EP0080978B1

EP0080978B1 - Standard line plant for the surface treatment of preheating, brushing, painting, drying and marking of metallic tubes

Info

Publication number: EP0080978B1
Application number: EP82830247A
Authority: EP
Inventors: Rosario Scuderi
Original assignee: Vianova SpA
Current assignee: Vianova SpA
Priority date: 1981-11-27
Filing date: 1982-10-04
Publication date: 1988-02-24
Also published as: EP0080978A3; DE3278131D1; IT1147191B; IT8183501A0; ATE32568T1; EP0080978A2

Abstract

A standard line plant for the surface treatment of preheating, brushing, painting, drying and marking of metallic tubes, comprising a loading conveyor by means of transversal translation (CT1), after a weighing station (S), which conveyor (CT1) transfers a set of tubes in a predetermined number transversally with loading step by step, one after the other, a determinate number of tubes on an orthogonal line conveyor (R1) formed by a plurality of transversal motorized rollers independently movable on a frame from the bottom upward and from under the translation line (CT1) on the same line to take said set of tubes and set them along the treatment line where are installed: a data checking and detecting station (CRD) to automatically control the plant according to the tube number and size, a station of preheating, with upper and lower burners, and cooling (R2-H); a surface treatment station with brushing in contraposition and blowing equipment (R3-SG); a following double cabin painting station (P), a following drying station (R4-E); a marking station (M) and an unloading station (R5-CT2) set up and functionally structured as the loading one, being the painting transport with cross slides instead of rollers.

Description

The present invention is related to a standardized line plant for the automatic surface treatment of preheating, brushing, painting, drying and marking of metallic tubes.
Automatic line plants for the surface treatment of semi-processed materials and particularly for the treatment of metallic plates and structurals in which a protective painting coating on the outside surface after preheating with burners and successive sandblasting, are well known in prior art.
For this purpose a reference has to be made to the surface-sandblasting-primerizing treatment line called "economy line" already realized by the same applicant.
Anyhow, these plants existing nowadays present the limitation of not being able to treat tubes in large different sizes on the respective surface. It is also well known that at present, determinate types of metallic tubes need an adequate surface protection by means of painting to be then directly utilized in the installation already painted on the outside.
These tubes generally present a 100 to 400 mm. diameter and a length from 3 to 20 m, said dimensioning not being anyway restrictive but only suggested for the purposes of individuating the problem.
The painting of these tubes is a normal treatment to avoid corrosion, and this treatment is carried out with extremely difficult and complicated manual processes, in which a great quantity of manual work is required and in not ecologically admissible working conditions.
A further inconvenience results from the fact that the painting in automatic painting plants must be carried out for each single sizing of the respective tubes, which involves a limitation in the production and supply line being obliged to supply tubes of the same size only or little different size, therefore increasing considerably production times and consequently high production costs.
Similar plants for treatment of elongated metallic members is described in US-A-4096300, this plant comprises a loading station, a cleaning and pre-heating section, a painting section, a drying section and an unloading station. In this surface treatment plant it is possible to treat elongated metal members of different sizes since it is partly mechanically and partly manually operated but also since the metal members can be placed on appropriate work carts during the transport through the plant. The purpose of the present invention is to provide a remedy for these difficulties and it solves the problem of realizing a line plant for automatized surface treatment of the tubes of largely different sizes, including preheating, brushing, painting and drying stations and eventually a tube marking station, comprising in line: a transversal chain loading station a preheating station, a surface cleaning station, a painting station, a tunnel drying station, a transfer and unloading station,
the invention being characterised in that the respective advancing line comprises:

-support transversal rollers means supplied with spaced apart annular tube bearings radially protruding from the respective roller cylindrical surface, to realize seat couples allowing the housing and supporting of a respective tube with a minimum "2r" or maximum "2R" diameter, each couple being spaced apart from an adjacent couple "i" equal one another to allow the support of a tube with a minimum diameter "2r" on each seat, or of a tube with a larger diameter "2R" on alternate seats, being the second ones spaced apart of "1=2i", in combination with
-support transversally positioned, advancing blade-bar means supplied with spaced apart tube seatings on the respective upper supporting edge, realizing similarly tube seats spaced apart of "i", equal one another each allowing to support said small diameter tubes "2r" on each seat, or said larger diameter tubes "2R" in alternate seats, being the second ones similarly spaced apart of "1=₂i_"; and wherein:
-at the end of the transversal chain loading station, and at the beginning of the unloading station, under the respective advancing chains, an orthogonal conveyor is placed, provided with said rollers means and said advancing blade-bar means respectively, set up on an independent frame vertically movable from a position under the conveyor plane to a position slightly over; an electronic data detecting station being placed downstream said roller conveyor, structured in such a way to detect the size, overall dimensions, number and position of the advancing tubes, in order to transmit these data to memory and data elaboration means for the control of the operative units of the respective stations;
-in the preheating tunnel station said roller means are provided, the tunnel including a plurality of burners placed on transversal rows respectively positioned under and over the advancing tubes;
-in the surface cleaning station said roller means are provided as well, at least two pairs of vertically adjustable roller brushes being placed between the roller means, each pair of brushes comprising an upper brush and opposite lower brush to brush up and down the respective advancing tubes, said vertically adjustable movement being controlled by said detecting and controlling means depending on the respective diameter of the treated tubes;
-in the painting station, two painting cabins, are positioned, supplied with upper and lower respectively spraying means with an alternate transversal movement;
-in the tunnel drying station, eventually followed by marking station, said advancing blade-bars means are provided.

In the preferred embodiment.

-each chain of said transversal loading conveyor and of said transversal unloading conveyor is supplied with spaced apart support tube seats for the progressive loading of each tube and its relative orthogonal translation on the horizontal plane, spaced of one step (i) for a determinate range of diameters, with a step by step advancing program for transferring a predeterminate number (n) of tubes in the respective tubes advancing line, the seats of the last ones for the corresponding rows of the advancing tubes being spaced of centre distance (i) equal to the orthogonal loading and unloading conveyors, being said loading and unloading conveyors further conceived in such a way to support tubes of the larger diameter to interfere with the nearby support area to allow the transversal translation and the longitudinal transport of said tubes along the treatment line in alternate juxtaposition of the respective support seats according to a centre distance 1=2i and with a number of treated tubes: n=(n+₁):₂.
-the respective pairs of brushes in the surface treatment station are placed according to a plane angled both as regards the vertical plane and the advancing line of tubes, the upper brush of the first pair and the upper brush of the last pair being outwardly advanced with respect to the respective lower brush of each pair.
-each respective painting cabin includes two small windows, respectively a lower one and an upper one, placed in contraposition in connection with a rotary filter which is of the tape type which unwinds from a coil of new material to be filtered in order to wind in a coil of the tape clogged after passing through the respective filtering small window.

With this solution a fully automated surface treatment plant for the treatment of tubes is realized allowing treatment of tubes also if it concerns treatment of largely different sizes in diameter, starting from loading to unloading.
The above characteristics will be anyhow better understood and pointed out and other ones will appear in the following detailed description of a preferred form of the present invention in connection with the fourteen accompanying sheet of drawings in which:

Fig. 1 is a schematic plan view of the entire line consituting the plant of the present invention;
Fig. 2 is a schematic view in frontal upright projection on the parallel plane to the treatment line, of the transversal loading system of the line;
Fig. 3 is a schematic plan view of the loading station, represented in Fig. 2 without weighing;
Fig. 4 is a schematic section view on the vertical plane parallel to the treatment line, along the treatment line, of the structuring system of the preheating furnace;
Fig. 5 is a schematic horizontal section view of the preheating furnace structure in Fig. 4;
Fig. 6 is a schematic section view on the longitudinal vertical plane along the treatment line of the structure of the surface cleaning by means of a brushing station;
Fig. 7 is a schematic section view on the horizontal plane of the structure of the surface cleaning station in Fig. 6;
Fig. 8 is a schematic section view on the vertical longitudinal plane on the treatment line of the painting station;
Fig. 9 is a schematic plan view on the horizontal plane of the structure of the painting station in Fig. 8;
Fig. 10 is a schematic section view on the vertical longitudinal plane along the treatment line of the drying tunnel structure;
Fig. 11 is a schematic view in upright projection on the vertical longitudinal plane taken from the same side as the preceding figures, of the unloading station;
Fig. 12 is a schematic plan view with partial visualization of the inside structure of the drying tunnel, in Fig. 10;
Fig. 13 is a schematic plan view of the unloading station, in Fig. 11;
Fig. 14 is a partial view of support and advancing roller of the set of advancing tubes along the line;
Fig. 15 is an enlarged partial view of a wall portion of the cylindrical roller in Fig. 14 between two supports intended to support the advancing tubes to be treated on the surface;
Fig. 16 is a partial view of a transversal bar fit to carry the tubes within the painting and drying stations;
Fig. 17 is a section view X-X on the transversal plan of the bar in Fig. 16;
Fig. 18 is a section view on the transversal plan of the bar in Fig. 16 on plan Y-Y;
Fig. 19 is a perspective view of the loading station with the preheating station concerning the first stages of the surface treatment line in which the transversal loading conveyors of the tubes are in a different number from those represented in the preceding figures and without initial weighing;
Fig. 20 is a schematic perspective representation of the terminal of the surface treatment line and visualizing in detail the second painting chamber, the drying tunnel and the unloading station, the marking station not being set up, in this specific case, between the two last stations and utilizing a final portion with rollers instead of blades.

The line in the preceding figures is meant for the surface treatment of the tubes, preferably in a multiple number, which nevertheless does not prevent the treatment also of a lower number than the maximum transportable number, allowing the treatment even of a single tube.
The represented line is to be considered preferred for tubes with diameters varying from 115 to 355/380 mm. and length from 5 to 14 m.
The tubes can be transported in sets respectively of seven for tubes with a maximum diameter of 220 mm. and four for tubes of a diameter larger than 220 mm.; this is one of the main innovations of the transport system as it can be noticed from Fig. 14 and Fig. 16 which represent respectively the shape of the rollers and transversal bars of transport and advancing of the tubes in their exact half; the support system is arranged in such a way that the fixed support seats are seven
so that with small diametertubes on each support seat a tube will fit, whereas with larger diameter tubes a support will be left out using the intercalated supports and thus the set of transported tubes will be reduced to four, as it will be explained later on.
With reference to Fig. 1, it can be noticed that the transferring and weighing bench is indicated with CT1, being the transfer carried out orthogonally to the loading line R1, the data detecting electronic power station is indicated with CRD, the preheating tunnel is indicated with R2-H, the cleaning by means of surface brushing station is indicated with R3-SG, the painting station is indicated with P, the drying tunnel is indicated with R4-E the marking station is indicated with M, the unloading line is indicated with R5 and the transversal transferring bench from the unloading line R5 is indicated with CT2.
From the same representation of Fig. 1 it can further be noticed that the control consoles of the plant line are indicated respectively with: PB1 manual control console CT1-R1; PBR weighing and length manual control console; PBH manual control console R2-H; RB1 general relay set; PBSG manual control console R3-SG; CD1 moving manual control console; PBP painting manual control console; PBM marking station M manual control console; PB2 manual control console CT2-R5 and CGL general line control console. Of course, units CT1 and CT2 are similarly structured, the only difference consisting in the presence at the inlet of CT1 of the respective weighing devices S.
The plant control system is obviously supplied with a manual commutation which will prearrange the working cycle with four or seven tubes.
The weighing and transfer system at the inlet to the station CT1-R1 and the relative structure in Figs. 1, 2, 3, 19 is organized as follows.
The transfer bench CT1 is provided in the inlet with a set of platforms with standard weighing devices S commonly available on the market and therefore not represented, while the transfer system is carried out with a set of orthogonal chains 1 provided with seats to move either seven small tubes or four large tubes as above said.
The set of chains 1 forming the chain conveyor CT1 is driven with a motor-reducer means operated by a central working panel system CGL and also by the manual control console PB1, being a chain supporting structure 1 through working wheels provided in an end operated by the motor-varying-reducer 2 step by step and regulated by the central system in accordance with the line advancing system and loading need.
For this purpose in Fig. 19 a number of feeding chains 1 different from that in Fig. 2 is represented, not being the number limitative or essential to the scope of the invention and the same for the presence of weighing devices S which may or may not be provided (in Fig. 19 weighing devices are not represented). At the opposed end of the transfer chains 1 the loading line R1 is set up, which is constituted by a set of motorized rollers 3 driven by chains 4 by means of a motor-varying-reducer 5 and mounted on a frame 6 not connected with the transversal conveyor 1 and fit to be lifted and lowered by means of a fluid-dynamic cylinder system 7 in synchronous alternation with the arrival on the rollers 3 of the set of loading tubes in a number of four or seven in the precise corresponding position to the support and transfer seats of the rollers 3 forming the roller set of the loading system R1.
In detail, each roller 3, as represented in Figs. 14 and 15, is constituted by a tubular cylinder 8 with two supporting journals 9 welded at the ends for the relative rotation on the bearings and clutch of the connected wheel for motion transfer.
On the roller cylindrical surface 8 the seat rings 10 are annularly welded in couple bevelled in contraposition with a suitable bevelment to allow the housing and supporting of a respective tube with a minimum or maximum diameter as above said, being obviously provided a spacing and dimensioning "i" fit to allow either the support of a roller according to the minimum radius "r" for each seat or the support of a tube with a larger radius "R" on the alternate seats (1=₂i).
It is thus plain that the conveyor CT1 with the respective chains provided with seats perfectly corresponding to those of the supports 10 will rotate toward R1 only when R1 is lowered, to stop then on the roller set 3 waiting for the same roller plan R1 to be lifted for the tube removal, transferring them orthogonally along the treatment line R2-R5, according to the following explanations. For this purpose the chain conveyor CT1 is provided with an inlet position, a wait position and an outlet position. The chain conveyor CT1 will obviously be provided with a multiple cycle control which supplies the working sequences. The sequences provide to the tube transfer from the inlet and buffer positions to the conveyor R1.
The conveyor control R1 is designed to work with a single motor and is provided with an automatic starting and stopping circuit. The line transfer rollers 3 are driven by said motor-reducers 5, continually working. But the motors can be manually operated and stopped by means of the respective buttons on the plant control consoles.
Of course, as said, the roller position is variable in accordance with the advancing requirements prearranged for the same plant. The structure system is similar and symmetrical with an inverted working for the unloading station defined by the blade unit R5 and the orthogonal unloading chain conveyors CT2.
The roller system 3 is then repeated along the line also in stations R2-H and R3-SG.
The continuation of the tube transfer under the painting station P and the drying R4-E is instead carried out by means of a transfer chain system with transversal support blades of the type represented in Figs. 16, 17, 18.
Said transversal bars or blades 11 are essentially reverse "T" shaped and the upper edge presents grooves 12 corresponding to the tube receiving seat in the Fig. 14, spaced apart of "i", exactly equal one another.
It will be thus understood that to support said small diameter tubes, these ones will be spaced of "i" either in the rollers 3 or on the transversal bars 11, whereas to support large diameter tubes in a number of four, these ones will be spaced according to a wheelbase of "I" equal to twice "i".
In detail, the height of the roller plan is of about 1 m and the variable advancing speed is set to arrive till about 5 m/min., whereas the roller diameter for all the similar conveyors is 406 mm.
In the specific case of Figures 1 to 18, the plant structure is provided with eighteen distributed rollers: eight rollers for R1, five rollers for R2 and five rollers for R3, whereas for the remaining line portion starting from the painting station P said chain transfer with transversal support blades shaped as represented in Figs. 16, 17 and 18 and above described is provided.
In detail, the conveying portion to the drying station R4 is provided with 62 blades with a blade spacing of 571 mm. and blade length of 2,240 mm., as for R1 and R3 rollers (R2 rollers are longer, due to the operating requirements of the preheating system, as will be later explained); each blade is supported by four bearings on the hinges 13 for the advancing chain of the type 1_-1/ 2" as for the roller transmission chain. The conveyor R4 is also provided with a guide chain of 1-1/4".
A similar structure for the blade transfer prosecution is carried out in the conveyor R5 with four sets of nine blades each placed in each spacing sector between each orthogonal chain 1 of the plurality of unloading chains for the transfer and unloading of the tubes, thus being four independent chain sections stretched between the respective motorized stretching and support wheels 14 (Figs. 11, 13).
The conveyor R4 presents in the specific case a length of 17.4 m, whereas the drying station E presents a length of 14 m so that there will be a projection of the conveyor 4 of more than 3 m from the front to serve the painting station P as represented in Fig. 10 and for this purpose not represented for simplification but separately represented in a larger size in Figs. 8, 9.
Analogously, a conveying portion of the same type will be provided in connection with R5 to serve the marker M.
The support structure of the whole conveying system will obviously be realized with metallic structurals welded or bolted together according to well known technique, not being the specific realization bound to the invention effects. In detail, each chain conveyor chain moves on two wheels, one of which is driving and the other is loose and is supplied with a stretching device structured and placed according to well known shape and not represented.
In detail, for the transversal blade conveyor 11 it is to be noted that the sector R4 concerning the drying station includes a horizontal support guide beams respectively upper and lower lateral opposite 15 connected by orthogonal connection support structures 40 and the system of support chain couples 16 of the transversal bars 11 is provided with opposite sprocket devices 14, one of which is motor-driven by a respective motor-varying-reducer control 5 and the opposite one is supplied with stretching means not represented but of a common type.
Of course, the chain portions with the relative transversal blades of the respective unloading station units R5 for the alternate feeding of the transversal conveyor CT2 are vertically mounted on a movable structure by means offluid dynamic cylinders 7 as for the loading system in order to transfer the tubes on the unloading orthogonal conveyor constituted by the unloading orthogonal chain set 1 realizing the structure CT2 (Figs. 11, 13).
The conveyor set is checked by the control provided with a main contactor and the same conveyors can work only if this contactor is closed (not represented).
Each control console includes an accessible emergency stop and two manually operated emergency stops are further provided for each fixed conveyor. The emergency stops are mounted on both sides of the conveyors (not represented); the pushing of an emergency stop will cause an immediate cutting out of the main contactor, cutting out all the motors and connecting all the brakes connected to the motor systems.
In the loading with CT1 and unloading with CT2 systems, the working will be obviously carried out according to two steps, respectively of advancing "i" for small diameter tubes or "I" (equal to 2 "i") for larger diameter tubes.
At each step the orthogonal conveyor will stop to successively receive an electric signal of next movement for transferring the next tube. After each movement, the loading unit will supply an electric signal to CT1 to confirm that the motion has been completed, so that CT1 will advance of one or respectively two steps forward.
When a set of seven small tubes or four larger tubes has been placed on CT1, the transport to R1 starts and at the same time the loading unit is stopped.
CT1 will stop with the centre of the tube set exactly on the longitudinal line R1 and in this position the starting to the lifting of R1 will be carried out, to move the set of tubes along the treatment line from CT1 for then lowers again and allows the feeding station CT1 to carry on the transferring sequence of a new set of tubes.
CT1 is supplied with control means for the manual operating through the pushbuttons PB1.
The unloading system works in a similar way and the transport sequence is automatically carried out as follows: CT2 starting position is placed on R5 and when a set of tubes transferred on R5 is stopped by the suitable predisposition of a presence indicator the lowering of R5 will be carried out with the support of the set of tubes on CT2, which will start the conveying toward the unloading unit (not represented) and obviously placed at CT2 end. In detail, when the first tube of the set is in the precise unloading position, CT2 stops and will supply an electric signal to the unloading unit which moves the first tube and sends an electric signal in confirmation. Then CT2 will advance of one or two steps (according to the small or large diameter of the transported tubes) in order to place the next tube in the same unloading position.
When all the tubes of the set have been moved from R5 and unloaded step by step from CT2, this one will return to the starting position under the R5 area and the sequence will start again. Obviously both can be manually operated by means of pushbuttons placed on the manual control system PBD as said for the loading system.
Of course all the conveyors can be manually operated by means of the respective above described control console for each operating station, respectively: PBH for R2-H, PBSG and CD1 for R3-SG, PBP for the painting station P and the drying station R4-E.
The preheating station R2-H includes a portion R2 of the above described roller conveyor and a tunnel H surrounding said portion, for treating the tubes T while these ones advance in this portion R2 through the tunnel (Figs. 1, 4, 5).
The unit is planned for preheating the tubes by means of a front preheating section and a back conditioning section.
The front preheating section includes a plurality of burners, in the specific case gas burners, arranged in transversal rows respectively under and over the advancing line of the tubes 17. The same burners are supported by means of transversal support beams on the rollers 3 of the conveyor and under the rollers 3 of the same conveyor R2 in such a way to hit with the flame respectively the lower and the upper part of the tubes.
The burners 17 are placed inclined and revolving for an optimum position of the tube treatment and the upper rows are vertically movable. The tunnel H is constructed with self-suppport- ing modular portions riveted together.
The walls and roof of the preheating station are insulated in order to reduce to a minimum the loss of heat for the difference of the outside temperature. The inside parts and the roof of the unit are realized in heat resistant, refractory stainless steel. The supports for each roller of the conveyor system R2 and the relative chain transmission are placed on the outside of the unit in order to avoid problems with the lubrificants deriving from the high temperature and for this reason the rollers are obviously longer than the other ones of the transferring system.
Over the roof of the burner area the installation of an aspirator 18 for fuel-gas is provided, whose piping 19 is meant to carry the waste-heat to the next drying station R4-E for a higher efficiency of the plant.
The aspirator for fuel-gas 18 will be on the non-sparking type and will be operated by the control unit in connection with the detector CRD.
The burn-in system of the burners will be connected after the aspirator has worked the necessary time to ensure the effective cleaning of the tunnel, and the burners can light only when the aspirator works, while the same burners will immediately blow out if the aspirator stops.
Downstream the burner section 17 a drying or ventilation or conditioning section is placed, which is provided with fans 38 for the forced ventilation of the tubes by means of blower ramps (not represented but of a well known type) placed over and under the advancing tubes, thus ensuring an effective drying of the same tubes. The drying fans, after being connected, will work only when the tubes are conveyed through the drying section as for the burners.
The fans will be obviously automatically operated and stopped, after the burners are respectively lighted and blown out. The discontin- ous working of the drying fans will reduce to a minimum the loss of heat.
The control panels PBH and RB1 placed near the station R2-H are meant forth is purpose for the relative working near the same unit.
The unit includes a common main contactor with a circuit switch, with complete protection of each motor.
Sensors are provided to set out the flow of the tubes and these sensors are placed on the conveyor, at the inlet of the tubes, and cover the entire width of a set of tubes, but record also a single tube.
The burner width selection switch can be set in various positions in which a burner width is provided mainly to fit standard set of small diameter tubes or for burner width fit for treating large diameter tubes.
A selector of heat delivery is further provided, which regulates the increase of the temperature required for the tubes, with different transport speed, according to the tubes to be treated.
The selector of heat delivery makes the regular emission of heat possible step by step between about 10% and 100% of the maximum delivery.
The selection switch will preferably have six trips when the plant is provided with three rows of burners and four trips when it is provided with two rows of burners.
The unit will be further supplied with a safety thermostat for protection against overheating and this in such a way that these burners are disconnected if the thermostat trips for the overheating, simultaneously switching on a pilot lamp, placed on the control panel, which shows the too high temperature.
Obviously the upper burners will be automatically regulated in height by means of the control system connected with the detecting unit CRD, and this according to the tube size.
Working is thus carried out:

-the unit control system records the tube inlet and automatically checks the functions of the burners and ventilators according to the tube inlet; when the tubes approach, the respective front edge will operate the sensors placed immediately before the unit which will cause the ignition of the same burners.

The burners will obviously be provided with ignition electrodes and checking unit of the same ignition.
The ignition electrode of each row of burners will receive current by means of a high-voltage transformer, at the same time, opening a solenoid valve, gas will be distributed after receiving an ignition signal. The function of the extension electrode is obviously to switch off immediately after the ignition checking unit records the presence of the flame.
The ignition checking unit might not record the presence of the flame after gas has been emitted for an adequate time, or during the heating process. The gas supply will thus be automatically interrupted, and a red alarm lamp will be provided for this purpose in the control panel which lighting up will show the irregular working.
The manual working can be operated on the same control panel in order to facilitate the operating checking and the possible recordings.
The brushing and blowing unit R3-SG, as schematically represented in Figs. 6 and 7, includes the roller transport system R3 and the tunnel of the treatment of the tubes or the actual brushing SG. The tube brushing tunnel SG includes two couples of rotating brushes inserted between the rollers respectively 20, 21, 22, 23 which are placed according to an inclined plane on the vertical plane of a=₁₅° and the horizontal plane of (3=87° in contraposition, being the first couple inclined forward with reference to the vertical and the second one backward, and further, the first one with metallic wires and the second one with edged plastic wires; being further the two upper rollers 22, 23 movable and adjustable in height according to the tube diameter.
The tunnel is further supplied with a blowing system (not represented) of a well-known type for the removal of the residual dust and the blowing will be carried out with blasts of compressed air in order to avoid the dust outlet from the same tunnel.
The blowing system will be realized with nozzles placed over and under the transfer line transversally to the advancing direction of the tubes.
An electro-pneumatic valve will operate the air inflow to the nozzles when the brushes work, a delay breaker connected in line with the electro- valve control will allow the delayed closure of the compressed air when the operating of the brushes 7 stops.
The dust removal will be effected by means of a suitable centrifugal fan of a well-known technique, placed downstream a filter, as for example the filter F in Fig. 20, or any other of a suitable type. The air change system must ensure a change of at least 100 times the volume of the tunnel chamber per hour, in order to maintain a suitable vacuum degree inside the tunnel to avoid the possible dust transfer in the outside surrounding environment.
The brushes will preferably have a diameter of about 1,200 mm. and will preferably operate at 150 r.p.m. and the same brushes will be overhung on systems of spring cushioning of the bucket type or any other suitable type, while the lifting will be carried out by means of motor-reducers.
For the control, the console PBSG-CB1 is provided as above described.
The painting station P includes two painting cabins P1, P2, as represented in Figs. 8 and 9 which provide upstream in connection with the preceding conveyor R3 an electronic detecting station of the tubes to be painted 24 fit to operate the complete painting unit.
The painting cabins P1, P2, include respectively: the first one a couple of upper guides 25 for an upper translation trolley in a transversal alternate movement 26 supporting a plurality of painting means 27, the second one a couple of lower guides 28 for a lower support trolley 29 supporting a plurality of under painting upward oriented means 30, placed under the tube treatment line.
The two cabins P1 and P2 are separate and independent and are further supplied with over and under opposite rotating filters respectively 31, 32, 33 and 34 to allow a suitable air change and to maintain the painting environment clean.
The system is structured for a translation speed in accordance with the treatment line equal to a maximum of 5 m/min. and with this maximum translation speed a painting with a 15% of dry tubes can be carried out covering a smooth or horizontal surface with a 25 micron thickness film carrying out the spraying with one coat. The paint supply system will preferably be of Airless type but does not obvously exclude electrostatic systems, in this specific case eight sprayers are provided and the painting pumps are two, with two high pressure types, while the sprayers speed is of about 1.5 m/sec.
The ventilation is carried out with two aspirators of a suitable power flow to ensure an air change of about 500 t./hr.; on the floor a water trickle washing will be preferably provided for recovery of the paint not utilized in the cabin (not represented but of well-known type).
Each painting unit can paint in two ways, with an alternate forward and backward movement over and under the advancing tubes so that the painting will be carried out both going and returning. The automatic control of the plant will ensure an even spraying, applying an even painting thickness reducing to a minimum the paint waste.
The spraying means are of an interchangeable type and are supplied completely set up and cabled reducing to a minimum the setting up times. Each support trolley, respectively 26, 29, runs over three support points in the respective guide couplers by means of connection and sliding rollers 41, 42 and 43.
Each sliding system consists of a couple of rollers so that a roller goes on the upper side of the motion path and a roller goes on the lower part of the same path.
The motion paths are covered for their entire length so as to protect them from the painting together with the rollers and are placed outside the cabins. The coverings will be easily removable. It is further to note that the painting trolleys respectively 26, 29 are operated by a common motor-reducer and chain transmission (not represented but of a well-known technique), and similarly supports for cables and tubes for the painting trolleys are provided, by means of two track systems, one for the upper trolley and the other for the lower trolley.
The distance of the sprayers from the tubes is programmed through the control central unit particularly for the upper sprayers which are operated at a varying height according to the tube diameter. The upper sprayers are always positioned at the ideal distance from the upper surface of the tubes as they will obviously automatically lifted and lowered according to the height of the tubes passing through the cabin.
For this purpose a fluidoildynamic cylinder 44, of a well-known technique, is provided, operated by outside pushbuttons in the respective control consoles so as to ensure that the distance between the top surface of the tubes to be treated and the spraying means is always the optimum.
A pointer will be further provided to visually represent the position of the spraying means with reference to the tubes. A safety system will prevent the plant working if the distance between the top surface of the tubes to be treated and the sprayers is not the right one.
The sprayers are placed in sets of two as represented in Fig. 8 and each will be set up at a corner of 90° as regards the other and at 45° as regards the direction of translation.
During the spraying, both the sprayers of a set will work alternatively according to the direction of translation of the painting trolleys.
The oblique position of the sprayers will ensure that the tube is painted on the oblique and vertical surfaces with the most suitable angle.
The opening and closing positions of the sprayers will be changed according to the width of the tubes, that is according to the type of the advancing tubes and their number.
The changes of the opening and closing positions of the sprayers will be automatically carried out by the above described control system, reducing to a minimum the painting waste.
Of course the spraying structure, in this particular case Airless, will be supplied with all the necessary means for the relative working as the high pressure pump, the recirculation system on the suction side of the pump, filtering systems and relative delivery systems.
Each cabin is constituted by independent modular units and is inside provided with fluorescence lighting means (P1, P2).
The supporting structure is mainly realized in metallic structurals welded and bolted together with a rigid frame which supports the motion paths for the painting trolleys.
Each cabin is provided with an aspirator of suitable characteristics and section placed near the same cabin. In order to avoid the disadvantages caused by the painting, the two support systems of cables and tubes to the painting trolleys are contained, for their length, in housings inside the same painting cabin.
The inside surfaces of each cabin are smooth and without inward jutting out components to avoid paint obstructions.
The aspirators will be of a non-sparking type, set up in a separate cabinet placed at one end of the painting cabin to convey through a suction pipe 35 the air containing the paint to the waste and/or regeneration.
Every aspirator will work continually and the painting spray can be carried out only if every aspirator works, whereas if the aspirator, for any reason, should stop while working, the spraying must immediately stop.
Each cabin supports, as above described, two dry filtering systems with rotating filters with winding off coil at one side and winding coil at the other 36, 37 or vice versa, the coils being easily accessible from the outside for their replacement.
The starting of the filtering carpets will be automatic and regulated by differential pressos- tats.
Every single painting delivery will be automatically controlled according to the advancing tubes and the transport speed (trolfey translation).
The advancing speed of the tubes will be recorded by means of a pulse generator (not represented but of a well-known type) which transmits a pulse to the control system every time a set of tubes moves according to-a predetermined measure.
The pulse generator is switched on and off according to the actual feed of the tubes by means of an electric sensor placed just in front of the painting cabin.
The start and stop, as also the regulation of the automatic spraying, are carried out by the control console preferably of a transistorized type placed near the cabin PBP as above described. The control is delayed for the opening and closing of the sprayers according to the 45° angle by the blast of paint as regards the tubes and the delays for the opening and closing of the sprayers can be regulated independently from the control and working panel. The control and working panel further includes a main contactor of the spraying unit and emergency stop.
The unit can work only if the main contactor is closed. The pressing of the emergency stop during the working will cause the immediate switching off of all the motors and the interruption of the air supply to the sprayers.
The unit control system will trace the feed of the tubes and automatically control the working according to the flow through the cabin. The system starts for the first paint delivery and settles when the painting of the tubes is finished.
At the beginning, the automatic working of the painting station is the following:

-at the starting the automatic working is controlled by a data detecting station placed outside the painting cabins and is indicated with the reference number 24 as above described;
-seven extensometers placed on the roller path will detect the tube length;
-a photocell will be placed to transport on a special frame perpendicular to the tube set detecting the spaces to paint and the empty spaces of every paint delivery (tube diameter and distance between them);
-an electric programmer will collect these data and elaborate and transmit them to the spraying unit;
-when the last delivery is completed the system will set to zero and will wait for the next set of tubes to be treated.

The drying station R4-E is structured as represented in Figs. 10, 12 and consists essentially of the drying cabin E, with the enclosed conveyor R4 above described.
The cabin is of a tunnel type with closing walls according to well-known technique and the drying air recovered from the preheating tunnel 19 is conveyed to it and further a suction system 39 is provided by means of a couple of aspirators not represented but of a well-known technique.
At the exit of the drying tunnel a marking unit M is provided, of a commonly available type, as for example the marker produced by Magnemag, Metervuen 18, COPENAGHEN.

Claims

1. Line plant for automatized surface treatment of tubes of largely different sizes, including pre- heating, brushing, painting and drying stations and eventually a tube marking station, comprising in line: a transversal chain loading station (CT1), a preheating station (R2-H), a surface cleaning station (R3-SG), a painting station (P), a tunnel drying station (R4-E), a transfer and unloading station (R5-CT2), characterized in that the respective advancing line comprises:

-support transversal rollers means (3) supplied with spaced apart annulartube bearings (10) radially protruding from the respective roller cylindrical surface (8), to realize seat couples allowing the housing and supporting of a respective tube with a minimum "2r" or maximum "2R" diameter, each couple being spaced apart from an adjacent couple "i" equal one another to allow the support of a tube with a minimum diameter "2r" on each seat, or of a tube with a larger diameter "2R" on alternate seats, being the second ones spaced apart of "1=2i", in combination with

-support transversally positioned, advancing blade-bar means (11) supplied with spaced apart tube seatings on the respective upper supporting edge (12), realizing similarly tube seats spaced apart of "i", equal one another each allowing to support said small diameter tubes "2r" on each seat, or said larger diameter tubes "2R" in alternate seats, being the second ones similarly spaced apart of "1=₂i";

and wherein:

-at the end of the transversal chain loading station (CT1), and at the beginning of the unloading station (CT2), under the respective advancing chains (1), an orthogonal conveyor (R1, R5) is placed, provided with said rollers means (3) and said advancing blade-bar means (11) respectively, set up on an independent frame vertically movable from a position under the conveyor plane (1) to a position slightly over; an electronic data detecting station (CRD) being placed downstream said roller conveyor (R1), structured in such a way to detect the size, overall dimensions, number and position of the advancing tubes, in order to transmit these data to memory and data elaboration means for the control of the operative units of the respective stations;

-in the preheating tunnel station (R2-H) said roller means (R2-3) are provided, the tunnel (H) including a plurality of burners (17) placed on transversal rows respectively positioned under and over the advancing tubes;

-in the surface cleaning station (R3-SG) said roller (R3-3) are provided as well, at least two pairs of vertically adjustable roller brushes (20, 21, 22, 23) being placed between the roller means (3), each pair of brushes comprising an upper brush (21,23) and opposite lower brush (20, 22) to brush up and down the respective advancing tubes, said vertically adjustable movement being controlled by said detecting and controlling means (CRD) depending on the respective diameter of the treated tubes;

-in the painting station (P), two painting cabins (P1, P2) are positioned, supplied with upper (27) and lower (30) respectively spraying means with an alternate transversal movement;

-in the tunnel drying station (R4-E), eventually followed by marking station (M), said advancing blade-bars means (11) are provided.

2. A plant as claimed in claim 1, characterized in that each chain of said transversal loading conveyor (CT1) and of said transversal unloading conveyor (CT2) is supplied with spaced apart support tube seats for the progressive loading of each tube and its relative orthogonal translation on the horizontal plane, spaced of one step (i) for a determinate range of diameters, with a step by step advancing program for transferring a predeterminate number (n) of tubes in the respective tubes advancing line (R1, R2, R3, R4, R5), the seats of the last ones for the corresponding rows of the advancing tubes being spaced of centre distance (i) equal to the orthogonal loading and unloading conveyors (CT1, CT2).

3. A plant as claimed in claim 2, characterized in that said support, translation and advancement seats of tubes spaced of a centre distance (i) are conceived in such a way to support tubes of a much larger diameter and such to interfere with the nearby support area to allow the transversal translation and the longitudinal transport of said tubes along the treatment line in alternate juxtaposition of the respective support seats according to a centre distance 1=2i and with number of treated tubes:

4. A plant as claimed in claim 1, characterized in that said pairs of brushes in the surface treatment station (R3-SG) are placed according to a plane angled both as regards the vertical plane and the advancing line of tubes, the upper brush (21) of the first pair (21-20) and the upper brush (23) of the last pair (23-22) being outwardly advanced with respect to the respective lower brush (20, 22) of each pair.

5. A plant as claimed in claim 1, characterized in that each of said painting cabins (P1, P2) includes two small windows, respectively a lower one and an upper one, placed in contraposition in connection with a rotary filter (31, 32, 33, 34) which is of the tape type which unwinds from a coil (36) of new material to be filtered in order to wind in a coil (37) of the tape clogged after passing through the respective filtering small window.