EP3643421A1

EP3643421A1 - Bending machine and method for using the same

Info

Publication number: EP3643421A1
Application number: EP19204659.7A
Authority: EP
Inventors: Franco BARCA
Original assignee: Mg Srl
Current assignee: Mg Srl
Priority date: 2018-10-23
Filing date: 2019-10-22
Publication date: 2020-04-29
Anticipated expiration: 2039-10-22
Also published as: IT201800009727A1; EP3643421B1

Abstract

A bending machine (10) comprising an upper roller (12), a lower roller (13), a rear side roller (14), a front side roller (15) and a supporting frame (11) to which said upper roller (12), lower roller (13), rear side roller (14) and front side roller (15) are mounted, wherein said upper roller (12), lower roller (13), rear side roller (14) and front side roller (15) are cylindrical rollers, and wherein at least one of the upper roller (12) and the lower roller (13) is a motor-driven roller. The upper roller (12) is mounted vertically displaceable, so as to be translatable along a rectilinear vertical direction of translation by moving away from or close to the lower roller (13), and the lower roller (13) is mounted horizontally displaceable so as to be translatable relative to the upper roller (12) along a rectilinear horizontal direction of translation. The rear side roller (14) and the front side roller (15) are displaceably mounted to the frame (11) so as to be translatable by moving away from / close to the upper roller (12).

Description

Technical Field

The present invention relates to a four-roller bending machine for bending sheets, profiles and the like made of metal.
The present invention further relates to a method for using said bending machine for bending metal sheets, profiles and the like.

Background Art

Use of four-roller bending machines employed for bending metal sheets into cylindrical, conical or obround shapes is known within the field of the industrial manufacturing of metal artefacts.
For example, the document US2018133772 A1 describes a bending machine comprising a fixed top roller, a vertically displaceable bottom roller and two side rollers, these, too, being movable. The use of this bending machine for bending a metal sheet provides for a step, so-called invitation, in which an end of the metal sheet is clamped between the top roller and the bottom roller and in which a side roller, namely the roller on the side from which the metal sheet has been inserted, is lifted, thus moving closer to the top roller, so as to bend a portion of metal sheet close to the end thereof.
The Applicant has observed that four-roller bending machines like the one described in the above-mentioned document have the problem that they cannot bend the ends of the metal sheets in an optimal manner, because, following the invitation step, the metal sheet has a too long straight portion adjacent to the end of the metal sheet. More particularly, the Applicant has observed that such straight portion is at least twice the thickness of the metal sheet to be bent.
The object of the present invention is to overcome the problems and limitations of prior art by providing a four-roller bending machine that allows to bend metal sheets and the like in an optimal manner, reducing the length of the straight portions adjacent to the ends of the metal sheet.
A further object of the present invention is to provide a versatile four-roller bending machine that can take on different configurations as required.
These and other objects are achieved by the four-roller bending machine as claimed in the appended claims.

Summary of the Invention

The bending machine according to the present invention comprises an upper roller, a lower roller, a rear side roller and a front side roller as well as a supporting frame to which said upper roller, lower roller, rear side roller and front side roller are mounted.
Said upper roller, lower roller, first side roller and second side roller are all cylindrical rollers. In addition, each of said rollers is made as a single piece.
At least one out of the upper roller and the lower roller is a motor-driven roller, i.e. a roller associated with a motor in order to be rotated about its own longitudinal axis. Preferably, the upper roller and the lower roller and the front and rear rollers are all motor-driven rollers.
The upper roller is mounted vertically displaceable, in such a way that it can translate, moving away from or close to the lower roller, and the lower roller is mounted horizontally displaceable, in such a way that it can translate relative to the upper roller. More particularly, the lower roller is configured to be moved at least forward or backward relative to a vertical direction of translation of the upper roller.
The rear and front side rollers are displaceably mounted to the frame so as to be translatable by moving away from or close to the upper roller. More particularly, the side rollers can translate along rectilinear or curved trajectories.
The translational motions of said upper roller, lower roller, rear side roller and front side roller are imparted by means of respective hydraulic actuators and are preferably guided by means of suitable rectilinear or curved guides.
According to the present invention, a method for using the bending machine provides for the steps of:

inserting the metal sheet to be bent between the lower roller and the upper roller of the bending machine;
horizontally translating the lower roller forward/backward relative to a position in which the longitudinal axis of the lower roller is vertically aligned with respect to the longitudinal axis of the upper roller;
vertically lowering the upper roller so as to bend a portion of the metal sheet while the metal sheet rests on the rear side roller/front side roller, respectively.

The aforesaid steps of horizontally translating the lower roller forward/backward and vertically lowering the upper roller are carried out after the step of:

vertically lowering the upper roller so as to clamp the metal sheet between the upper roller and the lower roller which, with its longitudinal axis, is vertically aligned with respect to the longitudinal axis of the upper roller.

Advantageously, the aforesaid steps of horizontally translating the lower roller forward/backward and vertically lowering the upper roller are carried out when the front end/rear end of the metal sheet is clamped between the upper roller and the lower roller, respectively. This allows to bend the ends of the metal sheet while limiting the length of the portions adjacent to the ends that cannot be bent and therefore remain straight. More particularly, the Applicant has observed that with the bending machine and the method for using the same according to the present invention it is possible to obtain straight portions adjacent to the ends with a length up to about one and a half times the thickness of the metal sheet to be bent.
According to another method for using the bending machine, it is provided that the lower roller is kept with its longitudinal axis always vertically aligned with respect to the longitudinal axis of the upper roller.
According to a further method for using the bending machine, it is provided that the upper roller is kept always lifted and that, for bending the metal sheet, only three rollers are used, namely the upper roller (motor-driven) and two side rollers (either motor-driven or idle). This configuration is of advantage, for example, for obtaining large diameter bending.
In addition, by acting on the mutual inclination of the rollers, the bending machine can be used for carrying out frustoconical bending.
The bending machine according to the invention is therefore highly versatile, as it can take on different configurations as required.

Brief Description of the Figures

These and other features and advantages of the present invention will be more evident from the following description of preferred embodiments given by way of nonlimiting examples with reference to the annexed drawings, in which elements designated by same or similar reference numerals indicate elements that have same or similar functionality and construction, and in which:

Figure 1 is a front schematic view of a bending machine according to the invention;
Figures 2a-2o are schematic views of the steps of a first bending method using the bending machine according to the invention;
Figures 3a-3h are schematic views of the steps of a second bending method using the bending machine according to the invention;
Figures 4a-4e are schematic views of the steps of a third bending method using the bending machine according to the invention.

Description of Some Preferred Embodiments of the Invention

Referring to Figure 1, a preferred embodiment of a bending machine 10 according to the invention for bending metal sheets, profiles and the like (in the following, to simplify, reference will be made to a metal sheet 30) will be described here below.
The bending machine 10 comprises a supporting frame 11 to which an upper roller 12, a lower roller 13, a first side roller 14 and a second side roller 15 are mounted so as to be displaceable independently of one another.
The aforesaid upper roller 12, lower roller 13, first side roller 14 and second side roller 15 are all cylindrical rollers, i.e. they have a cylindrical outer surface. In addition, each of the said rollers is made as single piece, whereby the points of the cylindrical surface of each roller rotate all at the same speed when the roller is rotated.
The upper roller 12 is a motor-driven roller, for example actuated by a hydraulic motor (not shown) preferably associated to one of the ends of the roller, for example by means of a suitable gear motor, in order to transmit to the upper roller 12 a rotational motion about its longitudinal axis X.
According to the present invention, the upper roller 12 is vertically displaceable, i.e. it can be translated along a rectilinear vertical direction, in such a way that it can be moved away from or close to the lower roller 13. Preferably, the translational motion of the upper roller 12 is imparted by means of two hydraulic actuators 16 (only one of which is shown), each associated with a respective end of the roller 12. In addition, preferably, the translational motion is guided by means of rectilinear vertical guides 21.
Also the lower roller 13 is, preferably, a motor-driven roller, associated, similarly to what has been described above in connection with the upper roller 12, with a corresponding motor, for example by means of a gear motor, in order to transmit to the lower roller 13 a rotational motion about its longitudinal axis Y.
According to the present invention, the lower roller 13 is horizontally displaceable, i.e. it can be translated along a rectilinear horizontal direction, so as to be movable forward and/or backward relative to the rectilinear vertical direction of translation of the upper roller 12. The translational motion of the lower roller 13 is imparted, preferably, by means of two pairs of hydraulic actuators 17, 18 (only one of which is shown), each pair being associated with a respective end of the roller 13, and is guided, preferably, by means of rectilinear horizontal guides 22.
The first side roller 14 is arranged rearwardly with respect to the lower roller 13, i.e., by convention, on the side from which the metal sheet to be bent is inserted into the bending machine. The second side roller is arranged frontally with respect to the lower roller, i.e. on the side opposite to the side from which the metal sheet to be bent 30 is inserted into the bending machine.
Both side rollers 14, 15 are, preferably, motor-driven rollers, each of them being associated, in a manner similar to the one described above in connection with the upper roller 12, with a corresponding motor, for example by means of a gear motor, in order to transmit to each side roller 14, 15 a rotational motion about the respective longitudinal axis Z, W.
According to the present embodiment of the bending machine 10, the side rollers 14, 15 are displaceable along respective rectilinear directions that are oblique relative to the rectilinear vertical direction of translation of the upper roller 12 and to the rectilinear horizontal direction of translation of the lower roller 13, and are directed towards the upper roller 12, so that these rollers can be moved away from or close to the upper roller 12. The translational motion of each side roller 14, 15 is imparted, preferably, by means of two respective hydraulic actuators 19, 20 (only one of which is shown), associated with the ends of the respective side roller 14, 15. In addition, the translational motion of each side roller 14, 15 is guided, preferably, by means of corresponding rectilinear oblique guides 23, 24.
According to further embodiments of the invention (not shown), the side rollers translate along curved trajectories. For example, the rollers can translate guided by planetary guides or be supported by corresponding swinging arms hinged on side pivots.
In addition, according to further embodiments, the lower roller and/or the side rollers can be idle rollers rather than motor-driven rollers.
The rollers 12, 13, 14, 15 of the bending machine 10 are preferably supported by bearings (not shown) in order to enable rotational motion of said rollers.
The bending machine 10 according to the invention is preferably controlled by means of NC systems and is provided with electronic control of the parallelism of the side rollers 14, 15 and of the upper roller 12.
Referring to Figures 2a-2o, a method for using the bending machine 10 described above in order to bend a metal sheet 30 is described here below.
In a first step (Figure 2a), the rear side roller 14 is lowered and the upper roller 12 is lifted so as to enable the metal sheet to be bent 30 to be inserted between the lower roller 13 and the upper roller 12, from the insertion side (by convention, the rear side). The front side roller 15 lies at the height of insertion of the metal sheet 30 and is used as a striker for the front end 31 of the metal sheet 30, thus allowing to align said sheet.
Subsequently, the upper roller 12 is lowered so as to clamp the metal sheet 30 between the upper roller 12 and the lower roller 13, which has its longitudinal axis Y vertically aligned with respect to the longitudinal axis X of the upper roller 12 (Figure 2b). The metal sheet 30 is advantageously kept clamped during all the subsequent steps, thus preventing possible slipping of the metal sheet and therefore keeping the metal sheet aligned.
The upper roller 12 and the lower roller 13 are then rotated so that the metal sheet 30 is moved back until its front end 31 is clamped between the upper roller 12 and the lower roller 13, while the front side roller 15 is lowered (Figure 2c).
The lower roller 13 is then translated forward (Figure 2d) and the upper roller 12 is lowered (Figure 2e), so as to bend a portion 30a of the metal sheet 30 close to its front end 31 while the metal sheet 30 rests on the rear side roller 14. The aforesaid step of bending the portion 30a of the metal sheet 30 close to its front end 31 is called invitation (first invitation).
In Figure 2e, as well in all the subsequent figures, the portion of bent metal sheet is shown in grey.
After the first invitation, the rollers 12, 13, 14, 15 are rotated in such a way that the metal sheet 30 is advanced until its rear end 32 is clamped between the upper roller 12 and the lower roller 13 (Figure 2f).
The lower roller 13 is then translated forward (Figure 2g) and the upper roller 12 is lowered (Figure 2h), so as to bend a portion 30b of the metal sheet 30 close to its rear end 32 while the metal sheet 30 rests on the front side roller 15. The aforesaid step of bending the portion 30b of the metal sheet 30 close to its rear end 32 is called invitation (second invitation).
After the second invitation, the lower roller 13 is translated forward, so that it is brought back with its longitudinal axis Y vertically aligned with respect to the longitudinal axis X of the upper roller 12, and the front side roller 15 is lifted, thus bending a portion 30c of the metal sheet 30 comprised between the upper 12 and lower 13 rollers and the front side roller 15 (Figure 2i).
The upper roller 12 and the lower roller 13 are then rotated so that the metal sheet 30 is moved back until the portion 30c of the metal sheet 30 bent in the foregoing step lies rearwardly relative to the upper roller 12 and the lower roller 13 (Figure 2L). In this step, preferably, the front side roller supports the metal sheet, without bending it further.
The front side roller 15 is then lowered while the rear side roller 14 is lifted until it comes into contact with the metal sheet 30 (Figure 2m).
By continuing rotation of the upper roller 12 and lower roller 13, thus withdrawing the metal sheet 30, said sheet continues to be bent (Figure 2n) until a cylindrical shape, a so-called shell 33, is obtained (Figure 2o).
As an alternative to the sequence of steps illustrated above, it is possible to proceed to the bending of central portions of the metal sheet 30 after the first invitation and carry out the second invitation as a final step.
The bending machine 10 according to the present invention can also be used by keeping the lower roller 13 with its longitudinal axis Y always vertically aligned with respect to the longitudinal axis X of the upper roller 12.
Referring to Figures 3a-3h, a method for using the bending machine 10 in the aforesaid configuration with the non-translating lower roller 13 is described here below.
In a first step (Figure 3a), the rear side roller 14 is lowered and the upper roller 12 is lifted so as to allow the metal sheet to be bent 30 to be inserted between the lower roller 13 and the upper roller 12, from the insertion side (by convention, the rear side). The rear side roller 14 lies at the height of insertion of the metal sheet 30 and is used as a striker for the front end 31 of the metal sheet 30, thus allowing to align the metal sheet.
Subsequently, the upper roller 12 is lowered in such a way that the metal sheet 30 is clamped between the upper roller 12 and the lower roller 13 (Figure 3b). The metal sheet 30 is advantageously kept clamped during all the subsequent steps, thus preventing possible slipping of the metal sheet and therefore keeping the metal sheet aligned.
The upper roller 12 and the lower roller 13 are then rotated so that the metal sheet is moved back until its front end 31 becomes clamped between the upper roller 12 and the lower roller 13, while the front side roller 15 is lowered (Figure 3c).
The rear side roller 14 is then lifted, thus bending a metal sheet portion 30d comprised between the upper 12 and lower 13 rollers and the rear side roller 14 (Figure 3d). The aforesaid step of bending the metal sheet 30 is called first invitation.
The upper roller 12 and the lower roller 13 are then rotated so that the metal sheet 30 is advanced until the portion 30d of the metal sheet 30 bent during the preceding step lies frontally with respect to the upper roller 12 and lower roller 13 (Figure 3e). In this step, preferably, the front side roller supports the metal sheet without bending it further.
The rear side roller 14 is then lowered while the front side roller 15 is lifted, until it comes into contact with the metal sheet 30 (Figure 3f).
By continuing rotation of the upper roller 12 and lower roller 13, thus advancing the metal sheet 30, said sheet continues to be bent (Figure 3g) until a cylindrical shape, a so-called shell 33, is obtained (Figure 3h).
The bending machine 10 according to the present invention can also be used by keeping the upper roller 12 always lifted, thus using only three rollers for bending the metal sheet, namely the upper roller 12 and the two side rollers 14, 15.
Referring to Figures 4a-4e, a method for using the bending machine 10 in the aforesaid configuration with three rollers is described here below.
In a first step (Figure 4a), the rear side roller 14 is lowered so as to allow the metal sheet to be bent 30 to be inserted horizontally between the upper roller 12 and the rear side roller 14, from the insertion side (by convention, the rear side). The front side rollers 15 lies at the height of insertion of the metal sheet 30 and is used as a striker for the front end 31 of the metal sheet 30, thus allowing to align the metal sheet.
Subsequently, the rollers 12, 14, 15 are rotated so that the metal sheet 30 is advanced and a front portion 30e thereof is bent, thus carrying out the first invitation (Figure 4b).
After having brought the side rollers 14, 15 to the same height, the rollers 12, 14, 15 are rotated, thus bringing the rear portion 32 of the metal sheet 30 between the rear side roller 14 and the upper roller 12.
The rear side roller 14 is then lifted and the rollers 12, 14, 15 are rotated so that the metal sheet 30 is moved back and a rear portion 30f thereof is bent, thus carrying out the second invitation (Figure 4c).
The front side roller 15 is then lifted and the rollers 12, 14, 15 are rotated so that the metal sheet 30 is moved back and a central portion 30g thereof is bent (Figure 4d) until a cylindrical shape, a so-called shell 33, is obtained (4e).
As will be evident to the person skilled in the art, the methods of operation described above are given merely by way of examples and are not the only possible methods.
For example, when the bending machine 10 operates in its configuration with the non-translating lower roller 13, after the first invitation it is possible to advance the metal sheet 30 without bending it, and bend a portion of the metal sheet close to the rear end 32 thereof (i.e. carrying out the second invitation), and only thereafter the central portion of the metal sheet 30 is bent.
In addition, by acting onto the mutual inclination of the rollers, the bending machine 10 can be used for effecting frustoconical bending of the metal sheet.

Claims

A bending machine (10) comprising:
- an upper roller (12), a lower roller (13), a rear side roller (14) and a front side roller (15),

- a supporting frame (11) to which said upper roller (12), lower roller (13), rear side roller (14) and front side roller (15) are mounted,
wherein at least one of the upper roller (12) and the lower roller (13) is a motor-driven roller and wherein the rear side roller (14) and the front side roller (15) are displaceably mounted to the frame (11) so as to be translatable by moving away from / close to the upper roller (12),
wherein said upper roller (12), lower roller (13), rear side roller (14) and front side roller (15) are cylindrical rollers,
characterized in that
the upper roller (12) is mounted vertically displaceable, so as to be translatable along a rectilinear vertical direction of translation by moving away from or close to the lower roller (13), and the lower roller (13) is mounted horizontally displaceable so as to be translatable relative to the upper roller (12) along a rectilinear horizontal direction of translation.
The bending machine (10) according to claim 1, wherein the horizontally displaceably mounted lower roller (13) is configured to be movable forward and/or backward relative to the rectilinear vertical direction of translation of the upper roller (12).
The bending machine (10) according to claim 1 or 2, wherein the front side roller (15) and the rear side roller (14) are motor-driven rollers.
The bending machine (10) according to any of the preceding claims, wherein the side rollers (14, 15) translate along rectilinear or curved trajectories.
The bending machine (10) according to claim 4, wherein the side rollers (14, 15) translate along oblique trajectories relative to the rectilinear vertical direction of translation of the upper roller (12) and to the rectilinear horizontal direction of translation of the lower roller (13).
The bending machine (10) according to any of the preceding claims, which is controlled by means of NC systems.
The bending machine (10) according to any of the preceding claims, wherein the translational motions of said upper roller (12), lower roller (13), rear side roller (14) and front side roller (15) are imparted by means of corresponding hydraulic actuators (16, 17, 18, 19, 20).
The bending machine (10) according to any of the preceding claims, further comprising guides (21, 22, 23, 24) arranged to guide the translational motions of said upper roller (12), lower roller (13), rear side roller (14) and front side roller (15), respectively.
A method for using a bending machine (10) according to any of the claims 1 to 8, comprising the steps of:
- inserting the metal sheet to be bent (30) between the lower roller (13) and the upper roller (12);

- horizontally translating the lower roller (13) forward/backward relative to a position in which the longitudinal axis (Y) of the lower roller (13) is vertically aligned with respect to the longitudinal axis (X) of the upper roller (12);

- vertically lowering the upper roller (12) so as to bend a portion (30a, 30b) of the metal sheet (30) while the metal sheet (30) rests on the rear side roller (14)/front side roller (15), respectively.
The method according to claim 9, wherein said steps of horizontally translating the lower roller (13) forward/backward and vertically lowering the upper roller (12) are carried out after the step of:
- vertically lowering the upper roller (12) so as to clamp the metal sheet (30) between the upper roller (12) and the lower roller (13) with its longitudinal axis (Y) vertically aligned with respect to the longitudinal axis (X) of the upper roller (12).
The method according to claim 10, wherein said steps of horizontally translating the lower roller (13) forward/backward and vertically lowering the upper roller (12) are carried out when the front end (31)/rear end (32) of the metal sheet (30) is clamped between the upper roller (12) and the lower roller (13), respectively.