolling mill, enables the production of pipes with a range of values of inside and outside diameters which extends the narrow range of values according to the prior art. It is also an object of the present invention to ensure greater flexibility with regard to the pipe diameter to be manufactured in the same pilger rolling mill. Another object of the present invention is to enable shorter downtimes of the pilger rolling mill and faster swapping of the rollers of the pilger rolling mill.

At least one of these tasks is solved by a pilger rolling mill with the features of claim 1.

The rack holder according to the invention enables a pilger rolling mill to be made available which can be inexpensively adapted to the pipe diameter of the finished rolled pipe to be produced, so that it is possible to produce pipes with different diameters in the same pilger rolling mill. The finished tubes also have improved accuracy and precision due to the adaptation of the roll stand to the requirements of the tube diameter of the finished tubes.

In the context of the present invention, the term dimension of a roll stand encompasses the three spatial dimensions length, width and height and, moreover, also the dimensioning of the rolls and of the drive gearwheels, in particular with regard to their diameter.

In one embodiment of the present invention, the first roll stand has a different mass from the second roll stand.

In one embodiment of the present invention, the first and the second roll stand have mutually different widths (perpendicular to the direction of movement) and masses.

In one embodiment of the present invention, a material of the slug is selected from a group consisting of an unalloyed steel, a low-alloy steel and a high-alloy steel or a combination thereof. In a further embodiment, the slug is made of stainless steel.

Furthermore, the rack holder according to the invention enables the roll stand to be exchanged in a simple manner for a second roll stand with a different dimension without any significant loss of time. In contrast to the conventional processes for changing rolls, the breaks in operation due to the replacement of the roll stand can be significantly reduced and the system productivity can be increased considerably.

According to the invention, the pilger rolling mill is equipped with a rack holder which is designed in such a way that the rack can be received on the rack holder at at least two positions spaced apart in a direction parallel to the shafts of the rolls.

The rack holder according to the invention enables a drive gear of the roll stand to engage in the rack fastened to the rack holder at at least two spaced-apart positions in a direction parallel to the shafts of the rolls. Thus, at least two roll stands with two different widths can be installed on the same pilger rolling mill, the width of the roll stand in the sense of the present application defining its extension in the direction parallel to the shafts of the rolls. This is important insofar as the rolling stand is also built to be more stable and solid as the diameter of the rolls increases, which in the end also goes hand in hand with an increase in the width of the rolling stand.

In one embodiment of the present invention, the pilger rolling mill is equipped with a rack holder, which is designed in such a way that the rack can be held on the rack holder at at least two positions spaced apart in a direction perpendicular to the shafts of the rolls and perpendicular to the direction of movement of the roll stand, the individual distance between the positions is at least 10 mm. In one embodiment, the distance between the positions is understood to mean the distance between the position of the tooth heads measured in a direction perpendicular to the shafts of the rolls and perpendicular to the direction of movement of the roll stand.

The rack can thus be adjusted in height at at least two positions spaced apart from one another, the individual distance between the positions being at least 10 mm, so that the Have axes of rotation of the rollers at least two mutually different distances. This enables two roll stands with different roll diameters to be installed in the same pilger rolling mill. A drive gear on the shaft of the upper or lower roller, preferably the lower roller, is adapted to the respective roller diameter, while the drive gear can nevertheless engage in the rack.

In one embodiment, the individual distance between the positions is at least 20 mm. In a further embodiment, however, the individual distance between the positions is at most 100 mm. In a further embodiment, the individual distance between the positions is at most 40 mm.

The drive gear, which is arranged on one shaft with one of the two rollers, transmits its rotational movement to the rollers, so that the roller diameters which can be used in various ways can each process a narrow range of tube diameters with high accuracy. This extends the value range of the diameter of the finished rolled pipes, which can be produced with the same pilger rolling mill, without any loss of quality being expected.

A further embodiment of the present invention is a pilger rolling mill which has two toothed rack holders with toothed racks attached to it, which are arranged mirror-symmetrically to a reference plane running perpendicular to the shafts of the rolls. The shaft of one of the two rollers, preferably the lower roller, carries a drive gear on both sides of the reference plane, the two drive gears each engaging in one of the toothed racks and with a cylinder axis of the slug to be accommodated between the rollers lying in the reference plane.

The mirror-symmetrical arrangement of the toothed racks attached to the rack holders reduces the occurrence of torques, which have a disruptive influence on the rolling process, since the torques that occur compensate one another through the mirror-symmetrical arrangement. As a result, such a mirror-symmetrical arrangement leads to significantly less wear on the individual components of the pilger rolling mill. This is reflected in reduced operating and repair costs, making the pilger rolling mill more economical.

In a further embodiment of the present invention, the pilger rolling mill has a rack holder which extends away from the roll stand by a parallel to the direction of movement of the Rolling axis is pivotally arranged, so that a quick exchange of the roll stand is possible.

The pivoting of the rack holder away from the roll stand describes a folding mechanism for the rack holder. Unfolding the rack holder away from the roll stand releases the roll stand in such a way that when it is lifted, e.g. B. is not blocked by the rack holder by means of a crane. The roll stand can thus be removed unhindered and in a simple manner from the pilger rolling mill in the direction perpendicular to the shafts of the rolls and perpendicular to the direction of movement of the roll stand.

In a further embodiment of the present invention, the pilger rolling mill has a rack holder which is arranged so as to be pivotable about an axis running parallel to the direction of movement of the roll stand, the rack holder being hydraulically clampable in a direction perpendicular to the shafts of the rolls, so that the rack holder is in operation the pilger rolling mill absorbs the forces acting in a direction parallel to the reference plane.

By providing a counter pressure or a counter force, large forces and torques that occur during the rolling operation can also be absorbed by the rack. The use of hydraulic nuts instead of mechanical clamping nuts saves time during assembly work and enables easier handling.

In one embodiment of the present invention, the rack holder of the pilger rolling mill or parts thereof are interchangeable with a rack holder or parts thereof, so that the rack on the rack holder can be received at at least two positions spaced apart in a direction parallel to the shaft of the rolls.

The interchangeability of a first rack holder with a second rack holder at a second position, which is spaced from the position of the first rack holder in the direction parallel to the shafts of the rolls, thus enables the rack holder to be adapted to the width of at least two roll stands with different widths can.

In a preferred embodiment, the rack holder is constructed in two parts and comprises a base support and an adapter plate. The base support is arranged so that it can pivot away from the roll stand about an axis running parallel to the direction of movement of the roll stand. The adapter plate can be easily attached to the base support so that the rack attached to the rack holder can assume at least two spaced apart positions in a direction parallel to the shafts of the rollers. By such an attachment of adapter plates of different sizes in a direction parallel to the shafts of the rollers on the base support or removal of these adapter plates from the base support is a simple adjustment of the rack attached to the rack holder to the width and optionally to the position of the shafts of the rollers of at least two roll stands with different widths possible.

Another advantage here, in contrast to the replacement of the entire rack holder, is that the pivotability is not influenced or even impaired by the mere attachment and / or removal of attachments and thus readjustment of the axis about which the rack holder can be pivoted is not necessary is. In one embodiment of the present invention, the pilger rolling mill has a rolling stand which is movably mounted in a floating slide bearing, preferably on a hydraulically liftable slide. The plain bearing is designed in such a way that it allows the play between the drive gear and the rack to be adjusted in a direction perpendicular to the shafts of the rolls and perpendicular to the direction of movement of the roll stand.

An advantage of slide guides with maintenance-free, low-wear plain bearings is that they do not require any special lubrication. The engagement of the drive gearwheel in the rack can thereby be determined very precisely, so that wear and tear that occurs over time can be reduced, which, in addition to saving material costs, also entails a cost advantage due to shorter downtimes of the pilger rolling mill.

In a further embodiment of the present invention, the pilger rolling mill has two rolls arranged vertically one above the other, the shafts of the two rolls being connected to one another via two intermeshing gear wheels such that a rotary movement of one of the two rolls leads to a rotary movement of the other of the two rolls in the leads in the opposite direction.

In one embodiment of the present invention, the shafts of the rollers of the pilger rolling mill each have at least one bearing, at least one bearing of one of the two rollers and one bearing of the other of the two rollers being hydraulically braced against one another.

Such a hydraulic bracing of the bearings of the two rollers against each other makes it possible to set the roll gap very precisely. This has a positive effect on the quality of the tubes to be processed, which are given a very uniform shape during the rolling process due to the precise setting of the roll gap. Furthermore, the wear to which the rollers are subject during operation due to abrasion can be reduced by precisely adjusting the roller gap.

In a further embodiment of the present invention, the stroke length of the roll stand, which is determined by an eccentricity of a crank pin on which a push rod is accommodated, is set for the largest machinable pipe diameter and is constant for all machinable pipe diameters.

The larger the pipe diameter to be machined, the larger the diameter of the rolls must be in order to carry out the rolling process with high accuracy and quality. The increase in the diameter of the rolls is accompanied by an increase in the mass of the roll stand. As a result, the rolling force also increases. In order to ensure a constant distribution of force per surface, the size of the surface on which rolling takes place also increases with the increase in the rolling force. The feed length of a single stroke is consequently larger with a larger diameter of the rolls, so that the stroke length of the roll stand is also larger. The stroke length of the roll stand is therefore determined by the largest pipe diameter to be processed in the pilger rolling mill. However, this stroke length represents a compromise for significantly smaller machinable pipe diameters. The feed length of a single stroke is significantly smaller for smaller pipe diameters to be machined due to the smaller diameter of the rolls, so that a larger number of strokes is used in the rolling process. However, this cannot be as high as desired, since from a certain speed of the rolling process the processing of the pipes becomes inaccurate and irregularities in the wall thickness occur, so that there is a loss of quality.

In a further embodiment, the stroke length of the roll stand, which is determined by an eccentricity of a crank pin on which a push rod is received, can be set for different machinable pipe diameters. To adjust the stroke length, the distance between the axis of rotation of the flywheel or the crank mechanism and the attachment point of the push rod on the flywheel is adjusted accordingly, i.e. the eccentricity of the crank pin is modified and selectively modified. There is therefore a possibility of adapting the pilger rolling mill in a quick and inexpensive manner for the production of pipes of different types.

In one embodiment of the present invention, the crankshaft of the crank mechanism has a rotating balancing mass, the balancing mass being designed in such a way that it compensates for or almost compensates for the moments exerted by the first rolling mill taken up in the pilger rolling mill, the mass of the first rolling mill is smaller than the mass of the second roll stand. It is expedient if this balancing mass is offset from the crank pin by approximately 180 ° relative to the axis of rotation of the crankshaft.

A crankshaft in the sense of the present application is understood to mean any type of shaft with a crank pin arranged concentrically thereon for receiving the push rod.

When rotating a crankshaft with a push rod and without mass balancing on the crankshaft of the crank drive, forces arise due to the rotating arrangement of the crank pin that is eccentric with respect to the axis of rotation, so-called rotating mass forces, which are felt as vibration of the shaft radially to the axis of rotation. In order to ensure a smooth running of the roll stand and thus to ensure a high quality of the rolled tube, it is necessary to ensure that the crank mechanism runs as smoothly as possible, so that essentially no free forces and free moments occur, or the free forces and free moments are minimized.

For this purpose, it is expedient to compensate for these free forces with the aid of at least one balancing mass that rotates on the crankshaft of the crank drive, in that the total moments of the first order acting on the crank drive are compensated for as best as possible by the balancing mass.

The rotating inertial forces occurring during the operation of the pilger rolling mill can be completely balanced with the aid of a compensating mass, which is arranged eccentrically to the axis of rotation of the crankshaft at 180 ° to the pivot point of the push rod on the crank mechanism. This balancing mass leads to a mass distribution of the crankshaft with a push rod that is rotationally symmetrical with respect to the axis of rotation of the crankshaft and ensures first-order torque compensation.

In one embodiment, the balancing mass is designed in such a way that it compensates for or almost compensates for the moments exerted by the first rolling stand received in the pilger rolling mill, the mass of the first rolling stand being smaller than the mass of the second rolling stand.

A second roll stand with a large mass is driven with a lower angular velocity of the crankshaft compared to a first roll stand with a lower mass. The rotating mass forces increase quadratically with the angular velocity of the crankshaft, whereas they increase only linearly with the rotating mass. In the case of a second roll stand of large mass, the difference in mass between this and the first roll stand of lower mass can thus be at least partially reduced by the corresponding reduction in the angular velocity be balanced. As a result, a balancing mass, which is designed for the first roll stand, also compensates the rotating mass forces for the second roll stand with a larger mass.

An alternative to this embodiment is an embodiment of the balancing mass such that the balancing mass compensates as best as possible for the moments acting on the crank drive for a mass of the roll stand which results from the average of the masses of the first and the second roll stand.

Another alternative to this embodiment is that the compensating mass is releasably attached to the crank mechanism, so that when the first rolling stand is replaced, it is adapted as precisely as possible to the mass of the second rolling stand accommodated in the pilger rolling mill, in order to enable the crank mechanism to run, which is free of free forces or moments, or where the free forces and moments are minimized.

In one embodiment of the present invention, the pilger rolling mill has a balancer shaft with a second rotating balancing mass, the crankshaft and the balancer shaft being so effectively connected to one another via a central control that the balancer shaft rotates at twice the angular speed of the crankshaft during operation of the cold pilger rolling mill and wherein the second balancing mass is designed in such a way that it compensates or almost compensates for the moments exerted by the first rolling stand received in the pilger rolling mill, the mass of the first rolling stand being smaller than the mass of the second rolling stand.

In addition to the compensation of the free mass forces of the first order, free mass forces of the second order are added when an pilger rolling mill is operated with an oscillating linear movement of the roll stand. The free second order mass forces transmit second order moments via the push rod to the crankshaft and negatively influence the smooth running of the crankshaft.

The second order free mass forces oscillate in time with twice the angular velocity of the crankshaft. Therefore, the mass forces of the second order can be minimized or compensated for with the help of the balancer shaft according to the invention, which is effectively connected to the crankshaft via a central control and, together with the balancing weight attached thereto, rotates at twice the angular velocity of the crankshaft. The balancing mass is adapted in such a way that it enables the best possible balancing of the second-order moments for the first rolling stand, the first rolling stand having a smaller mass than the second rolling stand.

As already explained above, a compensating mass, which is designed for the first roll stand, can also compensate the rotating mass forces for the second roll stand with a larger mass. In addition, the second-order moments make a smaller contribution to the sum of the rotating mass forces than the first-order moments.

• Figur 1 zeigt eine schematische seitliche Schnittansicht des Aufbaus einer Pilgerwalzanlage gemäß einer Ausführungsform der vorliegenden Erfindung.
• Figur 2a zeigt eine Frontansicht auf ein erstes Walzgerüst der Pilgerwalzanlage aus Figur 1.
• Figur 2b zeigt eine Schrägsicht von oben auf das Walzgerüst aus Figur 2a mit dem Zahnstangenhalter in geöffneter Position.
• Figur 3a zeigt eine Frontansicht auf ein zweites Walzgerüst der Pilgerwalzanlage aus Figur 1.
• Figur 3b zeigt eine Schrägsicht von oben auf das Walzgerüst aus Figur 3a mit dem Zahnstangenhalter in geöffneter Position.

Further advantages, features and possible uses of the present invention will become apparent from the following description of a preferred embodiment and the associated figures.

• Figure 1 shows a schematic side sectional view of the structure of a pilger rolling mill according to an embodiment of the present invention.
• Figure 2a shows a front view of a first roll stand of the pilgrim rolling mill Figure 1 .
• Figure 2b shows an oblique view from above of the rolling stand Figure 2a with the rack holder in the open position.
• Figure 3a shows a front view of a second roll stand of the pilgrim rolling mill Figure 1 .
• Figure 3b shows an oblique view from above of the rolling stand Figure 3a with the rack holder in the open position.

In Figure 1 the construction of a pilger rolling mill according to the invention is shown in a schematic sectional side view, in which features which are not essential for understanding have been dispensed with. The pilger rolling mill shown comprises a roll stand 1 with rolls 2, 3, two drive gears 6 arranged on the shaft of the lower roll 3, two toothed racks 5 fastened to a rack holder 4 each, a calibrated rolling mandrel 7 and a feed clamping slide 8. The drive toothed wheels 6 are not shown here to see, since one of the two is covered by the lower roller 3 and the other has been omitted in the illustration for the sake of clarity. The racks 5 and rack holder 4 are also not in Figure 1 pictured.

In the illustrated embodiment, though not recognizable from Figure 1 , The pilger rolling mill has two toothed rack holders 4, which are arranged symmetrically with respect to a reference plane 11 running perpendicular to the shafts of the rolls, with fixed toothed racks 5 attached to them. The rack holder 4 are away from the roll stand 1 to parallel to the Direction of movement of the roll stand 1 pivot axes 13 extending pivotally.

During the pilgrimage on the in Figure 1 As shown in the rolling mill, the slug 9 experiences a step-wise feed in the direction of the rolling mandrel 7 towards or over it, while the rollers 2, 3 are rotated horizontally back and forth over the mandrel 7 and thus over the slug 9. The horizontal movement of the rollers 2, 3 is predetermined by a roll stand 1 on which the rollers 2, 3 are rotatably mounted. The roll stand 1 is moved back and forth in a direction parallel to the rolling mandrel 7 with the aid of a crank drive, while the rolls 2, 3 themselves receive their rotary movement through the toothed racks 5, which are fixed relative to the roll stand 1, into the drive gearwheels 6 which are fixedly connected to the lower roll axes intervention. First, a translational movement of the roll stand 1 is converted into a rotational movement of the drive gears 6. On the shaft of the lower roller 3, the drive gears 6 are not on the right and left of one each Figure 1 shown lower gear wheel 14, so that the rotational movement of the drive gears 6 causes a rotational movement of the lower gear wheels 14. The lower gearwheels 14 in turn do not mesh with one vertically one above the other Figure 1 shown upper gear gear 15 of the same diameter, which is arranged on the shaft of the upper roller 2. As a result, the upper gearwheels 15 are set in rotation at the same angular velocity as the lower gearwheels 14, but in the opposite direction of rotation compared to the lower gearwheels 14. By combing the lower gearwheels 14 arranged on the shaft of the lower roller 3 with the upper gearwheels 15 arranged on the shaft of the upper roller 2, a rotational movement of the rollers 2, 3 in the opposite direction to one another is thus brought about.

Furthermore, the shafts of the upper and lower rollers 2, 3 each have a left and a right bearing, the left bearing of the upper roller against the left bearing of the lower roller 3 and the right bearing of the upper roller 2 against the right bearing of the lower one Roller 3 are hydraulically clamped. The hydraulic bracing of the left and right bearings of the two rolls 2, 3 against one another enables the roll gap to be set precisely, as a result of which the pipes are given a very uniform shape during the rolling.

The advancement of the slug 9 over the mandrel 7 takes place with the aid of the advancement clamping slide 8, which enables a translational movement in a direction parallel to the axis of the rolling mandrel 7. The conically calibrated rolls 2, 3 arranged vertically one above the other in the roll stand 1 roll against the feed direction of the feed clamping slide 8 on the lateral surface of the pipe to be machined in a direction parallel to the cylinder cylinder axis. The so-called pilgrim's mouth, which is formed by the rollers, detects the hole 9 and the rollers 2, 3 press one from the outside small material wave from which a smoothing caliber of the rolls 2, 3 and the mandrel 7 extends to the intended wall thickness until an idling caliber of the rolls 2, 3 releases the finished tube. During rolling, the roll stand 1 with the rollers 2, 3 attached to it moves counter to the direction of advance of the blank 9. With the aid of the feed clamping slide 8, the base 9 is moved a further step onto the mandrel 7 after the idle caliber of the rollers 2, 3 has been reached pushed forward while the rollers 2, 3 return to their horizontal starting position with the roll stand 1. At the same time, the plate 9 is rotated about its axis in order to achieve a uniform shape of the finished tube. By rolling over each pipe section several times, a uniform wall thickness and roundness of the pipe as well as uniform inside and outside diameters are achieved.

For precise adjustment of the play between the drive gear 6 and the rack 5 in a direction perpendicular to the shafts of the rolls 2, 3 and perpendicular to the direction of movement of the roll stand 1, the roll stand is in Figure 1 , if not recognizable, movably mounted in a floating slide bearing, implemented here by a hydraulically liftable slide. In addition to the precise setting option between the drive gear 6 and the rack 5, the hydraulic mounting is characterized by its ease of installation, which in particular makes the replacement of the roll stand 1 much easier and faster. As a result, the operational downtime associated with replacing the roll stand can be significantly reduced. Furthermore, such a mounting of the rollers 2, 3 does not require seals and pistons that are susceptible to wear, ie the hydraulic mounting is essentially maintenance-free and wear-free.

The stroke length of the in Figure 1 Pilger rolling mill shown is fixed for all machinable pipe diameters and by the largest pipe diameter to be machined in the pilger rolling mill. This enables a simplified operating sequence, since it is not necessary to change the eccentricity 21 of the crank pin, but the eccentricity 21 remains the same for all machining processes.

In an alternative embodiment, it would be conceivable to make the stroke length of a pilger rolling mill adjustable for different machinable pipe diameters. For this purpose, the distance between the axis of rotation of the flywheel of the crank mechanism and the attachment point of the push rod on the flywheel is adjusted accordingly, ie the eccentricity 21 of the crank pin is modified. The stroke length can consequently be optimally adapted to the pipe diameter to be machined, so that the different machinable pipe diameters can be produced with better accuracy compared to a constant stroke length for the different machinable pipe diameters. However, a complex change in the eccentricity 21 of the crank pin has to be accepted.

In the illustrated embodiment, a central controller 20 is also provided, which is connected both to the drive motor of the balancer shaft 17 and to the drive motor of the crankshaft. The controller 20 controls the motors in such a way that their drive shafts rotate in the same direction of rotation, the rotational frequency of the balancer shaft 17 being twice the rotational frequency of the crankshaft.

In addition, the controller 20 guarantees an angularly synchronous rotation of the two balancing masses 16, 18 of the crankshaft and balancing shaft 17. That is, the two balancing masses 16, 18 lie at the same angle after one revolution of the crankshaft, the balancing mass 18 of the balancing shaft 17 in the time that the Crankshaft needed for one revolution, made two full revolutions.

In Figure 2a is a front view of a roll stand of the pilgrim rolling mill Figure 1 shown. The roll stand 1 with a mass M ₁ is designed for the processing of blanks with a diameter between 30 mm and 60 mm. The maximum number of strokes of the roll stand, ie the maximum number of back and forth movements of the roll stand per unit of time, is in Figure 2a present embodiment at 200 / min. Since the productivity of a cold pilger rolling mill is directly dependent on the number of strokes of the roll stand, the greatest possible number of working strokes per minute is aimed for reasons of economy.

The mill stand 1 in Figure 2a has a mirror-symmetrical arrangement of both the rollers 2, 3 and the drive gearwheels 6 with respect to a reference plane 11 running perpendicular to the shafts of the rolls 2, 3, a cylindrical axis of the plate 9 to be received between the rolls 2, 3 lying in the reference plane 11. Here, the drive gears 6 are firmly connected to the shaft of the lower rollers 3 and engage in the toothed racks 5, which are also attached to the toothed rack holders 4, which are also arranged in mirror symmetry. The racks 5 are in Figure 2a not visible, since these are covered by the rack holders 4.

In order to absorb the forces acting in a direction parallel to the reference plane 11 during operation of the pilger rolling mill, the rack holders 4 can be hydraulically clamped in a direction perpendicular to the shafts of the rolls. The hydraulic bracing takes place here via a system of hydraulic nuts 12, which essentially consist of an annular piston and a cylinder. A temporary pressurization creates a force in the direction perpendicular to the shafts of the rollers 2, 3. This can temporarily create clamping or pushing forces, so that the rolling stand 1 during the rolling process in a direction parallel to the shafts of the rollers 2, 3 on one is held in a fixed position and is thus prevented from sliding away due to torsional forces.

The in Figure 2a The rack holder 4 shown is also pivotably arranged away from the roll stand about a pivot axis 13 which runs parallel to the rack 5 and which consists of Figure 2a is not recognizable due to its orientation into the image plane. By simply folding up the rack holder 4 away from the roll stand, the drive gear wheels 6 lose contact with the rack 5, so that the roll stand 1 is not blocked by the rack holder 4 when it is lifted by a crane. The rolling stand 1 can thus be exchanged freely and in a simple and quick manner. This brings with it greater flexibility in the machining process with regard to an expanded range of machinable tube diameters.

Figure 2b shows an oblique view from above of the rolling stand Figure 2a , but with the rack holder 4 in an open position such that the rack holder 4 has been pivoted about its pivot axis 13 in accordance with the direction of the arrow shown away from the roll stand and as a result the rack 5 attached to the rack holder 4 has no contact with the drive gear 6. The roll stand 1 is thus no longer blocked by the rack holder 4 and can be removed simply and quickly by lifting it out of the pilger rolling mill and replaced by a second roll stand 1 'with different dimensions by means of a crane.

In Figure 3a is a front view of a second roll stand 1 'of the pilger rolling mill Figure 1 shown. In contrast to Figure 2a it is a roll stand 1 'with larger dimensions with regard to the three spatial dimensions and the diameter of the rolls 2', 3 'and drive gears 6', which, however, in the same pilger rolling mill Figure 1 can be installed. The larger dimensions of the in Figure 3a The rolling stand 1 'shown is also reflected in one in comparison to the rolling stand 1 Figure 2a and 2 B increased mass. The mass of the second roll stand in the present embodiment is 2.5 times the mass M _{1 of} the roll stand 1 Figure 2a and 2 B . Furthermore, that is in Figure 3a Roll stand 1 'shown designed for the processing of billets with a diameter between 40 mm and 88 mm and thus for larger diameters compared to the roll stand 1 Figure 2a and 2 B . The maximum number of strokes of the roll stand 1 'is 150 / min with a correspondingly lower value.

The rack holder 4 'according to the invention is located in Figure 3a at a position further away from the reference plane 11 'perpendicular to the reference plane 11' compared to that in FIG Figure 2a rack holder shown 4. In the embodiments of the Figures 2a and 3a this is made possible by the fact that the rack holder 4, 4 'is constructed in two parts. On the one hand, it includes a base support and on the other hand an adapter plate which can be attached to the base support in such a way that the respective drive gear 6, 6 'of the roll stand 1, 1' at at least two positions spaced apart from one another in a direction perpendicular to the reference plane 11 into that on the respective rack holder 4, 4 'fixed rack 5, 5' can engage. In case of Figure 2a this adapter plate is built larger in a direction parallel to the shafts of the rollers 2, 3 than in the case of Figure 3a , so that the rack 5 has a smaller distance from the reference plane 11 in the direction of the normal to the reference plane 11.

In addition to the position in the direction parallel to the shafts of the rollers 2 ', 3', however, it is also necessary to adapt the rack holders 4 'in the direction perpendicular to the shafts of the rollers 2', 3 'and perpendicular to the direction of movement of the roll stand 1'. The required adjustment is due to the larger diameter of the drive gear 6 'compared to that in Figure 2a Drive gear 6 shown. Such an adaptation is realized by a two-part rack holder 4 'in the form of a base support with an appropriately designed adapter plate attached thereto, so that the drive gear 6' of the roll stand 1 'can engage in the rack 5' fastened to the rack holder 4 ' .

Figure 3b shows an oblique view from above of the roll stand 1 ' Figure 3a . The rack holder 4 'has been pivoted away from the roll stand 1' about a pivot axis 13 'running parallel to the direction of movement of the roll stand 1' and is located accordingly Figure 2b in an open position such that the rack 5 'fastened to the rack holder 4' no longer has any contact with the drive gear 6 'of the roll stand 1'. Also in the embodiment of a roll stand 1 'with larger dimensions compared to that in FIG Figures 2a and 2 B The illustrated dimensions of the roll stand 1 'can be removed from the pilger rolling mill in a simple and quick manner with the aid of the pivoting device which releases the roll stand 1'.

For the purposes of the original disclosure, it is pointed out that all of the features that are apparent to a person skilled in the art from the present descriptions, the drawings and the claims, even if they have only been described concretely in connection with certain further features, both individually and in any combinations with other, the features and groups of features disclosed here can be combined, unless this has been expressly excluded or technical circumstances make such combinations impossible or senseless. Only the brevity and the legibility of the description are omitted here from the comprehensive, explicit representation of all possible combinations of features.

While the invention has been illustrated and described in detail in the drawings and the foregoing description, this illustration and description is provided by way of example only and is not intended to limit the scope of protection as defined by the claims. The invention is not limited to the disclosed embodiment.

Changes to the disclosed embodiment will be apparent to those skilled in the art from the drawings, the description, and the appended claims. In the claims, the word "comprise" does not exclude other elements or steps, and the indefinite article "one, one" or "an" does not exclude a plurality. The mere fact that certain features are claimed in different claims does not preclude their combination. Reference signs in the claims are not intended to limit the scope.

Reference symbol list

1, 1 '

Mill stand

2, 2 '

top roller

3, 3 '

lower roller

4, 4 '

Rack holder

5, 5 '

Rack

6, 6 '

Drive gear

7

calibrated rolling mandrel

8th

Feed carriage

9, 9 '

Bob

10th

Cylinder axis of the billet

11

Reference plane

12, 12 '

Hydraulic nut

13, 13 '

Swivel axis of the rack holder

14, 14 '

lower gear wheel

15, 15 '

upper gear gear

16

Leveling compound

17th

Balance shaft

18th

second leveling compound

19th

Push rod

20th

central control

21st

eccentricity

Claims (13)

1. Pilger rolling system for forming a hollow (9) into a pipe with a first roll stand (1) which is mounted so as to be movable linearly in a direction of movement,
   wherein two rollers (2, 3) for forming the hollow (9) into the pipe are mounted on the roll stand (1) so as to be rotatable on shafts,
   wherein one of the rollers (2, 3) is arranged with a drive gear (6) on a shaft and wherein the drive gear (6) engages in a fixed gear rack (5),
   which is attached in such a way to a gear rack holder (4) that a translational movement of the roll stand (1) causes a rotational movement of the drive gear (6) and the roller (2, 3), and
   a crank drive which is connected to the roll stand (1) and which transfers a rotary movement of a drive motor via a push rod into an oscillating translational movement of the roll stand (1) during operation of the pilger rolling system,
   and

   the gear rack holder (4) is designed in such a way that the first roll stand (1) is interchangeable with a second roll stand (1') of a second dimension different from the first dimension,

   characterised in that the gear rack holder (4) is designed in such a way that the gear rack (5) can be received on the gear rack holder (4) at at least two positions spaced apart from one another in a direction parallel to the shafts of the rollers (2, 3) .
2. Pilger rolling system according to one of claims 1, characterised in that the gear rack holder (4) is designed in such a way that the gear rack (5) can be received on the gear rack holder (4) at at least two positions spaced apart from one another in a direction perpendicular to the shafts of the rollers (2, 3) and perpendicular to the direction of movement of the roll stand (1), wherein a distance, measured in a direction perpendicular to the shafts of the rollers (2, 3) and perpendicular to the direction of movement of the roll stand (1), between the positions is at least 10 mm.
3. Pilger rolling system according to one of claims 1 or 2, characterised in that the pilger rolling system has two gear rack holders (4), arranged mirror-symmetrically to a reference plane (11) extending perpendicularly to the shafts of the rollers (2, 3), with gear racks (5) attached thereto, wherein the shaft of one of the rollers (2, 3), preferably the lower roller (3), supports a drive gear (6) on both sides of the reference plane (11), wherein the two drive gears (6) respectively engage in one of the gear racks (5) and wherein a cylinder axis of the hollow (9) to be received between the two rollers (2, 3) is located in the reference plane (11).
4. Pilger rolling system according to one of claims 1 to 3, characterised in that the gear rack holder (4) is arranged so as to be pivotable away from the roll stand (1) about an axis extending in parallel to the direction of movement of the roll stand (1) so that it is possible to quickly exchange the roll stand (1).
5. Pilger rolling system according to one of claims 1 to 4, characterised in that the gear rack holder (4) is arranged so as to be pivotable about an axis extending in parallel to the direction of movement of the roll stand (1), wherein the gear rack holder (4) can be hydraulically braced in a direction perpendicular to the shafts of the rollers (2, 3) so that during operation of the pilger rolling system, the gear rack holder (4) absorbs forces acting in a direction parallel to the reference level (11).
6. Pilger rolling system according to one of claims 1 to 5, characterised in that the gear rack holder (4) or parts thereof are interchangeable with a gear rack holder (4') or parts thereof so that the gear rack (5) can be received on the gear rack holder (4) at at least two positions spaced apart from one another in a direction parallel to the shafts of the rollers (2, 3).
7. Pilger rolling system according to one of claims 1 to 6, characterised in that the roll stand (1) is movably mounted in a floating sliding bearing, preferably on a hydraulically liftable slide, wherein the sliding bearing is designed in such a way that adjusting the clearance between the drive gear (6) and the gear rack (5) in a direction perpendicular to the shafts of the rollers (2, 3) and perpendicular to the direction of movement of the roll stand (1) is made possible.
8. Pilger rolling system according to one of the previous claims 1 to 7, characterised in that the rollers (2, 3) are arranged one above the other, wherein the shafts of both rollers are connected to each other by means of two mutually engaging gears in such a way that a rotary movement of one of the two rollers (2, 3) results in a rotary movement of the other of the two rollers (2, 3) in the opposite direction.
9. Pilger rolling system according to one of claims 1 to 8, characterised in that the shafts of the rollers (2, 3) each have at least one bearing, wherein at least one bearing of one of the two rollers (2, 3) and a bearing of the other of the two rollers (2, 3) are hydraulically braced against each other.
10. Pilger rolling system according to one of claims 1 to 9, characterised in that a stroke length of the roll stand (1), which is determined by an eccentricity of a crank pin on which a push rod is received, is adjusted for the largest processable pipe diameter and is constant for all processable pipe diameters.
11. Pilger rolling system according to one of claims 1 to 10, characterised in that a stroke length of the roll stand (1), which is determined by an eccentricity (21) of a crank pin on which a push rod is received, is differently adjustable for different processable pipe diameters.
12. Pilger rolling system according to one of claims 1 to 11, characterised in that the crankshaft of the crank drive has a co-rotating mass-balancing gear (16), wherein the mass-balancing gear (16) is designed in such a way that it compensates in the first order or nearly compensates the moments exerted by the first roll stand (1) received in the pilger rolling system, wherein the mass of the first roll stand (1) is less than the mass of the second roll stand (1').
13. Pilger rolling system according to one of claims 1 to 12, characterised in that the pilger rolling system has a balance shaft (17) with a second co-rotating mass-balancing gear (18), wherein the crankshaft and the balance shaft (17) are operatively connected to each other in such a way that the balance shaft (17) rotates with double the angular speed of the crankshaft during operation of the cold pilger rolling system and wherein the second mass-balancing gear (17) is designed in such a way that it compensates in the second order or nearly compensates the moments exerted by the first roll stand (1) received in the pilger rolling system, wherein the mass of the first roll stand (1) is less than the mass of the second roll stand (1').

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