A ROLLER BENDING MACHINE FOR PRODUCING FUEL TANKS OF PUBLIC

TRANSPORTATION VEHICLES

Field of Invention

The present invention relates to metal shaping machines and particularly to roller bending machines.

Background Art

The manufacture of large-size fuel tanks of public transportation vehicles such as busses or trucks is carried out by roller bending machines. With respect to the background art, such machines are referred to as 2 rollers bending machines, 3 rollers bending machines, etc. depending on the number of roller they include.

In the most general sense, a roller bending machine is composed of a main body, plurality number of rollers extending between the two sides of this body, and driving assemblies to properly drive these rollers. In detail, one of said rollers (typically referred to as the upper roller) rotates around itself by means of the drive it receives from the driving means it is connected, whereas other rollers (typically referred to as side and lower rollers) are idle and can displace on the vertical plane by means of the drive they receive from the relevant driving means. Thanks to this machine, a sheet metal with a flat/planar form can be converted into an enclosed form (e.g. a rectangle with radiused edges) by properly controlling said driving means. Since the fuel tanks has large sizes, even a very simple positioning error during the bending process may lead to a failure in joining the two ends of a metal plate, therefore one of the most crucial points to be paid attention in roller bending machines is accuracy.

Under the light of the information supplied above, the driving elements providing both the rotational and the vertical motions in current embodiments are based either on

belt & pulley means, or on hydraulic means, both such means brining about serious drawbacks.

The most crucial problems with the belt & pulley-based driving means with a gradually diminishing usage are the friction losses, and as a natural result of wearing, unwanted dislocations encountered during operations. Accordingly, a machine of this type has both high operation costs and high erroneous operation rates.

Regarding the systems with hydraulic driving means, the driving means does not response immediately to a "stop command" due to the inertia of the hydraulic system, thus failing in providing the required accuracy. In order to compensate the accuracy problem of the hydraulic system, the machine operates quite slowly particularly after a certain phase of the bending process, leading to long bending-operation times.

Additionally, hydraulic-based roller bending machines operate with low efficiency due to friction-based losses and become extremely susceptible to malfunctioning. On the other hand, particularly since the pistons providing the drive of vertically-displacing rollers are directly supported within the machine body, the gaps between the body and the piston negatively influences the system's accuracy and additional losses are encountered due to friction.

In brief, a roller bending machine specifically with an ideal accuracy and high production rate would be an extremely desired novelty in the relevant technical field.

Brief Description of Invention

The present invention relates to a novel roller bending machine used in manufacturing the fuel tanks of public transportation vehicles, eliminating all aforesaid problems and brining additional advantages to the relevant background art.

Accordingly, the main objective of the present invention is to provide a roller bending machine, which is capable to perform a bending process on a desirable accuracy and extremely more rapidly as compared to equivalent bending machines.

Another objective of the present invention is to provide a roller bending machine, which — thanks to minimizing the friction losses occurring therein — is capable to operate more efficiently and more longer periods of time without causing any malfunctioning, thus having a lower operation cost as compared to equivalent roller bending machines.

In order to achieve all objectives, including those indicated above and those to appear with the following detailed disclosure, the present invention provides a roller bending machine comprising a main body, at least one rotationally movable roller extending between two ends of said main body, rotational motion means to rotate said rotationally movable roller around itself, at least one vertically displaceable roller extending sufficiently parallel to said rotationally movable roller, and vertical motion means to displace said vertically displaceable roller up and down, said roller bending machine being characterized in that said rotational motion and vertical motion means each comprise at least one servo motor in order to produce the actuation required for said rollers.

Thanks to using the servo motor, it becomes possible to control the bending process electronically with high accuracy. Additionally, since no inertial problems shall occur —as has been the case of hydraulic systems — each phase of the bending process is conducted very rapidly so that this process is completed in a much shorter period of time.

In a preferred embodiment of the present invention, said rotational motion means comprise also a reducer positioned between said servo motor and the rotationally movable roller.

In another preferred embodiment of the present invention, a drive transmission assembly is embodied between the vertical motion means' servo motor and the vertically displaceable roller in order to convert the rotational motion of said servo motor to a motion on the vertical plane.

In a further preferred embodiment of the present invention, said drive transmission assembly comprises a worm gear reducer coupled to the servo motor's output, a threaded shaft extending between the bearing of the vertically displaceable roller and said worm gear reducer, a threaded shaft bearing supporting said threaded shaft, and a guide assembly whereon bearing of the vertically displaceable roller displaces.

Yet in another preferred embodiment of the present invention; said guide assembly comprises a guide rail mounted to the main body, and a guide carrier engaged to said guide rail by being mounted from one side to the bearing of the vertically displaceable roller.

Still in another preferred embodiment of the present invention, said guide carrier is a ball guide carrier.

As a result, the friction is minimized thanks to said guide assembly, thus the machine is operated more efficiently.

In a further preferred embodiment, the present invention comprises an upper roller as the rotationally movable roller, as well as one side roller, each extending on one side of the machine, plus a lower roller, as the vertically displaceable rollers.

Structural and characteristic features and all advantages of the present invention shall be made clear by means of annexed figures described here below and a detailed description written by making references to said figures; therefore the present invention must be evaluated by taking into consideration these figures and the detailed description.

Brief Description of Figures

Figure 1 gives a top perspective view of the subject roller bending machine.

Figure 2 gives a side view of the subject roller bending machine.

Figure 3 gives a side view of the vertical driving system of the subject roller bending machine.

Figure 4 gives a view of internal structure of the guide assembly employed in the present invention.

Figures 5a and 5b illustrates a bending process conducted by means of the subject machine.

Reference Numbers in Figures

1. Main body

1.1 Chassis

1.2 Large frame 1.3 Small frame

1.4 Side frame

1.5 Side support rollers

1.6 Central support

2. Upper roller 3. Side rollers

4. Lower roller

5. Intermediate bar

6. Rotational motion means 6.1 Servo motor 6.2 Reducer

7. Vertical motion means

7.1 Servo motor

7.2 Worm gear reducer

7.3 Threaded shaft bearing

7.4 Threaded shaft nut 7.5 Threaded shaft

7.6 Drive transmission rollers

7.7 Rollers bearings

7.8 Guide rails

7.9 Guide carrier 8. Metal sheet

Detailed Description of Invention

In the following detailed description, the present invention shall be described illustratively by making references to annexed figures, only to make it clear without imposing any restrictions thereon.

As can be seen in Figure 1 , the main body (1) of the subject roller bending machine comprises in the most general sense a chassis (1.1) located on the ground, a small (1.3) and a large frame (1.2) assembled vertically to the ground between two mutual edges of said chassis (1.1), and a side frame (1.4) extending from the upper section of the large frame (1.2) to the side. The intermediate bars (5) extending between the large (1.2) and small (1.3) frames ensure the chassis ¹ (1.1) stability. In this preferred embodiment of the present invention, the machine comprises an upper roller (2), a lower roller (4), and two side rollers (3) each extending on one side, all said rollers extending mutually in parallel between the large (1.2) and small (1.3) frames. Additionally, there are embodied side support rollers and one central support on the machine in order to support a bent metal sheet.

As can be seen both from figures 1 and 2, a servo motor (6.1) serving as the driving unit in the rotational motion means (6) to rotate the upper roller (2) around itself is

mounted from below to the upper profile of the side frame (1.4) and at the output of said servo motor is provided a reducer that properly transmits the motor's drive to the upper roller (2). On the other hand, three servo motors (7.1), respectively, which function as the driving unit in the vertical motion means (7) in order to displace the lower roller (4) and side rollers (3) vertically, are assembled externally to the lateral surface of the large frame (1.2). The servo motor (7.1) driving one of the side rollers (3) can be seen in figures 1 and 2, the other two motors, however, are not illustrated therein.

As is seen in Figure 3, a worm gear reducer (7.2) is coupled to the output of the vertical drive's servo motor (7.1), and this reducer is connected to a threaded shaft (7.5). The threaded shaft (7.5) is supported by a threaded shaft bearing (7.3) comprising a threaded shaft nut (7.4) provided on the reducer's (6.2) upper part and illustrated in Figure 3. The other end of said threaded shaft (7.5) is connected to the bearing of the relevant roller (lower "4" or side "3" rollers). As illustrated in the same Figure, the roller bearings (7.7) are coupled to the large frame (1.2) so as to displace linearly on the vertical plane by means of a guide assembly. In a more detailed description, said guide assembly comprises a guide rail mounted to the large frame, and a guide carrier (7.9) engaged to said guide rail (7.8) by being assembled from its other side to the relevant roller bearing (of the lower or side rollers) .

Figure 4 illustrates the details of said guide assembly. Accordingly, the guide carrier (7.9) is of a ball-bearing structure, minimizing the friction occurring during the vertical displacement. Since two side rollers (3) and one lower roller (4) are employed in this preferred embodiment of the present invention, the present machine of the invention comprises three apiece of each such element referred to in this paragraph. In varying embodiments of the present invention, this number can be altered depending on the number of these rollers.

While the equivalent of the structure indicated in Figure 3 is provided at the small frame's (1.3) side as well, no servo motor is provided there (1.3). The drive of the

servo motors (7.1) providing the vertical displacement is transmitted to the side of the small frame (1.3) by means of drive transmission rollers (7.6) extending between the reducer (6.2) at the motor's output and the reducer (6.2) at the other side with no coupling to any motors.

According to the structural details above and with respect to figures 5a and 5b, the operation of the subject machine is as following. When the metal sheet to be formed into a fuel tank is fed into the machine, the positions of rollers are as shown in Figure 5a. When the bending process is commanded, the electronic control unit starts generating the required signals in line with the software installed on its memory. Accordingly and in the most general sense, the control unit first drives the servo motor (6.1) providing the upper roller's (2) rotational motion, and starts the upper roller (2) preferably to rotate on the counterclockwise direction. Since the side rollers (3) and the lower roller (4) are in their idle mode, the metal sheet (8) is thus brought into movement. At the end of time period varying depending on the shape of bending produced, the control unit activates the vertical drive's servo motor (7.1) coupled to the side roller (3) at the relevant side.

In this manner, the rotational motion of the motor is transmitted to the threaded shaft (7.5) via the worm gear reducer (7.2). The threads of the threaded shaft (7.5) are engaged to corresponding threads at the internal surface of the side roller (3) bearing.

Thus, when the threaded shaft (7.5) starts rotating around itself, it shall move the side roller (3) bearing upward so that the side roller bearing (7.7) is moved upward on the guide rail (7.8). Meanwhile, the same drive is also transmitted to the counter side by means of the drive transmission roller (7.6). In this manner, the machine shall assume the position given in Figure 5b and once the upper roller (2) rotates around itself and the side roller (3) comes to an upper position, the bending of metal sheet (8) shall commence. In result, with the upper roller (2) rotating around itself and the lower (4) and side rollers (3) arriving at proper vertical locations in proper time, it shall become feasible to bend the metal sheet (8) in the form of a rectangle, square, or any other desired shape.

Thanks to this structure, a very accurate roller bending machine is achieved capable to perform very rapid bending operations. It is because the servo motors are such devices controllable very accurately by means of electronic control units, this feature —once compared to hydraulic systems causing inertial problems — ensuring very serious advantages to such bending machines. Furthermore, both not using any hydraulic means and the use of said guide assembly substantially reduces the friction losses within the machine to obtain a very efficient embodiment.

In alternative embodiments, the number of rollers and accordingly the number of motors and their positions on the chassis (1.1) can be altered. In brief, the protection scope of the present invention is set forth in annexed Claims and cannot be restricted to the illustrative disclosures given above, under the detailed description. It is obvious that a person skilled in the relevant art can produce similar embodiments under the light of the foregoing disclosures, without departing from the main principles of the present invention.