Welding arrangement, method for joining plastic products by welding and use of the method and the plastic product produced therewith

Abstract

A method for manufacturing a plastic product (10), the method comprising the following steps: (a) providing a first plastic part (11) and a second plastic part (21) to be joined to form a plastic product (10), wherein the first and second plastic parts (11, 21) comprise flanges (12, 22) to be welded together along respective interface regions (13, 23); (b) arranging the first plastic part (11) in a first clamping tool (30), wherein the first clamping tool (30) comprises a first tool tip (31) designed to interact with the flange (12) of the first plastic part (11); arranging the second plastic part (21) in a second clamping tool (40), wherein the second clamping tool (40) comprises a second tool tip (41) designed to interact with the flange (22) of the second plastic part (21); and fixing at least parts of the Flanges (12,22) at the respective first and second tool tips (31, 41) of the clamping tools (30, 40) in fixed positions, (c) Inserting a heat source (50) between the first and second clamping tools (30, 40), (d) Clamping the interface areas (13, 23) of the flanges (12, 22) by means of the first and second clamping tools (30, 40) against the heat source (50) in order to at least partially melt the interface areas (13, 23), (e) Removing the first and second plastic parts (11, 21) from the heat source (50), wherein at least areas of the flanges (12, 22) are in the fixed positions, (f) Bringing the interface areas (13, 23) of the flanges (12, 22) into contact, wherein at least areas of the flanges (12, 22) are in the fixed positions, (f) Clamping the interface areas (13, 23) of the flanges (12, 22) against each other in order to firmly join together the at least partially melted interface areas (13, 23) of the first and second flanges (11, 21),and (g) Releasing the manufactured plastic product (10) from the first and second clamping tools (30, 40); characterized in that the fixing of at least parts of the flanges (12, 22) on the respective clamping tool (30, 40) in fixed positions is achieved by providing a respective alignment blade (33, 43) in a guide channel (32, 42) which is arranged such that it extends through each of the respective first and second tool tips (31, 41), and by moving the alignment blade (33, 43) along the guide channel (32, 42) such that it projects through an outlet end (34, 44) of the guide channel (32, 42) into an active position in which it engages in a fixing engagement with a part of the flange (12, 22) of the first and second plastic part (11, 21).

Description

Field of TechnologyThe invention relates to a method and a welding arrangement for producing a plastic product. The invention also relates to a use of the method for producing a plastic product and to a use of the plastic product produced in this way in a vehicle.BackgroundIn the automobile industry, plastic products such as containers for cooling water, washer fluid or the like are used. A common method of making such products is to form two parts, for example halves, of the plastic product which are then joined together by welding.In particular, the parts to be joined may be provided with a flange containing additional material which is designed to be heated and, while in the molten state, may be clamped to the flange of the other plastic part which is also provided with a flange containing additional material which is also heated, thus forming a composite plastic product.In order to form a strong connection over the entire interface between the plastic parts to be connected, a sufficiently large contact surface should preferably be present along the entire connection. This has proved difficult in some geometries, partly because the plastic product can deform slightly during the heating process, so that the provided contact surfaces do not oppose each other over the entire provided contact surface.JP 2001-239 586 A discloses the generic prior art.SUMMARY OF THE INVENTIONIt is an object of the invention to at least partially eliminate the problems of the prior art.The object is achieved by: a method according to claim 1, a welding arrangement according to claim 4, a use of the method for producing a plastic product according to claim 7 and a use of the plastic product produced by the method in a vehicle according to claim 9.According to a first aspect, the invention relates to a method for manufacturing a plastic product, the method comprising the following steps:(a) providing a first plastic part and a second plastic part to be joined into a plastic product, the first and second plastic parts comprising flanges to be welded together along respective interface regions,(b) disposing the first plastic part in a first clamping tool, the first clamping tool comprising a first tool tip configured to cooperate with the flange of the first plastic part (11), and disposing the second plastic part in a second clamping tool, the second clamping tool comprising a second tool tip configured to cooperate with the flange of the second plastic part, fixing at least parts of the flanges to the respective first and second tool tips of the clamping tools in fixed positions,(c) inserting a heat source between the first and second clamping tools,(d) clamping the interface regions of the flanges against the heat source by means of the first and second clamping tools to at least partially melt the interface regions,(e) removing the first and second plastic parts from the heat source with at least portions of the flanges in the fixed positions,(f) contacting the interface portions of the flanges, wherein at least portions of the flanges are in the fixed positions,(f) clamping the interface portions of the flanges together to firmly join the at least partially fused interface portions of the first and second flanges; and(g) releasing the manufactured plastic product from the first and second clamping tools.An advantage of the method described is that the fixing of at least parts of the flanges contributes to the fact that the two plastic parts can be better joined to one another and the quality and structural strength of the end product can be increased.In the method, fixing at least parts of the flanges to the respective clamping tool in fixed positions is achieved according to the invention by providing a respective alignment blade in a guide channel arranged to extend through each of the respective first and second tool tips and by moving the alignment blade along the guide channel to project through an outlet end of the guide channel into an active position in which it is in fixing engagement with a part of the flange of the first and second plastic parts.This is an advantageous way to achieve the object of the invention, which allows to use and connect conventional plastic parts without any adjustments to the plastic parts being required.In examples of the method, each alignment blade, in the active position, is configured to extend outwardly away from a wall of the respective plastic part into engagement contact with an edge of the respective flange, the edge forming an outer portion of the flange, a recessed portion being formed between the wall of the plastic part and the edge, and the first and second tool tips, respectively, are positioned in the respective recessed portion in steps (b) to (f).By incorporating the alignment blade into the rim, the fixing step has no influence on the final product, since the rim is an outer part which does not actually influence the structural strength of the final product.In examples of the method, the clamping tools are held in the fixed positions with respect to the flanges at least during steps (e) and (f).According to a second aspect, the invention relates to a welding arrangement for producing a plastic product by welding a first and a second plastic part to each other, the welding arrangement comprising:a first clamping tool for applying pressure to a flange of the first plastic part,a second clamping tool for acting on a flange of the second plastic part, wherein the first clamping tool and / or the second clamping tool can be moved toward one another into an interaction position,a heating plate for heating interface areas of the flanges, wherein the heating plate is insertable into a position between the first and the second clamping tool, wherein the first clamping tool and the second clamping tool are configured in the interaction position to:when the heating plate is positioned between the first and second clamping tools, clamping the interface regions of the flanges of the first plastic part and the second plastic part against the heating plate to heat the interface regions, and when the heating plate is not positioned between the first and second clamping tools for clamping the interface regions of the flanges of the first and second plastic parts in a direction towards each other to connect them to each other, wherein the first and second clamping tools have a respective first and second tool tip for fixing the flanges of the first and second plastic parts to the respective first and second clamping tools such that the first and second clamping tools are movable away from the interaction position with the flanges of the first and second plastic parts fixed to the respective clamping tool.With respect to a conventional clamping tool, it is sufficient to adapt the tool tips in order to achieve the advantages of the invention.In the welding arrangement according to the invention, the flanges of the first and second plastic parts have a respective recessed region in which the respective first and second tool tips of the first and second clamping tools are receivable, and wherein a movable alignment blade is arranged at the respective first and second tool tips, each tool tip comprising a guide channel for guiding the respective movable alignment blade, the guide channel having an outlet end from which an outer end of the alignment blade is arranged to extend to an edge of the flange with respect to the respective first and second tool tips, the alignment blade being movable between a rest position and an active position in which it is adapted to be in engagement contact with the edge of the flange.In examples of the welding arrangement, the guide channel has a bent portion in the region of the tool tip which is configured to be positioned within the recess between the wall and the opposite edge, wherein the bent portion is configured to bend the outer end of the alignment blade, when in the active position, towards the edge of the flange.This allows the alignment blade, which is preferably resilient, to flex towards the edge to cut into the edge in a direction that ensures good engagement. The engagement effect is better at a larger angle of inclination between the blade of the engagement blade and the rim, but already has a positive effect at a small angle, such as 10 degrees. In examples of the welding assembly, the outer end of the alignment blade includes a blade configured to cut into the edge to fix the edge with respect to the tool tip of the clamping tool. The cutting edge may be sharp.According to a third aspect, the invention relates to a use of the above-described method for producing a plastic product.In particular, the plastic product may be a container configured to hold a liquid, such as a container for cooling water, washer fluid or the like.According to a fourth aspect, the invention relates to a use of the plastic product produced by the method described above in a vehicle.Other embodiments and advantages will be apparent from the detailed description and the accompanying drawings. It is understood that all of the various examples of the method and welding arrangement disclosed herein also apply to the plastic product manufactured with the method described herein and to a vehicle comprising such a plastic product.Brief Description of the DrawingsSpecific embodiments of the invention will now be described with reference to the accompanying drawings, in which: FIG. 1 is a perspective view of an example of a plastic product that can be made in accordance with the invention, FIG. 2 shows a detail view of a part of the plastic product in FIG. 1, FIG. 3 is a sectional view of an example of a plastic product as may be made in accordance with the invention, FIG. 4 shows a rotated detailed view of section IV in FIG. 3, FIG. 5 shows a detailed view of section V in FIG. 3, and FIG. 6 shows a schematic illustration of a method for producing a plastic product according to an example of the invention.DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTSAspects of the present disclosure will now be described more fully. Like reference numerals refer to like elements throughout the specification. Known functions or designs are not necessarily described in detail for brevity and / or clarity.Figure 1 shows a plastic product 10 according to the invention. The plastic product 10 is produced by welding two mutually complementary plastic parts 11 and 21 along their flanges 12 and 22, respectively. The flanges 12 and 22 extend along the length of the respective periphery of the walls 17 and 27 of the plastic parts 11 and 21.The plastic product 10 may typically be used as a container for, for example, cooling water, washer fluid, or the like in a vehicle.FIG. 2 shows a portion of the plastic product 10 shown in FIG. 1 in detail, showing the shape of the flanges 12 and 22. The flanges 12 and 22 are joined together at opposite interface regions 13 and 23.In the parts of the flanges 12 and 22 that extend outside the walls 17 and 27 of the plastic product 10, edges 15, 25 are arranged such that recessed areas 14, 24 are formed between the edges 15, 25 and the walls 17 and 27 of the respective first and second plastic parts 11 and 21.Fig. 3 is a sectional view showing an example of a plastic product made according to the invention.FIG. 4 shows a detailed view of section IV in FIG. 3 and illustrates the interface between the flanges 12 and 22 of the respective first and second plastic parts 11 and 21, the view being rotated 90 degrees in the clockwise direction with respect to the view shown in FIG. 3.The interface regions 13 and 23 comprise protruding material configured to be heated, at least partially melted and bonded together, as described below with reference to FIG. 6.It should be noted that the flanges 12 and 22, as shown in the drawings, are of a conventional type already used in the prior art. The invention is therefore based in part on how the geometry of these flanges 12 and 22 can be used to optimize the welding process.FIG. 5 is a detailed view of section V in FIG. 3 illustrating the interface between flanges 12 and 22 when positioned in first and second clamping tools 30 and 40, respectively.As shown in FIG. 5, the first and second clamping tools 30 and 40 have a respective tool tip 31 and 41 for fastening the respective flanges 12 and 22 of the first and second plastic parts 11, 21 to the respective clamping tool 30, 40, so that the first and second clamping tools 30, 40 can be moved away from the interaction position with the flanges 12, 22 of the first and second plastic parts 11, 21 fastened to the respective clamping tool 30, 40.In the embodiment shown, the flanges 12, 22 of both the first and the second plastic product 11, 21 have a recessed region 14, 24, in which the respective tool tip 31, 41 of the first and second clamping tools 30, 40 can be received.The tool tips 31, 41 further comprise each a guide channel 32, 42 for guiding a movable alignment blade 33, 43. Each guide channel 32, 42 comprises an outlet end 34, 44 from which an outer end 35, 45 of the alignment blade 33, 43 is arranged to extend to an edge 15, 25 of the flange 12, 22 of the plastic products 11, 21 outside the respective recessed area 14, 24. The alignment blade 33, 43 is movable with respect to the tool tip 31, 41 between a rest position and an active position in which it is in engagement contact with the rim 15, 25 of the flange 12, 22.In the illustrated embodiment, the outer end 35, 45 of each alignment blade 33, 43 includes a cutting edge 36, 46 configured to cut into the edge 15, 25 to fix the edge 15, 25 with respect to the tool tip 31, 41 of the clamping tool 30, 40.At the opposite end of the alignment blade 33, 43, an arrangement (not shown) is provided for moving the alignment blade 33, 43 between the rest position and the active position.In Figure 5, the alignment blades 33, 43 are both in the active position in which their respective cutting edges 36, 46 cut into the edges 15, 25 of the flanges 12, 22.The alignment blades 33, 43 are preferably resilient and are adapted to follow the shape of the guide channels 32, 42. The alignment blades 33, 43 are preferably made of a thin steel material.In the embodiment shown, the guide channels 32, 42 comprise a straight portion 37, 47 in which the alignment blades 33, 43 can slide freely and a curved portion 38, 48 in the region of the tool tip 31, 41 which is designed to be positionable within the recess 14, 24 between the wall 17, 27 and the opposite edge 15, 25.Thus, in the rest position, the alignment blade 33, 43 is positioned such that its outer end 35, 45 lies within the outlet end 34, 44 of the guide channel 32, 42, preferably in the straight portion 37, 47 of the guide channel 32, 42 or possibly in the bent portion 38, 48.When the alignment blade 33, 43 is moved from the rest position to the active position, the alignment blade 33, 43 follows the shape of the guide channels 32, 42 so that its outer end 35, 45 bends when moving along the bent portion 38, 48 and the cutting edge 36, 46 points sideways. In the illustrated embodiment, the bent portion 38, 48 is bent outward so that the blade 36, 46 faces outward to engage the edge 15, 25 of the respective plastic part 11, 21 when it protrudes from the outlet end 34, 44 of the guide channel 32, 42.The angle of inclination between the blade 36, 46 of the engagement blade 33, 43 and the rim 15, 25 depends, inter alia, on the configuration of the bent portion 38, 48 and the elasticity of the engagement blade 33, 43 and can be tested by a person skilled in the art to meet the specifications of the arrangement as a whole.Now, referring to FIG. 6, a method for manufacturing the resin product 10 will be described. The method comprises steps (a) to (h) shown in the drawing. For reasons of clarity, not all reference numerals are indicated in all parts of the illustration.In step (a), a first plastic part 11 and a second plastic part 21 are provided, which are to be connected to form a plastic product 10. The plastic parts 11, 21 comprise flanges 12, 22 to be joined together along respective interface regions 13, 23, as shown in Figures 4 and 5.In step (b), the first plastic part 11 is arranged in a first clamping tool 30 and the second plastic part 21 is arranged in a second clamping tool 40, wherein the clamping tools 30 and 40 have respective first and second tool tips 31, 41 which are designed to cooperate with the flange 12, 21 of the respective plastic part 11 and 21.In step (c), a heat source 50 is inserted between the first and second plastic parts 11, 21, and in a subsequent step (d), the boundary surface regions 13, 23 of the flanges 12, 22 are clamped by applying a pressing force F against the heat source 50 in order to melt the boundary surface regions 13, 23, at least partially, by means of the first and second clamping tools 40.In conjunction with either step (b), (c) or (d), at least portions of the flanges 12, 22 are fixed to the respective clamping tool 30, 40 in fixed positions. This fixing serves to prevent deformation of the plastic products 11 and 21, in particular of the flanges 12, 22 thereof. By fixing the flanges 12, 22 and preserving the intended shape of the plastic products 11 and 21, the subsequent step of mutually joining the plastic products 11 and 21 becomes as efficient as possible. With reference to the embodiment shown in Figure 5, the fixing is achieved by moving the alignment blade 33, 43 to the active position shown, in which the sharp cutting edge 36, 46 of each alignment blade 33, 43 cuts into the edge 15, 25 of the flanges 12, 22 to fix the edge 15, 25 to the respective tool tip 31, 41 of the clamping tools 30, 40.In step (e), with the flanges 12, 22 in the fixed positions with respect to the clamping tool 30, 40, the first and second plastic parts 11, 21 are removed from the heat source 50 and the heat source is removed from the space between the plastic parts 11, 21, the fixed positions ensuring that the flanges 12, 22, or at least critical areas thereof, remain fixed to the tool tip 31, 41 so that they do not deform.Subsequently, in step (f), while the flanges 12, 22 are still in the fixed positions, the interface portions 13, 23 of the flanges 12, 22 are brought into contact with each other.Moreover, also in step (f), the interface areas 13, 23 of the flanges 12, 22, which are still warm from the heating in step (d), are clamped against each other by applying a pressing force F to firmly join the at least partially melted interface areas 13, 23 of the first and second flanges 11, 21.The flanges 12, 22 may be removed from the fixed positions before, during, or after the clamping phase of step (f).Preferably, however, the flanges 12, 22 should be in the fixed positions when the first and second plastic parts 11, 21 are removed from the heat source 50 until they have been brought into contact with each other.In a final step (g), the manufactured plastic product 10 is released from the first and second clamping tools 30, 40 and is ready for use or for post-treatment if such takes place.As can be seen from FIG. 3 and the above description, the plastic welding arrangement comprises a first clamping tool 30, a second clamping tool 40 for acting on the flanges 12, 22 of the first and second plastic part 11 and 21, respectively.The first clamping tool 30 and / or the second clamping tool 40 are movable towards each other into an interaction position. Thus, either the first clamping tool 30 or the second clamping tool 40 can be moved away from the other and towards the other, or both can be moved towards and away from each other.The welding assembly further comprises a heating plate 50 for heating the interface areas 13, 23 of the flanges 12, 22, the heating plate 50 being insertable into a position between the first and second clamping tools 30, 40 such that the first and second clamping tools 30, 40 can clamp the interface areas 13, 23 of the flanges 12, 22 of the first and second plastic parts 11, 21 against the opposing sides of the heating plate 50 to heat the interface areas 13, 23. The heating plate 50 is thus heated on both sides.The heating plate may comprise a heat source or be heated in an additional heating arrangement before it is put into operation.When the heating plate 50 is not positioned between the clamping tools 30, 40, the clamping tools 30, 40 are configured to clamp the interface regions 13, 23 of the flanges 12, 22 of the first and second plastic parts 11, 21 towards each other in a direction to connect them to each other.Other embodiments are of course possible to achieve a similar effect of securing the flanges of the plastic parts to the clamping tool. For example, the clamping tool may include a wedge device in which a wedge may be advanced through the tool tip 31, 41 to broaden a portion of the tool tip 31, 41 so as to achieve engagement contact with the recessed portion 14, 24 of the flange 12, 22.The invention has been described above with reference to specific embodiments. However, the invention is not limited to these embodiments. It will be obvious to a person skilled in the art that other embodiments are possible within the scope of the claims which follow.

Claims

A method of manufacturing a plastic product (10), the method comprising the steps of: (a) providing a first plastic part (11) and a second plastic part (21) to be joined into a plastic product (10), the first and second plastic parts (11, 21) comprising flanges (12, 22) to be welded together along respective interface regions (13, 23), (b) arranging the first plastic part (11) in a first clamping tool (30), the first clamping tool (30) comprising a first tool tip (31) configured to cooperate with the flange (12) of the first plastic part (11), and arranging the second plastic part (21) in a second clamping tool (40), the second clamping tool (40) comprising a second tool tip (41) configured to cooperate with the flange (12) of the first plastic part (11), with the flange (22) of the second plastic part (21), and fixing at least parts of the flanges (12, 22) to the respective first and second tool tips (31, 41) of the clamping tools (30, 40) in fixed positions, (c) inserting a heat source (50) between the first and second clamping tools (30, 40), (d) clamping the interface regions (13, 23) of the flanges (12, 22) against the heat source (50) by means of the first and second clamping tools (30, 40) in order to at least partially melt the interface regions (13, 23), (e) removing the first and second plastic parts (11, 21) from the heat source (50), wherein at least regions of the flanges (12, 22) are in the fixed positions, (f) bringing the interface regions (13, 23) of the flanges (12, 22) into contact, wherein at least portions of the flanges (12, 22) are in the fixed positions, (f) clamping the interface portions (13, 23) of the flanges (12, 22) against each other to firmly join the at least partially melted interface portions (13, 23) of the first and second flanges (11, 21) together, and (g) releasing the manufactured plastic product (10) from the first and second clamping tools (30, 40); characterized in that fixing at least portions of the flanges (12, 22) to the respective clamping tool (30, 40) in fixed positions is achieved by providing a respective alignment blade (33, 43) in a guide channel (32, 42) arranged to extend through each of the respective first and second tool tips (31, 41) and by moving the alignment blade (33, 43) along the guide channel (32, 42) to pass through an outlet end (34, 43), 44) of the guide channel (32, 42) protrudes into an active position in which it is in fixing engagement with a part of the flange (12, 22) of the first and second plastic part (11, 21).A method according to claim 1, wherein each alignment blade (33, 43), in the active position, is adapted to extend outwards away from a wall (17, 27) of the respective plastic part (11, 21) in engagement contact with an edge (15, 25) of the respective flange (12, 22), the edge (15, 25) forming an outer region of the flange (12, 22), a recessed region (14, 24) being formed between the wall of the plastic part (11, 21) and the edge (15, 25), and the first and second tool tips (31, 41) respectively being positioned in the respective recessed region (14, 24) in steps (b) to (f).A method according to any preceding claim, wherein the clamping tools (30, 40) are held in the fixed positions with respect to the flanges (12, 22) at least during steps (e) and (f).Welding arrangement for producing a plastic product (10) by welding a first and a second plastic part (11, 21) to one another, wherein the welding arrangement comprises: - a first clamping tool (30) for applying pressure to a flange (12) of the first plastic part (11), - a second clamping tool (40) for applying pressure to a flange (22) of the second plastic part (21), wherein the first clamping tool (30) and / or the second clamping tool (40) can be moved towards one another into an interaction position, - a heating plate (50) for heating boundary surface regions (13, 23) of the flanges (12, 22), wherein the heating plate (50) can be inserted into a position between the first and the second clamping tool (30, 40), wherein the first clamping tool (30) and the second clamping tool (40) are configured, in the interaction position: when the heating plate (50) is positioned between the first and second clamping tools (30, 40), to clamp the interface regions (13, 23) of the flanges (12, 22) of the first plastic part (11) and the second plastic part (21) against the heating plate (50) to heat the interface regions (13, 23), and when the heating plate (50) is not positioned between the first and second clamping tools (30, 40), to clamp the interface regions (13, 23) of the flanges (12, 22) of the first and second plastic parts (11, 21) towards each other to connect them to each other, wherein the first and second clamping tools (30, 40) have respective first and second tool tips (31, 41) to clamp the flanges (12, 22) of the first and second plastic parts (11, 11), 21) to the respective first and second clamping tools (30, 40) such that the first and second clamping tools (30, 40) can be moved away from the interaction position with the flanges (12, 22) of the first and second plastic part (11, 21) fixed to the respective clamping tool (30, 40), characterized in that the flanges (12, 22) of the first and second plastic part (11, 21) have a respective recessed region (14, 24) in which the respective first and second tool tips (31, 41) of the first and second clamping tools (30, 40) can be received, and wherein a movable alignment blade (33, 43) is arranged at the respective first and second tool tips (31, 41), wherein each tool tip (31, 41) comprises a guide channel (32, 42) for guiding the respective movable alignment blade (33, 43), wherein the guide channel (32, 42) has an outlet end (34, 44), From which an outer end (35, 45) of the alignment blade (33, 43) is arranged to extend to an edge (15, 25) of the flange (12, 22) with respect to the respective first and second tool tips (31, 41), the alignment blade (33, 43) being movable between a rest position and an active position in which it is adapted to be in engagement contact with the edge (15, 25) of the flange (12, 22).Welding arrangement according to claim 4, wherein the guiding channel (32, 42) comprises a bent portion (38, 48) in the area of the tool tip (31, 41) adapted to be positioned within the recess (14, 24) between the wall (17, 27) and the opposite edge (15, 25), the bent portion (38, 48) being adapted to bend the outer end (35, 45) of the alignment blade (33, 43) when in the active position towards the edge (15, 25) of the flange (12, 22).The welding arrangement according to claim 4 or 5, wherein the outer end (35, 45) of the alignment blade (33, 43) has a cutting edge (36, 46) configured to cut into the edge (15, 25) to fix the edge (15, 25) with respect to the tool tip (31, 41) of the clamping tool (30, 40).Use of the method according to any of claims 1 to 3 for the production of a plastic product (10).Use of the method for manufacturing a plastic product (10) according to claim 7, wherein the plastic product (10) is a container configured to hold a liquid.Use of the plastic product (10) manufactured according to claim 7 or 8 in a vehicle.

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