Automatic method and device for calendering aluminium profiles for producing spacer frames for insulating glazing units

Abstract: An automatic method and device for calendering aluminum profiles for producing spacer frames for insulating glazing units, the method consisting in producing calendering by preliminarily deforming the surface (3) on which minute holes (4) are formed so as to obtain an inside curve (7). A consecutive plurality of minute bends, the pitch increment whereof tends to zero and the bending angle increment whereof tends to zero, is then performed at an automatically controlled microbending station (9).

Description: The present invention relates to an automatic method and device for calendering aluminum profiles for producing spacer frames for insulating glazing units. In the specific field of machines for machining the components of insulating glazing units, which are constituted by two glass plates between which a spacer frame usually constituted by a bent aluminum profile is interposed, the leading manufacturers have developed and built specific machines for automatically bending and semiautomatically or automatically calendering said hollow aluminum profiles in order to obtain the spacer frame. Accordingly, it is known to perform bending and, separately, calendering at independent machines; as an alternative, if they are carried out on the same machine unit, these machining operations occur in independent steps of the production cycle; this known method entails manually transferring the partially machined profile from the station for bending and marking the centerline of the curve to be formed to the calendering station. Said calendering station is essentially constituted by three rollers of adequate diameter: one is an intermediate roller and the other two are end rollers. A notch formed on the inside wall of the profile in the preceding bending station is positioned at the intermediate roller. This notch acts as a register for the centerline of the curved band to be obtained by virtue of a back-and-forth movement between the three rollers. Even if the calendering process is performed in a computer-assisted mode, that is to say, after supplying the information related to the shapes of the radius of curvature and of the breadth of the angle of curvature respectively, drawbacks are observed even though calendering is performed automatically: the need to manually transfer the bent and notched profile from the bending station to the calendering station, and the duplication of the placements in the calenderer, in addition to the repetitions of the duplications if a plurality of calendered regions are required, make the overall bending-calendering process too demanding from the point of view of manual work, and the qualitative result, including the aesthetic one, highly depends on the precision with which the centerline of the region to be bent, identified by the registering notch, is positioned manually. It is also known to perform combined bending and calendering, using a machine in which the two processes occur; that is to say, there is a machining head that performs equally either bending, by means of a punch and a rotation arm, or calendering, by means of a wheel and a rotation arm that is converted and arranged so as to become a contrast arm. A severe shortcoming of this method and of this machine is due to the fact that in order to switch from bending to calendering it is necessary to manually change the tool, and this occurs according to the succession of shapes (folds or curves) required in the spacer frame; the pattern of this succession can entail more than one tool change. A possible alternative could be to first form only the bends on all the frames belonging to the same batch and then calender said frames, so as to change tools only once per batch instead of changing tools for each frame: this alternative, however, is not allowed, since the design of the machine is such that it requires feeding with a continuous straight profile obtained by gradually and automatically joining the bars of the profile. A further shortcoming of this method is the difficulty, and the consequent poor aesthetic result, of producing small radiuses, since calendering is obtained by pushing the profile, which passes between the wheel, the lower face of the vice, and the contrast arm. Since said contrast arm has a large positioning angle to produce the tight calendering radius, the thrust entailed by an axial stress on the profile, and therefore its instability, are high and accordingly cannot be withstood by the profile, which yields below a certain radius. It is also known to perform combined bending and calendering after other operations, particularly after filling with hygroscopic granules mixed with deformable granules of foamed polystyrene, which can be placed inside the profile. This filling must of course be performed prior to the bending-calendering operations. In addition to the above mentioned drawbacks, this solution also entails a considerable shortcoming, which consists in having, at the end of the process, a frame that is already finished since it contains the hygroscopic material in its hollow part. Accordingly, there is the restriction of having to form the frame only a few minutes before its final utilization, that is to say, before hermetically closing on said frame two glass plates to form the insulating glazing unit. In industrial practice, therefore, this solution is not feasible, in that it is not possible to manufacture spacer frames that are already filled with hygroscopic granules, since it would be necessary to provide a storage buffer prior to its application in the line for producing insulating glazing units and therefore the salts would absorb the surrounding moisture, losing their effectiveness once they are coupled to the glass plates. There is also another problem, linked to the high cost of any machine having the above mentioned characteristics, since the section for automatically filling with the hygroscopic material can be compared with the bending-calendering section in terms of complexity. EP-A-0332049 discloses apparatus for bending hollow distance profiles for insulating glass panes including an abutment over which the profile is advanced and bent by a bending tool. The profile is advanced during the bending and the bending tool preforms an oscillatory movement towards and away from the abutment. GB-A-2114201 discloses forming a spacer frame for a double glazing unit by simultaneously bending a single length of tubing at two locations and then at two further locations. The bends are produced at each location by making two indentations in the outside wall of the tube and a deeper indentation in the inside wall between the two outside indentations by means of a punch, and then the tubing in bent by 90° about the punch. A principal aim of the present invention is therefore to eliminate the described technical problems, eliminating the drawbacks of the mentioned known art and thus providing an automatic method and device which allow to give a curved shape to aluminum profiles for producing spacer frames for insulating glazing units, in which said shape can be given at the bending machine itself, without interrupting the production cycle to change or calibrate tools. Within the scope of this aim, an important object is to provide a method and a device that allow to obtain curved shapes in which the curvature radiuses are minimal and even tend to zero. Another important object is to provide a device comprising a very small number of components, having a low cost, and associable with a known bending machine. Another object is to provide a device that is reliable and safe in use. In accordance with the invention, there is provided a device and method for calendering spacer frame profiles for insulating glazing units as defined in the appended claims. Further characteristics and advantages of the invention will become apparent from the following detailed description of a particular but not exclusive embodiment thereof, illustrated only by way of non-limitative example in the accompanying drawings, wherein: figures 1 to 5 are schematic views of the various steps for achieving calendering; figure 6 is a lateral perspective view of the schematic diagram of figure 4; figure 7 is a view, similar to the preceding one, of the calendered profile condition shown in figure 5; figure 8 is a sectional view, taken along the plane VIII-VIII of figure 7; figure 9 is a cross-sectional view showing the bending fulcrum of the bending machine; and figure 10 is a lateral view of the microbending station. With reference to the above figures, the reference numeral 1 designates a spacer frame for insulating glazing units constituted by a profile 2 having a surface 3 on which a plurality of minute holes 4 are formed. Said surface 3 is connected to the inner space provided in the insulating glazing unit. The profile 2 contains a cavity 5 that acts as a seat for hygroscopic material. The method according to the present invention allows to give the profile 2 a curved shape; said profile is fed at an adapted and known bending machine, starting from a "magazine" at which the profiles, essentially arranged longitudinally, are coupled sequentially one with another. For this purpose, the method entails producing a preliminary deformation at the surface 3 of the profile, for example by means of a wheel 6, producing an inside curve 7 proximate to the perimetric edges 8a and 8b of the surface 3. In this manner, the profile 2 is radiused transversely. Specifically, the wheel 6 is pressed against the surface 3 to produce the inside curve 7 upstream of the subsequent microbending station, schematically designated by the reference numeral 9. After producing the inside curve 7, an adapted station 10 for conveying and feeding the profile 2, which is part of the bending machine, pushes said profile until the inside curve affects the microbending station 9. The bending machine comprises a bending station 13 that can assume the desired shape, such as for example the one disclosed in Italian Patent application TV93A000084 filed on September 14, 1993 and thus can use two punches, each punch interacting at one of the perimetric edges 8a and 8b of the profile 2. The punches may be of the type shown in figure 9 which are constituted by hooks 14 forming a fulcrum. The hooks 14 act on the inside surface of the profile 2 and force it to remain adherent to the walls 15 of a vice 16 for the microbending. The device comprises automatically controlled microbending means adapted to produce a number n of minute bends, with a desired increment in pitch p that can be determined beforehand by the conveyance and feeding station 10, and forming a bending angle α that is achieved by means of an adapted rotation arm 11 associated with the bending machine. Figures 2, 3, and 4 are views of an embodiment, given by way of example only to show the characteristics involved in order to achieve the calendering of the profile 2 with the help of the bending machine: essentially, according to the method, a number n of minute bends that tends to infinity, with a bending angle increment Δα that tends to zero (see figure 5) and a pitch increment Δp that tends to zero, are produced by virtue of microbending means of said microbending station controlled by and comprising an electronic computer 12. The microbending means also comprise in a preferred embodiment two microbending protusions 17, having a cylindrical shape and protruding from the lateral walls of the vice 16 (see figure 10). In this manner the configuration shown in figures 5 and 7 is obtained. It has thus been observed that the invention has achieved the intended aim and objects, a device having been provided which, when associated at a known bending machine, allows to give a curved shape to aluminum profiles for producing spacer frames for insulating glazing units without interrupting the production cycle, since it is not necessary to perform any tool change or calibration. This calendering, which therefore essentially consists of microbending with angles and pitch increments that tend to zero, allows to use known bending machines without lower limits to the value of the radius of curvature and allows to perform a machining of the spacer frame with very low production costs. The invention is of course susceptible of numerous modifications and variations. For example, the method can be applied to profiles 2, on which cusp-folded shapes can be optionally inserted alternately. The components, as well as the materials that constitute the individual components of the device, may of course also be the most appropriate according to the specific requirements. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims: An automatic device for calendering aluminum profiles (2) for producing spacer frames for insulating glazing units, said profiles (2) having a surface (3) on which minute holes (4) are formed, said device comprising a bending station (13) and automatically controlled microbending means (9,12,16,17) with a microbending station (9) for forming a number (n) of minute bends in which an increment of a bending angle (α) tends to zero and an increment in pitch (p) tends to zero, the device being characterized in that it further comprises a curving means (6) adapted to produce a preliminary deformation of said surface to obtain an inside curve (7) at which said calendering is performed, said curving means comprises a wheel (6) located upstream of said microbending station (9), said wheel (6) being pressed against said surface (3) to obtain said inside curve (7) upstream of said subsequent microbending station (9), said wheel (6) having an axis that lies at right angles to a plane of arrangement of said spacer frame (1) and allowing to pre-orientate the subsequent deformation of said surface of said profile (2). Device according to claim 1, characterized in that said microbending means comprises an electronic computer (12) with a CAM (Computer Aided Manufacturing) process, said computer collecting, in an appropriate program, data such as the pitch increment (Δp), the bending angle increment (Δα), and the number of bends (n) as a function of a radius of curvature and of a maximum value of the final curvature angle of said profile (2). Device according to claims 1 and 2, characterized in that said microbending station (9) comprises a vice (16) having jaws (15) from which two microbending projections (17) protrude. Device according to any of the claims from 1 to 3, characterized in that said bending station (13) comprises a pair of hooks (14) forming a fulcrum, said hooks acting on an inside surface of said profile (2) for forcing the profile to remain adherent to walls (15) of said vice (16). Automatic method for calendering aluminum profiles (2) for producing spacer frames (1) for insulating glazing units, the profiles having a surface (3) on which minute holes (4) are formed, with a device of the type set forth in claim 1, the method including forming a plurality of minute bends the pitch increment whereof tends to zero and the bending angle increment whereof tends to zero, the method being characterized in that said calendering is achieved by deforming in a first step said surface (3) so as to obtain an inside curve (7) and consecutively in said step of forming a plurality of minute bends the pitch increment whereof tends to zero and the bending angle increment whereof tends to zero, and a preliminary deformation is formed at a surface of said profile (2) through at least one wheel (6) adapted to form said an inside curve (7) proximate to the perimetric edges (8a,8b) of said surface (3). Method according to claim 5, characterized in that said profile (2) is radiused transversely as a consequence of said preliminary deformation. Method according to claims 5 and 6, characterized in that after forming said inside curve (7), said profile (2) is pushed until said inside curve (7) reaches a microbending station (9). Method according to claim 5, characterized in that said consecutive steps for forming minute bends are automatically controlled by an electronic computer, so as to obtain a number (n) of minute bends that tends to infinity, with an increment in the bending angle (α) that tends to zero and a pitch increment (Δp) that tends to zero. Method according to claim 8, characterized in that said calendering is obtained by always using a same type of microbending means provided at a microbending station (9) and without having to perform replacements or adjustments of components. Method according to claim 5, characterized in that profiles are bent on which cusp-bent shapes are optionally included alternately.

Inventors: MOSCHINI DINO, VIANELLO FORTUNATO, MOSCHINI, DINO, VIANELLO, FORTUNATO
Applicants: VIANELLO FORTUNATO DAVANZO NAD, VIANELLO FORTUNATO - DAVANZO NADIA
Application year: 1995
Main classification: E06B3
IPC codes: E06B3, B21D7, B21D53