Welding device for PVC profiles

Abstract

A device for heat welding PVC profiles 1, 2 together, uses a first heater (not shown) and at least one second (12) heater, to heat the PVC profiles 1, 2, prior to pressing them together to complete the weld. The PVC profiles 1, 2 each have a mitered end, with a groove 7, 8, 9, 10 formed on the upper surfaces 3, 5 and lower surfaces 4, 6 of each profile’s mitered end; by a milling device. Profiles 1, 2 have support means which can move them towards and away from each other. The first heating device may be a heating plate (not shown). There may be two second heating devices 12; with the upper heating device 12 for heating the upper grooves 7 & 9; and a lower heating device 12 for heating the lower grooves 8 & 10. The polyvinyl chloride profile materials can be used in manufacturing doors and windows.

Description

TECHNICAL FIELD The present invention relates to an arrangement that enables the joining of Polyvinyl Chloride (PVC) profile materials commonly used in the production of doors, windows, and related components by heat welding. BACKGROUND OF THE INVENTION Structures designed for the assembly of PVC profiles are produced by positioning the profiles perpendicularly to each other and welding them in a way that defines a frame shape. This welding process involves cutting the profile ends at a 45-degree angle and joining these angled cut ends (i.e., "miter" ends) through a heat source. EP2255942 discloses such PVC profiles for instance. PVC profile welding machines are traditionally equipped with a profile table and an upper pressing element, which support the profiles from below and above, respectively. Since the positional accuracy of moving components in PVC welding machines is of importance, these components are configured to be driven through electronically controlled motors. In some known PVC profile welding machines, the ends of the profiles to be welded are milled to remove shavings by a milling device before the welding process is carried out. This milling device moves generally in a plane perpendicular to the cutting ends of the profiles, creating a groove along the outer circumference of the cutting ends. This milling process allows the joining surfaces of the profiles to take a form that slightly protrudes relative to the outer circumference for welding. Traditional welding machines include a heating plate equipped with a heating element. Before the welding process, the heating plate is positioned at a point away from the ends of the profiles and, when the time comes, it is moved to have a position between the joining surfaces of the profiles. Then, the profiles are brought closer to each other and brought into contact with the hot heating plate. This contact can be maintained for a certain duration (e.g., 10s.-20s.). During the contact between the heating plate and the profiles, the protrusions on the joining surfaces of the profiles to be welded (i.e., the protrusions remaining after milling) are heated. Afterwards, the heating plate is removed by being withdrawn from between the ends of the profile, and the heated joining surfaces are pressed against each other to weld. During the welding process, the melting protruding parts on the joining surfaces of the profiles to be welded spread in a planar direction perpendicular to the joining surface (both inward and outward of the profile). The outwardly spreading melted material may slightly protrude outwards from the weld seam. This situation is far from an aesthetically acceptable appearance for the end user. Therefore, the material overflowing from the weld seam is shaved off from the seam with a cutting blade. However, this additional operation not only increases the cost but may also create an unpleasant result in terms of aesthetic appearance in the weld seam area. On the other hand, traditional PVC profile welding machines may not be able to weld the profiles together perfectly. This is because, during welding, one profile may end up slightly above or below the level of the other profile. Such a mismatch can reduce the mechanical strength of the welded joints and the overall product quality. Therefore, achieving perfect alignment between profiles during the welding process is critical for production efficiency and product quality. SUMMARY OF THE INVENTION The object of the invention is to provide a welded Polyvinyl Chloride (PVC) profile connection that ensures perfect compatibility with one another and has high mechanical strength. A device for heat-welding a first profile and to a second profile, each made of a PVC material and each having a mitered end, comprising support means for supporting each profile from below and above, driving means to bring the profiles towards and away from each other, at least one milling device to form a groove on the upper surfaces and lower surfaces of each profile's mitered end, and a heating device movable between and out of the mitered ends of the profiles, characterized in that at least one second heating device is provided for heating the outer edge of each groove, each outer edge being at a direction along the upper surfaces and lower surfaces of the profiles. According to some example embodiments of the invention, the second heating device comprises a heating body and a heating element placed in the heating body. Furthermore, according to some example embodiments of the invention, the heating body comprises at least one contact surface that makes an acute angle with the horizontal to contact the outer edge of the groove. BRIEF DESCRIPTION OF THE FIGURES Figure 1 presents a front view of the end parts of two PVC profiles to be welded, brought close to each other. Figure 2 presents a front view at the moment when the heating device contacts the outer edge ends of the grooves made at the miter ends of the PVC profiles. Figure 3 presents a focused front view on the miter ends of the PVC profiles as seen in Figure 2. DESCRIPTION OF THE PARTS IN THE FIGURES 1. First profile 2. Second profile 3. Upper surface of the first profile 4. Lower surface of the first profile 5. Upper surface of the second profile 6. Lower surface of the second profile 7. Upper groove of the first profile 8. Lower groove of the first profile 9. Upper groove of the second profile 10. Lower groove of the second profile 11. Outer edge of the groove 12. Second heating device 13. Heating body 14. Heating element 15. Heating contact surface 16. End face 17. Heat barrier DETAILED DESCRIPTION OF THE INVENTION Through the device of the invention, as seen in Figure 1, a first profile (1) made of PVC material is welded to a second profile (2) made of PVC material after applying heat to the ends of the profiles to be joined using a heating device (the heating device is not deemed necessary to be shown in the figures). The ends of the profiles (1, 2) to be joined are previously cut at a 45-degree angle to form a miter form (it is not deemed necessary to show the miter shape in the figures). At the mitered end of the first profile, an upper groove (7) and a lower groove (8) are formed, respectively, on the upper surface (3) and the lower surface (4) of this profile through a milling device (the milling device is not deemed necessary to be shown in the figures). Similarly, at the mitered end of the second profile, an upper groove (9) and a lower groove (10) are formed on the upper surface (5) and the lower surface (6) of this profile through the milling device. The grooves (7, 8, 9, 10) along with the upper and lower surfaces (3, 4, 5, 6) of the profiles (1, 2) define an outer edge of the groove (11). In other words, the edge formed outward by the groove along both the upper and the lower surface of each profile, that is, in the direction of the vertical width of the profile, is the outer edge of the groove. As seen in Figure 2 or Figure 3, after the first profile (1) with a groove (7, 8) formed at the mitered end and the second profile (2) with a groove (9, 10) formed at the mitered end are brought closer by driving means, a second heating device (12) contacts the outer edges of the grooves (11) of each profile (1, 2) and melts these edges longitudinally. Thus, the outer edges of the grooves (11) are freed from their "sharpy" form and take a shape as if they have been chamfered or the corners have been rounded. The application method of the second heating device (12) can be configured in such a way that, in case the profiles (1, 2) are covered with a coating material, the melting in the material caused by the contact of the second heating device (12) with the outer edges of the grooves (11) will not allow the underlying material to be visible from the outside. The second heating device (12) may comprise a heating body (13) and a heating element (14) placed inside thereof, such as a resistor. A heat barrier (17) is provided on the upper part of the heating body (13). The heat barrier (17) can be selected from materials (preferably plastic-based materials) known in the art, such as composite and / or glass fiber reinforced material. The heat barrier (17) prevents the heat generated in the heating body (13) from adversely affecting the second heating device (12) and / or other components of the device of the invention. The surfaces (15) of the heating body (13) that come into contact with the outer edges of the grooves (11) are formed to make an acute angle with the horizontal. According to some example embodiments of the invention, the acute angle can preferably be between 10 degrees and 75 degrees. In some embodiments of the invention, the acute angle can be between 30 degrees and 60 degrees. In yet other embodiments of the invention, the acute angle can be between 40 and 50 degrees. As shown in Figure 2, there can be more than one second heating device (12). In this case, the outer edges of the grooves (11) on the upper surfaces (3, 5) of the first profile (1) and the second profile (2) can be heated with one second heating device (12), and the outer edges of the grooves (11) on the lower surfaces (4, 6) with another second heating device (12). The movement of the second heating device(s) (12) can be facilitated by a driving means known in the art, such as a servo motor, stepper motor, or piston etc. The second heating device(s) (12) can preferably be configured to move in a vertical direction. The temperature resulting from the heat applied by the second heating device (12) to the outer edges of the grooves (11) can be at a suitable level to cause melting, for example, 140°C, 150°C, etc., and the contact time can also be suitably determined, for example, between 5-20 seconds etc. After the second heating device (12) applies heat to the outer edges of the grooves (11), it is moved away from the profiles (1, 2). Then, the profiles (1, 2) are moved to slightly increase the distance between them, and a heating device, generally in the form of a plate as known in the art, is positioned to enter between the end faces (16) of the profiles. In a manner known in the art, the profiles (1, 2) are brought closer together and allowed to contact this hot heating device for a while to melt the end faces (16). Afterward, the profiles (1, 2) are separated, the heating device is removed from the profiles (1, 2), and the profiles (1, 2) are pressed towards each other to ensure welding. When the profiles (1, 2) are welded to each other, a very slight indentation form along the weld seam may occur since the outer edges of the grooves (11) were previously melted by the second heating device (12), as these edges have a shape as if they have been chamfered or the corners rounded.

Claims

1. A device for heat-welding a first profile (1) and to a second profile (2), each made of a PVC material and each having a mitered end, comprising support means for supporting each profile (1, 2) from below and above, driving means to bring the profiles (1, 2) towards and away from each other, at least one milling device to form a groove (7, 8, 9, 10) on the upper surfaces (3, 5) and lower surfaces (4, 6) of each profile's mitered end, and a heating device movable between and out of the mitered ends of the profiles (1, 2), characterized in that at least one second heating device (12) is provided for heating the outer edge (11) of each groove, each outer edge (11) being at a direction along the upper surfaces (3, 5) and lower surfaces (4, 6) of the profiles (1, 2).

2. A device according to claim 1, characterized in that said second heating device (12) comprises a heating body (13) and a heating element (14) placed in the heating body (13).

3. A device according to claim 2, characterized in that said heating body (13) comprises at least one contact surface (15) making an acute angle with the horizontal for coming into contact with the outer edge (11) of each groove (7, 8, 9, 10).

4. A device according to claim 3, characterized in that the acute angle is between 10 degrees to 75 degrees.

5. A device according to claim 4, characterized in that the acute angle is preferably between 30 degrees and 60 degrees, more preferably between 40 and 50 degrees.

6. A device according to any of the above claims, characterized by comprising two second heating devices (12), one for applying heat to the mitered ends on the upper surfaces (3, 5) of the first profile (1) and the other for applying heat to the mitered ends on the lower surfaces (4, 6) of the second profile (2).

7. A device according to any of the above claims, characterized in that a heat barrier (17) is provided on the upper part of the heating body (13).

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