Roller hemming tool

Abstract

A roller hemming tool having a main hollow body including a first end for fastening to a robot and a second end having a secondary body which, in turn, includes at least one roller. The tool also includes the following elements which are axially distributed therein: a load cell on the first end; a die in contact with the load cell; a first cylinder in contact with the die; a second cylinder to which the secondary body is fastened; an elastic means in contact with the first cylinder and the second cylinder; and a cap limiting the axial movement of the second cylinder. When in use, the roller continuously exerts pressure in an axial direction, said pressure being successively transmitted to the secondary body, the second cylinder, the elastic means, the first cylinder, the die and up to the load cell.

Claims

1. A roller hemming tool, comprising: a main body comprising a hollow structure having a first end for fastening to a robot and a second end which comprises a secondary body which, in turn, comprises at least one roller; wherein the main body comprises, axially distributed inside: a load cell in the first end; a die in contact with the load cell; a first cylinder in contact with the die; a second cylinder to which the secondary body is fastened; an elastic element in contact with the first cylinder and the second cylinder; and a cap limiting the axial movement of the second cylinder towards an external part of the main body; wherein: in use, the roller continuously exerts a pressure in an axial direction, said pressure being successively transmitted to the secondary body, to the second cylinder, to the elastic element, to the first cylinder, to the die and, finally, to the load cell, and the cap is screwed into the second end such that the compression of the elastic element, with the roller at rest or in use, is adjustable by screwing the cap into the second end.

2. The roller hemming tool, according to claim 1, further comprising clamp screws exerting pressure against an exterior cylindrical surface of the second end after being screwed into threaded-through orifices angularly distributed in an exterior perimeter of the cap.

3. The roller hemming tool, claim 2, further comprising blind orifices for the screwing and unscrewing of the cap into the second end through mechanical means.

4. The roller hemming tool, according to claim 3, further comprising anti-rotation means which prevent the relative rotation of the second cylinder with respect to a central longitudinal axis while allowing for axial movement of the second cylinder.

5. The roller hemming tool, according to claim 2, further comprising anti-rotation means which prevent the relative rotation of the second cylinder with respect to a central longitudinal axis while allowing for axial movement of the second cylinder.

6. The roller hemming tool, according to claim 1, further comprising a first key attachable to the main body by screwing a first screw into an elongated orifice in the first key, the first key being partially and tightly placeable in a hole of a castellated edge in the cap.

7. The roller hemming tool, claim 6, further comprising blind orifices for the screwing and unscrewing of the cap into the second end through mechanical means.

8. The roller hemming tool, according to claim 7, further comprising anti-rotation means which prevent the relative rotation of the second cylinder with respect to a central longitudinal axis while allowing for axial movement of the second cylinder.

9. The roller hemming tool, according to claim 6, further comprising anti-rotation means which prevent the relative rotation of the second cylinder with respect to a central longitudinal axis while allowing for axial movement of the second cylinder.

10. The roller hemming tool, claim 1, further comprising blind orifices for the screwing and unscrewing of the cap into the second end through mechanical means.

11. The roller hemming tool, according to claim 10, further comprising anti-rotation means which prevent the relative rotation of the second cylinder with respect to a central longitudinal axis while allowing for axial movement of the second cylinder.

12. The roller hemming tool, according to claim 1, further comprising anti-rotation means which prevent the relative rotation of the second cylinder with respect to a central longitudinal axis while allowing for axial movement of the second cylinder.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a perspective view of a roller hemming tool, which is the object of the present invention, according to a FIRST embodiment;

(2) FIG. 2 shows a perspective view of a longitudinal section of the roller hemming tool of FIG. 1;

(3) FIG. 3 shows a view of a cap according to a first embodiment; and

(4) FIG. 4 shows a view of a cap according to a second embodiment.

(5) Below is a list of the different components represented in the figures and comprised in the invention:

(6) 1. Main body

(7) 2. Secondary body

(8) 3. Roller

(9) 4. First end

(10) 5. Second end

(11) 6. Load cell

(12) 6.1. Die

(13) 6.2. Connector

(14) 7. Elastic means

(15) 8. Cap

(16) 9.1. First plain bearing

(17) 9.2. Second plain bearing

(18) 10. Fourth screw

(19) 11. First cylinder

(20) 12. Second cylinder

(21) 12. Protrusion

(22) 13. Reference element

(23) 14. Anti-rotation means

(24) 14.1. Removable gusset

(25) 14.2. Second key

(26) 14.3. Second screw

(27) 15. Blind orifice

(28) 16. Clamp screws

(29) 17. First key

(30) 17. Elongated orifice

(31) 18. Hole

(32) 19. Plate

(33) 20. Rolling bearing

(34) 21. Threaded-through hole

(35) 22. Recess

(36) 23. First screw

(37) 24. Third screw

(38) 25. First orifice

(39) 26. Second orifice

(40) 27. Fastening

DESCRIPTION OF THE INVENTION

(41) As indicated, and as it can be appreciated in FIGS. 1 and 2, the present invention describes a roller hemming tool (3) which preferably comprises a main body (1) of hollow cylindrical longitudinal structure, which comprises a first end (4) to which a robot is fastened.

(42) The first end (4) comprises a plate (19) as a limit to connect the present tool to a robotised arm by means of second orifices (26), while the plate (19) comprises first orifices (25) angularly distributed for their fastening to the end of the main body (1) by screwing third screws (24), as it may be appreciated in FIG. 2. This configuration provides access to the inside of the main body (1) through the first end (4). In another preferred embodiment, not represented in the figures, this plate (19) is used as closure of the first end (4) of the main body (1), which is also fastened to a coupling cylinder, which is in turn fastened to the robotised arm. With this preferred embodiment, an extension in the final position of the rollers (3) is obtained.

(43) A second end (5) of the main body (1) comprises a secondary body (2) partially inserted therein. The secondary body (2) is fastened in an axial and rotating manner with respect to a second cylinder (12), as described further on. The secondary body (2) comprises four fastenings (27) distributed angularly every 90 to arrange a roller (3) in each of the fastenings (27). The fastenings (27) may vary in length and orientation depending on the folding operations to be carried out in each piece. In other preferred embodiments, the number of fastenings (27) varies from 1 to 8, thus changing the number of rollers (3) comprised by the present roller (3) hemming tool. Each of the fastenings (27) additionally comprises a rolling bearing (20) for the rotation of each of the rollers (3) in their rolling through the flanges of the component or panel outlines, conducting progressive foldings of said flanges through pre-defined paths.

(44) Additionally, the secondary body (2) comprises a reference element (13) of the robot fastened to the central part, a Tool Control Point (TCP) protruding in a centred and axial manner from the rest of the tool. The reference element (13) comprises a metallic rod preferably fastened by being screwed in the secondary body (2). In other preferred embodiments, the reference element (13) may be fastened to another area of the roller hemming tool.

(45) For the axial and rotational fastening of the secondary body (2) to the second cylinder (12) arranged in the inside of the main body (1) in its second end (5), the present tool comprises a fourth screw (10). In addition, the secondary body (2) is partially inserted in the second cylinder (12) favouring its axially centred arrangement.

(46) The second cylinder (12) is wrapped by first plain bearings (9.1) to ensure and favour their guiding during their axial movement inside the main body (1). Additionally, the second cylinder (12) is prevented from rotating with respect to its own central longitudinal axis due to anti-rotation means (14) arranged, in the preferred embodiment shown in the figures, in a section near the inner end of the second cylinder (12), that is, in the end of the second cylinder (12) which is closest to the first end (4). The main body (1) comprises an access opening to said anti-rotation means (14) which is covered with a removable gusset (14.1).

(47) The anti-rotation means (14) preferably comprise a second key (14.2) fastened to the exterior of the second cylinder (12) by means of a second screw (14.3). The second key (14.2) is provided with a hole in the main body (1) of longitudinal extension, according to the longitudinal extension of the main body (1), for it to be housed and moved, since the second cylinder (12) moves axially without rotation.

(48) In the embodiment shown in FIG. 2, the interior end of the second cylinder (12) comprises in a round surface a perfectly centred protrusion (12), which serves for tightly placing an end of an elastic means (7), such as an elastic spring or spring element, in said inner end of the second cylinder (12). Preferably, at least half the length of the elastic means (7) is inserted through the centre of a round surface of a first cylinder (11) facing the round surface of the inner end of the second cylinder (12) in the inside of the main body (1). In a preferred embodiment shown in FIG. 2, the length of the elastic means (7) inserted is of approximately three fourths of the total length.

(49) By having the elastic means (7) partially inserted in the first cylinder (11) and wrapping through pressure the protrusion (12) of the second cylinder (12), it allows for obtaining a fastening and an axial guiding of the longitudinal extension of the elastic means (7) without allowing said elastic means (7) to be laterally deformed, especially by being compressed.

(50) Preferably, the first cylinder (11) is wrapped by second plain bearings (9.2) to ensure and favour their guiding when moving axially in the inside of the main body (1). Additionally, the first cylinder (11) comprises an external end that is the end closest to the exterior of the main body (1) following an axial path, with a round surface, the central part of which supplements a die (6.1). In this manner, any pressure arising from the axial movement of the first cylinder (11), especially towards the plate (19), is withstood by the die (6.1).

(51) The die (6.1) transmits the pressure exerted by said movements of the first cylinder (11) to a conventional load cell (6), the load cell (6) being withheld by the plate (19) in the first end (4) against the main body (1). Placing the die (6.1) prevents the wear of the first cylinder (11) and/or the load cell (6), the replacement of the die (6.1) being cheaper than the replacement of the first cylinder (11) and/or the load cell (6).

(52) The load cell (6) is inserted in the main body (1) except for at least one connector (6.2) for the connection of the load cell (6) to a conventional analogue/digital converter, not shown in the figures. The analogue/digital converter transforms into numerical values the stresses or pressures measured by the above-mentioned load cell (6) through the die (6.1), and in turn, it works as a wireless transmitter to transmit the measured values. The numerical values obtained are sent to a monitoring device, PC or specific display unit for them to be viewed and assessed.

(53) The assembly formed by the die (6.1), the first cylinder (11), the elastic means (7), the second cylinder (12) and the secondary body (2), perfectly and axially aligned with each other by their centres, is axially located and defined by a cap (8) arranged in the second end (5) of the main body (1). It is important that said assembly is arranged in an aligned manner, preferably with their central longitudinal axis, for a linear and effective transmission of the stresses or pressure exerted by the present tool against the components to be treated in the longitudinal direction of said tool.

(54) The secondary body (2) is inserted through the cap (8). The cap (8) is screwed in the second end (5) and is in contact with the second cylinder (12) such that it prevents its movement to the exterior of the main body (1) through the second end (5).

(55) The present hemming tool comprises blind orifices (15), more clearly appreciated in FIGS. 3 and 4, performed in the outer cylindrical perimeter of the cap (8), angularly distributed, to partially insert mechanical means to facilitate the rotation of the cap (8). Preferably, these mechanical means are hook spanners or a similar mechanical element of longitudinal extension which comprises an end placeable in said blind orifices (15).

(56) To ensure or fasten the position of the cap (8) once it is desirably screwed in the second end (5), the cap (8) is fastened in said position by screwing some clamp screws (16), preferably headless screws, in threaded-through orifices (21) arranged in the exterior cylindrical perimeter of the cap (8). The clamp screws (16) are screwed in said threaded-through orifices (21) until the required pressure is exerted against the exterior main body (1) to ensure that the cap (8) will not suffer undesired movements while the present tool is in operation or at rest. This preferred embodiment allows the cap (8) to be fastened in a desired position or the cap (8) to be released from said desired position, without the need to be handled by any other element.

(57) FIG. 4 shows a preferred embodiment as an alternative to the one shown in FIG. 3. In this preferred embodiment, the tool which is the object of the present invention comprises a castellated edge in the cap (8) and a first key (17) with an elongated orifice (17) to insert a first screw (23) that is screwed in the exterior cylindrical surface of the main body (1) for fastening said first key (17) to the exterior surface of the main body (1). The first key (17) is fastened, preferably, in a recess (22). Preferably, in the exterior surface of the main body (1) there are 1 to 8 recesses (22) angularly distributed to ensure lateral immobilisation, preventing the first key (17) from rotating or displacing.

(58) The elongated orifice (17), extending longitudinally based on the longitudinal extension of the main body (1), facilitates the adjustment of the longitudinal position of the first key (17) to the different degrees of cap (8) screwing in the second end (5). Once the cap (8) is screwed up to its desired position in the second end (5), a hole (18) of the castellated edge of the cap (8) closest to the first key (17) is made to coincide with the first key (17), thus leaving the first key (17) tightly introduced in the hole (18) and in the desired longitudinal position by means of the elongated orifice (17).

(59) During the pre-hemming stage, the behaviour of the tool must be similar to that of a rigid body, as in this stage of the hemming operation in which the flange of the outline of an exterior panel is folded towards a pre-defined angle with respect to an interior panel, the precision in the folding of the curved panel areas is not a restrictive parameter, the speed of the operation being more relevant. Therefore, given that the roller hemming tool of the present invention comprises an elastic means (7), it is necessary to establish a pre-load of said elastic means (7), through which the behaviour of the tool is equivalent to that of a rigid body. This pre-load results from the compression of the elastic means (7) such that the pressure exerted by the robot on the flange during the pre-hemming stage is smaller than the pre-load carried out on the elastic means (7). In this manner, as the pre-load to which the elastic means (7) is subject is not exceeded by the pressure exerted by the robot on the flange during the pre-hemming stage, the behaviour of the elastic means (7) and, therefore, that of the roller hemming tool of the present invention is equivalent to that of a rigid body.

(60) For the embodiment of this pre-load, the cap (8) is screwed until it exerts pressure against the second cylinder (12) which, in turn, compresses the elastic means (7) according to certain desired values. When the cap (8) is screwed until the elastic means (7) reaches the desired compression, said position of the cap (8) is fixed inside its screwing path, as previously explained. In this manner, the rotation of the cap (8) is prevented, thus avoiding undesired variations of the pre-load to which the elastic means (7) is subject.

(61) During the hemming stage, it is necessary to obtain a high degree of precision in the paths and, therefore, correct the deviations existing during the folding of the curved areas of the panels; therefore, during this stage an elastic behaviour of the tool is necessary.

(62) In the hemming stage, a load or pressure is exerted by the hemming tool against the component to be hemmed, resulting in a compression of the elastic means (7). Said compression of the elastic means (7) prevents the rollers (3) from losing contact with the components or the pressure on the components from being reduced as a result of following paths defined by linear segments.

(63) This is so because when the rollers (3) lose contact with the flange of the outline of the panel or component being hemmed, the elastic means (7) pushes the second cylinder (12) and the latter, in turn, pushes the secondary body (2), thus keeping the roller (3) in contact with the flange of the outline of the panel or component being hemmed, correcting the deviation existing between the linear path of the robot and the curvature of the panel or component.

(64) The tool which is the object of the present invention, apart from monitoring the stresses during the hemming process, makes it possible to adapt the status of the elastic means (7) to the requirements of the pre-hemming stage in a quick and simple way, and also facilitates the adjustment or change of the elastic means (7) status, if necessary, when going from the pre-hemming stage to the hemming stage, reducing the time required for that.

(65) Once the nature of the invention is described, it is stated for the relevant purposes that it is not limited to the exact details of this description, but on the contrary, whichever amendments are deemed appropriate may be introduced, insofar as the essential features thereon are not altered. In consequence, the scope of the invention is defined by the following claims.