Forming process of curved reflective glass for head-up display

Abstract

The invention provides a curved reflective glass forming process for a head-up display. The curved reflective glass forming process comprises the following steps: preparing flat original glass; correspondingly fixing an upper die and a lower die on the upper heating plate and the lower heating plate respectively, wherein the upper die and the lower die are in a separated state; setting the temperatures of an upper heating plate and a lower heating plate, and after the temperature of the lower mold reaches T1, putting plate glass into the lower mold; after the plate glass is put into the lower mold for a certain time, pushing the radiation heat source device into a gap between the upper mold and the lower mold; setting a radiation heat source opening formula according to the shape characteristics of the product, and heating the upper mold, the lower mold and the plate glass; when the temperature of the lower die reaches T2, the radiation heat source is closed and pushed out; the upper die falls until the upper die and the lower die are completely assembled, and the condition is kept for a period of time; in a mold closing state, gradually reducing the temperature of the heating plate, preserving heat and annealing; closing the heat source in a mold closing state, and reducing the mold temperature to a certain temperature; and opening the mold and taking materials. The product precision is high, operation is easy, efficiency is high, polishing treatment is not needed, and the production cost is greatly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of optical element processing, and in particular to a curved reflective glass molding process for a head-up display. Background Art

[0002] With the development of the times in recent years, head-up displays (HUD) have been widely used in automobiles. Its working principle is that the image generated by the image source (PGU) is reflected by the internal structure of the HUD (primary reflector, secondary reflector) and the front windshield into the human eye, forming an enlarged virtual image at a certain distance from the front windshield. As one of the core components of the HUD, the reflector's surface shape, slope error, curvature deviation and other parameters will directly affect the imaging effect of the HUD system. The reflector surface accuracy is generally expressed by the PV value. By comparing the deviation between the actual value and the ideal value of the optical surface, the reflector surface quality and surface error index are determined.

[0003] At present, the curved reflective glass used for head-up displays has high precision, the surface size tolerance is generally controlled within 100μm, the slope error is controlled within 1, and the surface is smooth, without bumps or foreign matter. In order to achieve such specifications, the market generally adopts a preliminary bending of the curved surface shape, and then adopts a chemical mechanical polishing method to achieve the required dimensional accuracy, such as the high-precision curved mirror preparation method disclosed in the Chinese patent application number CN202311289503.0. This preparation process has a long process, low efficiency, high cost, and difficult operation. In order to solve this problem, the present invention proposes a curved reflective glass forming process, which has high product precision, simple operation, and no need for polishing, greatly reducing production costs. Summary of the invention

[0004] The present invention provides a curved reflective glass forming process for a head-up display, which has high product precision, simple operation, high efficiency, and no need for polishing, thereby greatly reducing production costs.

[0005] In order to achieve the above object, the present invention adopts the following technical solution: a process for forming curved reflective glass for a head-up display, which specifically comprises the following steps: Step 1: Prepare flat glass: Design and cut the flat glass according to the 3D glass, and then obtain the flat glass through CNC finishing, washing and drying; Step 2: fix the upper mold on the upper heating plate, fix the lower mold on the lower heating plate, and keep the upper and lower molds in a separated state; Step 3: Set the temperature of the upper and lower heating plates. After the temperature of the lower mold reaches the set temperature T1, put the flat glass into the lower mold. Step 4: After the flat glass has been placed in the lower mold for a certain period of time, the radiation heat source device is pushed into the gap between the upper and lower molds; Step 5: Set the radiation heat source according to the product shape characteristics to start the recipe, and heat the upper mold, lower mold, and flat glass at the same time; Step 6: When the temperature of the lower mold reaches the preset temperature T2, close and push out the radiation heat source; Step 7: The upper mold falls until it is completely molded with the lower mold; Step 8: After the mold is completely closed, keep it for a while; Step 9: In the mold closing state, the temperature of the heating plate is gradually reduced to perform heat preservation annealing; Step 10: In the mold closing state, turn off the heat source and lower the mold temperature to a certain temperature; Step 11: Open the mold, take out the 3D glass and cool, clean and coat it to complete the 3D glass hot bending process.

[0006] Preferably, in step 2, both the upper and lower heating plates use heating rods as heat sources, and temperature adjustment can be achieved; when the upper and lower molds are in a separated state in step 2, the distance is 200 to 400 mm; the upper heating plate can be adjusted in height by a lifting device.

[0007] Preferably, in step three, the temperature setting value of the upper heating plate is 50-100°C lower than the temperature setting value of the lower heating plate; the set temperature T1 is 500-600°C.

[0008] Preferably, in step 4, the radiation heat source device is pushed into the gap between the upper and lower molds 1 minute after the flat glass is put into the lower mold; the radiation heat source device moves in the gap between the upper and lower molds in the mold opening state and has no contact with the upper and lower molds.

[0009] Preferably, the radiation heat source device described in step 4 includes a plurality of IR lamp heat sources, and the power, height and opening time of each lamp are adjustable.

[0010] Preferably, the radiation heat source setting formula described in step five is designed according to the product shape and specific needs, and the power, height, and time of a single IR lamp are designed to form multiple groups of formulas, and different formulas can be used in combination.

[0011] Preferably, in step five, the upper mold, the lower mold and the flat glass are heated for 3 to 10 minutes.

[0012] Preferably, after the mold is completely closed in step eight, the temperature is maintained for 10 to 90 seconds; in step eight, the mold temperature is always maintained at a preset temperature T2, and the preset temperature T2 is 560 to 650°C.

[0013] Preferably, in step nine, the upper and lower heating plates are set to the same temperature, and the time can be set by oneself; Preferably, the gradient described in step nine sequentially reduces the temperature of the heating plate, specifically referring to: the annealing is divided into i stages, i≥2, the first stage annealing temperature is 560°C, and the preset temperature of the i-th stage annealing station is 450°C.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention proposes a curved reflective glass forming process for a head-up display. The glass is heated in steps by using two sets of heating systems to meet the temperature distribution required by the glass at different forming stages. The two sets of heating systems are used in combination to accurately control the product forming accuracy. In the early stage, a radiant heat source is used to adjust the power of the radiant heat source at different positions to improve the temperature difference of the glass and reduce the occurrence of stress concentration. In the later stage, the mold is heated by contact heat conduction to achieve temperature uniformity in the annealing process and reduce participating stress. The scheme of first overheating and then cooling to the softening point is adopted to press the glass at a relatively low temperature so that the glass reaches the expected shape. The annealing effect is enhanced by gradient cooling to suppress the glass rebound phenomenon. Compared with the traditional 3D glass hot bending process, the curved reflective glass forming process of the present invention has high product accuracy, high efficiency, simple operation, stable product dimensional accuracy within 100μm, and good appearance without polishing, which greatly reduces the production cost. DETAILED DESCRIPTION

[0016] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0017] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed", "provided with", etc. should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be internal communication between two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0018] The present invention provides a curved reflective glass forming process for a head-up display, wherein the flat original glass is sequentially subjected to four processes of preheating, forming, heat preservation annealing, and cooling in a hot bending forming device. The following steps 3 to 5 belong to the preheating stage, steps 7 and 8 belong to the forming stage, step 9 belongs to the heat preservation annealing stage, and step 10 belongs to the cooling stage. The curved reflective glass forming process for a head-up display of the present invention specifically includes the following steps: Step 1: Prepare flat glass: Design and cut the flat glass according to the 3D glass, and then obtain the flat glass through CNC finishing, washing and drying; Step 2: fix the upper mold on the upper heating plate, fix the lower mold on the lower heating plate, and keep the upper and lower molds in a separated state; Step 3: Set the temperature of the upper and lower heating plates. After the temperature of the lower mold reaches the set temperature T1, put the flat glass into the lower mold. Step 4: After the flat glass is put into the lower mold for a certain period of time, specifically 1 minute after the flat glass is put into the lower mold, the radiation heat source device is pushed into the gap between the upper and lower molds; Step 5: Set the radiation heat source according to the product shape characteristics to start the recipe, and heat the upper mold, lower mold, and flat glass at the same time. The specific heating time is 3 to 10 minutes; Step 6: When the temperature of the lower mold reaches the preset temperature T2, close and push out the radiation heat source; Step 7: The upper mold falls until it is completely molded with the lower mold; Step 8: After the mold is completely closed, keep it for a while, specifically 10 to 90 seconds; Step 9: In the mold closing state, the temperature of the heating plate is gradually reduced to perform heat preservation annealing; Step 10: In the mold closing state, turn off the heat source and lower the mold temperature to a certain temperature; Step 11: Open the mold, take out the 3D glass and cool, clean and coat it to complete the 3D glass hot bending process.

[0019] It is worth noting that in step 2, both the upper and lower heating plates use heating rods as heat sources and both have temperature setting functions to achieve temperature regulation.

[0020] In step 2, when the upper and lower molds are separated, the distance is 200 to 400 mm.

[0021] In step 2, the upper heating plate is adjusted in height by a lifting device, and the lifting device can specifically adopt an existing lifting device, such as a cylinder, an electric push rod, etc., so that the upper heating plate has a height lifting function.

[0022] In step 3, the temperature setting value of the upper heating plate is 50-100° C. lower than the temperature setting value of the lower heating plate. The set temperature T1 is generally 450-600° C., and can be preferably set at 500-600° C.

[0023] The radiation heat source device described in step 4 uses IR lamps as heat sources, and specifically includes multiple IR lamp heat sources (>20), and also includes a slidable frame that serves as a support, and the power, height and opening time of each lamp are adjustable.

[0024] In step 4, the radiation heat source device moves in the gap between the upper mold and the lower mold in the mold opening state, and has no contact with the upper mold and the lower mold.

[0025] The radiation heat source device described in step 5 has a recipe calling function; each recipe includes parameters such as IR lamp position, quantity, power, and opening time. After the lower mold is put into the flat glass, the IR lamp radiation heat source heats the glass, the upper mold cavity, and the lower mold cavity at the same time to achieve temperature regulation and control.

[0026] The radiation heat source setting formula described in step 5 can set the power, height, and opening time of a single IR lamp according to the product shape and specific needs and form multiple groups of formulas (such as formula 1, 2, 3...j, j>3). Different formulas can be used in combination.

[0027] During the preheating stage, the upper mold never contacts the flat glass, which can reduce glass surface problems and stress concentration problems.

[0028] After the mold enters the fully closed state in step eight, it is only maintained for 10 to 90 seconds to reduce the occurrence of surface defects.

[0029] In step eight, the mold temperature is always maintained near the preset temperature T2. The temperature range of T2 varies according to different glass materials. For example, the preset temperature T2 is 560-650°C.

[0030] In step nine, the upper and lower heating plates are set to the same temperature, and the time can be set by yourself.

[0031] The gradient described in step nine reduces the temperature of the heating plate in sequence, specifically: the annealing is divided into i stages, i≥2, the first stage annealing temperature is 560°C, and the preset temperature of the i-th stage annealing station is 450°C.

[0032] The present invention discloses a curved reflective glass forming process for a head-up display, which mainly includes four processes: preheating, forming, heat preservation annealing, and cooling. The present invention meets the temperature requirements of differentiation before glass forming and uniformity in the annealing stage by using an IR lamp radiation heating system and a heating plate contact heating system. The two sets of heating systems are used in combination to accurately control the product forming accuracy; in the early stage, a radiation heat source is used to adjust the power of the radiation heat source at different positions to improve the temperature difference of the glass and reduce the occurrence of stress concentration; in the later stage, the mold is heated by contact heat conduction to achieve temperature uniformity in the annealing process and reduce participating stress; at the same time, a scheme of first overheating and then cooling to the softening point is adopted to press at a relatively low temperature so that the glass reaches the expected shape; by gradient cooling, the annealing effect is enhanced and the glass rebound phenomenon is suppressed. Compared with the traditional one set of heat source with low forming accuracy, the present invention adopts two sets of heat sources to achieve high-precision control of the product through process design and experiments. It is simple to operate, efficient, and does not require polishing, which greatly reduces the production cost.

[0033] Obviously, the specific implementation of the present invention is not limited by the above-mentioned methods. As long as various non-substantial improvements are made by adopting the method concept and technical solution of the present invention, they are all within the protection scope of the present invention. The technical solution in the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Example 1

[0034] A process for forming curved reflective glass for a head-up display according to this embodiment includes the following steps: Step 1: Design and cut the flat glass according to the 3D glass, and then obtain the flat original glass through CNC finishing, washing and drying.

[0035] Step 2: Fix the upper mold on the upper heating plate, and fix the lower mold on the lower heating plate, and the upper and lower molds are in a separated state.

[0036] Step 3: Load the dried flat glass into the mold, set the temperature of the upper and lower heating plates, and when the temperature of the lower mold reaches 480°C, put the flat glass into the lower mold.

[0037] Step 4: 1 minute after the flat glass is put into the lower mold, push the radiation heat source device into the gap between the upper and lower molds.

[0038] Step 5: Set up a radiation heat source recipe to heat the upper mold, lower mold, and flat glass simultaneously for 5 minutes.

[0039] Step 6: When the temperature of the lower mold reaches the preset temperature of 580°C, close and eject the radiant heat source.

[0040] Step 7: The upper mold falls until it is completely closed with the lower mold.

[0041] Step 8: After the mold is fully closed, keep the mold fully closed for 30 seconds.

[0042] Step nine: Then enter the annealing stage, and gradually reduce the temperature of the heating plate in the mold closing state, such as 560, 530, and 500°C.

[0043] Step 10: In the mold closing state, turn off the heat source and reduce the mold temperature to 450℃.

[0044] Step 11: Open the mold, take out the 3D glass and cool, clean and coat it to complete the 3D glass hot bending process. Example 2

[0045] A process for forming curved reflective glass for a head-up display according to this embodiment includes the following steps: Step 1: Design and cut the flat glass according to the 3D glass, and then obtain the flat original glass through CNC finishing, washing and drying.

[0046] Step 2: Fix the upper mold on the upper heating plate, and fix the lower mold on the lower heating plate, and the upper and lower molds are in a separated state.

[0047] Step 3: Load the dried flat glass into the mold, set the temperature of the upper and lower heating plates, and when the temperature of the lower mold reaches 450°C, put the flat glass into the lower mold.

[0048] Step 4: 1 minute after the flat glass is put into the lower mold, push the radiation heat source device into the gap between the upper and lower molds.

[0049] Step 5: Set up a 3-stage radiation heat source formula to heat the upper mold, lower mold, and flat glass simultaneously for 10 minutes.

[0050] Step 6: When the temperature of the lower mold reaches the preset temperature of 630°C, close and eject the radiant heat source.

[0051] Step 7: The upper mold falls until it is completely closed with the lower mold and remains in the closed state for 10 seconds.

[0052] Step 8: Then enter the annealing stage, and reduce the temperature of the heating plate in a gradient manner in the mold closing state, such as 580, 560, 530, 500, and 480°C.

[0053] Step 10: In the mold closing state, turn off the heat source and reduce the mold temperature to 450℃.

[0054] Step 11: Open the mold, take out the 3D glass and cool, clean and coat it to complete the 3D glass hot bending process. Example 3

[0055] A process for forming curved reflective glass for a head-up display according to this embodiment includes the following steps: Step 1: Design and cut the flat glass according to the 3D glass, and then obtain the flat original glass through CNC finishing, washing and drying.

[0056] Step 2: Fix the upper mold on the upper heating plate, and fix the lower mold on the lower heating plate, and the upper and lower molds are in a separated state.

[0057] Step 3: Load the dried flat glass into the mold, set the temperature of the upper and lower heating plates, and when the temperature of the lower mold reaches 570°C, put the flat glass into the lower mold.

[0058] Step 4: 1 minute after the flat glass is put into the lower mold, push the radiation heat source device into the gap between the upper and lower molds.

[0059] Step 5: Set up 3 sections of radiation heat source formula, and heat the upper mold, lower mold, and flat glass at the same time for 3 minutes.

[0060] Step 6: When the temperature of the lower mold reaches the preset temperature of 650°C, close and eject the radiant heat source.

[0061] Step 7: The upper mold falls until it is completely closed with the lower mold and maintains the complete closing state for 50 seconds.

[0062] Step 8: Then enter the annealing stage, and reduce the temperature of the heating plate in sequence in the mold closing state, such as 620, 590, 560, 530, 500, and 480°C.

[0063] Step 10: In the mold closing state, turn off the heat source and reduce the mold temperature to 450℃.

[0064] Step 11: Open the mold, take out the 3D glass and cool, clean and coat it to complete the 3D glass hot bending process.

[0065] The above-described embodiments only express a certain implementation mode of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the patent scope of the present invention. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.

Claims

1. A process for forming curved reflective glass for a head-up display, characterized in that: The following steps are involved: Step 1: Prepare flat glass: Design and cut the flat glass according to the 3D glass, and then obtain the flat glass through CNC finishing, washing and drying; Step 2: fix the upper mold on the upper heating plate, fix the lower mold on the lower heating plate, and keep the upper and lower molds in a separated state; Step 3: Set the temperature of the upper and lower heating plates. After the temperature of the lower mold reaches the set temperature T1, put the flat glass into the lower mold; Step 4: After the flat glass has been placed in the lower mold for a certain period of time, the radiation heat source device is pushed into the gap between the upper and lower molds; Step 5: Set the radiation heat source according to the product shape characteristics to start the recipe, and heat the upper mold, lower mold, and flat glass at the same time; Step 6: When the temperature of the lower mold reaches the preset temperature T2, close and push out the radiation heat source; Step 7: The upper mold falls until it is completely molded with the lower mold; Step 8: After the mold is completely closed, keep it for a while; Step 9: In the mold closing state, the temperature of the heating plate is gradually reduced to perform heat preservation annealing; Step 10: In the mold closing state, turn off the heat source and lower the mold temperature to a certain temperature; Step 11: Open the mold, take out the 3D glass and cool, clean and coat it to complete the 3D glass hot bending process.

2. The process for forming curved reflective glass for a head-up display according to claim 1, characterized in that: In step 2, both the upper and lower heating plates use heating rods as heat sources, and can achieve temperature adjustment; in step 2, when the upper and lower molds are in a separated state, the distance is 200 to 400 mm; the upper heating plate can achieve height adjustment through a lifting device.

3. The process for forming curved reflective glass for a head-up display according to claim 1, characterized in that: In step 3, the temperature setting value of the upper heating plate is 50-100°C lower than the temperature setting value of the lower heating plate; the set temperature T1 is 500-600°C.

4. The process for forming curved reflective glass for a head-up display according to claim 1, characterized in that: In step 4, 1 minute after the flat glass is put into the lower mold, the radiation heat source device is pushed into the gap between the upper and lower molds; the radiation heat source device moves in the gap between the upper and lower molds in the mold opening state and has no contact with the upper and lower molds.

5. The process for forming curved reflective glass for a head-up display according to claim 1, characterized in that: The radiation heat source device described in step 4 includes a plurality of IR lamp heat sources, and the power, height and opening time of each lamp are adjustable.

6. The process for forming curved reflective glass for a head-up display according to claim 1, characterized in that: The radiation heat source setting formula described in step 5 is designed according to the product shape and specific needs, and the power, height, and time of a single IR lamp are designed to form multiple groups of formulas. Different formulas can be used in combination.

7. The process for forming curved reflective glass for a head-up display according to claim 1, characterized in that: In step five, the upper mold, the lower mold and the flat glass are heated for 3 to 10 minutes.

8. The process for forming curved reflective glass for a head-up display according to claim 1, characterized in that: After the mold is completely closed in step eight, the temperature is maintained for 10 to 90 seconds. In step eight, the mold temperature is always maintained at a preset temperature T2, and the preset temperature T2 is 560 to 650°C.

9. The process for forming curved reflective glass for a head-up display according to claim 1, characterized in that: In step nine, the upper and lower heating plates are set to the same temperature, and the time can be set by yourself.

10. The process for forming curved reflective glass for a head-up display according to claim 1, characterized in that: The gradient described in step nine reduces the temperature of the heating plate in sequence, specifically: the annealing is divided into i stages, i≥2, the first stage annealing temperature is 560°C, and the preset temperature of the i-th stage annealing station is 450°C.