Abstract:
In a tube-upsetting press, of the kind having a vertically split die with vertically spaced shaping faces for successive setting operations, metal tubes to be upset are handled by sets of grippers which move cyclically along a closed path perpendicular to the axes of the tubes and the die and respective grippers move cyclically towards and away from the die, these movements being so synchronized that successive tubes are gripped, moved into line with one shaping face of the die and advanced thereinto by a first gripper of the set, shifted to the next shaping face by another gripper of the set, and withdrawn from the die by a further gripper of the set after upsetting. Fixed retaining grippers hold the tubes during upsetting, and oscillating transfer grippers move the tubes laterally from a supply table into alignment with the first die-feeding grippers of the set. The drive train for the several sets of grippers is described.

Description:
BACKGROUND OF THE INVENTION 
     The upsetting of the thickened ends of tubes (which term includes pipes) is carried out in upsetting presses, and usually requires two, occasionally one or more than two (three or four) operations. Upsetting presses are therefore provided with vertically divided dies having to superposed shaping faces. The dies consist of a front pair of jaws for clamping the tubes and of a rear pair of jaws comprising the shaping faces involved in the upsetting operation. The two operations of preliminary and final upsetting that are usually carried out takes place one after the other in a single heat in the superposed shaping faces of the die. The efficiency of the upsetting operation depends to a considerable extent upon the mode of operation and therefore upon the construction of the loading equipment with which the tubes are manipulated. Thus, in the case of vertically divided dies, it is necessary to bring the tubes exactly into alignment on the middles of the shaping faces before closing the dies and to hold them there until the dies are closed, so as to avoid straining of, and damage to, the tubes. 
     Very accurate axial positioning of the ends of the tubes in the dies is also necessary, firstly so as to enclose, between the shaping faces, a sufficient amount of material for the upsetting operation, and secondly so as to prevent upsetting defects (dimensional deviations and the formation of folds, particularly in the case of internally thickened tube-ends), for which purpose it is particularly necessary for the transition zone between the hot tube-end and the cold tube to be accurately axially positioned between the shaping faces of the die. In order to limit the flow of heat from the heated tube-end to the cold tube and to keep the transition zone within narrow bounds, considerable importance attaches to a rapid transfer of the tubes from the heating installation to the precise positions for upsetting. The creation of noise during manipulation of the tubes must nevertheless be borne in mind and limited to a low level. Thus, there arises the problem of providing tube-loading equipment that operates accurately, rapidly and with little noise. 
     Loading equipment previously used for manipulating tubes on upsetting presses of the stated kind consists of a roller bed comprising V-shaped rollers as the means for receiving the tubes to be manipulated, these rollers being mounted on an upwardly and downwardly movable bridge and having reversible drives. The roller bed is loaded from a support grid, which bridges the space between the induction coils for heating the tube ends and the upsetting press and which slopes towards the press. Each tube resting on the roller bed is aligned with the middle of the shaping faces of the die by vertical displacement of the bridge and is moved, by the rollers, axially into and out of the zone of the dies. In operation, these loading systems are too slow, too inaccurate and, in addition, relatively noisy. A further disadvantage resides in the fact that a fresh tube can be manipulated in the upsetting press only when the preceding tube has been removed from the press and the upwardly and downwardly displaceable bridge has been returned to its upper position. Thus, it is not possible to manipulate a second tube in the upsetting press with the result that it is impossible to carry out work simultaneously in two superposed sets of shaping faces of the dies. This loading equipment does not therefore solve the problem whose solution forms the object of the present invention. 
     SUMMARY OF THE INVENTION 
     The object with which the invention is concerned is achieved in that there are provided, as a means for accommodating the tubes, tongs, at least two of which are arranged along the length of the tubes and which are superposed in sets of three in a vertical plane in the vertical space between the shaping faces and are displaceable simultaneously and unidirectionally transversely of the axes of the tubes in a closed path, and the highest and lowest points of the path lie vertically one above the other at a distance corresponding to that separating the shaping faces in the dies, the movement-imparting drive briefly interrupting the movement cycle each time that the highest and lowest points of the path are reached, and the lower dwell position of the upper tongs having an axial tube position congruous with a tube clamped in the upper shaping face of each die; in that the upper and lower of the three tongs are furthermore displaceable opposite each other at right angles to the path forming a normal plane, the displacement being toward and away from the dies over distances greater than the axial length of the dies; and in that, during the upwardly directed part of the movement cycle, the tongs are brought into the open position and during the downwardly directed part of the movement cycle they are brought into the closed position. 
     The use of movable tongs in loading systems for manipulating workpieces on forging machines is known, but the present invention is based on the overall combination of the above-mentioned features and in this combination, enables the stated object to be achieved. 
     The tubes clamped in the shaping faces of the dies when the die-halves are closed are satisfactorily held in position if the tubes are short. A simple support would suffice for longer tubes. However, in accordance with a further feature of the invention and for the purpose of securing the tubes at all times, especially against unwanted disadvantageous axial displacement, there are provided, in association with the tongs (conveyor tongs) moved along the path, stationary tongs (retaining tongs--at least two along the length of the tube), which tongs are aligned with the mutually corresponding lower dwell positions of the upper conveyor tongs and the upper dwell positions of the lower conveyor tongs. 
     In their top position, the upper of the movable tongs (conveyor tongs) superimposed in sets of three receive the tubes, each heated at one of its ends, from a ready position which, in the known manner, can be located at the end of an inclined support grid. Movement over the support grid may lead to a change in the axial position of the tubes and may make it necessary to readjust the tubes axially in the ready position. Furthermore, the noise that develops when the tubes roll down the support grid is undesirable. To avoid these disadvantages and in accordance with a further feature of the invention, there are associated with the conveyor tongs, transfer tongs which are mounted on swivel levers and one of the end positions of which has an axial tube position congruous with the upper conveyor tongs in the top dwell position, while the swivel range of said transfer tongs bridges the distance to a tube-receiving table at the side of the upsetting press, this table accommodating the tubes which emerge from the heating installation of which are released therefrom over a short distance. 
     It is advantageous if, in accordance with a further feature of the invention, the conveyor tongs travel along a square movement path in which the vertical sections thereof correspond to the vertical distance between the shaping faces in the dies and the points at which the movement cycle is interrupted (dwell positions of the conveyor tongs) are provided at the middle of the horizontal portions of the path, since this facilitates the placing of the tubes in, and their removal from, the shaping faces of the dies as well as their placement in and removal from the stationary retaining tongs. 
     The square path of movement, in an advantageous arrangement, is achieved by mounting the conveyor tongs on lifting beams which, in known manner, form the couplers of two parallel linkages designed as wheel crank drives, in which arrangement an auxiliary crank, mounted on a main crank, executes, by way of the wheel drive, a number of revolutions which is four times that of the main crank, and the radius of the auxiliary crank is approximately equal to half the height of the arc of a quarter-circle segment in the circle of the main crank. 
     In accordance with a further feature of the invention, the necessary interruption of the movement cycle at the top and lower point of the path of the conveyor tongs is achieved by means such as a stepping gear fitted between a variable-speed drive, and the drive imparting movement, for which stepping gear the invention provides, as an advantageous solution, a cycloidal gear, known per se, which is formed by combining a wheel crank drive with a crank guide, an auxiliary crank, mounted in the main crank of the wheel crank drive, executing, by way of the wheel drive, twice the number of revolutions as are executed by the main crank, while the radius of the auxiliary crank is approximately one-third of that of the main crank, and the auxiliary crank engages in a guide lever mounted coaxially with the main crank. 
     As regards the design of a gear for achieving a square path of movement and for providing a stepped gear on equipment for manipulating workpieces on forging presses, reference is made to German Pat. No. 28 06 987 in which such gears--as mentioned above--have been disclosed. 
     In accordance with a further feature of the invention and for the purpose of providing a particularly advantageous form of the gear for the additional movement of the upper tongs in the opposite direction to the lower tongs at right angles to the path of the common movement of the tongs that takes the form of a normal plane, the upper and lower conveyor tongs are mounted on upper and lower slides, the upper slides being movable in the opposite direction to the lower slides at right angles to the normal plane on lifting beams and being driven by the counter-moving strands of cables or chain drives or by counter-running rack-and-pinion drives, and each cable, chain and/or pinion drive is powered, by way of a sectorial rocker arm, by a crank drive having an adjustable stroke and adjustable reversal points. 
     As already mentioned, rapid transfer of the tubes is of considerable importance. This requirement is met by various of the above-described features of the invention and further improvement is achieved if, in accordance with yet another feature of the invention, downstream of the stepping gear, there is provided a gear branch system with branches having a 1:1 reduction ratio, to the lifting beam drives for the main movement of the conveyor tongs, to the slide drives for the transverse movement of the upper and lower conveyor tongs, and to the swivel drives for the transfer tongs, so that all of the movements of the tongs derive form a single drive. The timed execution of all the movements of the tongs is thus ensured, and costly follow-up control means requiring safety times are not necessary. 
     Special measures have to be taken so as to enable the tubes to be moved, without loss of time, by the transfer tongs from the receiving table to the rear of the heating installation. Therefore, in accordance with a still further feature of the invention, the swivel levers of the transfer tongs form the couplers of double rocker four-bar linkages, the tongs are arranged on extensions of the couplers and the drive rocker arms are designed as angled levers, their second arms form the rocker arms of crank rocker four-bar linkages with driven cranks. Thus it is possible to achieve, for the movement of the tongs, a coupling curve which, in the zone of the receiving table for the tubes, extends parallel to the surface of the table so that the tubes can be deposited on the table and the transfer tongs can be set in motion without any particularly precise timing and without the need for safety times. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     An embodiment of the invention is illustrated by way of example in the accompanying drawings, in which: 
     FIG. 1 shows an overall view of the front of the loading equipment. 
     FIGS. 2a to 2g are diagrammatic front and side views respectively illustrating seven steps in the loading of a tube, 
     FIG. 3 shows, on a larger scale, a portion of FIG. 1, 
     FIG. 4 shows a side view of the FIG. 3 material as seen in the direction indicated by the arrow IV, 
     FIG. 5 illustrates the construction of the stepping gear, in connection with which 
     FIG. 6 illustrates the kinematic principle, and 
     FIG. 7 shows the speed ratio produced by the stepping gear, 
     FIG. 8 illustrates the construction of the gear for providing the main movement transversely of the axis of the tube, in connection with which 
     FIG. 9 illustrates the kinematic principle, 
     FIGS. 10 and 11 are side views from the plane designated X--X in FIG. 3, two operating positions of the transfer tongs being illustrated, in which connection 
     FIG. 12 shows the coupling curve along which the transfer tongs are moved, and 
     FIG. 13 shows an overall perspective view of the driving arrangement. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As shown in FIG. 1, the loading equipment is made up of two conveyor tong mechanisms 1, two lateral transfer tong mechanisms 2, and three retaining tong mechanisms 3, which are in each case similar to each other. The loading equipment is powered by a motor 4 which drives an intermittent-motion transmission in the form of a stepping gear assembly 6 by way of a variable speed transmission in the form of a steplessly variable gear 5. Combined with the stepping gear assembly 6 is a branching gear assembly 7 forming a drive distributing transmission, which drives a second branching gear assembly 9 by way of a universal-joint shaft 8. Leading off from the branching gear assembly 7 are two power take-offs, which through universal-joint shafts 10 and 11, each power a feed drive 12 which serves to drive the conveyor tong mechanisms 1. The components are contained in a main frame 13 to form a single unit. 
     The diagrammatic drawing in FIG. 2 shows the mode of operation of the loading equipment in stages a to g. The numeral 15 designates the manipulated tubes, 15 1  designating a first, 15 2  a second, 15 3  a third and 15 4  a fourth tube of a series, the different positions of the tubes in the sequence being designated by α,β, γ, δ and ε. At least two sets of conveyor tongs 16 are disposed along the length of the tube, each comprising upper tongs 16o, middle tongs 16m and lower tongs 16u in line vertically at a spacing equal to that of the upper and lower shaping surfaces 191, 192 of a vertically split die 19,20 comprising a front pair of jaws 20 for clamping the tubes, and a rear pair of jaws 19 provided with the shaping surfaces. The numeral 17 designates one of at least two transfer tongs disposed along the length of each tube, and 18o/18u designate pairs of retaining tongs. The tongs are provided with respective operating means 78 for opening and closing the tongs. In FIG. 2a, 15 1  α indicates the position of a first tube 15 in the location α, i.e. the location of the tubes on a receiving table after they have left the heating installation. Transfer tongs 17 grip the tube 15 1  and carry it laterally into the location β above the die. At the same time, the conveyor tongs 160o, m and u move up along the first half B 1/2 of their path of movement which is a closed vertical loop, and into their top position in which the upper conveyor tongs 16o are aligned with the tube location β as can be seen from FIG. 2b. The transfer tongs 17 as well as the conveyor tongs 16 dwell for a short period in this location β and the transfer tongs 7 open, while at the same time the conveyor tongs 16o close. The conveyor tongs 16 with the tube 15 1 , gripped by the upper conveyor tongs 16o, then move along the descending second half B 2/2 of their path of movement and into their bottom position, in which the tongs 16o are in alignment with the upper retaining tongs 18o and an upper shaping face 19l of the die 19/20. The vertically divided die is in the open position at this stage, so that the tube 15 1  can move axially into the gap between the die-halves. At the same time as the conveyor tongs 16 are lowered, the upper tongs 16o are moved towards the die 19/20 so that the end of the tube 15 1  enters the upper shaping face over the distance necessary for upsetting the end of the tube. While this is happening, the transfer tongs 17 swing back into their initial position. The conveyor tongs again dwell in this lower position for a short time, during which the retaining tongs 18 and the halves of the die 19/20 close, and the conveyor tongs 16 open, the position γ, illustrated in FIG. 2c, being reached. While the first upsetting operation is being carried out in the die 19/20, with the tube 15 1  clamped between the jaws 20 of the die 19/20 and being supported by the retaining tongs 18, the conveyor tongs 16 again move along the first half B 1/2 of their path of movement into their top position, the upper conveyor tongs 16o again moving away from the die 19/20 into the location for receiving a next tube 15 2 , which is at the same time swung by the transfer tongs 17 from the location α into the location β. The conveyor tongs 16 and the transfer tongs 17 again dwell for a short time in this position, the conveyor tongs 16 close so that the middle tongs 16m grip the tube 15 1 , and the transfer tongs 17 as well as the retaining tongs 18 open. As shown in FIG. 2d, the die 19/20 is then opened, the transfer tongs 17 swing back into their original position, and the conveyor tongs 16 move back into their bottom position along the second half B 2/2 of their path of movement, the tongs 16m bringing the tube 15 1  from the upper shaping face as in position γ into the lower shaping face as in position δ, and the tongs 16o bringing the tube 15 2 , by simultaneous axial movement, into the upper shaping face of the die 19/20 as in the location γ. Then (see FIG. 2e) the die 19/20 is closed. The tubes 15 1  and 15 2  are gripped by the clamping jaws 20 of the die and upsetting of the tube 15 1  is completed in the shaping faces 192 of part 19 of the die, and the tube 15 2  undergoes preliminary upsetting in the shaping faces 191. At the same time, the transfer tongs swing a further tube 15 3  from the location α into the location β, and the conveyor tongs 16 move over the first half B 1/2 of the path of movement into the top position where they dwell for a short period, during which the conveyor tongs 16 are closed and the transfer tongs 17 and the retaining tongs 18 are opened. Then, as shown in FIG. 2f, the die 19/20 is opened, the conveyor tongs 16 move along the second half B 2/2 of their path of movement and again into the bottom position, and the transfer tongs 17 swing back into their original position corresponding to the tube location α. As this is happening, the tube 15 3  is moved from the location β and into the upper shaping face as in location γ, the tube 15 2  is moved from the upper to the lower shaping face as in location δ, and the tube 15 1 , by simultaneous axial movement of the lower conveyor tongs 16u, is moved from the lower shaping face and into the location ε. After the die 19/20 has been closed again--FIG. 2g shows this--the tube 15 3  undergoes preliminary upsetting in the upper shaping face, and upsetting of the tube 15 2  is completed in the lower shaping face. The retaining tongs are closed, the transfer tongs bring a fresh tube 15 4  from the γ location to the β location, the conveyor tongs 16 are opened and again move along the first half B 1/2 of the path of movement and into their top position. The completely upset tube 15 1  is released and is carried away by means not illustrated. In the case of tubes having large outside dimensions and/or a great wall-thickness and which do not permit the preliminary and final upsetting of two tubes in unison, the work cycle can be controlled in such manner that only during each second complete motional cycle of the conveyor tongs 16, do the transfer tongs 17 move a fresh tube and therefore only each second tube location is occupied each time. This can happen in a very simple manner by blocking the movement of tubes into the location α during each second cycle and by reducing the work cycle of the heating installation accordingly. 
     Details of the construction of the loading equipment are shown in FIGS. 3 and 13. 
     The stepping gear assembly 6 is driven by the motor 4 (see FIG. 1) through a steplessly variable gear assembly 5, and by means of the gear assembly 5 the work cycle of the loading equipment can be adapted to suit the work cycle of the installation for heating the ends of the tubes and that of the upsetting press. The main component of the loading equipment is constituted by the conveyor tong mechanisms 1, one of which is shown on a larger scale in FIGS. 3 and 4. The drive 12 of the conveyor tong mechanism 1 is driven from the branch 21 of the branching gear assembly 7 by way of a universal-joint shaft 10. In the drive 12 (FIG. 8) a shaft driven by shaft 10 carries an intermediate gear 23 which drives two gear-wheels 24. Each of these gear-wheels 24, together with a shaft 25 eccentrically and rotatably mounted therein, forms a main crank. Shaft 25 is provided with a pinion 26, which rolls on an internally toothed rim 27 secured in a housing 22. Since the internally toothed rim 27 has four times as many teeth as the pinion 26, the shaft 25 rotates four times for each revolution of the gear-wheel 24. At both of its ends the shaft 25 carries eccentric crank pins 28, 29, the eccentricity of which is such that, during rotation of the gear-wheel 24, the centre of the eccentric pins 28, 29 move along a path B as represented in FIG. 9. The eccentricity corresponds to approximately half the height of the arc of a quarter-circle segment of the rotational circle of the shaft 25, so that the path B corresponds to a square having slightly rounded corners. Mounted on the eccentric pins 28 and 29 are lifting beams 30, which carry the conveyor tongs 16 and move them along the path B and transversely of the longitudinal axis of each of the tubes 15 that are to be manipulated. The path B defines a plane perpendicular to the tube axis and feed direction. 
     As provided for in the mode of operation described with reference to FIGS. 2a to g, the path of movement B is divided into two halves B 1/2 and B 2/2, and between the two halves the movement is interrupted for a short while to permit closing and opening of tongs, when these and the tubes are stationary, in the respective locations α, β, γ, δ and ε. This interruption of movement is achieved by means of the stepping gear assembly 6 which is provided between the drive 4 and the branching gear assemblies 7 and 9. This stepping gear assembly will be described in detail by reference to FIGS. 5 to 7. The stepping gear assembly is powered by the motor 4 by way of the steplessly variable gear assembly 5, and the output shaft of which drives a shaft 33 at the input side of the stepping gear assembly 6 by means of a V-belt 31 and a V-belt pulley 32. A pinion 34, mounted on the shaft 33, meshes with a gear-wheel 35 which is mounted to rotate on a bearing pin 36. The bearing pin 36 is secured, but does not rotate, in a housing 37 and carries a toothed rim 38 which does not rotate relatively thereto. A crankshaft 39 constituting an auxilliary crank is rotatable in the gear-wheel 35 and rotates with the pinion 40 which is mounted thereon and rolls on the fixed toothed rim 38. The pinion 40 has half as many teeth as the toothed rim 38, so the crankshaft 39 turns twice for each revolution of the gear-wheel 35. The crankshaft 39 carries a crank pin 41 on which is mounted a roller and which is off-centre to an extent approximately equal to one-third of the eccentricity of the crankshaft 39 in the gear-wheel 35; by way of the crank pin 41, the crankshaft 39 engages in a groove formed in a drag lever 42, which is mounted on a shaft 43, coaxial with the bearing pin 36, so that the shaft 43 is intermittently rotated with its output gear 44. FIG. 6 shows each position of the crank pin 41 achieved in dependence on the rotation of the gear-wheel 35, whereas FIG. 7 shows the speed ratio n 1  /n 2  between the gear-wheel 35 to the rear of the input and the shaft 43 at the output of the stepping gear assembly 6, which ratio is obtained by the stepping gear assembly 6 under the stated conditions. It will be seen that the stepping gear assembly, during complete revolution of the output wheel 44 of the stepping gear assembly 6, interpolates, after each half-revolution, a dwell which is equal to approximately one-tenth of the total time required for a revolution. 
     A crankshaft 45 is driven by the branching gear assembly 7 by power take-off bevel gears shown in FIG. 13 at the same speed as the shaft 21, and the crankshaft 45 moves, by way of a connecting rod 46, a sectorial rocker arm 47 which is swivellably mounted at 48. This sectorial rocker arm 47 is provided, along its arc, with a toothed portion 49 which drives alternately in opposite directions of rotation a pinion 50 mounted on a shaft 51. The shaft 51 in turn rotates a capstan drum 53 through a univeral-joint shaft 52, which drum imparts movement to an endless cable guided over a jockey roller 54. The bearing 55 for the capstan drum 53 and the crossbar 56, supporting the jockey roller 54, are interconnected by a bridge 57 which is a constituent part of the lifting beam 30 and also carries the middle conveyor tongs 16m of the three tongs 16 as well as two guides 58 and 59 for an upper slide 60, which carries the upper conveyor tongs 16o, and for a lower slide 61 which carries the lower conveyor tongs 16u. 
     The slide 60 is secured to the upper strand of the cable between the capstan drum 53 and the jockey roller 54 and the slide 61 is secured to the lower strand of this cable; the two slides 60 and 61 secured to the strands of the cable are moved in a uniform manner in opposite directions to each other, and when a tube 15 is lowered to the middle of the upper shaping face of the die 19/20, the upper conveyor tongs 16o move the tube 15 axially into the die 19/20, and when a tube 15 is lowered from the middle of the lower shaping face of the die 19/20, the lower tongs 16u remove the tube 15 from the die 19/20 also in the axial direction. By adjusting the effective lengths of the radius on the crankshaft 45 and the length of the connecting rod 46, the end position of the tubes 15 in the die 19/20 and the distance over which the tubes 15 are axially displaced can be varied. 
     As in the case of the branching gear assembly 7, the branching gear assembly 9 also has a branch for driving the second conveyor tong mechanism 1. 
     A second branch of the branching gear assembly 7, likewise present on the branching gear assembly 9, is constituted by a crankshaft 62, which is driven at the same speed of revolution as the shaft 21 and the crankshaft 45 and which, by way of a coupler 63, rocks a bell-crank lever comprising two arms 64 and 65. The lever 64/65 is mounted on a pivot 66 which is flanged on to the housing 67 of the stepping gear assembly 6 and the branching gear assembly 7. The pivot 66 and the bearing for the crankshaft 62 form the fixed hinges on the housing 67, which serves as the fixed link, of a four-bar linkage forming a crank rocker and consisting of the crank 62, the coupler 63 and the arm 64 of the bell crank lever. The arm 65 of the lever, which executes a swing movement, constitutes a drive rocker in a further four bar-linkage which comprises the pivot 66 and a second pivot 69 carried by a bracket 68 on the housing 67, as the fixed hinges, a short rocker link or follower link 70 and a coupler 71; an extension 72 of the coupler 71 carries transfer tongs 17 forming part of the transfer-tong mechanism 2. The transfer tongs 17 of the second transfer-tong mechanism 2 are moved in a similar way by means of the corresponding branch on the branching gear assembly 9. The four-bar linkages of the transfer-tong mechanism 2 are so designed that the coupling curve 73 (FIG. 12), along which the transfer tongs 17 travel on the coupler extension 72 has a horizontal rectilinear portion in which the tongs 17 move slowly radially towards the tube resting on the receiving table 74, the distances between the points marked along the coupling curve 73 representing the distances travelled during equal units of time. This ensures that, without resorting to special measures, for example the allowance of safety periods, the tubes 15 are efficiently transferred from the receiving table 74 by the transfer tongs 17. The receiving table 74 can be swung into a top position, as shown in FIG. 7, about a hinge 75 with the aid of a lifting means 76, so that the passage of a tube 15 into the zone of the transfer tongs 17 is prevented. A further possible arrangement consists in providing, between the crankshafts 62 and their drives, clutches which can be engaged in the branching gear assemblies 7 and 9, so that the transfer tongs 17 can be halted during one revolution. The blocking of the tube feed or the halting of the transfer tongs 17 can be used to cater for breakdowns or may take place after each second cycle of the transport-tong movement if the two shaping faces of one of the dies are to receive one tube only. An adjustable stop 77 is provided for setting the precise position of the tubes 15 on the receiving table 74. 
     Regarding the perspective diagrammatic illustration of the entire gear arrangement as shown in FIG. 13 and for explaining how the groups of gears cooperate, reference is made to the description associated with the other figures. 
     Although, in practice, upsetting presses are usually equipped with dies which are provided with two superposed shaping faces, and although the invention has been described in relation to such upsetting presses, it is not limited to these but may also be used for dies having more than two shaping faces superposed at the same distance. In such cases, the conveyor-tong mechanisms 1 are provided with intermediate conveyor tongs 16m in a correspondingly larger number (n-1 for n superposed shaping faces), the intermediate conveyor tongs 16m 1  to 16m n-1  being vertically superposed and have the same vertical spacing as the shaping faces, and a correspondingly larger number of stationary retaining tongs have to be provided in an otherwise similar form of construction of the loading installation in accordance with the invention.