Low-temperature welding hot mold for car lamp and welding method

Abstract

The invention relates to a low-temperature welding hot mold for a car lamp and a welding method. The structure of an original welding hot mold is improved, a smoke exhaust hole and a smoke exhaust pipeline are removed, an original groove used for containing a welding rib is changed into a protruding rib strip, a polytetrafluoroethylene coating is sprayed on the surface of the hot mold, and a series of measures such as welding temperature reduction are taken. Reliable welding between the lamp parts such as the lens or the base and the decorative frame is finally achieved, the surfaces of the parts to be welded are prevented from being scalded, meanwhile, overflow of welding slag is reduced, the problem of toxic smog or wire drawing cannot be generated, the production cost is reduced, meanwhile, the appearance quality of the whole lamp is effectively improved, and the production efficiency is improved. And the market competitiveness of the product is enhanced.

Description

Technical Field

[0001] This invention relates to the field of automotive lighting technology, specifically to a low-temperature welding hot mold and welding method for automotive lighting. Background Technology

[0002] Automotive headlights involve many plastic parts, some of which have long, strip-shaped weld beads. These weld beads are melted using a welding hot mold, allowing different parts to be welded together. To achieve good welding results, traditional welding hot molds often require welding at relatively high temperatures (around 400℃), which leads to a series of problems such as burns on the surface of the parts, excessive weld slag, severe slag overflow, and the adhesion of toxic fumes.

[0003] To address the issue of toxic fume adhesion, common improvements include increasing the height of the weld bead and adding fume extraction systems. However, the former exacerbates the welding slag problem, while the latter, although mitigating toxic fume adhesion, cannot eliminate it entirely. More importantly, these improvements not only increase process complexity but also significantly raise costs. Another approach is to lower the welding temperature without altering the welding hot mold. While this alleviates the aforementioned problems to some extent, insufficient temperature leads to wire pulling when the weld bead separates from the hot mold after melting. These wires, if adhering to any component of the lamp, will cause aesthetic defects and render the entire fixture unusable. Current processes require frequent cleaning of the hot mold to address the wire pulling problem during low-temperature welding, severely impacting production efficiency. Summary of the Invention

[0004] The main objective of this invention is to solve the aforementioned problems in the prior art and provide a novel low-temperature welding hot mold for automotive lamps. The hot mold includes a metal plate and an anti-adhesion coating applied to the surface of the metal plate. Ribs for hot-melting welding tendons of automotive lamp components are protruding from the metal plate.

[0005] In the above scheme, the anti-adhesion coating is specifically a polytetrafluoroethylene coating. The anti-adhesion coating only needs to be applied to the surface of the metal plate on the side with the ribs, and its main purpose is to prevent the weld beads from remaining on the metal plate after hot melting and causing wire pulling problems.

[0006] In the above scheme, the shape and quantity of the ribs on the metal plate are matched with the shape and quantity of the weld beads on the headlight components.

[0007] In the above scheme, a boss is provided on the metal plate, and the boss is recessed in the middle to form a closed or continuous rib. By changing the original recessed groove structure into a raised rib, the heat melting effect of the weld bead is ensured on the one hand, and it can adapt to a lower welding temperature on the other hand, while avoiding burning the parts and reducing weld slag and its residue.

[0008] In the above solution, the height of the ribs does not exceed 10mm. Previously, to avoid the adhesion of toxic fumes, the depth of the grooves on the original hot mold was usually more than 15mm. The improved rib height has been significantly reduced.

[0009] In the above solution, the vehicle light components include components such as light distribution mirrors, lamp housings, decorative frames, and reflectors, and multiple plastic welding ribs of different shapes and layouts are set on these vehicle light components.

[0010] The second objective of this invention is to provide a welding method for different automotive lamp components based on the aforementioned low-temperature welding hot mold. The method includes: heating the automotive lamp low-temperature welding hot mold to the welding temperature and then keeping it at that temperature for later use; placing the automotive lamp component to be welded on the hot mold, ensuring that the weld beads are aligned with the ribs, and using the ribs to heat the weld beads to make them melt; removing the automotive lamp component, immediately aligning its melted weld beads with the welding position of another automotive lamp component, applying pressure to keep the two in contact, and releasing them after cooling to complete the welding.

[0011] In the above scheme, the welding temperature is specifically 200-250℃, such as 201℃, 205℃, 210℃, 218℃, etc.

[0012] Compared with existing similar products or technologies, the progress of this invention is mainly reflected in the following aspects: (1) The power consumption for maintaining the welding temperature for the same period of time is much lower at around 200°C than at 400°C for high-temperature welding. For large-scale mass production of multiple units in a factory, the energy saving and consumption reduction effect is very significant; (2) The low-temperature welding hot mold of this invention will not have solder residue and wire pulling problems during the welding process. There is no need to clean the hot mold regularly. The welding strength and appearance quality of the product can meet the requirements, and the production efficiency is greatly improved; (3) The low-temperature welding hot mold of this invention has lower requirements for the distance between the weld bars of the decorative frame and the base and other car lamp parts. Only 3mm is needed to avoid the decorative frame being burned. Therefore, the product design has more room to accommodate and can improve the designability of the product appearance; (4) Compared with the high-temperature welding hot mold, the welding slag of the low-temperature welding hot mold of this invention is smoother and the amount of welding slag overflow is reduced by 0.5-1mm, which significantly improves the appearance quality of the whole lamp and enhances the product competitiveness. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the structure of a traditional high-temperature welding hot mold.

[0014] Figure 2 This is a welding effect diagram of a traditional high-temperature welding hot mold.

[0015] Figure 3 This is a schematic diagram of the structure of the low-temperature welding hot mold of the present invention.

[0016] Figure 4 This is a welding effect diagram of the low-temperature welding hot mold of the present invention.

[0017] Reference numerals: 1-Metal plate, 2-Groove, 3-Smoke vent, 4-Smoke duct, 5-Boss, 6-Recessed area, 7-Rib. Detailed Implementation

[0018] To enable those skilled in the art to fully understand the technical solution of the present invention, further detailed descriptions are provided below in conjunction with specific embodiments and accompanying drawings. It should be emphasized that the following embodiments are merely some implementations of the present invention. Besides these, the present invention can have many other implementations, and any simple improvements and substitutions made based on these implementations will fall within the protection scope of the present invention.

[0019] Traditional high-temperature welding hot molds, such as Figure 1 As shown, the main body is a metal plate 1, with a groove 2 protruding from its surface. The shape and size of the groove match the weld bead on the headlight component to be welded. Before welding, the hot mold is heated to near the welding temperature (around 400℃). Then, the headlight component is placed on the hot mold, causing the weld bead to be inserted into the groove and melted. After a period of time, the headlight component is removed, aligned with another component, and welded together. This welding method has the following problems: Question 1: Due to the limitations of the structure and shape of the headlights, some headlight parts are too close together. For example, the minimum distance between the welding rod on the lens and the base and the decorative frame is only 2.5mm. If the above-mentioned high-temperature welding hot mold is used for welding, it will burn some headlight parts and cause problems such as poor appearance.

[0020] Question 2: Customers and consumers have very strict requirements for the product's appearance. The width of weld slag overflow after welding is typically not allowed to exceed 2mm; otherwise, it will be considered a surface quality issue. What are the welding effects of existing high-temperature welding hot molds? Figure 2 As shown in the figure, the welding slag is wide and overflows a lot, with serious air bubbles, resulting in poor overall lamp appearance quality and an unsightly appearance, which cannot meet customer requirements.

[0021] Question 3: When welding the lens and base using a high-temperature welding hot mold, the welding temperature of about 400℃ will cause a certain degree of thermal decomposition and generate a large amount of toxic fumes. These fumes will adhere to the inner surface of the lens, causing poor appearance. In order to reduce the adhesion of fumes to the hot mold, the commonly used methods include: (1) increasing the height of the hot mold groove 2 and the weld bead, for example, increasing it to more than 15mm (too high will lead to insufficient strength), thereby increasing the distance and space between the lens and the hot mold, reducing or avoiding the adhesion of fumes; (2) modifying the structure of the hot mold, adding a smoke vent 3 and a smoke duct 4 and a fan to promptly extract the generated toxic fumes. Although this method can reduce the adhesion of fumes, it cannot fundamentally eliminate fumes.

[0022] Given the aforementioned issues, we previously attempted to lower the welding temperature (from approximately 400℃ to approximately 200℃) without altering the hot mold. While the new process avoided burning the headlight components and effectively reduced slag escape, it also introduced new problems: slag residue remained on the hot mold due to the lower temperature. When the hot-melt weld beads separated from the hot mold, the residue adhered to the mold would form threads. These threads, if they adhered to any component, would render the product unusable. To resolve this thread-forming issue, the residue on the hot mold needed to be manually cleaned after each fixed number of welds, a process that took approximately 5 minutes, severely impacting production cycle time and efficiency.

[0023] Therefore, we optimized and improved the thermal mold, and redesigned it as follows: Figure 3 The low-temperature welding hot mold shown is a metal plate 1. The entire upper surface of the metal plate 1 is coated with polytetrafluoroethylene (PTFE) (commonly known as Teflon). Furthermore, the metal plate 1 has bosses 5, with a recessed area 6 formed in the center of each boss 5, and ribs 7 located at the edges of the recessed area. These ribs form an approximately rectangular shape. The size and shape of the ribs 7 match the welding ribs on the automotive headlight components. During welding, these raised ribs 7 are used to heat the welding ribs. As a complement, the height of the ribs 7 can be reduced to 10mm or less to accommodate the low-temperature welding hot mold and low-temperature welding process.

[0024] When welding the same automotive lamp components such as lens and base using the aforementioned novel low-temperature welding hot mold, the welding temperature can be reduced to no more than 220°C. Due to the lower welding temperature, the weld beads on the lens and base will not produce fumes due to thermal decomposition, thus eliminating the possibility of fumes adhering to the inner surface of the lens. Because the surface of this low-temperature welding hot mold is coated with Teflon, when the weld beads separate from the hot mold after melting, no residue will remain adhering to the hot mold if the Teflon coating is not damaged, preventing wire pulling problems and the resulting product scrap.

[0025] Automotive lighting products obtained by using the improved new low-temperature welding hot mold welding method, such as Figure 4 As shown in the figure, not only is the weld slag width small and the amount of overflowing slag minimal, but the weld surface is also smooth and aesthetically pleasing, resulting in a better overall appearance and higher customer acceptance. More importantly, welding can be performed continuously without interruption to clean residue from the hot mold, significantly improving production efficiency.

[0026] After testing, the vehicle headlights produced using the improved hot mold and welding process meet customer requirements in terms of both appearance quality and welding strength.

Claims

1. A vehicle light low temperature soldering hot block, characterized by: The heat die comprises a metal plate and a rib strip protruding from the metal plate, the metal plate and the rib strip are coated with an anti-adhesion coating, and the rib strip is in contact with the welding rib on the vehicle lamp part to heat and melt the welding rib.

2. The vehicle light low temperature soldering heat die of claim 1, wherein: The anti-adhesion coating is specifically a polytetrafluoroethylene coating.

3. The heat die for low temperature brazing of vehicle lamps according to claim 1, characterized in that: The shape and number of the rib strip are matched with the shape and number of the welding rib.

4. The vehicle lamp low temperature soldering hot block of claim 1 wherein: A boss is arranged on the metal plate, the middle part of the boss is concave downward, and the rib strip is formed at the edge of the boss in a closed or continuous manner.

5. The heat die for low temperature brazing of vehicle lamps according to claim 1, characterized in that: The height of the rib strip is not more than 10 mm.

6. The heat die for low temperature brazing of vehicle lamps according to claim 1, characterized in that: The vehicle lamp parts include a light distribution mirror, a lamp shell, a decorative frame, and a reflector.

7. The method of claim 1 for thermally bonding parts of a vehicle lamp using the low temperature solder, wherein The method comprises the following steps: heating the vehicle lamp low-temperature welding heat die to a welding temperature and keeping warm for standby; placing the vehicle lamp part to be welded on the heat die, ensuring that the welding rib is aligned with the rib strip and in close contact with the rib strip, heating and melting the welding rib by using the rib strip; taking off the heat-melted vehicle lamp part, aligning the vehicle lamp part with another vehicle lamp part, and keeping the welding parts in contact, and then cooling to complete the welding.

8. The method of claim 7, wherein: The welding temperature is specifically 200-250 DEG C.

9. The method of claim 8, wherein: The welding temperature is specifically 200-210 DEG C.

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