EP0272957B1 - Automatic machine for tamping coal cakes to become coked - Google Patents

Description

The invention relates to a machine for automatically pounding coal mixtures (possibly with other constituents) to prepare pounded coal bars which are then placed in a coke oven to be transformed into coke.

Machines of this type are already known, the role of which is to pack a mixture of coals in a mold also called pounding box. The mixture of fine charcoal is poured into the mold through the upper part of the latter and it is compacted by at least one pestle which has a pounding sole and which is constantly lifted and left in free fall on the coal to be compacted. The box has a small width to which is substantially equal to that of the pounding sole of each pestle; the ramming box has a significant length. In known machines, there are several pestles mounted side by side on a traveling crane in the lengthwise direction of the ramming box. The latter moves over the entire length of the box, during the operation of the drumsticks. Each movement corresponds to a ramming stroke which is approximately equal to the dimension of the soles of the drumsticks in the direction of movement. Thus, due to this movement of the pestles with the traveling crane, the coal ends up being pounded at all points in the direction of the length of the box.

Each pestle comprises a vertically disposed profile having a core which is covered on both sides with a lining with a high coefficient of friction; this core is contained on the one hand between two opposite eccentrics driven in rotation of a lifting device and on the other hand between two opposing elements of a braking and retaining device.

At each rotation of a revolution, the eccentrics tighten the web of the profile between them and propel it upwards, then release it and drop it freely. Thus occurs the pounding at each turn of the eccentrics by the sole mentioned above which is mounted at the lower end of the profile. When there are several neighboring pestles, the vertical movements of the profiles are not simultaneous so that the mechanical stresses are distributed over time.

The eccentrics of each pestle are rotated by a gear transmission made from the output shaft of a speed reducer itself coupled in rotation with an electric motor.

As a result of the conventional design, exposed above, of the pounding machines, their use has several drawbacks, one of the most serious of which is that the duration of the pounding of the entire surface of the coal contained in the pounding box is important.

The main object of the invention is to provide a pounding machine of new design with which the duration of the pounding is significantly reduced; in addition, although the shelling is carried out in a shorter time, the invention has the secondary aim of improving the quality of the shelling, in particular the homogeneity and the density of the shelling.

A further object of the invention is to achieve a robust and simple design which reduces the costs of production and maintenance of the pounding machine and which allows complete automation of the pounding operation.

Another object of the invention is to equip the machine defined above with a braking and retaining device for the drumsticks which is simpler in its design and more economical in its operation than the known conventional means.

In conventional pounding machines, the braking device of each pestle has as opposing braking elements two jaws opposite one another which contain between them the core of the profile of said pestle.

Since the eccentrics generally rotate at the speed of one revolution per second, there is a difficulty in coordinating with their movements the closing and opening movements of the brake shoes. In addition, it is preferable that the jaws close on the soul of the pestle just when the speed of this upward pestle goes to zero before it begins to descend. For various reasons which depend, among other things, on friction and wear, the eccentrics do not always launch the pestle upwards at an always equal speed. For this reason, the time which elapses after the moment when the eccentrics have ceased to tighten the pestle between them and the moment when the speed ends up canceling out is a variable time.

As a result, despite a relatively complex and costly assembly and control mechanism for the brake shoes, the shoes wear and even quickly deteriorate the lining with a high coefficient of friction of the core.

On the other hand, when you want to clear the box and put the rammer out of the way, you have to raise each pestle to a higher level of rest. This is when the brake shoes are used. When the eccentrics have launched the pestle upwards and released it, it is prevented from falling by tightening the web of the profile between the brake shoes. These jaws are opened as soon as the eccentrics tighten the web of the profile again to throw it up again; the pestle is immobilized between the jaws as soon as the eccentrics have released it. This is continued by successive ascent strokes until the pestle reaches its highest position where it is immobilized until the next use of the rammer.

It is therefore extremely desirable to equip an improved pounding machine such as that of the present invention with a braking and retaining device whose operation does not require coordination which is difficult to achieve with the operation of the eccentrics and is not the cause of deterioration or even excessive wear of the pestle friction lining.

In this field, the state of the art can be illustrated by the document FR-A-2 339 665 in which there is described a device for immobilizing the pestles of a coking plant rammer in the raised position. This device is composed of two sectors with an angular extent of approximately 50 °, placed on either side of the core of the profile forming part of each pestle, with an eccentric non-tangential position; thus, these two sectors when they are applied together against the core are attracted by the latter in a direction tending to bring them together and to wedge between them this core, preventing it from descending further under the effect of gravity. Each sector is associated with a toothed segment; these toothed segments mesh together and one of them is propped up on a maneuverable shaft in rotation using a jack, which requires good coordination, difficult to carry out and to keep over time, of the control of this cylinder and eccentrics of launching up the cylinders, as said above.

Another document FR-A-2 340 363 describes a flow device in which the pestles are distributed over three pestle-carrying carts coupled together to form a mobile assembly. This assembly is moved alternately in the direction of the length of the ramming box by a jack having a stroke, the importance of which is determined from the width of the sole of the drumsticks and the distance which separates the soles of two neighboring drumsticks d 'one cart. However, if the distance between successive drumsticks is constant on each carriage, the distance which separates the drumsticks closest to each other from two successive carriages has a greater value.

A machine according to the invention for pounding coking coal mixtures in a pounding box having a length (L) comprising several pestles spaced apart by a distance (E1) substantially constant in the longitudinal direction of the box, each pestle having a vertical profile with a core, also comprising on the one hand a lifting device having two lifting eccentrics containing between them said core, on the other hand a braking and retaining device having two opposing elements also containing between them said core, each vertical section also having a shelling sole having a second dimension in the longitudinal direction of the shelling box, is characterized in that the braking and retaining device of each pestle comprises two opposing rollers allowing only one direction of rotation which corresponds to the rise of the pestle and with locking means in opposite directions, these rollers being applied against the lining opposite faces of the core of the pestle, preferably by equal forces, during the operation of raising this pestle to its upper rest position.
Preferably, the two opposing rollers are carried by two levers at a first end thereof, and the second opposite end of the same levers is subjected to the effect of a tightening member which tends, during the use of the device , clamping said rollers against the core of the pestle.
According to one embodiment of the invention, said clamping member is joined at each second end of the two levers and it acts simultaneously on them in opposite directions. Advantageously, the second end part of one of the levers is offset relative to the other lever by means of a bar terminated by an end part parallel to this other lever and the tightening member is an elastomer tensioner which tends bringing said end part and the other lever towards each other to apply the rollers against the core of the pestle.

According to an improvement of the invention, a jack is coupled parallel to the tightening tensioner between the second end of the lever and the end part of the bar, the extension of this jack having the effect of rendering the rollers inoperative.

According to an additional improvement, the profile of each pestle is provided with at least one detectable mark, preferably with several detectable marks spaced in the direction of its length, and there are corresponding detection sensors which are connected to a central monitoring device.

The main characteristic of the invention defined above is advantageously usable on a machine mounted movable in alternating directions along the longitudinal dimension (L) of the ramming box, with a displacement travel of value (C) considerably less than the length (L) of the box, this machine being additionally equipped with a displacement motor member capable of imposing on it in the direction of the length of the box, alternative movements over said displacement stroke (C), the distance (E1) and the second dimension (L2) of the soles being determined as a function of the value of said stroke (C) so that satisfactory recovery of the effect of the soles of the drumsticks occurs during said reciprocating movements; such a machine is characterized according to the invention in that it is composed of several elementary rammers each comprising a chassis mounted on wheels extending in transverse direction to the ramming box and bearing on at least one assembly line at least one pestle and its operating members, these rammers being coupled to each other to form a pounding train constituting a ramming machine, the assembly lines being spaced apart by a distance substantially equal to said distance (E1) on each rammer elementary and between the following rammers.

According to a preferred embodiment of the invention, each elementary rammer is equipped with several pestles and the eccentrics of these pestles are mounted respectively on two common shafts each supported by the chassis by means of several bearings, these two shafts being connected one to the other by rotating transmission means and one of them being rotatably coupled to the output shaft of a speed reducer having an input shaft operatively connected to the output shaft of an engine mounted on the chassis.

Preferably, the frame of each elementary rammer has a recess on a transverse side and the following elementary rammer has on a transverse side of its frame a projection of complementary profile engaging in said recess.

Advantageously, the output shaft of the speed reducer is a hollow shaft and the end part of the corresponding common shaft is engaged in said hollow shaft in relation to the transmission of the torque.

More preferably still the displacement stroke (C) has a value which is substantially equal to half the distance (E1) while the second dimension (L2) of the sole of the drumsticks has a value which is substantially equal to half of the distance (E1).

• la figure 1 est une vue générale simplifiée de dessus d'une première pilonneuse élémentaire et d'une partie d'une deuxième pilonneuse élémentaire reunie à la première pilonneuse, ces deux pilonneuse élémentaires faisant partie d'une machine à pilonner selon l'invention,
• la figure 2 est un schéma montrant la disposition de l'ensemble des pilons par rapport à la longueur du caisson de pilonnage,
• la figure 3 est une vue générale en élévation de la partie supérieure d'un pilon faisant partie d'une pilonneuse de la figure 1 et montrant le dispositif de freinage de retenue du pilon, ce dispositif n'étant pas visible sur la figure 1,
• la figure 4 est une vue agrandie en élévation du dispositif de freinage de la figure 3.

A description will now be given, by way of example only and without limitation, of a preferred embodiment of a pounding machine, in accordance with the invention. Reference is made to the appended drawings in which:

• FIG. 1 is a simplified general view from above of a first elementary rammer and part of a second elementary rammer joined to the first rammer, these two elementary rammer forming part of a pounding machine according to the invention,
• FIG. 2 is a diagram showing the arrangement of all the pestles relative to the length of the pounding box,
• FIG. 3 is a general elevation view of the upper part of a pestle forming part of a rammer of FIG. 1 and showing the braking device for retaining the pestle, this device not being visible in FIG. 1,
• FIG. 4 is an enlarged view in elevation of the braking device of FIG. 3.

In the preferred example described here the pounding is composed of four elementary rammers 1 which consequently have a length equal to a quarter of the length of the ramming box after deduction of a ramming stroke as will be explained below.

Each elementary rammer 1 has a robust chassis 2 mounted on wheels, preferably bogies 3, which make it possible to circulate it on rails supported above the upper level of the ramming box in the direction of the length of the latter.

The chassis 2 has, in a known and current manner, a width in the direction transverse to the ramming box which is greater than the width of this box, which makes it possible to install various equipment there. We will be content in what follows to describe what is concerned by the invention in the area of each rammer which is located above the ramming box.

The chassis 2 supports a platform 4 which is partially broken away in FIG. 1 to reveal the bogies 3. On this platform, there are assembly lines 5A, 5B, 5C, 5D represented by dashed lines in the figures. These assembly lines 5A to 5D are parallel and arranged transversely to the length of the ramming box when the elementary rammer 1 is placed above the latter. These lines 5A to 5D are equidistant from each other and separated by a distance E₁. On each of these assembly lines 5A to 5D is installed a pestle 6, of any suitable type known per se and which it is not necessary to describe.

In the example described here, each pestle 6 is of a type in which a vertical section 7 in I is provided at its lower end with a pounding sole (not visible in FIG. 1) which has a first dimension in transverse direction to the shelling box of substantially equal value, slightly lower as usual, to the interior width of the box. In the longitudinal direction of the latter the sole has a second dimension which is, in this particular case, substantially equal to half the distance E₁ which separates two successive drumsticks 6. Each vertical section 7 is maneuvered in the vertical direction by two opposite eccentrics 8, 9 which contain between them the core of this section 7.

The eccentrics of all the pestles 6 are mounted on a common shaft, respectively 10 for the eccentrics 8, and 11 for the eccentrics 9. These two shafts 10, 11 extend in the longitudinal direction of the ramming box, in parallel with a side and other of the profiles 7. They are supported by several spaced bearings 12A, 12B ... and 13A, 13B ... which are themselves supported by the frame 2. At one of its ends the shaft 10 is coupled in rotation with the output shaft 14 of a speed reducer 15. Preferably this output shaft 14 is a hollow shaft into which the common shaft 10 penetrates through its end portion to produce a coupling in rotation.

The input shaft 16 of the reducer 15 carries a pulley 17 which is connected by a belt to the pulley 18 of the shaft of a motor 19. The latter can also be installed on the platform 4, or below the latter in the chassis 2. In the interval E₁ which separates two pestles 7, the common shaft 10 and the common shaft 11 are each provided with a toothed wheel 20, 21 respectively. These two wheels are equal and mesh together; thus a single motor 19 drives in synchronism the two common shafts 10, 11 and the set of eccentrics 8, 9 of all the pestles 7 of the elementary rammer 1.

In the example described here, this elementary rammer 1 has a length which is approximately a quarter of the length of the ramming box and it is equipped with four pestles 7 spaced apart. There therefore exists, so that the entire length of the box can be covered by the ramming machine, four successive rammers which are coupled to each other so that they can be moved together in the lengthwise direction of the ramming box. Figure 1 shows a first elementary rammer 1 and only part of the second elementary rammer 1ʹ; on this one we find the same organs as on the elementary rammer 1 designated by the same reference numbers with the index ʹ.

Between the last assembly line 5D of the elementary rammer 1 and the first assembly line 5Aʹ of the elementary rammer 1ʹ which follows, there is, when these two rammers are coupled with each other, a distance E₂ which is identical at distance E₁ or which is little different from it. It is indeed possible to tolerate a certain variation in the distance E₁.

To facilitate the reunion of the rammers one after the other, it is possible to provide a recess 22, with a trapezoidal profile in top view, in a transverse side of the frame 2 of an rammer and a corresponding complementary projection 23 of the same profile on the transverse side of the chassis 2ʹ of the elementary rammer 1ʹ which follows. The projection 23 engages in the recess 22 and ensures good centering and better securing of the rammers. In addition, the latter are securely attached together by known suitable coupling means not shown.

The elementary rammers 1, 1ʹ coupled to each other, constitute a rammer train which is the machine of the invention. The latter is easily displaceable in its entirety thanks to the bogies 3. A drive member such as a jack, not visible in FIG. 1, is articulated on the one hand on a fixed point external to the ramming machine, on the other hand on one of the elementary rammers, for example on the rammer 1. This member is constructed and controlled, in a known manner, in order to impose on the pounding machine alternative movements of displacement in the longitudinal direction of the ramming box. These back and forth movements take place over a race (distance between the opposite extreme points) which is determined as a function of the distance E₁ and of the second dimension of the sole of each pestle.

FIG. 2 schematically shows a pounding machine composed of four elementary rammers 1, 1ʹ, 1ʺ, 1 ‴ coupled together on each of which there are four pestles located on four assembly lines 5A, 5B, 5C, 5D. These lines are separated by a distance E₁ with a value of 785 mm; the distance E₂ between the two successive assembly lines 5D and 5Aʹ of two elementary rammers which follow one another has a value of 790 mm. A difference of 5 mm is quite tolerable. There is shown in phantom on the elementary rammer 1ʺ the sole of two pestles whose second dimension ℓ₂ is equal to about half of the distance E₁.

The total length of the ramming machine is less than the length of the ramming box designated by the letter L (12.630 mm). The difference is due to a clearance ε which is necessary at the two ends and to a distance C which represents the alternative stroke which the drive member can give to the machine, during the operation of the drumsticks, inside the box of shelling. In the present case the stroke C is 400 mm, that is to say a little more than half of the distance E₁. Consequently, the coal is pounded over the entire length of the pounding box (12,630 mm), with the exception of the end parts which correspond to the clearance ε, following a simple reciprocating movement over a distance C of 400 mm. The effect produced by two neighboring drumsticks spaced 785 mm overlaps on the carbon. The shelling is therefore carried out efficiently and quickly; in addition, the control of the movement of the machine over a short stroke of 400 mm between known limits is easy to make automatic. Automatic control includes for each movement on race C an acceleration phase, a constant speed phase and a deceleration phase.

The figures mentioned above are given for information only. One can modify the distance E₁, the second dimension ℓ₂ of the pestles and the number of pestles provided that the value of the stroke C remains low and allows satisfactory recovery of the pounding effect during the alternating movements of the pounding machine. To this end, the soles of the drumsticks can have a second dimension which is almost equal, apart from the clearance which must remain between two neighboring soles, at the distance E₁.

In either of the two cases, on the one hand the one where the shelling machine is made with a chassis in one piece of the specified total length, on the other hand the one where it is composed of several rammers coupled elementary, it could be motorized to move by itself along the ramming stroke without external displacement cylinder.

Reference will now be made to FIGS. 3 and 4 to describe the braking and retaining device for each of the drumsticks. This device is not visible in Figure 1. It is mounted above the robust chassis 2, preferably it is installed above a small platform 24 which allows easy access to the parts of this device . This platform 24 is itself supported by vertical uprights (not shown) which bear on the frame 2.

In the part of each pestle 6 visible in Figure 3, each pestle 6 is arranged vertically between two pairs of guide rollers 25,26 spaced vertically.

In the vertical direction between these pairs of guide rollers 25, 26, the core 27 of the vertical profile 7 passes between a pair 28 of two rollers mounted in opposition 28A, 28B which form part of the braking device. The latter is designated by the general reference 29.

Each roller 28A, 28B is of the type with free wheel in one direction of rotation and with locking means in opposite direction, well known per se. The free rotation takes place during the rise of the pestle.

Each roller 28A, 28B is mounted free on a respective shaft 30A, 30B so as to be contained between the wings of the profile 7 and to be able to be pressed against a friction lining 31 which covers each of the faces of the core 27. A set roller 28A-shaft 30A is mounted at a first end which is here the lower end of a lever 32; the latter is pivotally mounted about a horizontal axis 33 supported from the platform 24 and it extends vertically to end in a second end or upper end. The other roller assembly 28B-shaft 30B is similarly mounted at a first end or lower end of a lever 34 also mounted pivoting about a horizontal axis 35 also supported from the platform 24. This lever 34 extends vertically up to 'at a second end or upper end to which a horizontal bar 36 is firmly fixed. The latter is offset relative to the pestle 6 so as not to hinder the latter. The horizontal bar 36 ends in an extreme vertical part 37 which is parallel to the lever 32 opposite the second end of the latter. The distance between the lever 32 and the vertical end portion 37 of the bar 36 is fixed at the value which is suitable for attaching to these two parts a clamping member which is preferably an elastomer return tensioner or a return spring, shown by a dashed line 38. The arrangement which has just been described is equivalent to displacing the second end part of the lever 34 relative to the lever 32 so that the direction of approach of the ends of these levers is the same as the direction of approach rollers 28A, 28B. More precisely, when the elastic return tensioner 38 tends to bring the lever 32 and the vertical end portion 37 closer to the bar 36, it also tends to constantly apply the rollers 28A and 28 B against the friction lining 31 of the core 27 profile 7.

A compressed air cylinder 39 is coupled between the lever 32 and the vertical end portion 37 of the bar 36, parallel to the elastic tensioner 38. When this jack 39 is put in extension it separates the lever 32 and the end portion 38 and, thus , it moves the rollers 28A, 28B away from the core 27 by a distance sufficient for these rollers to become inoperative. Stops 40A, 40B are arranged to respectively limit the movement of the lever 32 and of the lever 34 in order to distribute the spacing of the rollers 28A, 28B equally on either side of the core 27. With this mounting, at when the rollers 28A, 28B are tightened on the core 27 under the action of the tensioner 38, there is self-centering of the rollers relative to the profile 7 even when the latter is off-center.

Throughout the duration of the pounding periods, the jack 39 is put into service in the direction of the extension so that the pestle 6 is completely free to move in the vertical direction under the effect of the eccentric cylinders 8,9. At each rotation, during a fraction of a turn, the latter tighten the core 27 of the pestle 6 and propel the latter upwards then let it fall during the rest of the turn to start again immediately.

When the shelling is finished and the pestle 6 must be raised to its highest position or rest position, the jack 39 is put to rest; it leaves free the elastic return tensioner 38 which then constantly clamps the rollers 28A, 28B against the core 27. These two rollers 28A, 28B are mounted so as to be free to rotate in the direction of the rise of the pestle 6 as indicated by arrows F in Figure 4 while the cylinders offset 8.9 cause this pestle to go up. As soon as the eccentric cylinders 8,9 release the pestle 6, it can continue to rise if it has received a sufficient impulse, but it is impossible for it to descend; in fact, the rollers 28A, 28B are locked in rotation in this direction and they are pressed by the tensioner 38 with a force, multiplied by the levers 32, 34, sufficient for the braking produced in cooperation with the friction lining 31 to immobilize that pestle.

The same effect takes place after each movement of driving the pestle 6 upwards by the eccentric cylinders 8, 9 so that the pestle quickly reaches its upper rest position. An additional locking means, not shown, makes it possible to prevent the free fall of the pestle 6 from its high position.

It will be noted that during the effective use of the braking device of the invention, the rollers 28A, 28B simply roll against the friction lining 31 and remain constantly in rolling contact with it. The risk of deterioration is eliminated and wear is minimized. In addition, the braking action due to the rollers 28A, 28B is automatic and completely independent of the movement of the eccentric cylinders 8,9; no coordination of movements is necessary. The clamping action of the rollers 28A, 28B against the lining 31 of the core 27, under the effect of the elastic tensioner 38 produces controlled braking which makes it possible to stop the pestle during its fall without brutality. In addition, the entire device is simple in its design and construction.

The described embodiment is preferred because of its simplicity and its operational safety. It will not depart from the scope of the invention by adopting other equivalent means for controlling the movements of the two rollers 28A, 28Bet the tightening of these rollers against the core 27 of the pestle in order to activate the braking device and of restraint during the rise of the pestle.

According to a further improvement of the invention, there are on each of the pestles 6 at least one and preferably several detectable marks 41 to which correspond, on respective supports mounted on the platform 4, detection sensors 42. These sensors 42 are connected to a central monitoring device. In this way it is possible to remotely monitor the proper functioning of each of the pestles and to detect any pestle becoming defective as a result, most often, of the wear of the linings 31 which cover the core 27 of the profile 7. The marks detectable may be plates 41 of stainless steel fixed for example on the outer face of a wing of the section 7 of each pestle 6. These plates 41 are shown only on the two pestles 6 furthest to the left when looking at FIG. 1. It is advantageous to put several plates 41 spaced by a constant pitch in the longitudinal direction of each pestle 6. Thus the operating speed and the amplitude of the movements, in the vertical direction of each pestle can be measured and controlled at all times, this which makes it possible to detect the beginnings of wear on the linings 31. The sensors 42 for detecting the stainless steel plates 41 are of the non-magnetic type and are known in the trade. this, and need not be described; the same is true for the central surveillance apparatus.

Claims (11)

1. A machine for stamping mixtures of coal for coking, the staping taking place in a stamping box having a length L, the machine comprising a plurality of stampers spaced apart at a substantially constant distance (E1) in the longitudinal direction of the stamping box, each stamper including a vertical bar (7) with a web and also including firstly a lifting device having two excentric lifting cams disposed on either side of said web, and secondly a braking and retaining device having two opposing elements also disposed on either side of said web, each vertical bar (7) further including a stamper shoe having a second dimension (l₂) extending in the longitudinal direction of the stamping box, the machine being characterized in that the braking and retaining device for each stamper comprises two facing rolls (28A, 28B) allowing rotation only in the direction which corresponds to the stamper being raised and preventing rotation in the opposite direction, said rolls (28A, 28B) being pressed against the coating (31) of the opposite faces of the web (27) of the stamper (6), preferably with equal forces, during the operation of raising the stamper to its top or rest position.
2. A machine according to claim 1, characterized in that the two opposing rolls (28a, 28B) are carried by two levers (32, 34) at first ends thereof, with the opposite second ends of said levers being subjected to the effects of a clamping member (38) which tends to clamp said rolls (28A, 28B) against the web (27) of the stamper (6) during utilization of the device.
3. A machine according to claim 2, characterized in that said clamping member (38) is connected to each of the second ends of the two levers (32, 34) and acts simultaneously thereon in opposite directions.
4. A machine according to claim 2, characterized in that the second end portion of one of the levers (34) is offset relative to the other lever (32) by means of a rod (36) terminated by an end portion (37) running parallel to said other lever (32), and the clamping member (38) is an elastomer tensioning device which tends to move the said end portion (37) and the said other lever (32) towards each other in order to press the rolls (28A, 28B) against the web (27) of the stamper (6).
5. A machine according to claim 4, characterized in that an actuator (39) is coupled parallel to the clamping tensioning device (28) between the second end of the lever (32) and the end portion (37) of the rod (36), extending said actuator (39) having the effect of making the rolls (28A, 28B) inoperative.
6. A machine according to any one of claims 1 to 5, characterized in that the bar (7) of each stamper (6) is provided with at least one detectable mark (41), and preferably with a plurality of detectable marks spaced apart in the lengthwise direction, and that detection sensors (42) are correspondingly disposed and connected to a central monitoring apparatus.
7. Machine according to any one of claims 1 to 6 which is displaceable alternately along the longitudinal direction (L) of the stamping box with a displacement step (C) notably lesser than the length (L) of the stamping box, said machine being further equipped with a displacement drive member suitable for imparting reciprocating movement thereto over said displacement step (C) in the lengthwise direction of the box, the distance (E1) and the second dimension (12) of the shoes being determined as a function of the value of said step (C) in order to ensure that the effects of the stamper shoes overlap satisfactorily during said reciprocating movements, characterized in that it comprises a plurality of elementary stamping machines (1, 1', 1", 1"',...) each comprising a wheel-mounted chassis (2, 2',...) extending in the transverse direction of the stamping box and carrying at least one stamper (6, 6',...) and its operating members on at least one mounting line (5A, 5B, 5C, 5D, 5A',...), said elementary stmping machines being coupled to one another to build up a stamping train constituting the stamping machine as a whole, the mounting lines (5A, 5B, 5C, 5D, 5A',...) being spaced apart at a distance which is substantially equal to said distance (E₁) both within each elementary stamping machine and between successive elementary stamping machines.
8. A machine according to claim 7, characterized in that each elementary stamping machine (1, 1', 1", 1"') is equipped with a plurality of stampers (6) and the excentric cams (8, 9) of these stampers are respectively mounted on two common shafts (10, 11) each supported by the chassis (2) by means of a plurality of bearings (12A, 12B, 12C), these two shafts (10, 11) being connected to each other by rotary transmission means (20, 21) and one of them being coupled to rotate with the outlet shaft (14) of a speed step down gear (15) having an inlet (16) which is operationally coupled to the outlet shaft of a motor (19) mounted on the chassis (2).
9. A machine according to claim 7, characterized in that the chassis (2) of each elementary stamping machine (1, 1', 1", 1"') has a notch (22) at one end and the following elementaty stamping machne has a tongue (23) on one end of its chassis (2'), said tongue having a complementary profile and engaging in said notch (22).
10. A machine according to claim 8, characterised in that the outlet shaft (14) of the speed step down gear (15) is a hollow shaft and the end portion of the corresponding common shaft (10) is engaged in said hollow shaft to transmit the rotary torque.
11. A machine according to claim 7, characterized in that the displacement step (c) has a value which is sustantially equal to one-half of the distance (E₁) while the second dimension (l₂) of the stamper shoes has a value which is sustantially equal to one-half of the distance (E₁).

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