A method for precisely thickening the inner coating of a shell-shaped diamond roller and a diamond roller

Abstract

The present application belongs to the technical field of electroplating process, and particularly relates to a method for precisely thickening the inner plating of a shell-shaped diamond roller and the diamond roller. The method is to place the sand-coated negative mold in the plating solution of an electroplating tank, place the anode at the center of the negative mold, and use a pulse power source for electroplating. During electroplating, the positive duty cycle and the negative duty cycle of the pulse power source are gradually adjusted. In the initial stage of electroplating, the positive duty cycle is above 70%. As the electroplating proceeds, the positive duty cycle is gradually reduced, and the negative duty cycle is gradually increased. The present application gradually adjusts the positive duty cycle and the negative duty cycle as the electroplating process proceeds. In the initial stage of electroplating, the difference between the positive duty cycle and the negative duty cycle is large, which ensures the basic deposition efficiency and appropriately increases the negative duty cycle, effectively eliminates the tip effect, and realizes uniform thickening of the plating layer. By using the above-mentioned pulse power source electroplating method, the plating layer thickness of the mouth end and the tank bottom can be effectively balanced, and the plating layer uniformity TP value tends to 1.

Description

Technical Field

[0001] This invention belongs to the field of electroplating technology, specifically relating to a method for precise thickening of the inner plating of a shell-shaped diamond roller and the diamond roller itself. Background Technology

[0002] In precision form grinding, traditional diamond dressing rollers generally suffer from insufficient contour replication accuracy and poor stability of the formed protrusions on asymmetric deep grooves, gradually curved surfaces, and complex transition contours, making it difficult to meet the high-precision, high-consistency machining requirements of high-end equipment manufacturing for complex surfaces. Shell-shaped diamond rollers, with a continuous smooth curved surface whose width gradually narrows from the inside out, exhibiting an overall shell-like gradient contour, can accurately replicate complex curved surfaces and single-slant deep grooves, making them a key dressing tool for achieving high-precision form grinding. These rollers are widely used in gear grinding, thread grinding, and form grinding machines, and are core equipment for achieving batch and efficient grinding of automotive gears, aerospace blades, precision cutting tools, and other components. They can improve the cutting performance and service life of grinding wheels, reduce downtime for dressing, and increase processing efficiency.

[0003] Shell-shaped rollers are generally produced using an internal plating method to ensure precision after molding. The internal plating method involves using a temporary female mold to electroplate the inner surface of the cavity, and then removing the female mold to expose the electroplated surface. This reference surface becomes the outer surface of the roller after the female mold is removed, which is also the working surface of the roller.

[0004] Chinese invention patent CN108044531B, with authorization announcement date of August 27, 2019, discloses a method for manufacturing diamond rollers for multi-process combined grinding. The method includes: 1) machining a female mold surface on the inner cavity surface of a female mold using a template tool; 2) applying sand to the female mold with the machined female mold surface; 3) electroplating the female mold after the sanding process; 4) assembling the female mold after the electroplating process with a mandrel, and pouring a low-melting-point alloy between the female mold and the mandrel to make the female mold, the low-melting-point alloy and the mandrel a single unit; and 5) performing a peeling process to obtain the diamond roller.

[0005] The key feature of diamond rollers is their ability to precisely control the cutting edge height, ensuring accurate forming. Achieving consistent cutting edge height relies on a thickening electroplating process to guarantee uniform plating. In reality, female molds often have deep groove structures (i.e., recessed areas). Due to the deep groove structure and the tip effect, the current density distribution at the edge of the female mold and the bottom of the groove is uneven. This leads to concentrated electric field lines at the opening, often resulting in premature thickening at the opening and premature sealing. Meanwhile, the plating at the bottom of the groove is too thin, causing production failures.

[0006] The harm of uneven coating is that the deep groove after peeling is the convex part during operation. During grinding, this part is subjected to great force and concentrated grinding load. If the abrasive embedment rate is insufficient and the coating uniformity is poor, it is very easy to cause product quality fluctuations and large service life dispersion, which seriously affects the reliability of processing.

[0007] Traditional electroplating thickening methods cannot solve the problem of uneven plating in deep tank areas. In addition, the roller diameter is small and the internal space is narrow, making it difficult for the shaped anode to play its role. The bottom of the tank cannot reach the designed thickness within the specified time. It usually requires special tooling, pulse power supply and precise material replenishment system, and the process control requirements are extremely high.

[0008] Chinese invention patent CN103603019B, with an authorization announcement date of July 6, 2016, discloses an electroplating method for diamond roller coating using a pulsed power supply. The electroplating method includes the following steps: immersing a sand-coated negative mold into the plating solution; adjusting the power supply to DC output mode and regulating the current output, setting the current density to 0.65~1 A / dm²; turning on the power supply and electroplating for 1~2 weeks; until the electroplating operation is completed, disconnecting the DC power supply, with the coating thickness reaching 0.3~0.6 mm; adjusting the power supply to pulsed output mode and regulating the current output, setting the current density to 1~2.5 A / dm², the pulse frequency to 1000 Hz, and the duty cycle to 25%~50%; turning on the power supply and electroplating for 3~4 weeks; until the electroplating operation is completed, disconnecting the pulsed power supply, with the coating thickness reaching 1.5~2.5 mm; and removing the coated negative mold from the plating solution. This method combines DC power and pulse power. The DC power is used to coat the diamond particles, while the non-continuous nature of the pulse power makes the coating crystallize finely and evenly, and can reduce the internal stress of the coating, thereby improving the dimensional accuracy of the coating surface.

[0009] Although the aforementioned prior art uses a pulse power supply during diamond roller electroplating, it employs a fixed duty cycle. While the uniformity of the resulting coating is improved compared to that of a DC power supply, there is still considerable room for improvement. Summary of the Invention

[0010] The first objective of this invention is to provide a method for precise thickening of the inner plating layer of a shell-shaped diamond roller, in order to solve the problem that the uniformity of the plating layer at the bottom and opening of the deep groove needs to be improved when electroplating workpieces with deep grooves.

[0011] The second objective of this invention is to provide a diamond roller manufactured by the above-mentioned method of precise thickening of the inner plating of the shell-shaped diamond roller, so as to solve the problem of poor consistency of the cutting edge height of existing diamond rollers.

[0012] To solve the above problems, the technical solution adopted by the present invention is as follows: A method for precise thickening of the inner plating of a shell-shaped diamond roller involves placing a sand-coated female mold in the plating solution of an electroplating tank, with the anode placed at the center of the female mold, and electroplating performed using a pulse power supply. During electroplating, the positive and negative duty cycles of the pulse power supply are gradually adjusted. In the initial stage of electroplating, the positive duty cycle is above 70%, and as electroplating progresses, the positive duty cycle is gradually reduced while the negative duty cycle is increased.

[0013] This invention is an improved invention. The positive and negative duty cycles are gradually adjusted during the electroplating process. Initially, the difference between the positive and negative duty cycles is large to ensure basic deposition efficiency. Subsequently, the negative duty cycle is appropriately increased to effectively eliminate the tip effect and achieve uniform coating thickness. Using the aforementioned pulse power electroplating method, the coating thickness at the tip and bottom of the tank can be effectively balanced, making the coating uniformity (TP) value infinitely close to 1.

[0014] Preferably, electroplating is divided into a pre-plating stage and a post-plating stage. In the pre-plating stage, the positive duty cycle is 70-80%, and the negative duty cycle is 10-15%. In the post-plating stage, the positive duty cycle is 50-60%, and the negative duty cycle is 22-30%. The pre-plating stage accounts for 30-40% of the total electroplating time. A slightly larger duty cycle in the pre-plating stage is beneficial for the deposition of the nickel layer. At the same time, the lower current density in the pre-plating stage minimizes the tip effect and has a limited impact on the uniformity of the electroplated layer. This configuration balances electroplating efficiency and quality, effectively ensuring plating speed while significantly improving the uniformity of the plating layer.

[0015] More preferably, during the initial stage of electroplating, the forward current density is 0.1~0.5 A / dm³. 2 The negative current density is 0.01~0.08 A / dm³. 2 During the later stages of electroplating, the forward current density is 0.5~0.9 A / dm³. 2 The negative current density is 0.08~0.18 A / dm². 2 .

[0016] More preferably, the pre-plating stage is divided into a first stage and a second stage, and the post-plating stage is divided into a third stage and a fourth stage: the positive duty cycle of the first stage is 80±2%, and the negative duty cycle is 10±2%; the positive duty cycle of the second stage is 70±2%, and the negative duty cycle is 15±2%; the positive duty cycle of the third stage is 60±2%, and the negative duty cycle is 22±2%; the positive duty cycle of the fourth stage is 50±2%, and the negative duty cycle is 30±2%. The first, second, and third stages account for 10±2%, 20±2%, and 40±2% of the total plating time, respectively; the frequency of the pulse power supply is 1000Hz. Through the meticulous design of the above four-stage electroplating, the process has good adaptability to various working conditions, and the stability of the electroplating process is significantly improved.

[0017] More preferably, the forward current density in the first stage is 0.1~0.2 A / dm. 2 The negative current density is 0.01~0.02 A / dm. 2 The forward current density in the second stage is 0.4~0.45 A / dm³. 2 The negative current density is 0.06~0.08 A / dm³. 2 The forward current density in the third stage is 0.5~0.6 A / dm³. 2 The negative current density is 0.08~0.1 A / dm³. 2 The forward current density in the fourth stage is 0.8~0.85 A / dm³. 2 The negative current density is 0.16~0.18 A / dm³. 2 .

[0018] Preferably, by optimizing the composition of the plating solution, the uniformity of the coating can be improved, and the hardness, wear resistance and internal stress of the coating can be synergistically optimized. That is, optimizing the composition of the plating solution to improve the uniformity of the coating, the plating solution used consists of the following components: nickel sulfamate 400-450 g / L, cobalt sulfamate 15-20 g / L, MnBr2 10-15 g / L, H3BO3 35-45 g / L, sodium 2,7-naphthalenedisulfonate 0.007-0.012 g / L, sodium hydroxypropyl thiosulfate 0.01-0.05 g / L, water as solvent, pH 3.5-4.0; the electroplating temperature is 35~40℃.

[0019] In conventional electroplating, the plating solution in the plating tank is circulated externally, which can improve the uniformity of the plating solution composition to some extent. However, for molds with deep tanks, the plating solution has poor fluidity, and the uniformity of the plating solution composition cannot be guaranteed. Preferably, during internal plating, plating solution is continuously introduced into the groove of the mold, enhancing the replacement and renewal of the plating solution at the bottom of the groove. This method ensures that the plating solution continuously flushes the bottom of the tank and rapidly replaces and renews the plating solution, thus guaranteeing the consistency and stability of the electroplating thickness.

[0020] More preferably, the anode comprises a titanium basket filled with nickel balls as the anode material; the titanium basket is provided with a multi-channel distribution structure to continuously supply plating solution to the groove position. The multi-channel distribution structure includes a main pipe coaxially arranged with the titanium basket, and the lower outlet of the main pipe is connected to a set of branch pipes arranged in different radial directions along the titanium basket. After entering the main pipe, the plating solution flows to the corresponding groove position along each branch pipe. Using a titanium basket anode form results in a simple structure that is easy to implement.

[0021] More preferably, during electroplating, the titanium basket adopts an alternating forward and reverse rotation mode. This alternating forward and reverse rotation mode further improves the uniformity of the plating solution renewal at the bottom of the tank.

[0022] A diamond roller manufactured using the aforementioned method of precise thickening of the inner plating of a shell-shaped diamond roller.

[0023] After the electroplating of the negative mold is thickened after sanding, the core is combined and the shell is peeled off using conventional methods. Because the uniformity of the plating at the bottom and opening of the deep groove is well controlled, the diamond cutting edge height of the formed working surface is consistent and the contour accuracy is well controlled, thereby improving the processing performance of the diamond roller with high precision and high consistency.

[0024] Compared with the prior art, the present invention achieves the following beneficial effects: 1. High coating uniformity By combining the plating solution composition, deep-tank plating solution circulation, and pulsed power supply, edge and tip effects are effectively suppressed. The uniformity of the thickened coating achieved by the shell-shaped diamond roller can reach over 95%, with consistent thickness distribution and no defects such as scorching, roughness, or localized excessive or insufficient thickness. The flushing-type trench plating solution circulation design not only ensures the circulation of the plating solution but also gradually increases the entry of the leveling agent in the plating solution, further enhancing the thickening effect.

[0025] 2. High contour accuracy The coating deposition process is stable and controllable, and the profile accuracy of the roller forming surface can be controlled within 0.008 mm, meeting the size and profile requirements of high-precision grinding and dressing tools.

[0026] The application of pulse electroplating technology, by controlling the current density in stages, controls the difference in coating thickness between the port and the bottom of the tank, so that the nickel-cobalt-manganese coating can be deposited more evenly on the grinding wheel substrate, thereby improving the wear resistance and service life of the grinding wheel.

[0027] 3. Excellent coating performance The nickel-cobalt-manganese ternary alloy coating has fine grains, a dense structure, high hardness, good wear resistance, and low internal stress. It exhibits high bonding strength with the substrate (temporary negative mold) and diamond, significantly improving the diamond embedding rate and enhancing the overall service life and structural reliability of the roller. The negative mold substrate is made of aluminum alloy, which facilitates electroplating and improves the structural reliability of the electroplated diamond coating. Aluminum alloys with Al, Cu, Mg, and Pb as their main components can be selected.

[0028] 4. Improved product stability and lifespan The coating thickness and performance in key stress areas such as the bottom of the tank are reliably guaranteed, the product batch consistency is good, the service life is significantly improved compared with traditional processes, and the grinding precision is better maintained.

[0029] 5. The equipment operates stably and reliably. The anode operates alternately in both forward and reverse directions to avoid wire tangling. The motor and rotating system have high concentricity and run smoothly, which can meet the requirements of long-term continuous production, and has high safety and production efficiency.

[0030] 6. The plating solution is stable and has a long service life. Bromine ions in the plating solution effectively improve the anode dissolution state, reduce passivation and anode sludge contamination. Combined with circulating filtration and precise temperature control, the plating solution has stable composition, long maintenance cycle, and high utilization rate, which helps reduce production costs. The minimal fluctuation of the main components results in less hydrogen analysis at the tip; fewer pinholes in the grooves lead to less hydroxide formation, making the plating solution more stable. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of a diamond roller female mold; Figure 2 for Figure 1 A cross-sectional view; Figure 3 This is a schematic diagram of the structure of the titanium basket anode; Figure 4 A schematic diagram of the titanium basket anode from another perspective; Figure 5 A schematic diagram of the titanium basket anode and cathode assembly; Figure 6 for Figure 5 A schematic diagram showing the combination of the central female mold and the titanium basket anode after the mold has been cut open. Figure 7 This is a schematic diagram of the electroplating apparatus. Among them, 1-roller female mold; 2-deep tank; 3-titanium basket; 4-titanium basket support frame; 5-motor interface; 6-main pipe; 7-branch pipe; 8-electroplating tank; 9-first circulation pipe; 10-electroplating solution external circulation pump; 11-titanium basket anode; 12-second circulation pipe; 13-variable frequency circulation pump; 14-workpiece support; 15-variable frequency rotary motor; 16-pulse power supply; 17-temperature control system. Detailed Implementation

[0032] (I) The method for precise thickening of the inner plating of the shell-shaped diamond roller of the present invention and the preferred embodiment of the diamond roller. Existing internal plating thickening processes mostly employ DC power supplies with a constant duty cycle in pulsed power sources. Experimental results show that this approach cannot effectively improve the uniformity of the plating thickness. This invention proposes a plating strategy that gradually changes the positive and negative duty cycles of the pulsed power supply. Based on the characteristics of deep-tank plating, it adjusts the plating distribution at the opening and bottom of the deep tank at different stages of plating, making the plating at the opening and bottom of the tank more consistent and minimizing thickness deviation. This effectively solves the problems of uneven plating and inconsistent lifespan in existing processes, meeting the needs of large-scale manufacturing of high-precision shell-shaped diamond rollers.

[0033] Generally speaking, the depth of the deep groove ranges from 6 to 20 mm, the maximum width of the deep groove opening reaches 8 mm, and the minimum width reaches 5 mm; the depth-to-width ratio of the groove is controlled at (2~3):1; and rounded corners are set at both the groove opening and the bottom of the groove.

[0034] This invention improves the uneven diamond embedding rate of the shell-shaped diamond roller groove by more than 90% compared with the same period last year by further synergistic plating solution composition and deep tank plating solution circulation, and controls the contour accuracy within ±0.008mm, thus achieving high-quality thickening in the electroplating process.

[0035] The working principles of the three core elements of this invention—the plating solution system, the plating solution circulation device in the deep tank, and the pulse power supply—are explained in detail below.

[0036] (1) Plating solution system The plating solution system of this invention comprises: nickel sulfamate 400-450 g / L, cobalt sulfamate 15-20 g / L, MnBr2 10-15 g / L, H3BO3 35-45 g / L, sodium 2,7-naphthalenedisulfonate 0.007-0.012 g / L, sodium hydroxypropyl thiosulfate 0.01-0.05 g / L, with water as the solvent and a pH of 3.5-4.0. The plating solution temperature is 35-40℃. During preparation, the components are uniformly dispersed in water to form a uniformly dispersed plating solution. Due to potential deviations in the properties of the water source and raw materials, a pH adjuster can be used to adjust the pH to meet the requirements after the raw materials are prepared. If the pH of the plating solution is too high, it can be adjusted using acidic substances such as sulfamate; if the pH of the plating solution is too low, it can be adjusted using alkaline substances such as nickel hydroxide.

[0037] In the formulation, sodium hydroxypropyl thiosulfate acts as a leveling agent, inhibiting the excessively rapid deposition of metal ions in high-current regions and directing more current to low-current recessed and planar areas. This fundamentally balances the coating thickness and ensures uniform nickel-cobalt-manganese co-deposition at the bottom of the deep plating tank. Sodium 2,7-naphthalenedisulfonate acts as a highly efficient leveling agent, accelerating crystal nucleation, inhibiting abnormal grain growth, refining coating grains, and forming a dense and smooth coating structure. Manganese bromide is the core functional component. On one hand, bromide ions promote normal dissolution of the nickel anode, eliminate anode passivation, stabilize the nickel ion concentration in the plating solution, and extend the service life of the plating solution. On the other hand, it can be adsorbed on the cathode surface, reconstructing the double-layer structure, enhancing cathode polarization, making the metal ion reduction process more stable, and avoiding coating roughness and scorching defects. Simultaneously, manganese, as a core component of the ternary alloy, can regulate the nickel-cobalt co-deposition ratio and optimize coating hardness, wear resistance, and internal stress performance. Boric acid acts as a pH buffer, maintaining the acid-base stability of the plating solution system and reducing fluctuations in electroplating process parameters.

[0038] (2) Plating solution circulation device in deep tank section To better illustrate the working process of the present invention, Figure 1 Taking the schematic diagram of the female mold as an example, its cross-sectional view is as follows: Figure 2 As shown, the roller female mold 1 has a deep groove 2, which needs to be thickened by electroplating in the deep groove 2 area, while other non-electroplated parts can be insulated.

[0039] Figure 3 and Figure 4 In this process, the rotatable titanium basket anode is placed at the center of the female mold during electroplating. The rotatable titanium basket anode includes a titanium basket 3, which is connected to a rotary motor via a titanium basket support frame 4. The titanium basket support frame 4 includes a connecting column coaxially arranged with the titanium basket, a motor interface 5 at the upper end of the connecting column, and three evenly distributed support bars at the lower end connecting the titanium basket 3.

[0040] A schematic diagram of the structure after the female mold and titanium basket anode assembly is shown below. Figure 5 and Figure 6 As shown. The anode rotation mechanism uses an adjustable-speed rotary motor and a dedicated gearbox, allowing for continuous speed adjustment within the range of 0~50 rpm. Each motor undergoes rigorous centering calibration before installation to ensure concentricity and smooth, unbiased operation. A titanium basket 3 is fixedly mounted at the lower end of the electrode rotation rod. The basket has a diameter of 30 mm and a height of 78 mm, and is filled with nickel balls as the anode material. The preferred rotation speed is 20~40 rpm, and more preferably 25~35 rpm.

[0041] A four-way distribution structure is installed on the titanium basket 3, with one main pipe 6 extending deep into the titanium basket. Three equally spaced branch pipes 7 are symmetrically arranged at the bottom of the main pipe 6. The ends of the branch pipes 7 extend at least 2 cm from the titanium basket wall, and the outlets are precisely aligned with the deep groove position of the diamond roller mold 1, ensuring rapid replacement and renewal of the plating solution at the bottom of the groove. The main pipe 6 of the four-way distribution structure is fixedly connected to a circulation pump. The circulation pump is frequency-controlled, with a power of 5kW and stepless flow rate adjustment. The flushing flow rate to the deep groove position can be controlled at 0.6~1.3L / min.

[0042] As the titanium basket rotates, the three liquid outlets rotate synchronously, continuously ensuring the rinsing effect of the plating solution and the replacement efficiency within the tank. To achieve uniform spraying of the plating solution at the bottom of the tank and to avoid tangling of the motor wires, the titanium basket adopts an alternating forward and reverse rotation mode, rotating three times clockwise and then three times counterclockwise, repeating the cycle to ensure electroplating quality and equipment operation safety.

[0043] During electroplating, the roller negative mold 1 is placed entirely in the plating solution of the electroplating tank. In addition to circulating in the conventional external circulation pipeline, the plating solution is also enhanced by this device to flush the plating solution at the deep tank 2 position, thereby ensuring the consistency of the plating solution at the deep tank 2 position and further ensuring the uniformity of the plating layer.

[0044] A schematic diagram of the electroplating equipment is shown below. Figure 7As shown, the roller female mold 1 is placed in the electroplating tank 8. A first circulation pipe 9 is connected to the electroplating tank 8. One end of the first circulation pipe 9 is connected to the lower part of the electrolytic tank, and the other end is connected to the upper part of the electrolytic tank. An external circulation pump 10 for the electroplating solution is also installed on the first circulation pipe 9. The plating solution is circulated between the lower and upper parts of the electroplating tank through the first circulation pipe 9, ensuring the consistency of the plating solution composition between the upper and lower parts of the electroplating tank.

[0045] The titanium basket anode 11 is placed at the center of the roller mold 1. The main pipe 6 of the titanium basket anode 11 is connected to the lower part of the electroplating tank 8 through the second circulation pipe 12. A variable frequency circulation pump 13 is installed on the second circulation pipe 12. The groove of the roller mold 1 is continuously flushed through the second circulation pipe 12, which enhances the replacement and renewal of the plating solution in this area.

[0046] The titanium basket anode 11 is placed on the workpiece support 14 at the bottom of the electroplating tank 8. The motor interface 5 on the upper part of the titanium basket anode 11 is connected to the variable frequency rotary motor 15. The roller female mold 1 and the titanium basket anode 11 are respectively connected to the pulse power supply 16. The electroplating tank is also equipped with a temperature control system 17.

[0047] (3) Pulse power supply control A segmented variable duty cycle pulse power supply control mode is adopted, with a fixed base frequency of 1000Hz and a total duty cycle of 90%. The positive and negative duty cycles are dynamically adjusted in four stages according to the electroplating thickening process to counteract the tip effect and achieve uniform coating growth. Throughout the electroplating cycle, the total electroplating thickness is guaranteed to reach 2.5~3mm. The total electroplating time is divided into four stages proportionally, with parameters dynamically decreasing / increasing in each stage. The specific control logic is as follows: Phase 1 (Total duration 10±2%): Positive duty cycle 80±2%, negative duty cycle 10±2%; Phase 2 (total duration 20±2%): positive duty cycle 70±2%, negative duty cycle 15±2%; Phase 3 (total duration 40±2%): positive duty cycle 60±2%, negative duty cycle 22±2%; Phase 4 (total duration 30±2%): positive duty cycle 50±2%, negative duty cycle 30±2%.

[0048] During the electroplating process, the current density is relatively low in the initial stage, the coating is thin, the tip effect is weak, and the difference between the positive and negative duty cycles is large, which ensures the basic deposition efficiency and ensures fine crystallization. As the thickness increases, the current density increases, and the coating in high-current areas such as the roller tip accumulates rapidly. The positive duty cycle is gradually reduced and the negative duty cycle is increased, which enhances the dissolution and trimming effect of the coating in high-current areas, balances the coating thickness at the tip and the bottom of the tank, and makes the coating uniformity TP value infinitely close to 1.

[0049] The preferred embodiments described above will be described in detail below with reference to specific examples. In the following examples and comparative examples, the inner plated roller has dimensions of Φ220×140 and an inner hole of φ60.

[0050] Example 1 The precise thickening method for the inner plating of the shell-shaped diamond roller in this embodiment is used for electroplating thickening of diamond abrasive particles with a particle size of conventional 40 / 45. The specific steps are as follows: (1) Place the sand-coated female mold in the plating solution of the electroplating tank, and place the anode in the center of the female mold.

[0051] The plating solution composition is as follows: nickel sulfamate 420 g / L, cobalt sulfamate 18 g / L, manganese bromide 12 g / L, boric acid 40 g / L, sodium 2,7-naphthalenedisulfonate 0.009 g / L, sodium hydroxypropyl thiosulfate 0.03 g / L, with water as the solvent; the pH value of the plating solution is 3.7. During solution preparation, each component is uniformly dispersed in water to form a uniformly dispersed plating solution. The plating solution temperature is set to 37℃.

[0052] Fix the motor, install the rotating rod and calibrate its concentricity; install a titanium basket and a four-way diverter at the lower end of the rotating rod, with the titanium basket wrapped with an anode sleeve and filled with nickel balls. Adjust the height of the titanium basket so that its lower end is flush with the lower end of the roller female mold, and align the three liquid outlets horizontally with the deep groove of the roller female mold.

[0053] (2) Turn on the rotary motor and set the speed to 25 rpm; turn on the circulation pump and set the plating solution circulation flow rate to medium (1 L / min) to continuously and dynamically replace the electrolyte in the tank. The rotary motor should run alternately three revolutions clockwise and three revolutions counterclockwise. Turn on the pulse power supply, connect the titanium basket to the positive terminal of the power supply, and connect the roller to the negative terminal of the power supply.

[0054] The pulse power supply has a fixed frequency of 1000Hz and a total duty cycle of 90%, employing a four-stage segmented control. The total electroplating time is 264 hours, with the duration and duty cycle parameters for each stage as follows: The first phase lasted 26.4 hours, with a positive duty cycle of 80% and a negative duty cycle of 10%; the positive current density was 0.1 A / dm³. 2 The negative current density is 0.01 A / dm. 2 .

[0055] The second stage lasted 52.8 hours, with a positive duty cycle of 70% and a negative duty cycle of 15%; the positive current density was 0.4 A / dm³. 2 The negative current density is 0.06 A / dm. 2 .

[0056] The third stage lasted 105.6 hours, with a positive duty cycle of 60% and a negative duty cycle of 22%; the positive current density was 0.5 A / dm³. 2 The negative current density is 0.08 A / dm.2 .

[0057] The fourth stage lasted 79.2 hours, with a positive duty cycle of 50% and a negative duty cycle of 30%; the positive current density was 0.8 A / dm³. 2 The negative current density is 0.16 A / dm. 2 .

[0058] In this embodiment, the diamond roller undergoes conventional processes such as core casting, machining, shell removal, precision inspection, and finishing after electroplating to obtain the finished diamond roller. The core casting process involves casting an electroplated, thickened negative mold onto a steel core. The machining process uses the outer circle of the negative mold as a reference to machine the inner hole and both end faces of the steel core. The shell removal process uses the inner hole of the steel core as a reference to remove the temporary negative mold. Finally, after precision inspection and finishing, the finished roller is obtained.

[0059] Example 2 The precise thickening method for the inner plating of the shell-shaped diamond roller in this embodiment is for electroplating thickening of diamond abrasive particles with a particle size of medium to coarse 30 / 35. The differences from Embodiment 1 are explained as follows: (1) Plating solution composition: nickel sulfamate 440 g / L, cobalt sulfamate 20 g / L, manganese bromide 14 g / L, boric acid 42 g / L, sodium 2,7-naphthalenedisulfonate 0.011 g / L, sodium hydroxypropyl thiosulfate 0.04 g / L, solvent is water; pH value of plating solution is 3.8, temperature is 38℃, basic current density is 0.8 A / dm 2 .

[0060] (2) Pulse power supply control mode: fixed frequency 1000Hz, total duty cycle 90%, optimized four-stage segmented control, total electroplating time 312h, the duration and duty cycle parameters of each stage are as follows: The first stage lasted 31.2 hours, with a positive duty cycle of 80% and a negative duty cycle of 10%; the positive current density was 0.1 A / dm³. 2 The negative current density is 0.01 A / dm. 2 .

[0061] The second stage lasted 62.4 hours, with a positive duty cycle of 70% and a negative duty cycle of 15%; the positive current density was 0.4 A / dm³. 2 The negative current density is 0.07 A / dm. 2 .

[0062] The third stage lasted 124.8 hours, with a positive duty cycle of 60% and a negative duty cycle of 22%; the positive current density was 0.5 A / dm³. 2 The negative current density is 0.09 A / dm. 2 .

[0063] The fourth stage lasted 93.6 hours, with a positive duty cycle of 50% and a negative duty cycle of 30%; the positive current density was 0.8 A / dm³. 2 The negative current density is 0.17 A / dm. 2 .

[0064] The anode rotation speed was set to 30 rpm, and the circulation pump used a medium-high flow rate (1.2~1.3 L / min) to enhance the rinsing effect of the deep tank plating solution and improve the uniformity of deposition. Other aspects not specified are the same as in Example 1.

[0065] Example 3 The precise thickening method for the inner plating of the shell-shaped diamond roller in this embodiment is for electroplating thickening of diamond abrasive particles with a relatively coarse particle size of 20 / 25. The differences from Embodiment 1 are explained as follows: (1) Plating solution composition: nickel sulfamate 450 g / L, cobalt sulfamate 15 g / L, manganese bromide 15 g / L, boric acid 45 g / L, sodium 2,7-naphthalenedisulfonate 0.012 g / L, sodium hydroxypropyl thiosulfate 0.05 g / L, solvent is water; pH value of plating solution is 4.0, temperature is 39℃, basic current density is 1.0 A / dm 2 .

[0066] (2) Pulse power supply control mode: fixed frequency 1000Hz, total duty cycle 90%, refined four-stage dynamic control, total electroplating time 360h, the duration and duty cycle parameters of each stage are as follows: The first phase lasted 36 hours, with a positive duty cycle of 80% and a negative duty cycle of 10%; the positive current density was 0.1 A / dm³. 2 The negative current density is 0.01 A / dm. 2 .

[0067] The second phase lasted 72 hours, with a positive duty cycle of 70% and a negative duty cycle of 15%; the positive current density was 0.4 A / dm². 2 The negative current density is 0.08 A / dm. 2 .

[0068] The third stage lasted 144 hours, with a positive duty cycle of 60% and a negative duty cycle of 22%; the positive current density was 0.5 A / dm². 2 The negative current density is 0.1 A / dm. 2 .

[0069] The fourth stage lasted 108 hours, with a positive duty cycle of 50% and a negative duty cycle of 30%; the positive current density was 0.8 A / dm³. 2 The negative current density is 0.18 A / dm. 2 .

[0070] In this embodiment, for coarser abrasive particles, the thickening time is longer, and the reduction area of ​​the coating between particles is larger. The anode rotation speed is adjusted to 35 rpm, and the circulating pump is dynamically speed-regulated using frequency conversion. The initial flow rate for initial flushing and the subsequent flow rate for enhanced plating (flow rates of 0.6, 0.8, 1.0, and 1.3 L / min for the first, second, third, and fourth stages, respectively) are adjusted to accelerate liquid-phase mass transfer in the plating solution and maximize the elimination of the tip effect. In this embodiment, the initial abrasive solidification requires a slow flow rate, while the increased current density and higher additive consumption in the later stages necessitate timely external circulation replenishment. This refined control of the plating solution circulation process further matches the different requirements of the plating layer during electroplating, achieving further optimization of the plating quality.

[0071] (ii) Comparative Example Comparative Example 1: Plating solution lacking sodium hydroxypropyl thiosulfate The method for thickening the inner plating of the diamond roller in this comparative example differs from Example 1 only in that sodium hydroxypropyl thiosulfate is not added to the plating solution.

[0072] Electroplating performance: Without a leveling agent to regulate current distribution, the deposition rate in the high current zone at the end of the roller die is too fast, the deposition at the bottom of the deep tank is insufficient, the maximum thickness difference of the coating reaches 1mm, and the thickness uniformity is extremely poor; coating accumulation occurs at the end, the end closes prematurely when the thickness is insufficient, the coating in the deep tank is too thin to meet the requirements for thickening, and the precision of the forming surface is out of tolerance.

[0073] Comparative Example 2 plating solution lacks sodium 2,7-naphthalenedisulfonate. The method for thickening the inner plating of the diamond roller in this comparative example differs from Example 1 only in that sodium 2,7-naphthalenedisulfonate is not added to the plating solution.

[0074] The plating after electroplating exhibits the following characteristics: There is no grain refinement inhibition mechanism, resulting in coarse grains, loose structure, poor surface roughness, and poor plating smoothness. Although the overall thickness meets the standard, the surface finish and wear resistance of the formed surface decrease.

[0075] Comparative Example 3 lacks manganese bromide The method for thickening the inner plating of the diamond roller in this comparative example differs from Example 1 only in that manganese bromide is not added to the plating solution.

[0076] The plating results after electroplating are as follows: severe passivation of the nickel anode, continuous fluctuation of nickel ion concentration in the plating solution, and unstable deposition rate; insufficient cathode polarization, rough coating, local scorching, and an increase in electroplating time of more than 30%; manganese deficiency leads to a significant reduction in the hardness and wear resistance of the alloy coating, shortening the service life of the roller by more than 40%, and failing to meet the requirements of special working conditions.

[0077] Comparative Example 4 lacks the composite additive (sodium hydroxypropyl thiosulfate + sodium 2,7-naphthalenedisulfonate). The method for thickening the inner plating of the diamond roller in this comparative example differs from that in Example 1 only in that the plating solution does not contain sodium hydroxypropyl thiosulfate and sodium 2,7-naphthalenedisulfonate.

[0078] Post-plating coating performance: It has the same defects as Comparative Example 1 and Comparative Example 2. The current distribution is severely unbalanced, the grains are extremely coarse, the coating thickness is uneven, the nickel layer at the bottom of the tank is insufficient, the minimum thickness at the bottom of the tank cannot be met within the specified time, the surface is rough with many nodular protrusions, and the precision of the forming surface exceeds the tolerance by more than 0.03mm, which does not meet the production standards.

[0079] Comparative Example 5 uses a DC power supply (no-pulse mode). The comparative example of the diamond roller internal plating thickening method eliminates the pulse power supply and replaces it with a conventional DC power supply. The current density, plating solution, and equipment parameters are the same as in Example 1.

[0080] The plating performance after electroplating: continuous DC power supply caused the tip effect to continue to intensify, the plating at the roller mouth end was excessively accumulated, the end was sealed prematurely, the plating thickness at the bottom of the tank was insufficient, the thickness difference was as high as 16μm, and electroplating could not continue; the plating grains were coarse, the internal stress was concentrated, the forming surface accuracy was low, and the tip needed to be shielded or the port plating needed to be physically removed. The yield rate was less than 30%.

[0081] Comparative Example 6: The negative duty cycle of the pulse remains constant. The method for thickening the inner plating of the diamond roller in this comparative example uses a pulse power supply, but the negative duty cycle is fixed at 10% throughout the process and is not dynamically increased with the electroplating stage (i.e., the same as the first stage of Example 1). The other parameters are the same as those in Example 1.

[0082] Post-electroplating coating performance: As the current density increases in the middle and later stages, the tip effect in the middle and later stages of electroplating cannot be offset, the coating at the mouth continues to accumulate, the coating at the bottom of the tank grows slowly, the uniformity is poor, the precision cannot meet the requirements of high-precision processing, and the coating consistency is insufficient.

[0083] Comparative Scale 7 does not flush the deep groove area of ​​the female mold. The method for thickening the inner plating of the diamond roller in this comparative example does not involve scouring the deep groove of the female mold; the remaining processes are the same as in the embodiment.

[0084] Electroplating performance: In the deep tank, the plating solution is refreshed quickly and the supply of metal ions is sufficient. Due to the tip effect, the plating layer continues to thicken and accumulate. In the deep tank bottom area, the plating solution flow is slow, and metal ions cannot be replenished in time. The concentration polarization is aggravated, and the growth of the plating layer at the bottom of the tank is further inhibited. The difference in plating thickness between the tank opening and the bottom of the tank is further widened, and the overall uniformity and consistency of the plating layer deteriorates. The dimensional accuracy of the workpiece is difficult to meet the requirements of high-precision processing. In severe cases, defects such as thin plating, incomplete plating, and loose and rough plating appear at the bottom of the tank.

[0085] (III) Experimental Examples This experiment tested key indicators such as coating adhesion (MPa), coating microhardness (HV), coating uniformity (TP value), and grinding ratio (G ratio) for each group of samples under the same conditions. Specific results are shown in Table 1 below. For the coating adhesion test, after the diamond roller is formed, the adhesion force of the diamond pulled out of the coating is measured. A vertical outward pulling force is applied to a single exposed diamond, and the maximum load on which the diamond is pulled out of the coating is measured. During the test, the testing machine is loaded at low speed, and the maximum pulling force at the moment the abrasive grain is pulled out is recorded. The actual contact projection area of ​​the diamond encased in nickel is statistically analyzed using a microscope, and the two values ​​are divided to obtain the adhesion force. The result is the average of 10 values. The TP value is the ratio of the coating thickness at the bottom of the tank to the coating thickness at the opening of the tank. Both values ​​are measured under a metallographic microscope, and the average value is obtained from multiple measurements. The closer the value is to 1, the more uniform the coating. The grinding ratio test uses the gravimetric method, dividing the weight of the material removed from the workpiece by the weight of the roller itself worn, and the calculated ratio is the grinding ratio.

[0086] Table 1. Coating performance test results for each embodiment and comparative example. As shown in Table 1, the leveling agent sodium hydroxypropyl thiosulfate, the leveling agent sodium 2,7-naphthalenedisulfonate, and manganese bromide are the core components that ensure a uniform, dense, and high-performance coating. The absence of any one of these components will lead to a decrease in coating quality. Compared to DC power supplies and fixed pulse parameter modes, segmented dynamic pulse duty cycle control can significantly offset the tip effect and greatly improve the roller thickening accuracy and coating consistency. Furthermore, in Comparative Example 7, during the electroplating reaction, the coating adhesion decreased because the old plating solution could not be flushed out of the deep tank in time; simultaneously, poor circulation within the tank easily caused hydrogen permeation, further reducing adhesion and lowering the TP value.

[0087] In summary, this process achieves synergistic optimization in multiple aspects, including plating solution formulation, tooling structure, flow field design, and power control. It effectively solves technical problems such as uneven plating thickness, insufficient bottom plating thickness, poor surface accuracy, and unstable lifespan in shell-shaped diamond rollers. It is suitable for the industrial production of high-precision, small-batch, and multi-variety diamond rollers.

[0088] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for precise thickening of the inner plating of a conch-shaped diamond roller, characterized in that, After sanding, the female mold is placed in the plating solution of the electroplating tank, and the anode is placed in the center of the female mold. Electroplating is performed using a pulse power supply. During electroplating, the positive duty cycle and negative duty cycle of the pulse power supply are gradually adjusted. In the initial stage of electroplating, the positive duty cycle is above 70%. As electroplating progresses, the positive duty cycle is gradually reduced and the negative duty cycle is increased.

2. The method for precise thickening of the inner plating of a shell-shaped diamond roller as described in claim 1, characterized in that, Electroplating is divided into pre-plating and post-plating. In the pre-plating stage, the positive duty cycle is 70-80% and the negative duty cycle is 10-15%. In the post-plating stage, the positive duty cycle is 50-60% and the negative duty cycle is 22-30%. The pre-plating stage accounts for 30-40% of the total electroplating time.

3. The method for precise thickening of the inner plating of a conchoidal diamond roller as described in claim 2, characterized in that, During the initial stage of electroplating, the forward current density is 0.1~0.5 A / dm³. 2 The negative current density is 0.01~0.08 A / dm³. 2 During the later stages of electroplating, the forward current density is 0.5~0.9 A / dm³. 2 The negative current density is 0.08~0.18 A / dm³. 2 .

4. The method for precise thickening of the inner plating of a conchoidal diamond roller as described in claim 2, characterized in that, The pre-plating stage is divided into the first stage and the second stage, while the post-plating stage is divided into the third stage and the fourth stage. The positive duty cycle of the first stage is 80±2%, and the negative duty cycle is 10±2%. The positive duty cycle for the second phase is 70±2%, and the negative duty cycle is 15±2%. The positive duty cycle for the third stage is 60±2%, and the negative duty cycle is 22±2%. The positive duty cycle of the fourth stage is 50±2%, and the negative duty cycle is 30±2%; the first, second, and third stages account for 10±2%, 20±2%, and 40±2% of the total electroplating time, respectively; the frequency of the pulse power supply is 1000Hz.

5. The method for precise thickening of the inner plating of a conchoidal diamond roller as described in claim 4, characterized in that, The forward current density in the first stage is 0.1~0.2 A / dm. 2 The negative current density is 0.01~0.02 A / dm. 2 The forward current density in the second stage is 0.4~0.45 A / dm³. 2 The negative current density is 0.06~0.08 A / dm³. 2 The forward current density in the third stage is 0.5~0.6 A / dm³. 2 The negative current density is 0.08~0.1 A / dm³. 2 The forward current density in the fourth stage is 0.8~0.85 A / dm³. 2 The negative current density is 0.16~0.18 A / dm³. 2 .

6. The method for precise thickening of the inner plating of a conchoidal diamond roller as described in claim 1, characterized in that, To improve coating uniformity, the plating solution composition was optimized. The plating solution used consisted of the following components: nickel sulfamate 400-450 g / L, cobalt sulfamate 15-20 g / L, MnBr2 10-15 g / L, H3BO3 35-45 g / L, sodium 2,7-naphthalenedisulfonate 0.007-0.012 g / L, sodium hydroxypropyl thiosulfate 0.01-0.05 g / L, water as solvent, and pH 3.5-4.

0. The electroplating temperature was 35-40℃.

7. The method for precise thickening of the inner plating of a conchoidal diamond roller as described in claim 1, characterized in that, During internal plating, plating solution is continuously introduced into the groove of the female mold to enhance the replacement and renewal of the plating solution at the bottom of the groove.

8. The method for precise thickening of the inner plating of a conchoidal diamond roller as described in claim 7, characterized in that, The anode includes a titanium basket filled with nickel balls as the anode material. The titanium basket is provided with a multi-channel distribution structure to continuously supply plating solution to the groove position. The multi-channel distribution structure includes a main pipe coaxially arranged with the titanium basket. The lower end outlet of the main pipe is connected to a set of branch pipes arranged in different radial directions along the titanium basket. After entering the main pipe, the plating solution flows to the corresponding groove position along each branch pipe.

9. The method for precise thickening of the inner plating of a conchoidal diamond roller as described in claim 8, characterized in that, During electroplating, the titanium basket adopts an alternating forward and reverse rotation mode.

10. A diamond roller manufactured using the precise thickening method for inner plating of a shell-shaped diamond roller as described in any one of claims 1 to 9.

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