APPARATUS FOR BENDING STRUCTURAL METAL RAILS

Abstract: The invention relates to an apparatus for bending structural metal rails, preferably rails for multi-glazed windows, and gives instructions for a bending unit (20) having two wring­ ing heads (6) which can be displaced relative to the width of the rail, for in an open position to allow the infeed of rails (5) having various width, and in an attracted position to clamp a portion of the rail (5) for the bending thereof by turning the wringing heads (6). Since each wringing head (6) is provided with a protrusion (6a) having an edge (6b) serving to position the rail (5) upon the closing of the wringing head (6) and to support the rail (5) during the bending operation, there is also defined a space (6c) bet­ ween the protrusions (6a), said space (6c) defining an in­ feed path for further supply of rail (5) immediately after a bending operation and after the opening of the wringing heads (6), so that the infeed of a further length of rail takes place synchronously with the return movement of the wringing heads (6) to the starting position for another ben­ ding operation.

Description: The present invention relates to an apparatus for bending structural metal rails, preferably structural rails for multi-glazed windows, which are used in the production of insulated windows. According to prior art, the parts which are to be included in the finished metal frame will be cut in separate lengths, thereafter to be joined at the corners by means of special, separate corner pieces. This involves a relatively complicated and work-consuming process, the known method being very unfavourable as regards automated production of metal frames. From SE -A- 439 514 (& US-A-4 261 145) there are known distance pieces for multi-glazed windows having several window panes, comprising a hollow structural rail which is made into a frame. The frame is manufactured by bending, there being used a bending device comprising a roller and a turnable bending element. The length of the rail which is to be bent is determined by a stopper which can be displaced relative to the bending device. However, the prior art gives no instructions as regards a rational and effective bending of metal rails for procuring bent blanks which only have to be put together by means of only one corner piece, the apparatus at the same time being able to handle structural rails having various dimensions. Neither does the prior art give instructions for a bending apparatus rendering finished metal frames having corners which do not include uneven surfaces, independent of the various widths of the metal rails. On the market for structural metal rails which are used for the manufacturing of multi-glazed windows, there exist today 10-15 various sizes. When known apparatuses are adjusted from one size of rails to another, it is necessary to exchange the main tool of the apparatus, a fact which involves that the manufacturing of frames having various metal rails is cumbersome and time consuming. Neither can it be found in the prior art how an accurate length measurement of the rail can be carried out, which is of utmost importance due to the consumption of material in the bending zones. The object of the present invention is to provide a bending apparatus which allows bending of a structural rail in three or more sequential bending operations, whereafter the bent rail can be put together to a frame by means of only one corner piece or one joining piece. Another object of the present invention is to provide a bending apparatus which can bend structural rails of various dimensions without exchanging the main tool, i.e. the bending unit itself is to be provided with means allowing for an automatic adjustment of the bending means relative to the various dimensions in question. A further object of the present invention is to provide a bending apparatus which measures very accurately the length of the structural rails which are to be bent, whether the dimensions are measured from a transversely cut edge or from a bent corner. EP-A-9703 discloses apparatus for bending structural metal rails to form a unitary bent closed frame structure suitable for framing windows when closed by a single corner piece, comprising a bending unit having first and second clamping heads which can be displaced relative to the rail to be bent from a first mutually distant position to allow infeed of rails having various width dimensions, to a second mutually close position to clamp a portion of the rail during the bending thereof; turning means for rotating the first and second clamping heads from an initial position to a bent rail position, thereby bending the rail; a centre pin between the clamping heads, around which centre pin the clamping heads are arranged to rotate and about which centre pin the rail is bent. According to the present invention a machine according to the preceding paragraph is characterised in that each of said clamping heads has a protrusion, said protrusions extending toward each other for supporting edge portions of the rail during the bending operation, each of said protrusions having an edge serving to engage the rail when said clamping heads are displaced from the first distant position to the second close position, to position the rail relative to the centre pin and to support said opposite edge portions of the rail; said clamping heads when in the second close position having their protrusions spaced from each other and defining an infeed path space for receiving another section of the rail immediately after a bending operation when the clamping heads have commenced travel from the second close position towards first distant position and before return rotation thereof to the initial position for another bending operation. By means of the two clamping heads which can be displaced, preferably sidewise relative to each other, into an open position to allow the infeed of structural rails having various widths, and into a retracted position to clamp a portion of the rail for the bending thereof, the clamping heads at the same time being turnable about a common axis for the performance of the bending operation of the rail clamped therebetween, there is provided a bending apparatus which does not have to exchange the main tool if rails having various sizes are to be bent into frames. Since between the protrusions on each clamping head there is left a space, even during the bending or twisting operation, this space will serve as an infeed path for further lengths of the rail immediately after a bending operation, i.e. immediately after the retraction of the clamping heads after a completed bending operation and a release of the bent rail portion, and prior to the return of the clamping heads to the starting position for bending operation. Thereby is achieved a quick and effective infeed of further profiled lengths, i.e. the new length which is to be bent, is brought forward and is ready for having the clamping heads clamped against itself immediately upon the return of the clamping heads to the starting position for a new bending operation. In a preferred embodiment the centre pin is of circular cross-section. Preferably the displacement of the clamping heads is carried out in the transverse direction of the rail by means of a power cylinder rendering a predetermined closing pressure against the rail, independent of the width thereof. The rotation of the clamping heads themselves can take place by means of a power turning means, preferably taking the shape of a turning arm which is driven by a stroke cylinder, and which cooperates with stopper means and signal transducers for the control of the bending movement and the return movement. The present apparatus can also comprise an adjustable stopper serving for the measurement of the structural rail which is to be bent, and which cooperates with an end stopper allowing for further displacement of the stopper so as to avoid that the stopper will lock the rail during the bending operation. Appropriately, the stopper comprises a stopping portion which in connection with a transversely cut rail stops the rail at the cut edge thereof, and which in connection with a bent rail stops the rail at the outer portion of the rail, a fact which renders a measuring difference corresponding to the height of the rail. The apparatus may also comprise an infeed device for the rail, which cooperates with stopper means and transducers, and in the housing of the bending unit there is appropriately provided a supporting means for the rail, which supporting means cooperates with the clamping heads and the centre pin for avoiding a deflection of the rail in the area of the clamping heads, and thereby aiding in giving the rail a correct bending point. Further features and advantages of the present apparatus will appear from the following description, reference being made to the attached drawings. Figure 1 is a front view of a working table including an apparatus for bending structural rails, Figure 1a is a sketch illustrating the principle of a stopper means which may be included in the present apparatus, Figure 2 is a side view of the apparatus illustrated in figure 1, Figure 3 is on a larger scale an end view of an embodiment of a bending unit, Figure 4 is a side view of the bending unit of figure 3, shown partly in section, and Figure 4a illustrates examples of various rail widths which can be used in the present apparatus. As appearing from the drawings which illustrates an embodiment of an apparatus for bending structural metal rails, in which the present invention is included, the apparatus comprises a bending unit 20. This bending unit 20 comprises a first stroke cylinder 1 (figure 4) which via conduits 1a and 1b is influenced by a fluid, such that the piston 1c with its piston rod 1d can move in different directions relative to the centre axis C-C of the bending unit 20. At the end of the piston rod 1d which is opposite to the piston 1c, there is provided a bevel roller bearing 3a, which by its reciprocating movement influences an electrical signal transducer 4, and which constitutes the main member of a first clamping head 6 having a protrusion 6a. In the bending unit 20 there is also provided a second bevel roller bearing 3b which is fixed relative to the centre line C-C of the bending unit 20, but which constitutes a second clamping head 6 having a protrusion 6a provided just opposite of the protrusion 6a of the clamping head 6 on the piston rod 1d. Since one of the clamping heads 6, here the one which is provided on the piston rod 1d, can be displaced, there will between the clamping heads 6 be defined an opening 6c for the infeed of a structural rail 5, the rail 5 being passed under a centre pin 7 which is provided at the centre portions of the clamping heads 6. Thus, at the start of a bending operation a rail 5 will be fed into the space 6c between the clamping heads 6 and beneath the centre pin 7, the protrusions 6a with their upper inclined edges 6b serving to position the rail 5 when the clamping heads 6 are approaching each other. After an appropriate feeding of the rail, the two clamping heads 6 will be displaced closer to each other and clamp against the sides of the rail, and the said protrusions 6a with their edges 6b will then support the rail 5 during the subsequent bending operation. In the area of the protrusions 6a, i.e. in the space 6c defined between the protrusions 6a, there is also provided a stabilising pin 8 serving for further stabilisation of the clamping heads 6 together with the above discussed centre pin 7. In connection with the bending unit 20 there is also provided a supporting means 13 (figure 3) cooperating with the clamping heads 6 and the centre pin 7 for thereby avoiding deflection of the rail 5 in the area of the space 6c between the clamping heads 6, and thereby rendering the rail 5 a correct bending point. It is to be understood that the relative displacement of the clamping heads 6, i.e. displacement of one or the other clamping head, takes place by means of the pressure cylinder 1, which provides a predetermined closing pressure against the rail 5 independent of the width thereof. Examples of various rails having different widths are illustrated in figure 4a. It is to be understood that the angle defined by the inclined edges 6b on the protrusions 6a, is to correspond to the inclined edges of the rail 5, here designated by the angle α at the bottom of figure 4a. However, it is to be understood that this angle will change very little with the width of the various profiles, and can for all practical purposes be considered as approximately constant for current rails. When the rail 5 has taken its correct position in the space 6c between the wringing head 6 and is clamped therebetween, the clamping heads 6 will be subjected to a turning movement by means of a power turning means in the form of a bending arm 9 which is driven by a second stoke cylinder 2, and which cooperates with stopper means 10 and signal transducers 10a and 10b for the control of the bending movement in the direction of the arrow T in figure 1 and 3, and for the control in opposite direction of the return movement following the accomplished bending operation. Due to the space 6c between the protrusions 6a and the clamping heads 6, the clamping heads 6 will immediately after the accomplished bending operation, and immediately after having been retracted from each other for thereby no longer effecting a pressure on the side edges of the rail, allow for the infeed of another length of the rail, at the same time as the clamping heads 6 are returned to the initial position for a new bending operation, i.e. in the opposite direction of the arrow T. Thus, a new length of the rail will be ready for being clamped by the clamping heads with their protrusions 6a, when the same take their return position after a previous bending operation. It is to be understood that the above discussed power turning means taking the form of a turning arm 9, will turn the clamping heads 6 to a predetermined angle, in the present case preferably 90 degrees, and that this angle can be adjusted according to prevailing conditions. As most clearly appearing from figures 1 and 2, the bending unit 20 with associated equipment is mounted on a working table 11 comprising a main plate which can be adjusted to various angular positions. At the rear side of the working table 11 there is provided a control cabinet 12 housing control instruments for both the electro mechanical and hydraulic functions. In connection with the bending unit 20 which is mounted on the working table 11, there is provided a cylinder 21 having an external glider, as well as an adjustable stopper 22 serving for the measurement of the rail portion which is to be bent, and which cooperates with an end stopper 23 serving for a further displacement of the stopper 22 for avoiding the hookup of the rail 5 to the stopper 22 during the bending operation. The end stopper 23 comprises a cylinder 23a rendering the further displacement possible. As appearing from figure 1a the above discussed stopper 22 comprises a stopper portion 22a which during the infeed of a straightly cut rail 5, as this is illustrated at the top of figure 1a, stops the rail 5 at said transversely cut edge, and this stopping of the rail 5 corresponds to a distance L1 to which the stopper 22 has been adjusted. After an accomplished bending the L-shaped stopper portion 22a of the stopper 22, allows the bent rail portion 5a to be entered onto itself, so that the rail with its outer portion of the bent corner slides over the narrow foot portion of the stopper 22a and stops against the leg portion of the stopper portion 22a after a certain length L2, as this appears from the bottom sketch of figure 1a. After a bending operation the rail 5 will, accordingly, with its bent outer portion stop against a larger upwardly extending portion of the stopper portion 22a, a fact which entails a measuring difference L3 - L2 = h , corresponding to the height of the rail. It is to be understood that the apparatus comprises a further mechanically adjustable end stopper 24 cooperating with the cylinder 21 with the outer glider. Further, the apparatus comprises an infeed device which in turn comprises an air motor 25 for the infeed of the rail 5, as well as a tightening device 26 rendering a stable and even gripping of the rail 5 during the infeed motion. One or more ball bearings 27 are provided on the working table 11 for the support of the rail 5 during the infeed thereof. Further, the apparatus comprises an electric signal transducer 28 which appropriately cooperates with other above discussed stopper means and transducers. In figure 4a there are illustrated various examples of rails having different widths, but which have substantially the same height. There are illustrated three various widths B1, B2 and B3, respectively, the height h being approximately constant. However, all of these rail widths can be fed into the space 6c between the clamping heads 6, the centre pin 7 and the inclined surfaces 6b of the protrusions 6a. This involves that even if the apparatus is to handle another rail width, it is not necessary to exchange the clamping heads 6 themselves, since the adjustment thereof to an appropriate maximum opening which allows for the receipt of the novel width is carried out automatically, whether this width is larger or smaller than the previous one. It is to be understood that the apparatus according to the invention can be implemented in other ways than the one which is discussed above. For example, the above discussed mechanical stoppers which are adjusted for certain rail lengths to be bent, can be replaced by electronic units, for example an electronic measuring wheel which can be programmed for monitoring the infeed of correct rail lengths.

Claims: Apparatus for bending structural metal rails to form a unitary bent closed frame structure suitable for framing windows when closed by a single corner piece, comprising a bending unit (20) having first and second clamping heads (6) which can be displaced relative to the rail to be bent from a first mutually distant position to allow infeed of rails having various width dimensions, to a second mutually close position to clamp a portion of the rail during the bending thereof; turning means for rotating the first and second clamping heads from an initial position to a bent rail position, thereby bending the rail (5); a centre pin (7) between the clamping heads (6), around which centre pin the clamping heads are arranged to rotate and about which centre pin the rail is bent, characterised by each of said clamping heads having a protrusion (6a), said protrusions extending toward each other for supporting oppositely disposed edge portions of the rail (5) during the bending operation, each of said protrusions having an edge (6b) serving to engage the rail (5) when said clamping heads (6) are displaced from the first distant position to the second close position, to position the rail relative to the centre pin (7) and to support said opposite edge portions of the rail; said clamping heads (6) when in the second close position having their protrusions spaced from each other and defining an infeed path space (6c) for receiving another section of the rail (5) immediately after a bending operation when the clamping heads have commenced travel from the second close position towards first distant position and before return rotation thereof to the initial position for another bending operation. Apparatus as claimed in claim 1 characterised in that the pin (7) is of circular cross section. Apparatus as defined in claim 1 or claim 2, characterised by providing a pressure cylinder (1) for displacing the clamping heads (6) transversely with respect to a longitudinal direction of the rail (5) and providing a predetermined closing pressure against the rail (5) independent of the width of the rail. Apparatus as defined in claim 3 characterised in that the turning means is a powered turning means for rotating the clamping heads (6) a predetermined angle. Apparatus as defined in claim 4 characterised in that the power turning means comprises a stroke cylinder (2); stopper means (10); and a turning arm (9) driven by the stroke cylinder (2) and cooperating with the stopper means (10) for controlling the bending movement and the return movement of the clamping heads (6). Apparatus as defined in any one of claims 1 to 5, characterised by providing an end stopper (23); and an adjustable stopper (22) movably displaceable with respect to end stopper (23) to allow for a further displacement of the stopper (22) with respect to the end stopper (23) to avoid jamming of that portion of the rail (5) which is bent during the bending operation. Apparatus as claimed in claim 6 characterised in that the end stopper (23) comprises a cylinder (23a) for movably displacing the end stopper (23) to achieve the further displacement. Apparatus as claimed in claim 7, characterised in that the stopper (22) has a stopper portion for engaging the rail (5) at the straightly cut edge thereof, and for engaging the rail (5) against bent outer portion of the rail after the rail has been bent, such as to provide measuring difference corresponding to the height of the rail. Apparatus as defined in any one of claims 1 to 8, characterised by providing powered infeed means (25) for feeding the rail (5) between the clamping heads. Apparatus as defined in any one of claims 1 to 9, characterised by providing supporting means (13) for engaging a lower face of the rail in a bending region of the rail adjacent the clamping heads (6) and the centre pin (7) to avoid deflection in the bending portion of the rail. A method of bending structural metal rails to form a unitary bent closed frame structure suitable for framing windows when closed by a single corner piece, comprising providing first and second clamping heads (6) each having a protrusion (6a), infeeding the rail (5) between the clamping heads and beneath a centre pin (7) between the clamping heads (6), said protrusions extending toward each other for supporting the rail (5) during a subsequent bending operation, and having an edge (6b) for positioning the rail (5) when said clamping heads (6) are subsequently displaced from a first distant position to a second close position; positioning the first and second clamping heads in the first mutually distant position for feeding therebetween rails having various width dimensions; displacing the first and second clamping heads (6) relative to the rail to be bent from the first mutually distant position to the second mutually close position with said protrusions spaced from each other to clamp a portion of the rail during the bending thereof; rotating the first and second clamping heads from an initial position to a bent rail position, thereby bending the rail (5) about said centre pin; thereafter feeding another section of the rail (5) between the clamping heads (6) in the space defined between the protrusions immediately after the bending operation as the clamping heads commence travel from the second close position towards the first distant position and as the clamping heads rotate from the bent rail position to their initial position, and thereafter rotating the clamping heads fully to their initial position for another bending operation. The method as defined in claim 11 characterised by the step of providing a support (13) adjacent the clamping heads (6) for supporting the rail during the bending operation to avoid deflection of the rail.

Inventors: DAHL, TOR
Applicants: RJUKAN METALL A/S
Application year: 1987
Main classification: B21D11
IPC codes: E06B3, B21D11, B21D7