Splicing method of nickel mold for micro-prism type light reflecting film

Abstract

The present application relates to the technical field of precision optical mold manufacturing, and particularly relates to a splicing method of a nickel mold for a micro-prism type reflective film, which first determines a welding damage zone width a through laser welding. Then, when splicing in the 0-degree direction, the cutting position is positioned at a position of moving a distance a / 2 along the 0-degree line of the 0-degree cone outward, so as to avoid the welding damage zone from affecting the effective cone. When splicing in the 90-degree direction, according to the bottom side length L of the effective cone and the distance b of the nearest effective cone from the 90-degree damage edge, the welding zone is determined to be alternately arranged by the combination of invalid cones and effective cones with different areas on both sides, so as to maximize the retroreflective efficiency. Then, in the 0-degree and 90-degree directions, cutting is respectively performed by using a precision cutting device, and after alignment on a splicing platform, welding is performed by using a precision laser welding device. The technical problem of poor retroreflective efficiency and overall uniformity in the splicing area in the prior art is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of precision optical mold manufacturing, and in particular to a splicing method of a nickel mold for micro-prism type reflective film. BACKGROUND

[0002] At present, the micro-prism reflective structure has very high retroreflective performance, can increase the brightness and directionality of reflected light, makes it easier for drivers or pedestrians to perceive and identify, and improves the visual guidance and safety under night or low visibility conditions, and is widely used in the fields of transportation, clothing and the like. The light reflection path of the micro-prism corner cube unit is as shown in Figure 1 Only the light that is reflected by 3 side surfaces can form effective retroreflection, the light that is vertically incident from the bottom surface of the corner cube unit can be divided into 3 regions according to the vertical projection of the edge, only the light that is incident in the region (1-2, 1-3, 2-2, 2-3, 3-2, 3-3) surrounded by the regular hexagon with the center of the bottom surface as the center and the edge length being 1 / 3 of the edge length of the corner cube can be reflected 3 times on the corner cube unit, and the light that is incident in the region (1-1, 1-4, 2-1, 2-4, 3-1, 3-4) region exceeds the third side surface region after the second reflection, forming invalid light effect, so the theoretical effective retroreflective efficiency of the micro-prism corner cube unit is about 66.7%.

[0003] In order to efficiently realize large-scale and continuous micro-prism reflective film production, it is usually necessary to manufacture the working mold into a large-area cylindrical roller. However, due to the uniformity problems caused by the processable size of the copper mold carving equipment and the wear of the large-area carving tool, it is generally necessary to precisely electrocast the carved copper master mold into a nickel sub-mold, and then process the working roller mold through splicing and electrocasting multiple times. The difference in splicing process and technology will have a great impact on the final reflective film. For example, the manufacturing method of a micro-prism mold for reducing the seam dark band disclosed in Chinese Patent Publication No. CN111055094A proposes a method of splicing after precise machining in the 0° direction using a special tool to reduce the seam dark band, which improves the retroreflective performance of the splicing area of the nickel sub-mold in the 0° and 0° directions, as shown in Figure 2 However, the machining method is complex, the angle, cutting position and cutting depth of the special tool need to be micro-controlled to make the tool completely coincide with the three-prism machining knife line, and the cutting depth also needs to be controlled to prevent the 180° corner invalid area from becoming larger due to overcutting.

[0004] Generally, during the production of nickel roller molds, in addition to 0°-to-0° splicing, 90°-to-90° or 0°-to-90° (yin-yang grid) splicing between sub-molds is also required. However, no research has been reported in this area. When performing 90° cutting, cutting and splicing are usually performed along the centerline of the pyramid. Due to the precision of the splicing angle and position, the half pyramids on both sides of the seam cannot form a complete triangular pyramid structure, and light cannot be effectively retroreflected, resulting in large dark bands on both sides of the seam, which seriously affects the retroreflection efficiency and overall uniformity of the splicing area. Summary of the Invention

[0005] Therefore, in response to the above-mentioned problems, the present invention proposes a splicing method for nickel molds for microprismatic reflective film. By changing the cutting position, the area of ​​the ineffective area of ​​the splicing area is reduced, and the overall uniformity of the mold after splicing is improved, thereby solving the technical problems of poor retroreflective efficiency and overall uniformity of the splicing area in the prior art.

[0006] To achieve the above-mentioned object, the present invention adopts the following technical solution: a method for splicing nickel molds for micro-prismatic reflective film, characterized in that it comprises the following steps:

[0007] The first step is to determine the width of the welding damage zone: take a nickel sub-mold that is the same as the nickel sub-mold to be cut and spliced, perform laser welding on the back side, and then check the front side of the welding position to determine the width a of the thermal damage zone caused by laser welding;

[0008] The second step is to determine the cutting position in the 0° direction: the micro-prismatic cone of the micro-prismatic reflective film is set as a valid cone when it has a complete shape, and as an invalid cone when it has an incomplete shape. The lowest valid cone is set as the 0° cone, and the lowest edge of the 0° cone is set as the 0° edge line. When splicing the nickel mold in the 0° direction, the cutting position is positioned at a distance a / 2 away from the 0° edge line of the 0° cone to avoid the welding damage area affecting the valid cone.

[0009] The third step is to determine the cutting position in the 90° direction: set the base length of the effective angle cone to L, set the distance between the 90° damage edge and the nearest effective angle cone to b, 0<b≤L / 2, and when splicing the nickel mold in the 90° direction, the two sides of the welding area are formed by alternating combinations of effective angle cones with an area greater than 1 / 2 and invalid angle cones with an area less than 1 / 2 of the effective angle cone, where b is the value that maximizes the retroreflection efficiency of the effective angle cone unit and the invalid angle cone unit;

[0010] Fourth step, 0 ° direction cutting and splicing: the nickel sub-mold is installed to the precision cutting equipment fixed clamp, the mold direction is adjusted, the 0 ° direction of the sub-mold is parallel to the equipment X axis, then the 0 ° edge line of the first row of effective angle cone to be reserved is used as the reference, the sub-mold is cut along the X axis at the position away from the 0 ° edge line by a / 2, after the cut sub-mold is aligned on the splicing platform, the precision laser welding equipment is used for welding;

[0011] Fifth step, 90 ° direction cutting and splicing: the nickel sub-mold is installed to the precision cutting equipment fixed clamp, the mold direction is adjusted, the 0 ° direction of the sub-mold is parallel to the equipment X axis, then the cutting tool is adjusted to the best cutting position b along the Y axis, the cut sub-mold is aligned on the splicing platform, and the precision laser welding equipment is used for welding.

[0012] Preferably, the retroreflective efficiency of the effective angle cone and the invalid angle cone unit combination is set as η, and the retroreflective efficiency change formula of the unit combination is:

[0013]

[0014] Preferably, in the third step, when b is one fourth of the length L of the bottom edge of the micro-prism angle cone, the retroreflective efficiency of the effective angle cone unit and the invalid angle cone unit reaches the maximum.

[0015] Preferably, in the third step, when the nickel sub-mold is cut in the 90 ° direction, the cutting position is set at the position away from the closest invalid angle cone edge corner point by b+a / 2, the minimum dark area is realized, the retroreflective efficiency of the welding area angle cone is improved, and thus the uniformity of the overall spliced nickel mold is improved.

[0016] By adopting the foregoing technical solutions, the present application has the beneficial effects that: the present application determines the best cutting position range by researching the relationship between the cutting position and the retroreflective efficiency change. By using the method provided by the present application, the retroreflective efficiency of the splicing seam area is effectively improved, the overall uniformity of the spliced nickel mold is improved, and the operation mode is simple and easy to implement without changing the existing laser welding process conditions. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a structural schematic diagram of the light reflection path of the existing micro-prism angle cone unit.

[0018] Figure 2 is a schematic diagram of the retroreflective performance of the 0 ° and 0 ° direction splicing area of the nickel sub-mold.

[0019] Figure 3 is a structural schematic diagram of the 0 ° direction cutting position of the nickel sub-mold.

[0020] Figure 4 is a structural diagram of a nickel sub-mold 90° direction cutting position.

[0021] Figure 5 is a nickel sub-mold 90° direction cutting different position diagram.

[0022] Figure 6 is a nickel sub-mold 0° direction splicing diagram.

[0023] Figure 7 is a first nickel sub-mold 90° direction splicing diagram.

[0024] Figure 8 is a second nickel sub-mold 90° direction splicing diagram.

[0025] Figure 9 is a first cutting and splicing nickel mold surface reflection effect diagram.

[0026] Figure 10 is a second cutting and splicing nickel mold surface reflection effect diagram.

[0027] Figure 11 is a third cutting and splicing nickel mold surface reflection effect diagram.

[0028] Figure 12 is a fourth cutting and splicing nickel mold surface reflection effect diagram. DETAILED DESCRIPTION

[0029] The present application will be further described in conjunction with the drawings and specific embodiments.

[0030] Reference Figures 3 to 8 The embodiment provides a nickel mold splicing method for micro-prism type reflective film, characterized by comprising the following steps:

[0031] First step, determine the welding damage width: take a nickel sub-mold same as the nickel sub-mold to be cut and spliced, laser weld on the back, then check the front of the welding position, determine the heat damage width a caused by laser welding;

[0032] Second step, 0° direction cutting position determination: set the micro-prism angle pyramid of the micro-prism reflective film as effective angle pyramid when it has complete form, set as invalid angle pyramid when it has incomplete form, set the lowermost effective angle pyramid as 0° angle pyramid, set the lowermost edge of the 0° angle pyramid as 0° line, when splicing the nickel mold in 0° direction, position the cutting position at a position moving outward along the 0° line of the 0° angle pyramid by a distance of a / 2, to avoid the welding damage area affecting the effective angle pyramid;

[0033] Third step, 90° direction cutting position determination: set the base length of the effective corner cone as L, set the distance between the 90° damage edge and the nearest effective corner cone as b, 0 < b ≤ L / 2, when the nickel mold is spliced in the 90° direction, the two sides of the welding area are alternately arranged by the combination of the effective corner cone with an area > 1 / 2 effective corner cone and the ineffective corner cone with an area < 1 / 2 effective corner cone, wherein b is the value that makes the retroreflective efficiency of the effective corner cone unit and the ineffective corner cone unit maximum;

[0034] Fourth step, 0° direction cutting and splicing: install the nickel sub-mold on the precision cutting equipment fixing clamp, adjust the mold direction, make the 0° direction of the sub-mold parallel to the X-axis of the equipment, then cut the sub-mold along the X-axis at a position away from the 0° line by a distance of a / 2, after the cutting, the sub-mold is aligned on the splicing platform and then welded using a precision laser welding equipment.

[0035] Fifth step, 90° direction cutting and splicing: install the nickel sub-mold on the precision cutting equipment fixing clamp, adjust the mold direction, make the 0° direction of the sub-mold parallel to the X-axis of the equipment, then adjust the cutting tool to the optimal cutting position b along the Y-axis to cut the sub-mold, after the cutting, the sub-mold is aligned on the splicing platform and then welded using a precision laser welding equipment.

[0036] In the first step, the size of a can be optimized and controlled by process parameters such as laser spot size, welding power, welding speed, laser frequency, sub-mold thickness, etc. The 0° cutting position is as shown in Figure 3 .

[0037] In the second step, when the nickel mold is spliced in the 0° direction, if the splicing welding damage area exceeds the 0° line of the 0° corner cone, it will cause the light in the damaged area and the symmetrical area of the corner cone unit to fail to form effective retroreflection, resulting in a significant decrease in the retroreflective efficiency of the corner cone on both sides of the splicing area, and the width of the dark area is significantly larger than the welding damage width. The position of b is as shown in Figure 4 .

[0038] In the third step, set the retroreflective efficiency of the combination of the effective corner cone and the ineffective corner cone unit as η, and the retroreflective efficiency change formula of the unit combination is:

[0039]

[0040] When b is one-fourth of the base length L of the micro-prism corner cone, the retroreflective efficiency of the effective corner cone unit and the ineffective corner cone unit reaches the maximum, η ≈ 61.11%, which is close to the retroreflective efficiency of the complete corner cone unit. We have also made theoretical calculations and TracePro software modeling simulations for b = 1 / 2, b = 1 / 3, b = 1 / 4, and b = 1 / 5, respectively, and the simulation results are basically consistent with the calculated values, as shown in Table 1.

[0041] Table 1, the change rule of the retroreflective efficiency of the corner cube unit adjacent to the welding area with the position of b is calculated and simulated

[0042]

[0043] When cutting the nickel sub-mold in the 90° direction, the cutting position is set at a position that is a distance of b+a / 2 away from the nearest invalid corner edge point, which realizes the smallest dark area and improves the retroreflective efficiency of the corner of the welding area, thereby improving the uniformity of the overall spliced nickel mold.

[0044] As shown in Figure 5 , two 90° cutting positions are given, which are 90° cutting position 1 and 90° cutting position 2 as shown in the figure.

[0045] Referring again to Figure 6 , it is the splicing of the nickel sub-mold in the 0° direction, and a spliced nickel mold with good retroreflective performance and uniformity is obtained. It can be seen that the dark area at the splicing position has no significant change from the effective corner position at the other positions, realizing good uniformity.

[0046] Referring again to Figure 7 , it is a splicing diagram of the 90° cutting position 1 as shown in Figure 5 . Although the two dark areas are spliced together at the splicing position, the overall effective retroreflection is not affected, realizing good uniformity.

[0047] Referring again to Figure 8 , it is a splicing diagram of the 90° cutting position 2 as shown in Figure 5 . The dark areas are misaligned at the splicing position, but the overall effective retroreflection is not affected, realizing good uniformity.

[0048] Specifically, taking an actual case as an example, refer to Figures 9 to 12 .

[0049] Under the process condition of splicing a damage area a=0.01mm, the nickel sub-mold is cut and laser welded under the condition of b=0.175mm, b=0.10mm, b=0.075mm and b=0.06mm using a micro-prism corner nickel mold with a bottom side length L=0.3mm, and the spliced nickel mold is as shown in Figures 9 to 12 . From the picture, it can be seen that the dark areas on both sides of the splicing area will change significantly at different cutting positions. The dark area at b=0.075mm is significantly smaller than the other three splicing cases, as shown in Figure 11 .

[0050] Figure 9, the first cutting and splicing nickel mold surface reflection effect diagram, wherein L=0.3mm, a=0.01mm, b=0.175mm;

[0051] Figure 10 is the second cutting and splicing nickel mold surface reflection effect diagram, wherein L=0.3mm, a=0.01mm, b=0.1mm;

[0052] Figure 11 is the third cutting and splicing nickel mold surface reflection effect diagram, wherein L=0.3mm, a=0.01mm, b=0.075mm;

[0053] Figure 12 is the fourth cutting and splicing nickel mold surface reflection effect diagram, wherein L=0.3mm, a=0.01mm, b=0.06mm.

[0054] In the manufacturing process of micro-prism type reflective film, the splicing quality of the nickel mold directly affects the optical performance of the final product, especially the retroreflective efficiency, which determines the visibility and safety of the reflective film under low light conditions at night. The traditional splicing method often ignores the specific influence of the cutting position on the retroreflective efficiency, resulting in the problem of optical performance decline in the splicing area, which affects the overall uniformity and use effect of the reflective film.

[0055] Compared with the closest prior art, the significant technical advantage of the present application lies in its in-depth exploration and application of the scientific relationship between the cutting position and the retroreflective efficiency. Through precise experiments and data analysis, the present application determines the optimal cutting position range in the 0° and 90° directions, which not only reflects a deep understanding of the characteristics of micro-prism structure, but also demonstrates the advanced concept of significantly improving the splicing quality by slightly adjusting the cutting position while keeping the existing laser welding process unchanged.

[0056] In the 0° direction, by positioning the cutting position at a / 2 outside the 0° cone edge line (a is the width of the laser welding heat damage zone), the effective cone is effectively protected from being directly covered by the welding heat affected zone, thus protecting the key optical structure of the reflective film and ensuring that the retroreflective efficiency is not damaged.

[0057] In the 90° direction, by accurately calculating the value of b (i.e. the distance between the 90° damage edge and the nearest effective cone), the optimal combination and arrangement of effective and ineffective cones in the splicing area is achieved. This design utilizes the principle of optical interference, by adjusting the size and distribution of ineffective cones, maximally reduces the interference of the splicing area to the light reflection path, and improves the overall retroreflective efficiency.

[0058] The method does not need to change the existing laser welding process, only needs to make fine adjustment in the cutting stage, thus is easy to popularize and implement on the existing production line, reduces the cost and risk of technology upgrading. By improving the splicing quality, directly improves the product performance and market competitiveness of the reflective film, and brings significant economic benefits for the enterprise.

[0059] Although the present application has been shown and described with respect to the preferred embodiments, it will be understood by those skilled in the art that various changes in form and detail can be made therein without departing from the spirit and scope of the application as defined in the appended claims.

Claims

1. A method for splicing nickel molds for microprismatic reflective film, characterized in that: The following steps are involved: The first step is to determine the width of the welding damage zone: take a nickel sub-mold that is the same as the nickel sub-mold to be cut and spliced, perform laser welding on the back side, and then check the front side of the welding position to determine the width a of the thermal damage zone caused by laser welding; The second step is to determine the cutting position in the 0° direction: the micro-prismatic cone of the micro-prismatic reflective film is set as a valid cone when it has a complete shape, and as an invalid cone when it has an incomplete shape. The lowest valid cone is set as the 0° cone, and the lowest edge of the 0° cone is set as the 0° edge line. When splicing the nickel mold in the 0° direction, the cutting position is positioned at a distance a / 2 away from the 0° edge line of the 0° cone to avoid the welding damage area affecting the valid cone. The third step is to determine the cutting position in the 90° direction: set the length of the bottom side of the effective angle cone to L, set the distance between the 90° damage edge and the nearest effective angle cone to b, 0<b≤L / 2, when the nickel mold is spliced ​​in the 90° direction, the two sides of the welding area are formed by alternating combinations of effective angle cones with an area greater than 1 / 2 and invalid angle cones with an area less than 1 / 2 of the effective angle cone, where b is the value that maximizes the retroreflection efficiency of the effective angle cone unit and the invalid angle cone unit. When cutting the nickel sub-mold in the 90° direction, set the cutting position at a distance of b+a / 2 from the nearest invalid angle cone corner point to minimize the dark area, thereby improving the retroreflection efficiency of the angle cones in the welding area and improving the uniformity of the overall spliced ​​nickel mold. Step 4: 0° direction cutting and splicing: Install the nickel sub-mold on the fixture of the precision cutting equipment, adjust the mold direction so that the 0° direction of the sub-mold is parallel to the X-axis of the equipment, and then use the 0° edge line of the first row of valid angle pyramids to retain as the reference, and cut the sub-mold along the X-axis at a distance a / 2 away from the 0° edge line. After the cut sub-molds are aligned on the splicing platform, they are welded using precision laser welding equipment; Step 5, 90° cutting and splicing: Install the nickel sub-mold on the fixed fixture of the precision cutting equipment, adjust the mold direction so that the 0° direction of the sub-mold is parallel to the X-axis of the equipment, and then adjust the cutting tool to the optimal cutting position b and cut the sub-mold along the Y-axis. After the cut sub-mold is aligned on the splicing platform, it is welded using precision laser welding equipment.

2. The splicing method according to claim 1, characterized in that: Assuming the retroreflection efficiency of the combination of effective and invalid corner cone units is η, the retroreflection efficiency change formula of the unit combination is:

3. The splicing method according to claim 2, characterized in that: In the third step, when b is one-fourth of the length L of the base of the micro-prism corner cube, the retroreflective efficiency of the effective corner cube unit and the ineffective corner cube unit reaches the maximum.

Images