Combined detachable coating embossing roller and preparation and maintenance method thereof

Abstract

The invention discloses a combined detachable coating embossing roller and a preparation and maintenance method thereof, and belongs to the technical field of embossing roller preparation. The embossing roller comprises a roller base body, a groove array is arranged on the surface of the outer circumference of the roller base body, and an independent coating block is embedded in each groove in an interference fit mode. The coating block is composed of an invar alloy base material with a small thermal expansion coefficient and a wear-resistant coating on the surface of the invar alloy base material, and patterns are carved on the outer surface of the coating. The preparation method comprises the following steps: heating the roller matrix to expand the roller matrix, embedding the roller matrix into the coating block, and cooling to realize interference fixation. The maintenance method comprises the steps of local replacement and overall renovation, wherein during local replacement, a damaged area is locally heated to be matched and loosened, and then a new block is replaced; during overall renovation, the coating blocks can be moved along the roller body for heating, and all the coating blocks are sequentially detached and replaced. Local rapid repairing of the embossing roller and convenient pattern renovation are achieved, the service life of the roller body is prolonged, and the production flexibility is improved.

Description

Technical Field

[0001] This invention relates to a method for preparing an embossing roller, specifically a method for preparing a composite embossing roller with a surface coating. Background Technology

[0002] Embossing rollers are specialized rollers used to press raised and recessed patterns onto the surfaces of materials such as plastic sheets, films, aluminum foil, leather, rigid boards, wallpaper, floor tiles, and glass. They are widely used in the printing of trademarks, stamps, floor patterns, postcards, and cards. Traditionally, roller substrates are made of low-carbon alloy steel or stainless steel. Printed patterns are created on the roller surface using laser engraving, electrical discharge machining (EDM), or chemical etching. Then, chromium or NiP alloy coatings are plated to improve surface hardness and corrosion resistance. However, electroplating is environmentally unfriendly and reduces the clarity of the printed pattern. Other processes use plasma spraying, supersonic flame spraying, or laser cladding to create a thick, wear-resistant coating (≥0.5mm) on the roller surface before engraving the pattern. However, traditional methods directly process the pattern on the roller surface; if there is localized damage, the roller is scrapped, requiring secondary processing to remove the pattern and re-make the roller, resulting in high costs. For small-batch printing, each pattern requires a custom-made embossing roller, leading to significant waste of materials and energy.

[0003] To address the aforementioned issues, several detachable embossing roller solutions have been proposed in the prior art. For example, patent CN206646277U discloses a detachable embossing roller "composed of several unit rollers," with adjacent unit rollers joined by "grooves and corresponding bosses," and detachable "engraved aluminum rings" provided on the surface of the unit rollers to support the patterns. However, the replaceable units in this solution are macroscopic roller segments or ring-shaped components, which cannot independently repair and replace the microscopic local pattern units on the embossed surface, and rely on mechanical structures such as tenons and bolts.

[0004] Another patent, CN115839007A, discloses a nonwoven embossing roller with a "quick-change mechanism." This mechanism uses a "middle embossing plate" and a "side embossing plate" on the outside of the roller body, and utilizes a mechanical locking structure consisting of a "moving cavity," a "push block," a "fixed spring," a "baffle," and the engagement of a "fixed groove" and a "fixed block" to achieve the assembly and disassembly of the embossing plate. Although this solution enables the replacement of plate-shaped components, it relies on an additional mechanical locking mechanism and does not achieve the connection based on the inherent properties of the material itself.

[0005] In summary, while existing detachable solutions have improved the repeatability of the roller body, they have common shortcomings: (1) the replaceable unit is still an integral component (roller segment or embossing plate), which cannot achieve true "local" repair; (2) they all rely on additional mechanical connections or locking mechanisms, rather than using the material's own properties to achieve the connection; (3) they do not utilize the difference in thermal expansion coefficients between the base material and the replacement unit material, thus they cannot achieve high-precision, high-reliability assembly and disassembly that can be completed without complex mechanisms and solely by thermal expansion and contraction.

[0006] Therefore, there is an urgent need for an embossing roller and its preparation method that can achieve independent replacement of surface micro-pattern units, eliminate external mechanical connectors, and make full use of the difference in thermal expansion coefficients of the paired materials to achieve stable interference fit assembly and disassembly. Summary of the Invention

[0007] To overcome the shortcomings of traditional embossing rollers, where partial damage renders the entire roller unusable, and the inconvenience of disassembly and assembly due to the integral mechanical connection of existing detachable embossing roller replacement units, this invention provides a modular detachable coated embossing roller and its preparation and maintenance method. This embossing roller utilizes a structure where independent coated blocks are embedded on the surface of the base roller, and leverages the difference in thermal expansion coefficients between the base roller and the coated block substrate to achieve an interference fit for assembly and disassembly. This allows for independent replacement of local pattern units and recycling of the base roller.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A modular, detachable coated embossing roller includes a roller base, characterized in that multiple square grooves are machined on the outer circumferential surface of the roller base to form a groove array; an independent coated block is fixedly embedded in each groove by an interference fit; the coated block includes a block-shaped substrate made of Invar alloy and a coating covering its outer surface, the outer surface of the coating being engraved with an embossed pattern; wherein the coefficient of thermal expansion of the block-shaped substrate is less than the coefficient of thermal expansion of the roller base.

[0009] Furthermore, the Invar alloys mentioned above include at least 4J36, 4J32 and 4J9 Invar alloys.

[0010] Furthermore, the coating is an alloy coating prepared by laser cladding, plasma cladding, or supersonic flame spraying. Preferably, it is a WC-12Co, Ni60, or Stellite6 alloy.

[0011] Furthermore, the alloy coating thickness is 0.5 mm.

[0012] To obtain the coating with the above-mentioned structure, the present invention provides a method for preparing an embossing roller with a combined detachable coating block, specifically including the following steps: Step 1: Prepare a carbon steel base roller substrate and machine an array of grooves on its outer circumferential surface for embedding coated blocks. The machining dimensional tolerances of the grooves are designed as follows: M is the length or width dimension of the groove; Step 2: Prepare a cylindrical material made of Invar alloy and prepare a functional coating on its outer surface; Step 3: Cut the coated Invar alloy cylinder into individual coated blocks that match the groove dimensions. The dimensions of the coated blocks are consistent with the groove dimensions, and their machining dimensional tolerances are [missing information]. ; Step 4: Heat the roller substrate to expand the groove size by thermal expansion, and embed the coating blocks into the groove one by one. After cooling, fix them by interference fit. Step 5: Engraving embossed patterns on the outer surface of the coated block.

[0013] Further: In step four, a mobile or segmented dynamic heating process can be used for assembly.

[0014] Furthermore, the embossed pattern engraving is obtained using laser engraving.

[0015] Further: In the fourth step, the temperature at which the roller substrate is heated is 100°C to 200°C. At this temperature, the thermal expansion of the carbon steel substrate is sufficient to expand the groove size to be larger than the coating block size, which facilitates embedding.

[0016] Further details: The roller diameter is 300-1500mm, the length is 800-3000mm, and the groove size is adapted to the printed pattern. For example, when printing a trademark, the pattern size ranges from 50×50mm to 100×100mm.

[0017] The modular, detachable coated embossing roller of this invention is easy to maintain and refurbish, mainly divided into two situations: partial coating block replacement and overall pattern refurbishment: wherein: (a) The method for replacing local coating blocks is: (1) Locally heat the area on the roller substrate corresponding to the coating block to be replaced; (2) When the temperature of the area reaches the preset value and the interference fit is loose enough, stop heating; then take out the loosened coating block to be replaced by utilizing the local thermal expansion effect of the roller substrate, and embed the new coating block into the corresponding groove. (3) After the roller substrate cools and shrinks, the new coating block is fixed by interference fit; then, according to the requirements, the corresponding embossed pattern is laser engraved on the surface of the newly replaced coating block to maintain the consistency of the roller surface pattern. (ii) The overall pattern renovation method is (1) Heat the roller substrate to release the interference fit between all the coated blocks and the grooves, and remove all the old coated blocks; (2) Prepare and assemble a batch of new coated blocks that meet the requirements of the new pattern; (3) Laser engrave new patterns on the surface of the newly assembled coating block to complete the renovation.

[0018] Furthermore, when renovating the overall pattern, step (1) is achieved in the following way: Induction heating coils are used for localized heating along the axial direction of the roller substrate, that is, heating is performed sequentially from one end to the other. By utilizing the difference in thermal expansion coefficients between the roller substrate and the coating block, the local area scanned by the induction heating coil expands, causing the interference fit of the coating block in that area to loosen immediately. After the induction heating coil moves past, the loosened coating block in that area can be removed and replaced. This continuous operation of moving heating followed by disassembly is repeated until all coating blocks are removed and replaced in sequence.

[0019] Compared with the prior art, the positive effects of the present invention are as follows: (1) A combined coating embossing roller was invented. The coating blocks can be processed and installed separately, replacing the traditional method of preparing and processing the roller surface coating as a whole. This enables flexible replacement of coating blocks with defects or damage on some surfaces, avoiding the problem of needing to replace the entire roller due to damage to a single coating block. It achieves local rapid repair and significantly improves the life of the roller.

[0020] (2) A novel method for preparing a combined coated embossing roller has been invented. The production of the base roller, the preparation of the coating block and the pattern engraving can be carried out separately. The finished embossing roller is obtained by combining the methods, which solves the problem that the traditional method requires the base roller to be prepared first, then the coating to be prepared, and then the pattern to be engraved as a whole. This not only improves production efficiency, but also increases the freedom of production process.

[0021] (3) The coating preparation process of this combined coated embossing roller can be laser cladding technology, plasma cladding technology, supersonic flame spraying technology, etc. Compared with the traditional electroplating process for preparing roller surface coating, the coating material and coating preparation process have a wide range of choices. The coating performance can be optimized according to production needs, and the service life of the embossing roller can be extended.

[0022] (4) When the printed pattern changes, the base roller can be recycled by replacing some or all of the coating blocks, which reduces the waste of materials, labor and energy in the production process. Users can also reserve standardized coating blocks with various patterns in advance. When it is necessary to switch products or repair the roller, the pattern can be changed or the part can be repaired in a very short time, which greatly improves the flexibility of the production line.

[0023] (5) This combined coated embossing roller uses Invar alloy as the substrate for the coating block, which has a small coefficient of thermal expansion. By heating the surface of the embossing roller and utilizing the difference in the coefficients of thermal expansion between the roller substrate and the coating block material, a firm interference fit installation and non-destructive disassembly of the coating block can be achieved through simple heating and cooling operations. This solves the problem of rapid repair of locally damaged embossing rollers and the problem of rapid replacement of printed patterns on the surface of the embossing roller, and provides strong operational controllability. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. The accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the base roller structure of the embossing roller.

[0026] Figure 2 This is a schematic diagram of the structure after the groove is machined on the roller surface; where 2a is the front view and 2b is the side view.

[0027] Figure 3 yes Figure 2 A schematic diagram of the BB cross-section of the central groove.

[0028] Figure 4 This is a schematic diagram of an Invar alloy cylinder with a coating; where 4a is a side view and 4b is a front view.

[0029] Figure 5 This is a schematic diagram of the coated block after processing.

[0030] Figure 6 This is a schematic diagram of the assembled combined coating embossing roller structure.

[0031] Figure 7 yes Figure 6 A schematic diagram of the AA cross-section.

[0032] In the diagram: 1-base roller, 2-groove, 3-coated block cylinder, 4-coating, 5-interference fit. Detailed Implementation

[0033] The technical solution of the present invention will now be clearly and completely described in conjunction with the accompanying drawings and several embodiments. Example 1

[0034] (1) Q235 carbon steel is selected as the base roller material for the embossing roller, and the preparation is as follows: Figure 1The base roller 1 is shown. The roller surface length of base roller 1 is 1200mm, the diameter (smooth roller diameter) is φ372mm, and the roller wall thickness is 25mm. The outer surface of the roller is machined to a surface roughness Ra0.8μm to ensure the geometric accuracy and surface quality of the base roller.

[0035] (2) Based on the printing requirements of the pattern, design an array of coating blocks on the roller surface. Use a precision CNC milling machine to process the coating blocks on the surface of the base roller 1. Figure 2 The square groove array shown has grooves 2 symmetrically distributed along the center of the roller surface, evenly distributed across the entire roller surface. The distance between the grooves is 12mm, and the roller surface is designed with 22×22 grooves. The cross-sectional shape of groove 2 is as follows. Figure 3 As shown, its depth h is set to 10mm, consistent with the substrate thickness of the subsequent coating block. The dimensions of the four sides of the groove are all... mm (meaning 40.99-41) should be slightly smaller than the design size of the coating block to ensure that the assembly conditions for an interference fit are formed at room temperature.

[0036] (3) A 4J36 Invar alloy cylinder with a wall thickness of 15mm was selected as the base material for the coating block cylinder 3. The outer diameter of the coating block cylinder 3 was machined to φ372mm, consistent with the outer diameter of the base roller. First, the outer surface of the cylinder was roughened by sandblasting with 20-40 mesh quartz sand to enhance the coating adhesion and remove oil and oxide layers. Then, WC-12Co alloy coating 4 was sprayed on the outer surface of the cylinder using a supersonic flame spraying process. The thickness of coating 4 after spraying was about 0.55mm. Spraying process parameters: powder particle size 15-45μm, spraying distance 390mm, kerosene flow rate 26 L / h, oxygen flow rate 900 L / min, argon flow rate 8.3L / min, powder feeding rate 75g / min. Subsequently, the coating surface was precision ground to obtain a uniform coating with a thickness of 0.5mm and a surface roughness of Ra0.8μm. The structural schematic diagram of the processed coating block cylinder 3 is shown below. Figure 4 As shown.

[0037] (4) The coated Invar alloy cylinder is cut into square blocks of the designed dimensions along the axial and circumferential directions using wire cutting equipment. Then, the four sides and bottom of each block are precision machined using a precision machine tool, ensuring that each surface is planar and perpendicular to each other. The processed square coated blocks are shown below. Figure 5 As shown, the dimensions of its four sides are all mm (meaning 41-41.01mm), slightly larger than or equal to the corresponding size of the groove on the base roller surface, with the Invar alloy substrate thickness being 10mm, perfectly matching the groove depth.

[0038] (5) Place the base roller with the processed groove array in the induction heating coil to heat the base roller as a whole. When the temperature of the base roller rises uniformly to 150℃, the groove size will increase slightly due to the thermal expansion of the carbon steel material. At this time, remove the base roller and immediately press the coating blocks one by one while the groove size is still larger than the coating block during the cooling process (it can be reduced from 150℃ to about 100℃ in 1-1.5 hours). After all the coating blocks are installed, let the base roller cool naturally to room temperature in the air. During the cooling process, take advantage of the large thermal expansion coefficient of the carbon steel base roller and the small thermal expansion coefficient of the Invar alloy coating block to form a firm interference fit 5 between the coating block and the groove, and realize mechanical locking. The schematic diagram of the overall roller structure after assembly is shown below. Figure 6 As shown, a partial cross-section is visible. Figure 7 As shown.

[0039] In the preparation of the printing roller, the coating block assembly can also adopt a dynamic heating process: that is, the base roller is heated in a moving or segmented manner. Specifically, the induction heating coil is moved along the axial direction of the base roller, and the coating block is embedded and installed immediately behind the coil (in the heated area); or a segmented method can be adopted, completing the heating and installation of one segment before proceeding to the next segment.

[0040] (6) Using laser engraving equipment, the required embossing pattern is engraved on the outer surface of each pre-embedded and fixed coated block. For example, anti-counterfeiting marks or trademark patterns can be made. After the engraving is completed, a complete embossing roller with modular and detachable coated blocks is obtained.

[0041] (7) Maintenance and replacement operations: Partial Replacement: When individual coated blocks of the embossing roller become damaged during use, heat the corresponding area of ​​the base roller to 150°C. After the area expands due to heat, the damaged coated block can be removed with a tool. Then, a pre-made, intact coated block is inserted, and after cooling, it is fixed in place. If a consistent pattern is required, the same pattern can be laser-engraved on the new block.

[0042] Overall refurbishment: When it is necessary to replace all the patterns, an induction heating coil is used to heat from one end to the other. After the induction heating coil has passed, the heated coating block can be removed and replaced. After all the coating blocks have been replaced, a clean, grooved base roller is obtained. Thereafter, according to the requirements of the new pattern, steps (3) to (6) can be repeated to prepare new coating blocks and complete assembly and engraving, so as to realize the recycling of the base roller.

[0043] Of course, to alleviate stress concentration and facilitate assembly, all internal corners of the groove (i.e., the four bottom corners of the sidewall and the bottom surface, and the four top corners of the sidewall and the roller surface) should be designed as rounded corners. Correspondingly, the outer edges of the bottom surface of the coating block are machined into rounded corners that match the bottom corners of the groove, and the outer edge of its top surface is chamfered to facilitate insertion and smooth fit with the rounded corners of the top corners of the groove, while maintaining the same assembly tolerance. Example 2

[0044] The main difference between Example 2 and Example 1 lies in the coating material and preparation process; the other steps are the same.

[0045] In step (3), the substrate for the coating block is still a 4J36 Invar alloy cylinder, and the surface pretreatment is changed to grinding and polishing with a grinding wheel to thoroughly remove surface deposits and rust layers. Then, a Ni60 nickel-based alloy coating is clad onto the cylinder surface using a laser cladding process. The coating thickness after laser cladding is approximately 0.65 mm. After precision grinding, the final coating thickness is 0.5 mm, and the surface roughness reaches Ra0.8 μm. Laser cladding process parameters: powder feeding rate 20 g / min, laser power 2200 W, cladding speed 540 mm / min, spot diameter 3.5 mm, argon flow rate 25 L / min, cladding distance 15 mm, overlap rate 50%.

[0046] The subsequent cutting, assembly, carving, and maintenance methods are exactly the same as in Example 1. Example 3

[0047] The main difference between Example 3 and Example 1 lies in the substrate material, coating material, and preparation process of the coated block; the other steps are the same.

[0048] In step (3), the substrate of the coating block was replaced with 4J32, and the coating material was replaced with Stellite6 alloy. Surface deposits and rust were removed by grinding and polishing with a grinding wheel. Then, a Stellite6 alloy coating was prepared using plasma cladding. The coating thickness was 0.65 mm, and after precision grinding and polishing, the coating thickness was 0.5 mm, with a surface roughness of Ra 0.8 μm. Plasma cladding parameters: cladding current 100 A, center gas flow rate (Ar) 3.5 L / min, protective gas flow rate (Ar) 10 L / min, powder feed gas flow rate (Ar) 4.5 L / min, gun distance 15 mm, powder feed rate 15 g / min, scanning speed 60 mm / min, and overlap rate 40%.

[0049] The subsequent cutting, assembly, carving, and maintenance methods are exactly the same as in Example 1.

[0050] It should be noted that the specific embodiments described above are only used to explain the technical solution of the present invention, and are not intended to limit it. Any readily conceivable substitutions or modifications made by those skilled in the art, based on the technical principles and core concept disclosed in this invention (i.e., achieving a detachable interference fit without external connectors by utilizing the difference in the thermal expansion coefficients of materials), regarding the array arrangement of the grooves, specific dimensions, interference amount, coating process parameters, and the specific form of the fillets or chamfers, should be included within the scope of protection of this invention. The scope of protection of this invention should be determined by the claims.

Claims

1. A modular, detachable coated embossing roller, comprising a roller substrate, characterized in that, Multiple square grooves are machined on the outer circumferential surface of the roller substrate to form a groove array; an independent coating block is fixed in each groove by interference fit; the coating block includes a block substrate made of Invar alloy and a coating covering its outer surface, and the outer surface of the coating is engraved with an embossed pattern; wherein, the coefficient of thermal expansion of the block substrate is less than the coefficient of thermal expansion of the roller substrate.

2. The combined detachable coated embossing roller as described in claim 1, characterized in that, The Invar alloys mentioned above include at least 4J36, 4J32 and 4J9 Invar alloys.

3. The combined detachable coated embossing roller as described in claim 1, characterized in that, The coating is an alloy coating prepared by laser cladding, plasma cladding or supersonic flame spraying process.

4. The combined detachable coated embossing roller as described in claim 1, characterized in that, The alloy coating has a thickness of 0.5 mm.

5. A method for preparing a combined detachable coated embossing roller as described in any one of claims 1-4, characterized in that, Specifically, the following steps are included: Step 1: Prepare a carbon steel base roller substrate and machine an array of grooves on its outer circumferential surface for embedding coated blocks. The machining dimensional tolerances of the grooves are designed as follows: M is the length or width dimension of the groove; Step 2: Prepare a cylindrical material made of Invar alloy and prepare a functional coating on its outer surface; Step 3: Cut the coated Invar alloy cylinder into individual coated blocks that match the groove dimensions. The dimensions of the coated blocks are consistent with the groove dimensions, and their machining dimensional tolerances are [missing information]. ; Step 4: Heat the roller substrate to expand the groove size by thermal expansion, and embed the coating blocks into the groove one by one. After cooling, fix them by interference fit. Step 5: Engraving embossed patterns on the outer surface of the coated block.

6. The method for preparing the combined detachable coated embossing roller as described in claim 5, characterized in that, In step four, a moving or segmented dynamic heating process is used for assembly.

7. The method for preparing the combined detachable coated embossing roller as described in claim 5, characterized in that, In step four, the temperature at which the roller substrate is heated is 100°C to 200°C.

8. The method for preparing the combined detachable coated embossing roller as described in claim 5, characterized in that, The embossed pattern is obtained using laser engraving.

9. A maintenance method for a combined detachable coated embossing roller as described in any one of claims 1-4, characterized in that, It includes partial coating block replacement and overall pattern renovation: Among them: (a) The method for replacing local coating blocks is: (1) Locally heat the area on the roller substrate corresponding to the coating block to be replaced; (2) When the temperature of the area reaches the preset value and the interference fit is loose enough, stop heating; then take out the loosened coating block to be replaced by utilizing the local thermal expansion effect of the roller substrate, and embed the new coating block into the corresponding groove. (3) After the roller substrate cools and shrinks, the new coating block is fixed by interference fit; then, according to the requirements, the corresponding embossed pattern is laser engraved on the surface of the newly replaced coating block; (ii) The overall pattern renovation method is (1) Heat the roller substrate to release the interference fit between all the coated blocks and the grooves, and remove all the old coated blocks; (2) Prepare and assemble a batch of new coated blocks that meet the requirements of the new pattern; (3) Laser engrave new patterns on the surface of the newly assembled coating block to complete the renovation.

10. The maintenance method for the combined detachable coated embossing roller as described in claim 9, characterized in that, When the overall pattern is refurbished, step (1) is achieved by: using an induction heating coil to scan and heat the roller substrate from one end to the other along the axial direction; using the difference in thermal expansion coefficients to loosen the interference fit of the coating blocks in the scanned area immediately; after the induction heating coil has passed, immediately remove the loosened coating blocks in that area; repeat this process until all coating blocks are removed in sequence.

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