FR2558396A1 - Method for pilger rolling of pipes, rolling mill for its implementation and pipes rolled in accordance with the said method - Google Patents

Abstract

The invention relates to the manufacture of pipes. The method forming the subject of the invention is characterised in that the speeds of the forced displacement of the blank 1 with the plug 2 during the forward travel and during the backward travel and the speed of displacement of the blank 1 through the working rolls 3 are varied according to a harmonic law, the forced displacement of the blank 1 during the forward travel and during the backward travel taking place in the same amount of time. The invention makes it possible to increase the production of the rolling mill.

Description

 The present invention relates to the field of manufacturing tubes and in particular relates to a method of rolling tubes with pilgrim's steps, a rolling mill for its implementation and the tubes laminated in accordance with said method.

 At present, the rolling of tubes is mainly carried out on rolling mills with rolls or rollers with movable cages. In the technique of manufacturing tubes, there is a tendency to perfect rolling mills and cold rolling methods of tubes by increasing the length of the deformation focus, by using cylinders of reduced dimensions, increasing speed. rolling mills, by applying multiline and medium-temperature rolling, by improving the grooving of the tools and methods of preparing the starting blank. The increase in the production of cold rolling mills is obtained by increasing the rate of operation of the cages, thanks to the reduction in their weight and the balancing of the masses driven by an alternating rectilinear movement. However, the reduction in weight of the cylinder cage causes a reduction in its rigidity, which significantly reduces the dimensional accuracy of the rolled tubes and their quality.

In addition, the use of lightweight cylinder cages does not lead to a significant increase in the production of rolling mills, since their low rigidity means that the rolling effort has to be reduced and, consequently, the degree of reduction in l and production of the rolling mill
A certain increase in the rate of running of the roll cages (that is to say the operating speed of the rolling mill) is obtained by using balancing devices of various types: pneumatic, heavy weight, spring loaded, etc. . However, the recourse to the balancing of the moving masses complicates the design of the rolling mill and increases its dimensions and its weight, makes more stringent the requirements relating to the precision of manufacture and assembly of the rapid subassemblies of the rolling mill.

 In order to increase the production of cold tube rolling mills, modernized cages with two tube rolling lines have also been used recently. These cages have an increased weight, which increases the dynamic loads in the system animating the cage with an alternating rectilinear movement and, consequently, only allows walking at a reduced rate or implies the presence of a mechanism. bulky balancing, hence a reduction in the operating speed of the rolling mill.

Cold roller mills for tube manufacturing have found wide applications in the production of extra-thin cold rolled tubes. In these rolling mills, unlike cold tube rolling mills operating by cylinders, the tube is deformed on a cylindrical mandrel by rollers with a radius of constant groove, equal to the radius of the finished tube;
In the case of roller rolling, the cage has a stroke length of 1.8 to 2.0 times greater than the stroke length of the rollers, i.e. it is greater than the length of the laminated section on the tube, which explains the significant dynamic forces transmitted to the actuation system. The total elongation obtained on cold tube rolling mills operating with rollers rarely reaches 3 times, since the tube is mainly reduced in thickness by wall, its reduction in diameter being insignificant.

 The practice of using roller mills has shown that the increase in advancement and total deformation per pass causes an alteration in the quality of the surface of the tubes and a reduction in their dimensional accuracy, which is manifested. by the appearance of a polygonal profile, transverse thickness differences, etc.

 What has just been said shows that it is advantageous to use roller mills for completion operations.

 The analysis of the methods of rolling cold tubes and rolling mills for their implementation which currently exist shows that the production of rolling mills increases when their operating speed increases.

 However, the increase in operating speed leads to an increase in dynamic loads in the elements of the kinematic chain of reciprocating rectilinear movement, which causes intense wear of these elements and, consequently, lowers the reliability and the production of the rolling mills.

 There is also known a cold tube rolling mill operating discontinuously with fixed cylinders in translation (Great Britain patent NO 1,149,822 cl. B3M). This rolling mill has a fixed cage in which two cylinders are mounted.

The chuck bar is rigidly linked to a coupling chuck, which in turn is connected to a carriage by a spring. The reciprocating rectilinear movement mechanism of the carriage is produced in the known rolling mill in the form of a drum cam with a loop-shaped groove. A projection integral with the carriage body is engaged in this groove. The rolling is carried out on a long cylindrical mandrel. The blank is advanced in the rolling mill by a screw which cooperates with the body of the reciprocating rectilinear movement mechanism of the carriage, body in which the drum is fixed. During advancement, the body of the mechanism moves towards the cage. The bar is pulled back using the same screw;
This rolling mill can only roll tubes with a reduction in their internal diameter from 1.5 to 3 times. When changing the setting of the rolling mill, the drum must be changed. In this rolling mill, the advancement of the blank must be carried out in common with the advancement of the entire tube displacement mechanism, which increases the dynamic loads on the actuation system and causes a reduction in the production of the rolling mill.

 There is a known process of rolling tubes with pilgrim's steps in a fixed cage with continuously rotating cylinders, and a rolling mill for carrying it out (United States patent NO 4,184,352 cl. 72/208).

 According to this process, the longitudinal profile of the active sector of the grooves of the cylinders is made curvilinear and, during the reverse stroke of the rotation of the cylinders, the forced displacement of the blank with the mandrel takes place with their rotation. simultaneous around the longitudinal axis and presentation of a blank portion to the cylinders. Then, during the stroke going in the direction of rotation of the cylinders, the speed of forced displacement of the blank with the mandrel is tuned with the speed of displacement of the blank by the working cylinders and the rough portion is reduced. on the chuck. In this process, the working rolls are driven in a uniform rotational movement, while the blank with the mandrel performs a reciprocating rectilinear movement.

 In the reciprocating rectilinear movement there are two so-called "dead points", at the start and at the end of the race, points at which the speed of the moving elements in translation is zero. To match the speed of movement of the blank and the mandrel with the linear speed of the working rolls, at the start of each outward stroke (movement in the direction of rotation of the rolls), accelerate the blank and the chuck, and to stop the blank and the chuck at the end of this stroke, they must be braked. The acceleration and braking of the blank with the mandrel is also carried out during the return stroke. In this process of rolling tubes with pilgrim steps, the deformation of the blank on the mandrel is performed by half or more than half of the groove of the cylinders with a uniform rotational movement, also the forward stroke, during which the cylinders deform the blank, occupies half or more than half of the rolling cycle. The acceleration and braking of the blank with the mandrel during the outward stroke takes place when the sectors passing through the deformation focus are the inactive sectors, so the duration of the outward stroke constitutes in the known process about 2/3 of the cycle, the duration of the return stroke (displacement of the blank with the mandrel against the rotation of the cylinders), constituting only about 1/3 of the cycle.

 When the cylinders rotate at a constant speed, the speed of the reciprocating rectilinear movement of the moving masses during the deformation of the blank is almost constant, if one neglects the variation in the rolling radius of the variable section groove of the cylinders , and the acceleration is zero. The speed only changes during the forward stroke during acceleration and braking of the preform with the mandrel, the absolute value of acceleration and deceleration being low.

 However, during the return race, when, in a time constituting 1/3 of the cycle, it is necessary to carry out the same displacement of the moving masses as during the duration of the outward race, which constitutes 2/3 of the cycle, the average speed of the varied rectilinear alternating movement of the moving masses increases twice compared to their speed during the outward race. The movement of the moving masses of the blank with the mandrel during the return stroke is a sudden acceleration movement up to half of the stroke, then a suddenly decelerating movement at the end of the stroke, the absolute value of I acceleration and deceleration being high.

 This is why, in the known method, the reciprocating rectilinear movement of the blank with the mandrel has a character without inertia during the outward stroke and a very accentuated dynamic character during the return stroke.

 The alternating dynamic loads which are then generated in the elements of the kinematic chain of the reciprocating rectilinear movement of the carriage (blank-tube) cause rapid wear of the parts of this chain, the lowering of its reliability and the production of all rolling mill.

 To carry out this process, there is a rolling mill comprising a fixed cage with working rolls driven in a continuous rotational movement by a main actuation system. This same actuation system drives a converter of uniform rotation into variable rotation and the advancement mandrel of the blank. Said blank advancement mandrel comprises aligned nuts, cooperating with the advancement screw, which is engaged in the carriage together with the mandrel bars. The reciprocating rectilinear movement mechanism of this rolling mill is linked to the main actuation system, to which are also linked a front coupling mandrel and a mechanism for advancing and rotating the blank, comprising a converter for continuous rotation in rotation intermittent and a rotating shaft.

Compared to the rolling mill described in the patent
Great Britain NO 1 149 822, cl. B3M, the rolling mill considered, rolls the tubes engaged end to end, in a row, on a short profiled mandrel, having a length of the order of that of the deformation hearth, which makes it possible to increase the reduction of the blank in thickness wall (up to 90%) and inside diameter (up to 60%), and thus reduce the cyclical nature of the process b
In this rolling mill, the advancement of the preform takes place by additional displacement during the return stroke of the advancement mandrel of the preform from the advancing screw. This increases the reliability of the whole rolling mill and increases production. Changes to the setting of the rolling mill when switching to another route are carried out (along with the change of cylinders) by changing the setting of the rectilinear movement mechanism alternative of the carriage (adjustment of the radius of the crank), which considerably simplifies the changes of adjustment and reduces their duration.

 In the rolling mill under consideration, the reciprocating rectilinear movement mechanism of the running carriage has a very accentuated dynamic speed during the idle stroke, which reduces the longevity of its force elements and, ultimately, hinders the increase in the production of the rolling mill .

 We therefore proposed to create a rolling process for pilgrim's tubes and a rolling mill to carry it out, which would be designed so that the speed conditions of the rolling process and the kinematic connections of the mechanism driving the carriage an alternating rectilinear movement, of the continuous rotation converter in intermittent rotation and of the uniform rotation converter in variable rotation of the rolling mill make it possible to increase the production of the rolling mill.

 This problem is solved by the fact that the process of rolling tubes with pilgrim's steps in a fixed cage with working cylinders rotating continuously, the longitudinal profile of the active sector of the groove being made curvilinear, of the type according to which, during the rotation of the cylinders, the blank and the mandrel are forcibly displaced with simultaneous rotation around their longitudinal axis and advancement of a portion of blank in the cylinders, then, during the outward stroke, the blank with the mandrel are forcibly displaced in the direction of rotation of the cylinders, the speed of this displacement being matched with the speed of displacement of the blank by the working cylinders and the blank portion being reduced on the mandrel, is characterized, according to the invention, in that the speeds of forced displacement of the blank with the mandrel in the forward and reverse stroke and the speed of displacement of the blank by the working rolls are varied according to a harmonic law, the forced displacement of the preform in the outward and return stroke takes place for equal times.

 The displacement of the blank with the mandrel for equal times on the outward and return journeys, at a speed varying according to a harmonic law (close to the sinusoidal law) during each stroke, ensures a progressively accelerated movement from the start of the race in its middle and gradually delayed from the middle of the race to its end. The harmonic character (close to the sinusoidal law) of the variation of the speed of the reciprocating rectilinear movement of moving masses makes that their acceleration varies according to a cosinusoldale law and, consequently, causes a strong lowering and an equalization of its extreme values. Such a method of rolling tubes with pilgrim steps makes it possible to reduce the dynamic loads in the reciprocating rectilinear movement mechanism and thereby to increase the operating speed, as well as, consequently, the production of the rolling mill.

 In addition, the problem set out above is solved by the fact that the rolling mill for implementing the method of the invention, of the type comprising a fixed cage with working rollers driven in a continuous rotational movement by a system of main actuation, to which are kinematically linked a converter of uniform rotation to varied rotation and a chuck for advancing the blank comprising aligned nuts which cooperate with a advancement screw engaged jointly with chuck bars in a carriage whose the reciprocating rectilinear movement mechanism is linked to said main actuation system, to which are also linked a front coupling mandrel and a mechanism for advancing and rotating the blank, comprising a converter for continuous rotation to intermittent rotation, is characterized, according to the invention, in that the converter from uniform rotation to non-uniform rotation is coupled by its output shaft to the working rolls , the main actuation system is linked to a sinus mechanism which comprises a shaft with a crank pin, which is linked to the reciprocating rectilinear movement mechanism of the carriage, equipped with a connecting rod which is linked to the front coupling mandrel, ci being kinematically linked to the continuous rotation converter in intermittent rotation, and said continuous rotation converter in intermittent rotation comprises a shaft engaged in a sleeve so that it can slide axially, one of its ends being mounted using of bearings in said front coupling mandrel, and its other end being coupled to the advancement screw by a ball joint.

The connection of the output shaft of the uniform rotation converter to non-uniform rotation with the working rolls makes it possible to vary the speed of movement of the blank by the working rolls according to a harmonic law. The sinus mechanism, kinematically linked to the main actuation system and comprising a shaft with a crank pin which is linked to the reciprocating rectilinear movement mechanism of the carriage, which is coupled by a connecting rod to the front coupling mandrel, and the kinematic connection to this sinus mechanism of the converter from continuous rotation to intermittent rotation, comprising a shaft engaged in a sleeve, so that it can slide axially, one of its ends being mounted in the front coupling mandrel by means of bearings, and its second end being coupled by a ball joint to the advancement screw, make it possible to vary according to a harmonic law the speed of forced displacement of the carriage in the outward and return stroke, and to carry out these strokes in equal times, value equal to half the duration of the rolling cycle. This makes it possible to lower and equalize the extreme values of the accelerations in the outward and return stroke of the masses driven by an alternating rectilinear movement, and, consequently, the increase in the operating speed and the production of the rolling mill ;;
It is advantageous that the advancement screw is linked by a pair of spare pinions to one of the ends of the rotation shaft, the second end of this shaft being coupled to the output shaft of a mechanism. transmission of rotation, inside the hollow input shaft which is engaged coaxially the shaft of the continuous rotation converter in intermittent rotation.

 Such a kinematic connection of the feed screw with the rotation shaft and of the rotation shaft with the converter shaft, movable in the axial direction, makes it possible to transmit the rotation of the converter from continuous rotation to intermittent rotation to the advancement screw by means of only two pairs of pinions, one of the pairs of pinions being changeable and used to change the value of the advance. The significant reduction in the number of gear transmissions in the kinematic chain of the advancement mechanism simplifies its design, increases reliability and operating speed, contributes to the increased production of the rolling mill.

 it is advantageous that the reciprocating rectilinear movement mechanism of the carriage comprises, in addition to the mentioned connecting rod, an arm mounted on a shaft, this arm being kinematically linked to the first crankpin of the sinus mechanism and having a radial groove in which is disposed a pad mounted so that it can carry out an adjustment movement and coupled to the connecting rod by a joint.

 The indicated constructive differences of the reciprocating rectilinear movement mechanism and its kinematic connection to the sinus mechanism make it possible to bring the speed of movement of the blank by the working cylinders into agreement with the speed of its forced movement during deformation when the The rolling route changes, while retaining the harmonic nature of the variation in these speeds.

 It is desirable that the shaft of the sinus mechanism be equipped with a second crankpin, mounted with an angular offset of 1800 relative to the first crankpin, this second crankpin being coupled by a vertical connecting rod to one of the ends of a lever. carrying reciprocally balanced weights on both arms.

 Thanks to such a design, the dynamic torque is completely balanced on the crankshaft of the sinus mechanism, which increases the reliability and longevity of the main actuation system and contributes to the increase in the production of the rolling mill.

 It is recommended that, in the converter from continuous rotation to intermittent rotation, the sleeve is mounted so that it can rotate continuously from the main actuation system, to increase the angle of rotation of the converter shaft when moving the blank forward and suppress the rotation of this shaft when moving the blank back.

When the sleeve turns and the converter shaft moves forward against the rotation of the cylinders (idle stroke), the shaft and sleeve rotations are added, which increases the angle of rotation of the tree
When the converter shaft moves backwards (useful stroke), the rotations of the shaft and of the sleeve become entrenched, so the shaft does not rotate, i.e. during the stroke useful there is no advancement or rotation of the blank. Such a constructive embodiment of the converter of continuous rotation to intermittent rotation makes it possible to simplify its design and, in this way, to increase the reliability and the longevity of one of the most complicated sub-assemblies of the rolling mill.

The invention will be better understood and other objects, details and advantages thereof appear better in the light of the explanatory description which will follow of various embodiments given only by way of nonlimiting examples, with references to the drawings. nonlimiting annexed in which
- Figures 1 to 4 show the relative arrangement diagram of the working rolls, the blank and the mandrel at different stages of the rolling of a tube by the pilgrim's step method, according to the invention;
- Figure 5 shows the graph of variation of the speeds and accelerations of the tube with the mandrel (as well as retaining mechanisms) and working cylinders, according to the invention;
- Figure 6 shows an overall view of a pilgrim tube rolling mill, produced according to the invention, horizontal section; ;
- Figure 7 shows the same rolling mill, vertical section along the axis of the rolling mill;
- Figure 8 shows section VIII-VIII of Figure 6;
- Figure 9 shows section IX-IX of Figure 6;
- Figure 10 shows section XX of Figure 6.

 The method of rolling pilgrim's pitch tubes according to the invention, in a fixed cage with working cylinders rotating continuously and whose longitudinal profile of the active sector of the groove is made curvilinear, consists of the following. The blank 1 (Figure 1), in which a mandrel 2 is placed, is forcibly moved from the extreme left position (left dead center) against the rotation of the cylinders 3 (return stroke). During this movement the portion "m" of the blank 1 is presented to the cylinders 3 by additional relative displacement of the blank relative to the mandrel 2 in the same direction and by rotation of an angle in common with the mandrel 2.So of the return stroke of the blank 1, the working cylinders 3 are positioned so that the inactive sectors "ab" of the grooves are opposite. At the end of the return stroke, in the extreme right position shown in FIG. 2 (right dead center), the forced movement of the blank 1 in common with the mandrel 2 is reversed and takes place in the direction of rotation of the 3 working cylinders (outward stroke). The forced displacement of the blank 1 with the mandrel 2 during the outward stroke takes place in such a way that at the instant it is contacted by the working cylinders 3 (FIG. 3), the speed of forced displacement of the blank 1 is equal to the speed of its displacement by the working cylinders 3. During the forward stroke of the blank 1 with the mandrel 2, the portion "m" of the blank 1 is reduced on the mandrel 2. During reduction, the speed of forced movement of the blank 1 is adjusted in value and direction to the speed of its movement by the working cylinders 3; The reduction of the blank 1 is carried out by the active sector "cd" of the grooves of the cylinders 3 and ends when the cylinders 3 reach the position in which the ends of the active sectors of their grooves are opposite. screw (FIG. 4, point d) 9 ′ according to the invention, the speed v1 (FIG. 5) of forced displacement of the blank 1 with the mandrel 2 in the forward and reverse stroke and the speed v2 of the displacement of the blank 1 by the working cylinders 3 are varied according to a harmonic law (close to the sinusoldal law). During the outward race (sector "cd", Figure 5) the speeds v1 and v2 are tuned in value and direction. The forced displacement of the blank 1 in the outward and return stroke takes place in equal times.

Point A of the linear speed variation graph
re working cylinders v3 corresponds to the position of the blank 1 and of the cylinders 3 shown in FIG. 1 (start of the return stroke).

 During the return stroke, the speed v1 of forced movement of the blank is varied from zero to the left dead center (point E in Figure 5) to the maximum value, then decreased again to zero at the right dead center (point F in Figure 5). At the end of the return stroke (right dead center), the forced movement of the draft 1 with the mandrel 2 is reversed, then the forced movement of the blank (forward stroke) is carried out with variation of the speed v1 according to the harmonic law (close to the sinusoldal law). The variation in the speed v1 of forced displacement of the blank 1 in the forward stroke corresponds to the FCDE portion of the graph in FIG. 5. The maximum value of the speed v1 in the forward stroke and in the return stroke depends on the operating speed (rate market) of the rolling mill. If the operating speed increases, v1 also increases.

 During the return stroke, when the blank 1 with the mandrel 2 is forcibly displaced against the rotation of the working cylinders 3, the linear speed V3 of these is varied according to a law characterized by the portion AB of the graph of FIG. 5. At the start of the outward stroke (portion BC of the graph), the rotation of the working cylinders 3 takes place with an increase in their linear speed from v3 to v2 at point C. At this point, the blank 1 is contacted by the cylinders 3, the speed v1 of forced displacement of the blank 1 then being tuned with the speed v2 of its displacement by the working cylinders 3 in value and in direction.

 The forced displacement continuing (outward stroke), the blank 1 is reduced on the mandrel 2 by the working cylinders 3 to the dimensions of the finished tube. During the reduction (outward stroke), the speed v1 of forced displacement of the blank 1 is tuned in value and direction with the speed v2 of its displacement by the working cylinders 3 (portion CD of the graph in FIG. 5).

During reduction, these speeds are varied according to the harmonic law (close to the sinusoidal law). At the end of the outward stroke, the reduction of the blank 1 on the mandrel 2 by the working cylinders 3 to the dimensions of the finished tube is completed (point D of the graph of variation of speeds v1 and v2 in FIG. 5) . The contact of the cylinders 3 on the blank 1 ceases. The speed v1 of forced movement of the blank 1 is reduced to zero (DE portion of the graph) (left dead center), and the speed v2 is decreased to the value of speed v3 (DA portion of the graph) . This completes the rolling cycle.

 The harmonic nature (close to the sinusoidal law) of the variation of the speed of the forced reciprocating rectilinear movement of the blank 1 with the mandrel 2 and of the mechanisms retaining them makes it possible to decrease the maximum value of the acceleration w (figure 5) , thus lowering the dynamic loads and, thereby, increasing the operating speed and, consequently, the production of the rolling mill. In addition, the variation of the speed of the reciprocating rectilinear movement of the blank 1 with the mandrel 2 and of the mechanisms retaining them according to a harmonic law makes it possible to resolve in a simple and sure manner the question of the balancing of the dynamic torque at the shaft of the sinus mechanism.

 The pilgrim tube rolling mill comprises a fixed cage 4 (FIG. 6), in which the working rolls 3 are mounted, driven in a continuous rotational movement by a main actuation system 5.

The main actuation system 5 comprises an electric motor 6, a belt transmission 7 and a reduction gear 8. The rotation of the motor 6 is transmitted by the belt transmission 7 and the reduction gear 8 of the main actuation system 5 to a converter 9 of uniform rotation in non-uniform rotation. The converter 9 of uniform rotation to non-uniform rotation transmits the rotation to the working cylinders 3 by means of the extensions 10. The converter of uniform rotation to non-uniform rotation can be any mechanism capable of ensuring the rotation of the working cylinders 3 in such a way that the speed of movement of the blank 1 by the working rolls 3 varies in the forward stroke (during the deformation of the blank 1 by the working rolls 3) according to a harmonic law (close to the law sinusoidal).

 The reduction gear 8 of the main actuation system 5 comprises pinions 11 and 12, by means of which the rotation is transmitted to the rotor 13 of a sinus mechanism 14, mounted on bearings in a casing 15 common with the reduction gear 8 of the system 5 main actuation.

 Such a constructive arrangement of the sinus mechanism 14 simplifies the design of the rolling mill.

 However, in another design variant, the sinus mechanism 14 can be mounted in its own casing and kinematically linked to the reduction gear 8 of the main actuation system 5.

 In the casing 15, a wheel 16 with internal teeth is mounted coaxially with the rotor 13. The rotor 13 has an eccentric bore in which is mounted on bearings a shaft 17 carrying a pinion 18 mounted fixed and meshed with the toothed wheel 16. End of the shaft 17 is wedged a crank pin 19. The radius of the original circumference of the pinion 18 is made equal to the radius of the crank pin 19 (crank radius), and the diameter of the original circumference of the pinion 18 is made equal to the radius of the original circumference of the fixed gear 16.

 Such a sinus mechanism 14, while being of simple kinematics and of reliable design (all the elements, except the crank pin 19, are animated by a uniform continuous rotation movement) makes it possible to carry out the transformation of the continuous rotation into movement alternating rectilinear pin 19 with a speed varying according to a harmonic law (sinusoidal).

 In the example considered, the sinus mechanism 14 is produced as described above. However, it can also be of any other known design fulfilling the same function.

 The crank pin 19 is coupled by a connecting rod 20 to the arm 21 of the mechanism 22 of reciprocating rectilinear movement of the carriage 23 (Figures 6, 7, 8). The arm 21 is wedged on the end of the rotation shaft 24, which is mounted on bearings 25. On its second end, the shaft 24 carries an arm 26 having a radial groove in which is placed a shoe 27 (figure 9) mounted so that it can execute an adjustment movement. The adjustment movement of the shoe 27 is effected by means of wedges 28, by means of screws 29. The shoe 27 is coupled by a connecting rod 30 to the front coupling mandrel 31, which is mounted in the runners of a frame 32.

 Thanks to the sinus mechanism 14 (FIG. 6), to the kinematic connection of its crank pin 19, by the connecting rod 20, to the arm 21 of the mechanism 22 of reciprocating rectilinear movement of the carriage 23, wedged on one end of the rotation shaft 24, in conjunction with the arm 26 mounted on the second end of the rotation shaft 24 and having a radial groove in which is placed a shoe 27 (FIG. 9) capable of carrying out an adjustment movement and coupled by a connecting rod 30 to the mandrel 31 d '' front hitch, it is possible to vary the speed of forced movement of the blanks 1 with the mandrels 2 (Figure 6) in forward and reverse strokes according to a harmonic law (close to the sinusoidal law), to carry out these movements during equal times and to grant with great precision, during the outward stroke, the speed of forced movement of the blanks 1 with their speed of movement by the working cylinders 3 when the rolling route changes. These favorable features make it possible to lower the extreme values of the accelerations of the reciprocating rectilinear movement of the blanks 1 and of the mechanisms retaining them, which makes it possible to increase the operating speed and, consequently, the production of the rolling mill.

 The end 34 of the shaft 35 of the converter 36 of continuous rotation to intermittent rotation is mounted in the body 33 of the front coupling mandrel 31 by means of bearings. In this same body 33 of the mandrel 31 (FIGS. 6,7) of the front coupling are placed pins 37, mounted on bearings and carrying tightening heads 38 and pinions 39, which are meshed with a pinion 40. The pinion 40 is wedged on the end 34 of the shaft 35. The shaft 35 of the converter 36 of continuous rotation to intermittent rotation is engaged coaxially in the bore of a sleeve 41 so that it can slide axially. The sleeve 41 comprises a bevel gear 42 and is mounted in the fixed casing 43 of the converter 36. The sleeve 41 is rotated by its pinion 42 driven by the pre-pinion ar 44, which is coupled by an intermediate shaft 45 to the shaft 46 on which the pinion 12 is mounted. The sleeve 41 is equipped with support rollers 47, which cooperate with helical surfaces of the shaft 35, the second end 48 of which is coupled by a ball joint 49 to the screw 50 advancing, cooperating with the nuts 51 of the mandrel 52 for advancing the blanks 1 and mounted on bearings in the body 53 of the carriage 23.

The mounting of the end 34 of the shaft 35 of the converter 36 of continuous rotation to intermittent rotation on bearings in the mandrel 31 of the front coupling and the coupling of its end 48 to the advancing screw 50 by a ball joint 49 make it possible to solve in a simple and reliable way the question of the transmission of the reciprocating rectilinear movement of the mandrel 31 of the front coupling to the carriage 23. The presence of the drive sleeve 41, the support rollers 47 of which cooperate with the helical surfaces of the shaft 35 makes it possible to transform in a simple manner the continuous rotation of the sleeve 41 into intermittent rotation of the shaft 35, using for this the reciprocating rectilinear movement of the blank 1 and of the retaining mechanisms, suitable for rolling in pilgrim's step. In such a system, during the outward stroke, the rotations of the shaft 35 and of the sleeve 41
are entrenched, so the shaft 35 moving in the axial direction does not rotate around its axis.

During the return stroke, the rotations of the shaft 35 and of the sleeve 41 add up, so the shaft 35 rotates by a determined angle. Such a converter design
36 of continuous rotation in intermittent rotation and such a kinematic connection of its shaft 35 with the mandrel 31 of front coupling and the advancing screw 50 make it possible to increase the operating speed of said mechanisms and of the whole rolling mill, and consequently, its production.

The end of the advancement screw 50 mounted in the carriage 23 is made hollow. At the end of the bore of the screw 50 is mounted a coaxial sleeve 54, in the central hexagonal hole which is engaged coaxially the hexagonal end 55 of the shaft 56 of advancement of the reducer
57 advancement and rotation. In the body 53 of the carriage 23 there are pins 58 mounted on bearings and provided with mandrels 59 for tightening the mandrel carrier bars 60, carrying the rolling mandrels 2. The end
48 of the shaft 35 has a hexagonal transverse profile. he
is engaged coaxially in the hole of the pinion shaft 61 of input of the mechanism 62 for transmitting the rotation and cooperates with the hexagonal hole of a socket 63 mounted in the bore of the pinion shaft 61 of The mechanism 62 for transmitting the rotation is mounted on the input side of the cylinder cage 4, in which the working cylinders 3 are mounted in the rails of the frame 64, between the cylinder 65 of the lower support and the cylinder 66 upper support. The rotation transmission mechanism 62 is produced in the form of a single-stage reduction gear. It consists of a housing 67 in which are mounted on bearings the hollow pinion shaft 61 input already mentioned and the output pinion shaft 68, coupled by a sleeve 69 to one of the ends of the shaft 70 of rotation.

 The presence of the transmission mechanism 62, its mounting on the input side of the cage 4 in combination with its simple and reliable design, make it possible to transmit the rotation from the shaft 35 to the rotation shaft 70 with a minimum number of meshes (only one pair of pinions 61, 68) -. However, the design indicated of the rotation transmission mechanism 62 does not exclude the use of any other variant ensuring reliable and precise transmission of the rotation from the shaft 35 to the rotation shaft 70.

 The rotation shaft 70 has a hexagonal transverse profile. it is engaged coaxially in the bore of the hollow pinion shaft 71, mounted in the body 72 d; mandrel 52 for advancing the blanks 1, and cooperates with the hexagonal hole of a socket ~ 73, mounted coaxially in the bore of the pinion shaft 71. Besides the pinion shaft 71, in the body 72 of the mandrel 52 for advancing the blanks 1 are mounted an intermediate pinion 74 (FIGS. 6, 7) and pins 75 with heads 76 for clamping and pinions 77 for rotation. The pinion shaft 71 is meshed with the intermediate pinion 74, and the pinion 74, with the pinions 77. The rotation shaft 70 is also engaged coaxially in the bore of a hollow pinion shaft 78 mounted in the body. 53 of the carriage 23, and cooperates with the hexagonal hole of a socket 79 mounted coaxially in the bore of the pinion shaft 78. As in the advancement mandrel 52, an intermediate pinion 80 is mounted in the body 53 of the carriage 23. Rotation pinions 81 mounted on pins 58 are kinematically linked to the rotation shaft 70, using the intermediate pinion 80 and the pinion shaft 78. The second end of the shaft 70 of rotation is coupled by a sleeve 82 to one of the ends of the input shaft 83, mounted in the casing 84 of the reduction gear 57. In the casing 84 of the advancement reduction gear 57, in addition to the indicated input shaft 83, there is mounted an intermediate shaft 85 with a front half-sleeve 86. The shaft 85 is linked by a pair of spare pinions 87 to the input shaft 83 and it is aligned with advancement shaft 56. On the grooved end 88 of the advancement shaft 56 is mounted a bilateral half-sleeve 90, which can slide under the action of a hydraulic cylinder 89. On the advancement shaft 56 is placed a pinion shaft 91 , mounted on bearings and meshed with a double conical and cylindrical pinion 92, which is mounted on the input shaft 83 using bearings. The double conical and cylindrical pinion 92 is also meshed with a conical pinion 93, mounted on a shaft 94 which is coupled by a sleeve 95 to a motor 96 for rapidly moving the sleeve 52 for advancing the blanks 1.

 The design variant which has just been described, in which the transmission of the intermittent rotation from the shaft 70 of rotation to the shaft 50 of advancement is effected by means of a pair of spare pinions 87, allows to reduce to a minimum the number of gears in the advancement reducer 57, to increase its reliability and, consequently, the operating speed and the production of the whole rolling mill.

 However, this does not exclude the possibility of using other constructive variants of the advancement reducer 57, capable of ensuring the transmission of the rotation of the shaft 70 of rotation to the advancement screw 50 by the intermediate of a pair of spare pinions 87.

 In the sinus mechanism 14, on the second end of the shaft 17, is mounted an additional crankpin 97 of the same radius as that of the main crankpin 19, but offset by 1800 relative to the crankpin 19. The additional crankpin 97 (Figure 10) is coupled by a connecting rod 98 to one end of a lever 99, mounted on bearings 100 and carrying at its ends weights 101 which balance each other (taking into account the mass of the vertical connecting rod 98), of value equal to the mass of the parts moving in an alternating rectilinear motion.

The presence of an additional crankpin 97, mounted on the second end of the shaft 17 of the sinus mechanism 14 with an offset of 1800 relative to the crankpin t9, and its connection by a vertical rod 98 to the lever 99 carrying at its ends weight 101 reciprocally balancing each other, of value equal to the mass of the parts of the rolling mill moving in a reciprocating rectilinear movement (mandrel 31 for front coupling, shaft 35, screw 50 for advancement, mandrel 52 for advancement with the blanks 1, carriage 23 with the mandrel carrier bars 60), make it possible to obtain on the shaft 17 two dynamic couples which balance each other: that due to said masses of the rolling mill driven by an alternating rectilinear movement and that due to the weights 101 of the lever 99.These couples
dynamics are equal in value, but their signs are opposite, due to the 1800 shift of crank pins 19 and 97 between them. Such a balance of the dynamic couples on the shaft 17 of the sinus mechanism 14 makes it possible to suppress their transmission to the elements of the main actuation system 5, thus making the running of the whole rolling mill smoother, of increasing its operating speed and its production.

 However, this does not exclude the use of balancing mechanisms of other designs, capable of ensuring the balancing of the dynamic couples and of allowing an increase in the operating speed of the rolling mill and its production.

 The rolling mill operates as follows.

 Before starting rolling, the blanks 1 of tubes are brought by a distributor to the loading line and transferred using a feeding device. The dispenser and the feed device have no influence on the substance of the invention. They are of the same design as that ordinarily adopted for front-feed rolling mills, so they are not shown in the drawings.

 Before loading, the clamping mandrels 59 release the ends of the mandrel bars 60 and the blanks 1 of tubes are threaded onto the mandrel bars 60.

Simultaneously with the interlocking of the blanks 1, the advancement mandrel 52 is moved backward in rapid traverse to its extreme left position. The clamping heads 76 of the advancement mandrel 52 are then loosened so that the tube blanks 1 can freely pass through them. For rapid retraction of the mandrel 52 for advancing the blanks 1, the bilateral half-sleeve 90, mounted if the grooved end 88 of the advancement shaft 56, is engaged with the pinion-half-sleeve 91 and uncoupled from with the half-sleeve 86 to cut the kinematic chain, this maneuver being ensured by the hydraulic cylinder 89 with short stroke. This done, the motor 96 is started. Its rotation is transmitted to the double conical and cylindrical pinion 92 by the sleeve 95, the shaft 94 and the bevel gear 93. The rotation of the pinion 92 is transmitted to the advancement screw 70 via the pinion-half-sleeve 91, the bilateral half-sleeve 90 and the rotation shaft 56. By cooperating with the nuts 51, the advancement screw 70 ensures the rapid displacement of the mandrel 52 for advancing the blanks 1. To allow, if necessary, the rapid displacement of the mandrel 52 in the desired direction, the rapid displacement motor 96 is made reversible.

 When the advancement mandrel 52 reaches its extreme position, for reloading, the motor 96 is stopped and the jack 89 returns the bilateral half-sleeve 88 to its extreme left position, by uncoupling it from the pinion-half-sleeve 91 and by engaging the front half-sleeve 86 of the intermediate shaft 85, which ensures the connection of the rotation shaft 70 with the advancing screw 50. After presentation of the blanks 1 of tubes in the working cylinders 3, the mandrels 59 tighten the ends of the mandrel bars 60, and the clamping heads 76 of the advancement mandrel 52 tighten the blanks 1 of tubes.

 This done, the cooling oil circuit (not shown in the drawing) is put into action and the electric motor 6 of the main actuation system 5 is started. The rotation of the motor 6 is transmitted by the belt transmission 7 to the converter 9 from uniform rotation to non-uniform rotation. The non-uniform rotation of the converter 9 is transmitted to the working cylinders 3 by the extensions 10. The speed of movement of the blanks 1 by the working cylinders 3 in forward travel varies according to a harmonic law (close to the sinusoidal law). At the same time, the rotation of the motor 6 is transmitted by the pinions i1 and 12 to the rotor 13 of the sinus mechanism 14. The rotor 13 rotates the shaft 17 which is mounted there on bearings with eccentricity, and the pinion 18 of the 'shaft 17 rolls along the fixed gear 16. The crank pin 19 mounted on one end of the shaft 17 then performs a reciprocating rectilinear movement at a speed which varies according to a sinusoidal law. The frequency of movements of the crankpin 19 is equal to the frequency of rotation of the working cylinders 3 and the durations of back and forth are equal.

The movement of the crankpin 19 is transmitted to the connecting rod 20 of the mechanism 22 of reciprocating rectilinear movement of the carriage 23. By means of the connecting rod 20, the arm 21 and the rotation shaft 24, mounted on bearings 25, the movement is transmitted to the arm 26, in the radial groove of which is mounted, with the possibility of adjustment displacement, the shoe 27, which is coupled by the connecting rod 30 to the mandrel 31 of the front coupling, sliding in the runners of the frame 32. As the value of the displacement of the crank pin 19 and, consequently, that of the angle of oscillation of the arm 21, of the shaft 24 of rotation and of the arm 26 are constant, the adjustment of the speed of forced displacement of the blanks in forward stroke with the speed of their displacement by the working cylinders 3 is obtained in this rolling mill by varying the radius R of oscillation of the shoe 27. To increase the radius R, the shoe 27 is moved upward, which causes an increase in the speed of the chuck 31 of att elage before and, therefore, the speed of the mandrel 52 for advancement with the blanks 1 linked thereto. To decrease the radius
R, the shoe 27 is moved down in the groove, using the corners 28, which causes a reduction in the forced displacement of the blanks 1 and, consequently, their speed (the operating speed of the rolling mill remaining the same )
The front coupling mandrel 31 is kinematically linked to the advancement screw 50 by means of the shaft 35, the end 34 of which is mounted on bearings in the body 33 of the mandrel 31 and the second end 48 of which is coupled to said screw 50 by the ball 49. The advancing screw 50 cooperates with the nuts 51 of the mandrel 52 for advancing the blanks 1; its second end is mounted in the carriage 23 and, in this way, the front coupling mandrel 31 executes, in common with the shaft 35, the advancement screw 50, the carriage 23 and the advancement mandrel 52 with the blanks 1 fixed in its clamping heads 76, a forced reciprocating rectilinear movement, printed by the arm 26 using the connecting rod 30. The speed of movement of all these elements in the forward and return stroke varies according to a law harmonic (close to the sinusoldal law), and the durations of the said strokes are equal. Thus, during the outward stroke, the speed of forced displacement of the blanks 1 is brought into agreement in value and direction with the speed of their displacement by the working cylinders 3 (at the rolling radius).

 The movement of the shaft 17 of the sinus mechanism 14 is transmitted by the additional crankpin 97, mounted on its second end, and by the vertical connecting rod 98, to the weights 101 located at the ends of the lever 99 mounted on the bearings 100. The weights 101 reciprocally balance and are animated by an oscillatory movement by the connecting rod 98, from the additional crankpin 97, at a speed varying according to a harmonic law (close to the sinusoidal law), identical to the law of variation of the speed of the reciprocating rectilinear movement of the blanks 1 with the mandrels 2 and the mechanisms retaining them. However, due to the offset at 1800 of the additional crank pin 97 relative to the crank pin 19, the dynamic torques generated on the shaft 17 of the sinus mechanism 14 by the weights 101 and by the blanks 1 with the mandrels 2 and the mechanisms retaining them animated by an alternating rectilinear movement, are at all times equal in value and with opposite signs. This results in their reciprocal balancing on the shaft 17. This balancing of the dynamic couples makes it possible to release the main actuation system 5 from their action and thereby increase the operating speed and, consequently, the production of the rolling mill.

 The frequency of the reciprocating rectilinear movement of the blanks 1 with the mandrels 2 corresponds in the rolling mill considered to the frequency of rotation of the working cylinders 3, and the speed of forced displacement of the blanks 1 in forward travel is tuned with great precision with their speed displacement by the working cylinders 3. The matching of these speeds allows, compared to traditional rolling cage rolling mills, to reduce by 8 to 10 times the axial forces exerted on the blank 1 and the mandrel 2 by the cylinders 3, and thus reduce the harmful effects. which are linked to them: increased wear of the advancement and rotation mechanism, junction of the ends of the laminated tubes, deterioration of the quality of their surface.

 The advancement of the blanks 1, obtained by transmitting a relative displacement "m" relative to the mandrels 2 during the return stroke, is carried out as follows. The shaft 35, engaged coaxially in the sleeve 41, moves during the return stroke in the axial direction, because its end 34 is mounted in the mandrel 31 of the front coupling. The helical surfaces produced along the axis of the shaft 35 cooperate with the rollers 47 mounted on the sleeve 41. The sleeve 41 is driven in continuous rotation by the toothed wheel 42, from the pinion shaft 44, which is connected by the intermediate shaft 45 to the shaft 46 of the pinion 12 located in the reduction gear 8 of the main actuation system 5. In such a system, during the return stroke, the rotations of the sleeve 41 and of the 'shaft 35 are added, this mistletoe results from the cooperation of the helical surfaces of the shaft 35 with the rollers 47 during the axial displacement of the shaft 35. It follows the rotation of the shaft 35 by an angle determined. During the outward stroke, said rotations are entrenched and the resulting rotation of the shaft 35 is zero.

 During the return stroke, the rotation of the shaft 35 of the converter 36 of continuous rotation to intermittent rotation is transmitted by its hexagonal end 48, the sleeve 63 cooperating with it and fixed in the bore of the pinion 61, the pinion 61 , the pinion shaft 68 of the mechanism 62 for transmitting the rotation and the sleeve 69, to the shaft 70 for rotation. The shaft 70 of rotation transmits the rotation, via the sleeve 82, of the shaft 83 of the reduction gear 57 of advancement, of the pair of spare pinions 87, of the intermediate shaft 85, of the front half-sleeve 86, to the bilateral half-sleeve 90, mounted on the grooved end 88 of the advancement shaft 56. The advancement shaft 56 transmits the rotation to the advancement screw 50, by means of its hexagonal end 55, engaged coaxially in the hole of the socket 54 with which it cooperates and which is fixed in the bore of the screw 50. By acting throughout the duration of the return stroke, by means of the nuts 51 of the mandrel 52 advancement, in the clamping heads 76 of which the blanks 1 are fixed, the screw 50 advances these blanks 1 in the working cylinders 3 of length "m", by transmitting to them an additional relative displacement relative to the mandrels 2 The value Wm "of the advance is adjusted by changing the spare pinions 87 of the gear 57 advancement.

 Thanks to the continuous rotation of the sleeve 41 of the converter 36 of continuous rotation in intermittent rotation, the rollers 47 of which cooperate with the helical surfaces of the shaft 35 which is engaged therein coaxially, the design of the converter 36 of continuous rotation in intermittent rotation is considerably simplified and its reliability is much greater.

 The presence of the rotation transmission mechanism 62 makes it possible to carry out, with a minimum number of pinions (two pinions 61 and 68), the transmission of the rotation from the shaft 35 of the converter 36 to the rotation shaft 70, from which the rotation is transmitted to the advancing screw 50 also by a single pair of spare pinions 87.

 The indicated constructional features of the rolling mill which is the subject of the invention make it possible to significantly reduce the number of gears in the kinematic chain of the advancement mechanism, the most complicated and the most highly stressed by the dynamic loads in the rolling mill.

 The features mentioned make it possible to increase the operating speed of the entire rolling mill and, consequently, its production.

 The blanks 1 are rotated in common with the mandrels 2 and the mandrel bars 60 during the return stroke, simultaneously with their advancement.

The rotation of the rotation shaft 70 is then transmitted to the blanks 1 by the sleeve 73 with which it cooperates, the pinions 71, 74 and 77, the pins 75 and the clamping heads 76, in which the blanks 1 are fixed.

Similarly, the rotation of the shaft 70 is transmitted to the chuck bars 60, clamped in the chucks 59, which are mounted at the end of the pins 58 of the carriage 23. The pins 58 receive the rotation via pinions 81 mounted on them, the intermediate pinion 80 and the pinion shaft 78, from the rotation shaft 70.

 In this way, during the return stroke, the blanks 1 and the mandrels 2, fixed on the mandrel bars 60, rotate in synchronism by the same angle.

 The rolling of the blanks 1 takes place until the advancement mandrel 52 arrives at the stand 4, then the rolling mill is stopped. The blanks 1 are then loosened by the heads 76 of the advancement mandrel 52, the ends of the mandrel carrier bars 60 are loosened by the mandrels 59 of the carriage 23 and new tube blanks 1 are threaded onto the mandrel carrier bars 60 , until their edges stop against the edges of incompletely laminated blanks. The ends of the mandrel carrier bars 60 are clamped in the mandrels 59 of the carriage 23, and the blanks 1 are clamped in the heads 76 for clamping the mandrel 52 for advancing the blanks 1. The heads 38 for clamping the mandrel 31 of front hitch are engaged. They clamp the incompletely laminated blanks and thus prevent their uncontrolled axial movement during the outward and return travel under the action of inertial forces.

The rotation of the incompletely laminated tube blanks is also carried out during the return stroke, in synchronism with the rotation of the newly engaged blanks.

For this, the rotation of the shaft 35 of the converter 36 of continuous rotation to intermittent rotation is transmitted by the pinion 40, mounted on the end 34 of the shaft 35, to the pinions 39 mounted on the pins 37 of the mandrel 31 of front hitch. The pins 37 rotate the heads 38 fixed on their ends, in common with the incompletely laminated blanks 1 which are clamped there. The incompletely laminated blanks 1 are pushed by the new ones until the rear edge of the finished tube leaves the cage. Then the clamping heads 38 of the front coupling mandrel 31 loosen the tube and the latter is transferred from the channel (not shown) to the receiving bins by ejectors (not shown) and cut into predetermined lengths. This does not exclude the cutting of the tubes in the receiving channel.

 The advance value "m" is chosen according to the material of the blanks and the total reduction per pass. It can vary from 1 to 8 mm.

 The rolling mill which is the subject of the invention is endowed with wide technological possibilities and makes it possible to laminate blanks 1 of tubes made of extremely varied metals and alloys, with a reduction of up to 90% in wall thickness and up to 60 % in internal diameter.

 The rolling mill according to the invention is particularly effective in the rolling of tubes made of materials which are difficult to deform and which tend to stick.

 Thanks to the simple and reliable design of the mechanism 22 of reciprocating rectilinear movement of the carriage 23, of the reduction gear 57 for advancing and rotating the blank 1, as well as to the new kinematic connections of these mechanisms to each other and to the kinematic connection of the converter 9 from uniform rotation to non-uniform rotation with the working cylinders 3, it has proved possible to reduce the dynamic loads in these mechanisms and to balance the dynamic torques, due to the rectilinear alternating movement of the blanks 1 and of the mechanisms retaining them, on the shaft 17 of the sinus mechanism 14. This made it possible to increase the operating speed (rate) of the rolling mill up to 160 strokes per minute, in the case of the use of working cylinders 3 with a diameter of 200 mm, and up to 140 strokes per minute in the case of the use of working rolls 3 with a diameter of 300 mm, the rolling being carried out on two lines, hence an increase in the production of the rolling mill.

In addition, the rolling mill which is the subject of the invention makes it possible to laminate solid blanks (bars). For this, the mandrel bars with the mandrels are removed and the rolling is carried out by the process described above.
In addition to the advantages indicated above, the design of the rolling mill in accordance with the invention has made it possible to automate it in a simple and safe manner.

 Example.

 According to the method of rolling tubes with pilgrim's step which is the subject of the invention, the blank 1 is forcibly displaced with the mandrel 2 in the forward stroke and in the return stroke, the durations of these strokes being equal.

The speed of forced displacement of the blank 1 with the mandrel 2 and of the mechanisms retaining them (carriage 23, mandrel 52 for advancement, mandrel 31 of front coupling) and the speed of displacement of the blank 1 by the cylinders 3 are varied according to a harmonic law (close to the sinusoidal law). The acceleration of the blank 1 with the mandrel 2 and of the retaining mechanisms, driven by an alternating rectilinear movement, varies according to a cosine law: W = V 2 S cos Y t
2
W being the acceleration of the masses "M" (blanks 1 with
mandrel 2 and mechanisms retaining them) animated by
alternative rectilinear movement. In the example con
flabbergasted M = 97 kg.s2 / m; W, the angular velocity; The average displacement of the blank 1 for all
the assortment. In the example considered S = 0.3 m; 9, the angle of rotation of the rotor 13 of the sinus mechanism 14.

W W. n
30 n being the speed of rotation of the rotor 13. In the example
considered n = 120 rpm.

# = 3.14.120
= 12.56s-1.

30
= 1800 when the mass "M" is in neutral, where the acceleration W is maximum.

W = 12.562. cos 1800 = -23.81 m / s2
2
The inertia force F of the masses "M" driven by an alternating rectilinear movement is determined by the formula
F = MW

In the example considered:
F = 97. (- 23.81) = -2309.6 kg.

 In the known method of rolling tubes with pilgrim steps, the acceleration is W = -42.85 m / s, and the force of inertia, F = -4151.6 kg.

 The example shows that in the rolling process of pilgrim pitch tubes which is the subject of the invention, the acceleration and the force of inertia are almost twice as small as in the known process.

This makes it possible to increase the speed of rotation of the rotor 13, that is to say to increase the operating speed of the rolling mill and, consequently, its production.

Claims (7)

 1. A method of rolling pilgrim's tubes in a fixed cage (4) with working cylinders (3) rotating continuously and whose longitudinal profile of the useful area of the groove is made curvilinear, of the type in which, when of the return stroke of the blank (1) with the mandrel (2) against the rotation of the cylinders (3), the draft (1) and the mandrel (2) are forcibly moved with simultaneous rotation around their longitudinal axis and advancement of part of the blank (1) in the cylinders (3), then, during the forward stroke, the blank (1) is forcibly moved with the mandrel (2) in the direction of rotation of the cylinders (3), the speed of this displacement being matched with the speed of displacement of the blank (1) by the working rolls (3) and said part of the blank (1) being reduced on the mandrel ( 2), characterized in that the forced displacement speeds of the blank (1) with the mandrel (2) in the forward and reverse stroke and the displacement speed of the blank (1) by the working cylinders (3) are varied according to a harmonic law, the forced displacement of the blank (1) in the outward and return stroke being effected for equal times.  2. Rolling mill for implementing the method which is the subject of claim 1, comprising a fixed cage (4) with working rolls (3) driven in a continuous rotational movement by a main actuation system ( 5) to which are kinematically linked a converter (9) of uniform rotation to non-uniform rotation and a mandrel (52) for advancing the blank comprising coaxial nuts (51) which cooperate with an advancing screw (50) engaged together with chuck bars (60) in a carriage (23) whose reciprocating rectilinear movement mechanism (22) is linked to said main actuation system (5), to which are also linked a front coupling chuck (31 ) and a mechanism for advancing and rotating the blank, comprising a converter (36) of continuous rotation into intermittent rotation, characterized in that the converter (9) of uniform rotation into non-uniform rotation is connected by its shaft outlet to working cylinders (3), the main actuation system (5) is connected to a sinus mechanism (14) which comprises a shaft (17) provided with a crank pin (19) and connected to the mechanism (22) ensuring the reciprocating rectilinear movement of the carriage (23) and comprising a connecting rod (30) linked to the front coupling mandrel (31), the latter being kinematically linked to the converter (36) of continuous rotation in intermittent rotation, said converter (36) comprising a shaft (35) engaged in a sleeve (41) so that it can slide axially and the end (34) of which is mounted by means of a rolling bearing in said mandrel (31), and the other end (48) of which is connected to the advancement screw (50) by a ball joint (49).  3. Rolling mill according to claim 2, characterized in that the advancement screw (50) is linked by a couple of replaceable pinions (87) to one of the ends of the rotation shaft (70), the second end of which (70) is coupled to the output shaft of the rotation transmission mechanism (62), inside the hollow input shaft (61) from which the shaft (35) of the converter (axially) is engaged 36) of continuous rotation in intermittent rotation.  4. Rolling mill according to one of claims 2 and 3, characterized in that the mechanism (22) of reciprocating rectilinear movement of the carriage (23) comprises, in addition to the connecting rod (30) 5 an arm (26) mounted on a shaft ( 24), kinematically linked to the first crankpin (19) of the sinus mechanism (14) and having a radial groove in which is disposed a shoe (27) mounted so as to be adjustable in position and articulated to the connecting rod 130).  5. Rolling mill according to one of claims 2, 3 and 4, characterized in that the shaft (17) of the sinus mechanism (14) is equipped with a second crankpin (97) mounted with an angular offset of 180 relative to to the first crank pin (19), this second crank pin (97) being connected by a vertical connecting rod (98) to one of the ends of a lever (99) carrying on its two arms weights (101) balancing each other.  6. Rolling mill according to one of the preceding claims, characterized in that, in the converter (36) of continuous rotation in intermittent rotation, the sleeve (41) is mounted so as to be able to receive a continuous rotational movement from the system main actuation (5) to increase the angle of rotation of the shaft (35) of the converter (36) when moving the blank (I) back and to suppress the rotation of this same shaft (35) when moving the blank (1) forward.  7. Tubes characterized in that they are laminated according to the method according to claim 1.