DAS DORES, Lee Antônio (Rua Professor Olavo Ferreira da Silva, 91Pombeava, Piracicaba - SP, BR)
BARINI, Fernando de Souza (Rua Coronel Barbosa, 333 - Ap. 103, Piracicaba - SP, BR)
DAS DORES, Lee Antônio (Rua Professor Olavo Ferreira da Silva, 91Pombeava, Piracicaba - SP, BR)
| CLAIMS 1. A jack for the construction of vertical cylindrical tanks of the type which comprises a plurality of cylindrical rings (1), each formed from a metal sheet strip (2), the lower edge (Ia) of each cylindrical ring (1) being seated and hermetically welded onto the upper edge (Ib) of the ring (1) disposed immediately below, the jack (M) being characterized in that it comprises: a base (10) to be seated onto a bearing surface; a vertical column (20) projecting upwardly from the base (10); a head (30) mounted to the vertical column (20), so as to be vertically displaced between a lowered position and an elevated position vertically spaced from each other by a value corresponding to the height of the metal sheet strip (2) which forms the cylindrical rings (1); a driving device (DA) mounted to one of the parts of base (10) and vertical column (20) and operatively coupled to the head (30), to vertically displace it between its lowered and elevated positions; and a train of free- rotating guide rollers (40), mounted side-by-side in the head (30) according to a horizontal alignment in circle arc with the radius corresponding to that of the tank (T) to be formed, said guide rollers (40) presenting a peripheral face with U-shaped section to receive the lower edge (Ia) of each cylindrical ring (1), during its formation. 2. The jack, as set forth in claim 1, characterized in that the train of guide rollers (40) presents a circumferential extension which projects to both sides of each respective jack (M) . 3. The jack, as set forth in claim 2, characterized in that each jack (M) comprises a rocking member (50) which is medianly, horizontally and superiorly pivoted to the head (30) and having end portions (51) projecting laterally to both sides of the head (30), and two support members (60), each being medianly, horizontally and superiorly pivoted in a respective end portion (51) of the rocking member (50), in symmetric positions in relation to the pivoting of the latter to the head (30), each support member (60) securing, in laterally symmetric positions in relation to its pivoting axis, the shafts (41) of a pair of guide rollers (40). 4. The jack, as set forth in claim 3, characterized in that the rocking member (50) is pivoted to the head (30) according to an axis above the pivoting axis of the two support members (60), the pivoting axes of the two support members (60) being disposed above the support plane of the lower edge (Ia) of the cylindrical ring (1) onto the train of guide rollers (40). 5. The jack, as set forth in any of claims 3 or 4, characterized in that it comprises an articulation plate (62) vertically pivoted in each end portion (51) of the rocking member (50), each articulation plate (62) securing a pivoting shaft (63) of a respective support member (60), the assembly being formed by an articulation plate (62) and by a support member (60) being coupled to the rocking member (50), by a tie rod (53) of adjustable extension, so as to vary, in a horizontal direction, the angle between the planes of the rocking member (50) and of each support member (60) . 6. The jack, as set forth in claim 5, characterized in that each articulation plate (62) comprises a front flange (62a) against which is seated and attached a respective support member (60), said front flange (62a) carrying two horizontal, rear and perforated ears (62b) vertically aligned to each other and rotatively supported around the opposite ends of an articulation pin (52) which is medianly housed in a tubular sleeve (54) vertically incorporated in a respective end portion (51) of the rocking member ( 50 ) . 7. The jack, as set forth in claim 6, characterized in that the adjustable-extension tie rod (53) is defined by a screw having an end connected to the respective front flange (62a) of the articulation plate (62) and an opposite end coupled, in an axially displaceable manner, to the adjacent end portion (51) of 'the rocking member (50) . 8. The jack, as set forth in any of claims 3, 4, 5, 6 or 7, characterized in that the rocking member (50) and the support members (60) of each jack (M) are defined by flat plates disposed in vertical planes. 9. The jack, as set forth in any of claims de 1 to 8, characterized in that the column (20) carries upper- position sensor means (Ss) and lower-position sensor means (Si), to be activated by the head (30) when in its lowered and elevated operational positions, respectively, said position sensor means (Ss, Si) being operatively associated with a control unit (C) which makes the motor reducer assembly (25) stop when the head (30) reaches its lowered and elevated operational positions. 10. The jack, as set forth in claim 9, characterized in that the control unit (C) instructs the joint elevation of the head (30) of all the jacks (M) at the end of the incorporation of a new cylindrical ring (1) to the body of the tank (T) being formed. 11. The jack, as set forth in any of claims 1 to 10, characterized in that the base (10) carries a plurality of adjustable-height support feet (11) and a pair of horizontal beams (12) projecting beyond the vertical projection of the respective train of guide rollers (40), each horizontal beam (12) having a free end (12a) which carries an adjustable-height shoe (13) to be seated onto the floor, in a manner radially external to the vertical projection of the contour of the tank (T) to be formed. 12. The jack, as set forth in claim 11, characterized in that the base (10) of each jack M further carries, anteriorly and medianly, an adjustment stop (18), comprising a tubular base portion (18a) internally threaded to receive a threaded upper rod (18b), onto whose end the rocking member (50) may be seated in an initial mounting and leveling phase of the jacks (M). 13. The jack, as set forth in any of claims 1 to 12, characterized in that the vertical column (20) of each jack (M) carries, superiorly, a supporting roller (70) freely rotating around a horizontal axis and which is selectively pressed against the inner face of the respective confronting cylindrical ring (1). 14. The jack, as set forth in any of claims 1 to 13, characterized in that the vertical column (20) carries a pair of longitudinal guide means (21), along which the head (30) is displaced between its lowered and elevated positions. 15. The jack, as set forth in claim 14, characterized in that the head (30) carries two pairs of opposite lateral rollers (31), each pair of said opposite lateral rollers being displaceably housed in the interior of one of the longitudinal guide means (21) . 16. The jack, as set forth in any of claims 14 or 15, characterized in that the head (30) carries a pair of stabilizing rollers (55), with horizontal shaft, so that each actuate against a confronting outer lateral wall (21a) of a respective longitudinal guide means (21) . 17. The jack, as set forth in any of claims 1 to 16, characterized in that the driving device (DA) is defined by a vertical spindle (23) , operatively coupled to the head (30) and having ends rotatively supported in the vertical column (20), and by a motor reducer assembly (25) mounted in one of the parts of base (10) and vertical column (20) and operatively coupled to the vertical spindle (23), in order to rotatively drive it in two opposite directions, so as to vertically displace the head (30) between its operational positions. |
Field of the Invention
The present invention refers to a jack to be used as a lifting device in the construction of vertical cylindrical tanks, generally large diameter tanks used for storing several bulk products, such as liquid, grain or powder materials, and which comprise a plurality of cylindrical rings formed by shaping a metal sheet strip, the lower edge of each ring being seated and hermetically welded onto the upper edge of the ring disposed immediately below.
Prior Art
There are known different systems for manufacturing vertical cylindrical tanks, of large capacity and presenting diameters of 5 meters or more, in which a metal sheet strip is progressively shaped to form cylindrical rings, which have the lower circular edge thereof welded to the upper circular edge of another identical cylindrical ring, which is subsequently formed under the previous one and so on successively, until forming all the cylindrical rings required to complete the height of the cylindrical wall of the tank.
In one of these known systems, described in patent US 4,142,284, a steel sheet strip is continuously supplied to a base support structure, in which the strip is progressively shaped to define a cylindrical ring, which is however arranged helically arranged and has its lower circular edge welded to the upper circular edge of the lower cylindrical ring, and so on, successively.
In this prior constructive solution, after forming the side wall of the tank, the cylindrical tubular structure is lifted by an adequate lifting device and transported to a proximal site, in which the tank will be installed. Although allowing the use of a base support structure that is stationary in a single location, this known solution requires severing the cylindrical tubular structure according to planes orthogonal to its longitudinal axis, as well as providing a base support structure with a relatively complex construction for imparting a helical development to the continuous strip metal sheet, while shaping each ring or coil of the metal sheet to the cylindrical contour corresponding to the diameter of the tank to be formed. Each base support structure is constructed in a fixed site, according to a certain tank diameter, and it is not an object of this prior patent to provide a constructive solution which can be easily and quickly adapted to form cylindrical rings or coils with different diameters.
Another constructive solution is described in patent US 3,239,927, proposing the manufacture of said vertical tanks in their respective installation locations, each of said locations being assisted by a hoisting equipment, generally a crane, and comprising: a foundation defining a flat base, generally in concrete; a positioning and shaping frame, temporarily mounted on said foundation; a device for storing a metal sheet strip; and a strip pulling device, mounted in the positioning and shaping frame, for progressively pulling, from the storage device to the positioning and shaping frame, a metal sheet strip extension which is shaped and severed to form a cylindrical ring on said base frame.
After forming each cylindrical ring, the latter is lifted by the hoisting equipment, so as to have its lower circular edge welded to the upper circular edge of another lower cylindrical ring subsequently formed on the positioning and shaping frame.
In this prior construction, the positioning and shaping frame is designed to shape the metal sheet strip to the cylindrical shape required for the tank to be manufactured, further including the required device for pulling the metal sheet strip to the frame during the operations of forming each lower cylindrical ring. These characteristics make the
•positioning and shaping frame more complex and little versatile .
In the construction commented above, the base frame operates as a mold to impart and maintain the desired circular contour for each cylindrical ring during its formation on said base frame, it being necessary to displace the latter, with all of its elements for pulling, shaping and positioning the metal sheet strip, to a new location for installing another tank, said location being already provided with the adequate foundation which defines the flat base for mounting the frame.
Another known solution, described in EP 0,282,126 Bl, refers to a method and an apparatus for the formation of vertical cylindrical tanks by successively joining cylindrical rings made of metal sheet, positioned one on top of the other. In this prior European construction, each cylindrical ring is formed by supplying a metal sheet strip on guide rollers positioned angularly spaced from each other, in a circumferential alignment corresponding to the diameter of the tank to be formed. After forming a first ring on the support guide rollers, the latter are lifted to a height corresponding to the height of each ring of the tank, allowing a new metal sheet strip to be supplied on the guide rollers as they are progressively lowered to receive the metal sheet strip being shaped, at the same time in which the upper edge of the latter is being welded to the lower edge of the cylindrical ring previously formed and lifted.
In this prior construction, each guide roller has its horizontal shaft mounted in a respective head, which is vertically displaced in a jack structure to be disposed close to the circular alignment, which forms the cylindrical wall of the tank, generally in the inner side of the latter. The vertical displacement of the movable head can be carried out by an adequate actuator, whether hydraulic, pneumatic or electric- mechanical, in the last form it being defined by an also vertical spindle driven by a motor- reducer assembly, each actuator being specific for each jack or group of jacks.
In said prior construction, the guide roller of each jack is lifted together with the others, at the end of the formation of each cylindrical ring, in order to allow supplying a new metal sheet strip for the formation of a new ring. As the already shaped new metal sheet strip is supplied into the mounting region of the tank, its lower edge is seated on the already lowered guide roller of each jack being reached by the leading front edge of the metal sheet strip being supplied, while its upper edge is progressively welded to the lower edge of the already formed cylindrical ring disposed immediately above, seated on the guide roller of the jacks still not reached by the metal sheet strip being supplied. Both the immediately upper ring and the metal sheet strip already welded to each other, even in only a small circumferential extension, are simultaneously and rotatively driven around the vertical axis of the tank by a driving means, generally formed by rollers provided internally and externally to the tank and driven by an adequate motor unit .
Although the European prior solution allows constructing tanks of different diameters, on the same fixed mounting station for different tanks or on the definitive installation base of each tank, it presents some inconveniences.
One of the inconveniences is that each jack comprises only one guide roller, making all the respective weight fraction of the tank being formed to be carried by the tangential seating of the lower edge of the base ring of the already formed body portion on the single guide roller of each jack. This fact tends to cause crushing of the lower edge of the base ring of the already formed body portion, mainly when said ring is already in its final mounting phase and supporting the weight of a greater number of cylindrical rings. The whole load in each jack is applied to the tangent point of the lower edge of the base ring on the single guide roller, deforming said edge and requiring its processing during and after the welding operation between the rings.
Another inconvenience of this construction for the jacks having a single guide roller results from the fact that many jacks are required to minimize the negative effect of edge crushing. However, the placement of multiple jacks, besides increasing the number of required equipment, making their installation at each tank formation base more complex and costly, generally meets the problem of lack of space for providing the adequate number of jacks to promote an adequate distribution of the tank weight on a convenient number of guide rollers, as well as the necessary provision of supporting and lifting means, which fact, in the case of large-diameter tanks, impairs the use of the adequate number of jacks provided with a single guide roller.
Yet another inconvenience of the solution proposed in P 0,282,126 Bl results from the fact that the weight fraction of the tank body, which is applied to each guide roller, tends to incline each jack superiorly outwardly. In face of this fact, the base structure of each jack is radially inwardly extended, to be seated on the ground to support the tension of tie rods that superiorly connect each two jacks, so as to prevent said jacks from inclining radially outwardly under the weight of the tank body.
The above characteristic requires a more complex and heavy construction for the jack assembly.
Summary of the Invention
As a function of the operational limitations and of the constructive complexity of the prior art solutions, as commented above, it is an object of the present invention to provide a jack for the manufacture of vertical cylindrical tanks, of the type already defined above and which allows, by means of a relatively reduced number of jacks, forming large- diameter tanks in a single mounting base station or over the definitive fixation base of the tank, without requiring stabilizing elements connecting the jacks or specific base constructions for each tank diameter, and guaranteeing a better weight distribution of the tank being formed on the guide rollers.
In order to attain the object mentioned above, the present invention provides a jack which comprises: a structural base to be seated on a bearing surface; a vertical column projecting upwardly from the base; a head mounted to the vertical column, so as to be vertically displaced between a lowered position and an elevated position, said positions being vertically spaced from each other by a value corresponding to the height of the metal sheet strip which forms the cylindrical rings; a driving device mounted to one of the parts of base and column and operatively coupled to the head, to vertically displace it between its lowered and elevated positions; and a train of free- rotating guide rollers mounted side-by-side in the head according to a horizontal alignment in circle arc with the radius corresponding to that of the tank to be formed, said guide rollers presenting a peripheral face with U-shaped section to receive the lower edge of the metal sheet strip of each cylindrical ring, during formation of the latter.
Further according to the present invention, the guide- roller train comprises an even number of guide rollers presenting a circumferential extension which projects to both sides of each respective jack, said guide- roller train being constructed to guarantee a homogeneous weight distribution of the respective body fraction of the tank over all the guide rollers of each train.
The present invention allows constructing vertical cylindrical tanks in the same location at the mounting site or directly on the installation location of each tank, by using a relatively lower number of lifting jacks presenting a simple construction and which can be easily adapted to different diameters of large- dimension tanks, without requiring the provision of a specific base for each project or additional bracing structures to guarantee the stability of the jacks during the formation of the vertical cylindrical tank. Brief Description of the Drawings
The invention will be described below, with reference to the enclosed drawings, given by way of example of a possible embodiment of the invention and in which:
Figure 1 represents a somewhat simplified and schematic partial side elevation view of a vertical cylindrical tank being formed with the use of a plurality of jacks constructed according to the present invention and having a electric-mechanical driving means to vertically move the head with the guide-roller train;
Figure 2 represents a top plan view of the assembly illustrated in figure 1, showing the formation of a new ring with the metal sheet strip being supplied and circumferentially conducted by the guide-roller train of the jacks already reached by the incoming sheet;
Figure 3 represents a top plan view of a jack supporting the corresponding region of the vertical cylindrical tank.
Figure 4 represents a side elevation view of one of the jacks, of the electronic-mechanical type, with its guide rollers supporting the lower edge of the metal sheet strip being supplied to form a new ring;
Figure 5 represents a view similar to that of figure 4, but illustrating the guide rollers of a jack in the elevated position and supporting the lower edge of the upper ring of the tank body portion already formed and elevated to allow supplying the metal sheet strip which forms the new ring;
Figure 6 represents a somewhat enlarged front view of the guide-roller train of a jack;
Figure 7 represents a top plan view of a jack, illustrating the relative positioning of the guide rollers of each guide-roller train; and
Figure 8 represents a partially sectioned side elevation view of the guide-roller train.
Detailed Description of the Invention
As already mentioned, the invention refers to a jack M to be used in the construction of vertical cylindrical tanks T, comprising a plurality of cylindrical rings 1 formed from a metal sheet strip 2, the lower edge Ia of each cylindrical ring 1 being seated and hermetically welded onto the upper edge Ib of another cylindrical ring 1 disposed immediately below the first ring.
As illustrated in figures 1 and 2 of the enclosed drawings, the jacks M are positioned internally to the contour of the vertical projection of the tank T to be formed, in an adequate number to support the final weight of the tank. It should be understood that the constructive solution proposed herein allows the jacks M to be also positioned externally to the contour of the tank T, it being only necessary to make some changes which are easily deductible by people skilled in the art . In figure 2 of the drawings, given by way of example, there are illustrated only six jacks M, which are angularly spaced from each other, internally to the contour of the tank T. However, the number of jacks M varies as a function of the diameter and the weight of the tank T to be formed.
Further according to figure 2, the operation of the jacks M is associated with an installation that comprises a coil 3, having a vertical shaft and containing a metal sheet strip 2 which is progressively uncoiled by actuation of an impelling device 4, generally in the form of driving rolls, and supplied to a calender 5.
Generally, after passing through the calender 5, the metal sheet strip 2 is supplied to a second impelling device 6, usually formed by driving rolls and free- rotating rolls, actuating against both the faces of the metal sheet strip 2 being supplied and also of the already formed last cylindrical ring 1.
As illustrated in the drawings, each jack M object of the present invention comprises a base 10, constructed in metallic profiles, to be seated onto an adequate bearing surface previously prepared in the tank construction location, said base 10 carrying a plurality of support feet 11 of adjustable height, generally through spindles threaded in the structure of the base 10, said support feet 11 allowing the base 10 of each jack M to be adequately leveled in its operational position in the construction of the tank T. In the illustrated constructive example, the base B of each jack M is provided with three support feet 11, one median-rear foot and two front-lateral feet, as illustrated in figures 1, 3, 4 and 5.
In the construction illustrated in the drawings, given by way of example, the jack M further comprises a vertical column 20 projecting upwards from the base 10 and which is also constructed in metallic profiles and incorporating, for example, a pair of longitudinal guide means 21 which, in the illustrated construction, take the form of two C-shaped beams vertically- disposed and turned opposite to each other, as better illustrated in figure 7.
The vertical column 20 is constructed to rotatively support the upper and lower ends of a vertical spindle 23 of known construction. The lower end of the vertical spindle 23 is operatively coupled to the outlet of a motor reducer assembly 25, generally- mounted in the base 10, but which may be mounted at least partially in the lower region of the column 20, the motor reducer assembly 25 being dimensioned to rotatively drive the vertical spindle 23 in two opposite directions.
The column 20 is constructed so as to allow a head 30, mounted thereon and operatively associated with the vertical spindle 23, to be vertically displaced, upon driving the motor reducer assembly 25, between a lowered and an elevated position, which positions are vertically spaced from each other by a value corresponding to the height of the metal sheet strip 2 which forms the cylindrical rings 1, as somewhat simplifiedly illustrated in figure 1. In said figure, an already formed cylindrical ring 1 is suspended and seated on a jack, while the metal sheet strip 2 is being supplied under the cylindrical ring 1 immediately above, so as to be welded thereto and inferiorly seated on the jacks into which said metal sheet strip 2 is being supplied.
As described above, the vertical spindle 23 and the motor reducer assembly 25 define a driving device DA designed to promote the vertical displacement of the head 30 between its lowered and elevated positions. Although the drawings present an electric-mechanical driving device DA, it should be understood that said device may be of the hydraulic, pneumatic or magnetic stripe type and the like, either separately or combined, as long as they are capable of carrying out the vertical displacement of the head 30 during the operation of each jack, as described ahead.
Further as illustrated in figures 7 and 8, the head 30 is preferably constructed with two pairs of opposite lateral rollers 31, which are housed in the interior of the respective guide means 21, to maintain stable the vertical displacement path of the head 30.
Each jack M, independently of the construction of the driving device DA, further comprises a train of free- rotating guide rollers 40 mounted in the head 30, in a side-by-side disposition and according to a horizontal alignment in circle arc with a radius corresponding to that of the tank T to be formed. The guide rollers 40 present a peripheral face with a U-shaped section to receive the lower edge Ia of each cylindrical ring 1 already formed and of each cylindrical ring 1 being formed by the supply of a metal sheet strip 2 to the mounting station of the tank T.
As better illustrated in figures 6 and 7, each train of guide rollers 40 presents a circumferential extension which projects generally symmetrically to both sides of each respective jack M, allowing the metal strip support region of each jack to be circumferentially larger than that of the structure of the jacks. Thus, if necessary, as a function of the tank weight, a high number of jacks M may be positioned in the mounting station, the jacks being angularly spaced from each other, without provoking any interference, but permitting the trains of guide rollers 40 of each two adjacent jacks to be positioned close to each other, guaranteeing a better distribution of the tank weight along a greater number of guide rollers 40, reducing the deformation of the edge of the cylindrical rings 1 when they are tangentially seated on the guide rollers 40. In the illustrated embodiment, each jack M, independently of the construction of the driving device DA, comprises a rocking member 50, generally in the form of a flat plate disposed in a vertical plane and which is medianly, horizontally and superiorly pivoted to the head 30, and having end portions 51 projecting laterally to both sides of the head 30. Each jack M further comprises two support members 60, also preferably in the form of flat plates disposed in vertical planes, each of said support members 60 being medianly, horizontally and superiorly pivoted in a respective end portion 51 of the. rocking member 50, parallelly and anteriorly to the latter, in symmetrical positions in relation to the axis for pivoting the rocking member 50 to the head 30. Each support member 60 secures, in laterally symmetrical positions in relation to its pivoting axis, the shafts 41 of each pair of guide rollers 40.
Further as illustrated, the rocking member 50 is pivoted to the head 30 according to an axis which is above the axis for pivoting the two support members 60, said pivoting axes of the two support members 60 being disposed above the support plane of the lower edge Ia of the cylindrical ring 1 onto the train of guide rollers 40.
The constructive arrangement described above for the guide rollers 40 allows not only the whole assembly to oscillate around its pivoting region above the head 30, but also each pair of guide rollers 40, supported in each support member 60, to oscillate around its axis for pivoting to the respective end portion 51 of the rocking member 50. Thus, the guide rollers 40 are automatically positioned so that the whole weight of the respective tank portion seated thereon exerts, onto said rollers, a homogeneous force, guaranteeing an excellent weight distribution on each train of guide rollers 40 and effectively minimizing or even eliminating the problem regarding the plastic deformation of the lower edge Ia of the cylindrical rings 1 during the construction of the tank, which deformation, as already mentioned in the introduction of the present specification, impairs the welding and finishing operations of the circumferential junction between each two consecutive cylindrical rings 1.
With the purpose of allowing each pair of guide rollers 40 to be rotated around a vertical shaft, so as to better adapt in the curvature of the cylindrical wall of each tank to be constructed, there is provided an articulation plate 62 vertically pivoted in each end portion 51 of the rocking member 50, each articulation plate 62 securing a pivoting shaft 63 of a respective support member 60. Thus, the assembly formed by an articulation plate 62 and by a support member 60 is coupled to the rocking member 50, by a tie rod 53 presenting an adjustable extension, so as to vary, in a horizontal direction, the angle between the planes of the rocking member 50 and of each support member 60.
In the illustrated embodiment, each articulation plate 62 comprises an anterior flange 62a against which is seated and attached, generally by screws, a respective support member 60, the annular anterior flange 62a carrying two horizontal, rear and perforated ears 62b, vertically aligned to each other and rotatively supported around the opposite ends of an articulation pin 52, which is medianly housed in a tubular sleeve 54 vertically incorporated, generally by welding, into the respective end portion 51 of the rocking member 50. This arrangement defines a sort of hinge with vertical axis, between each support member 60 and the rocking member 50, allowing the planes of the support members 60 to be angularly adjusted in relation to the plane of the rocking member 50, making possible to achieve a certain circumferential alignment of the rollers of the two pairs as a function of the diameter of the tank T being constructed, as better illustrated in figure 7.
Also according to the illustrated embodiment, each adjustable-extension tie rod 53 is defined by a screw, having an end connected to the respective anterior flange 62a of the articulation plate 62 and an opposite end coupled, in an axially displaceable manner, to the adjacent end portion 51 of the rocking member 50. This construction allows the angular adjustment of each pair of rollers in relation to the rocking member 50 to be achieved through a quite simple and reliable construction. However, it should be understood that other mechanical arrangements may be applied so as to obtain the same technical effect regarding angular adjustment of each pair of rollers in relation to the plane of the rocking member 50.
For better stabilizing the displacement of the head 30 and of the respective train of guide rollers 40, when carrying the tank being constructed, the head 30, or more specifically its rocking member 50, carries a pair of stabilizing rollers 55, having horizontal shaft and projecting backwards from said rocking member 50, each actuating against a confronting outer lateral wall 21a of a respective guide means 21.
With the construction considered herein, a metal sheet strip 2 is uncoiled, calendered and progressively supplied to the mounting station of the tank T, the leading edge of said metal sheet strip 2 being directed to a first jack M with the train of guide rollers 40 displaced to the lowered position, as illustrated in figure 1. Upon reaching the train of guide rollers 40 of the first jack M, the metal sheet strip 2 is seated on said guide rollers which are in the lowered position, said metal strip 2 being progressively supplied until having its lower edge seated on all the trains of guide rollers 40 of all the jacks M, said metal sheet strip 2 being adequately cut, in a manner already well known in the prior art, so as to have the respective cylindrical ring 1 formed by the welding of its confronting end edges.
After the formation of the first cylindrical ring 1 with its lower edge Ia seated on the trains of guide rollers 40 in the lowered position in all the jacks M, the driving devices DA of the jacks M (which devices DA are exemplified as motor reducer assemblies 25 with the vertical spindles 23) are simultaneously driven to produce the joint and leveled lifting of said cylindrical ring 1 to the elevated position of all the trains of guide rollers 40, as illustrated in the upper left part of figure 1, said cylindrical ring 1 being maintained in this position, while a new metal sheet strip 2 is being supplied exactly as illustrated in figure 1. Before the leading edge of the new metal sheet strip 2 reaches the first jack M, the train of guide rollers 40 of the latter is individually displaced to a lowered position, as illustrated in the right part of figure 1, to receive and support the lower edge of the new metal sheet strip 2 while its upper edge is progressively welded to the lower edge Ia of the cylindrical ring 1 previously formed and maintained in an elevated position.
As a new metal sheet strip 2 is rotated, by the second impelling device 6 and jointly with the already formed upper cylindrical ring 1, said strip reaches the other jacks, whose trains of guide rollers 40 are displaced to a lowered position, in order to support the lower edge of the incoming metal sheet strip 2, while the upper edge of the strip 2, already welded to the lower edge Ia of the upper cylindrical ring 1, supports the latter and all the rings already previously formed, which fact allows, at the end of supplying the metal sheet strip 2 and after its closure for the formation of a new cylindrical ring 1, all the trains of guide rollers 40 to be again simultaneously lifted to the elevated position, so as to allow supplying a new metal sheet strip 2.
Although the lowered and elevated positions of the trains of guide rollers 40 may be determined in different manners, a constructive possibility includes the provision, in each column 20, of upper-position sensor means Ss and lower-position sensor means Si, to be activated by the head 30 itself, when in its lowered and elevated operational positions, respectively. The upper-position sensor means Ss and the lower-position sensor means Si can be defined in different manners, for example, by electric switches, electro-mechanical switches, optical sensors, etc., operatively associated with a control unit C constructed to make the driving device DA stop when the head 30 reaches its lowered and elevated operational positions, and also to instruct the joint elevation of the heads 30 of all the jacks M at the end of the incorporation of a new cylindrical ring 1 to the body of the tank T being formed.
In order to impart to the jacks M a higher degree of stability, without requiring them to be structurally interconnected in the interior of the tank, as it occurs with the closest prior art considered herein, the base 10 of each jack M carries a pair of horizontal beams 12 which projects beyond the vertical projection of the respective train of guide rollers 40, each horizontal beam 12 presenting a free end 12a which inferiorly carries a shoe 13 of adjustable height to be seated onto the floor in the mounting station, in a manner radially external to the vertical projection of the contour of the tank T to be formed. This construction allows the whole weight of the tank being formed to be applied according to a direction contained between the shoes 13 and the front-lateral support feet 11 of each jack M, preventing forming undesirable moments which would tend to force the structure of each jack, particularly of its column 20, radially outwards.
Aiming at guaranteeing a better stability for each jack M, its vertical column 20 carries, superiorly, a support roller 70 rotating freely around a horizontal axis, preferably constructed in an elastomeric material, and to be selectively pressed, for example by a manually adjustable spindle 71, against the inner face of the respective cylindrical ring 1 confronting the upper region of the vertical column 20 of each jack M.
The base 10 of each jack M also carries, anteriorly and medianly, an adjustment stop 18, comprising a tubular base portion 18a internally threaded to receive a threaded upper rod 18b, onto whose end the rocking member 50 may be seated in an initial phase of mounting and leveling the jacks M, so that all of them present their respective trains of guide rollers 40 perfectly leveled to each other.
While only one possible exemplary embodiment of the present invention has been illustrated herein, it should be understood that different constructive modifications may be made in the associated elements, without such alterations, which are obvious to one of ordinary skill in the art, departing from the inventive concept defined by the claims that accompany the present specification.
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