Diamond polishing apparatus

Abstract

The application discloses a kind of for diamond grinding device, including grinding system and grinding fluid modulation system;Grinding system has recovery pipeline and liquid outlet pipeline.Grinding fluid modulation system is connected in series between recovery pipeline and liquid outlet pipeline, it includes acid storage tank (103), reaction tank (105) and two-way circulation channel;Reaction tank is heatable container, and its inlet is connected with recovery pipeline, and outlet is connected with liquid outlet pipeline;Two-way circulation channel includes A channel (104) and B channel (102) with condensing device, respectively for acid liquid is transported to reaction tank and volatile acid is condensed and flows to acid storage tank.The solid-state iron-based particles that cast iron disc is ground and falls off are converted into liquid-state iron ions on line in the application, improve catalytic efficiency, realize the high efficiency grinding of diamond.

Description

Technical Field

[0001] This invention relates to the field of superhard material processing technology, specifically to a high-efficiency grinding device for diamond surface grinding, which is particularly suitable for the online conversion of iron-based particles that fall off in the grinding fluid during mechanical grinding with cast iron discs to reduce surface damage and improve grinding efficiency. Background Technology

[0002] Diamond, as a superhard material with excellent comprehensive properties, has broad application prospects in many technological fields. However, due to its extremely high hardness and outstanding chemical inertness, its processing difficulty is far greater than that of ordinary materials. Diamond processing methods rely on lasers, mechanical polishing, and chemical and photocatalytic aids, among which mechanical polishing using cast iron discs as diamond grinding media is one of the most basic processing methods. The reason why cast iron discs can polish diamond is that, although the hardness of iron-based materials is much lower than that of diamond, as a diamond graphitizing element, it can catalyze the graphitization transformation of the diamond's surface structure under the high temperature state during grinding, and work synergistically with oxidants and diamond micro / nano abrasive powder to efficiently remove diamond.

[0003] Although cast iron discs can efficiently polish diamonds, their hardness is far lower than that of diamonds, making them easy to be scraped off by the diamonds during the polishing process. These iron-based catalyst particles, in the form of discrete granules, mix into the polishing agent, which can easily cause uncontrollable damage to the diamond surface. Furthermore, since the detached iron-based particles are in solid form, they come into solid contact with the diamonds during the polishing process, resulting in low efficiency. Summary of the Invention

[0004] This invention aims to overcome the shortcomings of existing technologies that use cast iron discs for mechanical polishing of diamonds. In these discs, granular iron-based catalysts (iron particles, iron oxide particles) detach from the surface of the disc and become mixed in the polishing slurry, resulting in low catalytic efficiency through solid-solid contact. This invention provides a low-damage polishing device. The device fundamentally transforms the morphology of the iron-based catalyst by converting solid iron-based particles into liquid iron ions online, thereby improving polishing efficiency and reducing damage to the diamond surface caused by solid iron-based particles.

[0005] To achieve the above objectives, the present invention provides a diamond grinding apparatus, which includes a grinding system and a grinding fluid preparation system.

[0006] The grinding system includes a grinding disc, a rotating component, a grinding fluid circulation device, and a control system. The grinding disc is preferably a cast iron disc, used for grinding against the diamond sample to be ground. The grinding fluid circulation device has a recovery pipeline and an outlet pipeline, used to transport the grinding fluid to the grinding interface and recover the used grinding fluid. The grinding fluid composition includes diamond powder, an oxidant, and water, with hydrogen peroxide being the preferred oxidant. The grinding fluid circulation device is also equipped with an oxidant dripping pipeline for replenishing the oxidant lost during the grinding process.

[0007] The grinding slurry preparation system is connected in series between the recovery pipeline and the outlet pipeline of the grinding slurry circulation device in a fluid communication manner. It is used to receive the grinding slurry containing particulate iron-based catalyst from the recovery pipeline and send the processed grinding slurry back to the grinding interface through the outlet pipeline.

[0008] The grinding fluid preparation system includes an acid storage tank, a reaction tank, and a bidirectional circulation channel arranged between the acid storage tank and the reaction tank.

[0009] Acid storage tank: Used to store acid, preferably hydrochloric acid, with a mass concentration range of 1% to 30%.

[0010] The reaction vessel is a heatable container with an inlet for receiving liquid from the recovery pipeline and an outlet for supplying liquid to the outlet pipeline. An ultrasonic disperser is installed inside the reaction vessel to accelerate the reaction between the iron-based particles and the acid solution. A vent is provided on the reaction vessel to release the hydrogen gas produced during the reaction and prevent pressure buildup.

[0011] A bidirectional circulation channel includes channel A and channel B. One end of channel A is connected to the outlet of the acid storage tank, and the other end is connected to the inlet of the reaction tank, used to unidirectionally transport the acid from the storage tank to the reaction tank. One end of channel B is connected to the outlet of the reaction tank, and the other end is connected to the return port of the acid storage tank. A condensation device is installed on channel B to condense the acid vapors that evaporate during heating in the reaction tank into liquid acid, which then flows unidirectionally back to the storage tank.

[0012] As an optimization, the grinding slurry preparation system also includes a concentration tank and a dilution tank: Concentrator: Connected in series between the inlet of the recovery pipeline and the inlet of the reaction tank, i.e., the inlet of the concentration tank is connected to the outlet of the recovery pipeline, and the outlet of the concentration tank is connected to the inlet of the reaction tank. The concentration tank has a built-in filter membrane to remove some of the water from the grinding slurry, achieving volume concentration. The concentration tank is equipped with a water outlet pipeline and a one-way valve for discharging the separated water.

[0013] Dilution tank: Connected in series between the outlet of the reaction tank and the outlet pipeline, i.e., the inlet of the dilution tank is connected to the outlet of the reaction tank, and the outlet of the dilution tank is connected to the inlet of the outlet pipeline. The dilution tank is used to add deionized water to the iron-containing liquid discharged from the reaction tank to dilute it to a suitable concentration and pH value, thereby improving the fluidity and performance of the grinding slurry.

[0014] In addition, the grinding fluid preparation system also includes a delivery pump and / or a one-way valve, which are respectively arranged in the A channel, between the concentration tank and the reaction tank, and between the reaction tank and the dilution tank, to realize the directional delivery of liquid between the components.

[0015] In a preferred embodiment, the acid stored in the acid storage tank of the grinding slurry preparation system is hydrochloric acid with a concentration range of 1%-30%.

[0016] The reaction principle of hydrochloric acid and granular iron-based catalyst is as follows: The working process of the device of the present invention is as follows: a. Load the diamond sample to be ground onto the grinding system, place the pressure block on top, and generate sufficient shear force between the cast iron disc and the diamond during the grinding process.

[0017] b. Start the grinding system. The grinding disc rotates under the drive of the rotating component. The grinding fluid circulation device delivers the basic grinding fluid containing diamond powder, hydrogen peroxide and water to the interface between the cast iron disc and the diamond to start the grinding operation.

[0018] c. Simultaneously with step b, or at set time intervals, start the grinding slurry preparation system: c1. The recovery pipeline transports the used grinding fluid (containing granular iron-based catalyst Fe and Fe2O3 detached from the cast iron pan) to the concentration tank, where some water is removed by filtration membrane to obtain concentrated grinding fluid.

[0019] c2. The concentrated grinding slurry enters the reaction vessel, while hydrochloric acid is simultaneously added dropwise from the acid storage tank through channel A. With the aid of an ultrasonic disperser, the hydrochloric acid reacts fully with the iron-based particles: Fe + 2HCl = FeCl2 + H2↑ Fe₂O₃ + 6HCl = 2FeCl₃ + 3H₂O The hydrogen produced by the reaction is safely discharged through the vent (it can be connected to a flame arrester and led outdoors).

[0020] c3. After the reaction is complete, heat the reaction vessel to the set temperature (e.g., 80~95℃) to cause the excess unreacted hydrochloric acid to evaporate into vapor. The vapor enters the condenser through channel B, condenses into liquid hydrochloric acid, and then flows back to the acid storage tank for recycling.

[0021] c4. Remove the remaining Fe²⁺-containing material from the reaction vessel. + and Fe³ + The acidic liquid is drawn into a dilution tank and diluted with deionized water to a predetermined concentration (e.g., iron ion concentration 0.01~0.1 mol / L, pH 3~5). Simultaneously, hydrogen peroxide is added via an oxidant dripping line to form a Fenton-like polishing solution system. The diluted polishing solution is then returned to the polishing interface via an outlet line to continue participating in the polishing process.

[0022] The beneficial technical effects of this invention are as follows: (1) Polishing solutions containing ferric or ferrous ions, such as Fenton's reagent, have been widely used in diamond surface processing and are a mature polishing solution system. This invention uses iron particles that slide off the cast iron disc during operation as an iron source. A reaction system of strong acid and iron source is arranged in the grinding device. Without adding an external iron source, solid iron and iron oxide particles are converted into liquid iron ions, thereby increasing the reaction area and efficiency between iron and diamond.

[0023] (2) During diamond grinding, the detached solid iron or iron oxide particles are prone to play a role in the local micro-area of ​​diamond due to the interaction between diamond and abrasive and cast iron disc, forming non-uniform abrasive and causing uncontrollable grinding marks, resulting in poor uniformity of diamond surface. The present invention can effectively avoid the influence of iron-based particles on the local diamond through the grinding fluid modulation system. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structural arrangement of a diamond grinding device according to the present invention; In the diagram: 1-Grinding slurry preparation system; 101-Dilution tank; 102-Channel B; 103-Acid storage tank; 104-Channel A; 105-Reaction tank. 106 - One-way valve; 107 - Concentration tank. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0026] Example 1 Reference Figure 1This invention provides a diamond grinding apparatus, including a grinding system and a grinding slurry preparation system 1. The grinding system includes a grinding disc, a rotating component, a grinding slurry circulation device, and a control system. The grinding disc is made of cast iron and is used for grinding against the diamond sample to be ground. The grinding slurry circulation device includes a recovery pipeline and an outlet pipeline for transporting the grinding slurry to the grinding interface and recovering the used grinding slurry. The grinding slurry composition includes diamond powder, an oxidant, and water, with hydrogen peroxide being the preferred oxidant. The grinding slurry circulation device also includes an oxidant dripping pipeline for replenishing the oxidant lost during the grinding process. The grinding slurry preparation system 1 is connected to the grinding slurry circulation device of the grinding system. The grinding slurry preparation system 1 includes: a concentration tank 107, a reaction tank 105, an acid storage tank 103, a dilution tank 101, and two reciprocating channels (channel A 104 and channel B 102) arranged between the acid storage tank 103 and the reaction tank 105.

[0027] The inlet of the concentration tank 107 is connected to the outlet of the recovery pipeline of the grinding slurry circulation device. The concentration tank 107 is equipped with a filter membrane to remove some of the water from the recovered grinding slurry, thus achieving volume concentration of the grinding slurry. The concentration tank 107 is also equipped with a water outlet pipeline and a one-way valve 106 for discharging the separated water.

[0028] The outlet of the concentration tank 107 is connected to the inlet of the reaction tank 105 via a pipeline. The reaction tank 105 is a heatable container with a built-in heater (such as an electric heating mantle or an immersion heating rod) that can control its internal temperature between 40°C and 95°C. An ultrasonic disperser is also installed inside the reaction tank 105 to apply ultrasonic vibration to the reaction mixture, accelerating the reaction between the iron-based particles and the acid solution. A vent is provided at the top of the reaction tank 105 to release the hydrogen gas produced during the reaction and prevent pressure buildup inside the tank.

[0029] Acid storage tank 103 stores hydrochloric acid solution with a mass concentration of 1% to 30%, preferably 5% to 15%. Channel A 104 and channel B 102 are provided between acid storage tank 103 and reaction tank 105. Channel A 104 is equipped with a transfer pump and a one-way valve for unidirectionally transferring the hydrochloric acid solution from acid storage tank 103 to reaction tank 105. Channel B 102 is equipped with a condensation device (such as a serpentine condenser or plate condenser), through which cooling water or refrigerant is circulated. Channel B 102 is used to condense the hydrochloric acid vapor that evaporates due to heating in reaction tank 105 into a liquid state, which then flows unidirectionally back to acid storage tank 103 by gravity or a slight pressure difference.

[0030] The outlet of reaction vessel 105 is connected to the inlet of dilution vessel 101 via a pipeline. Dilution vessel 101 is equipped with a stirrer and is connected to a deionized water replenishment pipeline. The outlet of dilution vessel 101 is connected to the outlet pipeline of the grinding slurry circulation device of the grinding system, returning the treated grinding slurry to the grinding interface.

[0031] The grinding slurry preparation system 1 in this embodiment is also equipped with necessary delivery pumps (not shown) and one-way valves to achieve directional delivery of liquid in each step.

[0032] Work process: a. Load the diamond sample to be ground onto the sample holder of the grinding system, place the pressure block on top, so that the cast iron disc and the diamond generate sufficient shear force during the grinding process.

[0033] b. Start the grinding system. The grinding disc rotates under the drive of the rotating component. The grinding fluid circulation device delivers the basic grinding fluid containing diamond powder, hydrogen peroxide and water to the interface between the cast iron disc and the diamond to start the grinding operation.

[0034] c. While the grinding operation is underway, start the grinding slurry preparation system 1: c1. The grinding slurry in the recycling pipeline of the grinding slurry circulation device is introduced into the concentration tank 107, and a portion of the water is removed by the filter membrane (for example, the volume is concentrated to 1 / 2 to 1 / 3 of the original volume). The concentrated grinding slurry is then sent into the reaction tank 105 through the pipeline.

[0035] c2. Turn on the transfer pump between the acid storage tank 103 and channel A 104, and add a 10% hydrochloric acid solution dropwise into the reaction tank 105. The hydrochloric acid reacts with the iron-based particles (iron particles Fe and iron oxide particles Fe2O3) in the concentrated grinding slurry as follows: Fe + 2HCl = FeCl2+ H2↑Fe2O3+ 6HCl = 2FeCl3+ 3H2O Simultaneously, the heater and ultrasonic disperser of reaction vessel 105 are started, the temperature is set to 80℃, the ultrasonic power is 200W, and the reaction time is 15-30 minutes. The hydrogen gas produced by the reaction is discharged through the vent.

[0036] c3. Stop the hydrochloric acid dripping and continue heating the reaction vessel 105 to 95°C to make the excess unreacted hydrochloric acid evaporate into vapor. The vapor enters the condenser through channel B 102 and is condensed into liquid hydrochloric acid by cooling water, which is then returned to the acid storage tank 103 for recycling.

[0037] c4. Remove the remaining Fe²⁺-containing material from reaction vessel 105. + and Fe³ + The acidic liquid is drawn into dilution tank 101, where deionized water is added to dilute it to a suitable acid concentration (e.g., pH 3-5). A small amount of hydrogen peroxide is added as needed to form a Fenton-like polishing solution system. The diluted polishing slurry is then transported to the polishing interface through the outlet pipe of the polishing slurry circulation device, continuously participating in the polishing process.

[0038] Step c (grinding slurry preparation) can be performed continuously and synchronously with step b (grinding operation), or it can be performed intermittently every 30 minutes during the grinding process.

[0039] Example 2 This embodiment is basically the same as Embodiment 1, except that the grinding slurry preparation system 1 does not include a concentration tank 107 and a dilution tank 101. The recovered grinding slurry is directly fed into the reaction tank 105 to react with hydrochloric acid from the acid storage tank 103; after the reaction is completed, it is directly returned to the grinding system without dilution. This simplified scheme is suitable for situations where the grinding slurry itself has a high water content and the acid concentration after the reaction is acceptable, but the heating and evaporation time of the reaction tank 105 needs to be appropriately extended to remove excess water.

[0040] Example 3 This embodiment further optimizes upon embodiment 1: The reaction vessel 105 is equipped with a pH sensor and an iron ion concentration sensor. When the pH value of the solution in the reaction vessel 105 reaches a predetermined threshold (e.g., pH=2.5) and the iron ion concentration stabilizes, the hydrochloric acid addition automatically stops and the heating and evaporation process begins. The concentration tank 107 is equipped with a level sensor to achieve automatic liquid inlet and outlet. The entire grinding slurry preparation system 1 is uniformly controlled by the grinding system's control system, achieving fully automatic operation.

[0041] Example 4 In this embodiment, the hydrochloric acid stored in the acid storage tank 103 has a concentration of 20%. The reaction tank 105 is heated to evaporate excess hydrochloric acid at a temperature of 85°C, and the condensation device uses circulating water cooling, with the water temperature controlled below 15°C. The ultrasonic disperser has a frequency of 40kHz, a power of 500W, and a reaction time of 10 minutes. Testing showed that the conversion rate of the iron-based particles reached over 85%, and the surface roughness of the diamond after grinding was less than 400nm, exhibiting overall uniformity without obvious uneven wear marks.

[0042] Experimental effect verification A grinding test was conducted on a polycrystalline diamond sheet using the apparatus described in Example 1. The grinding time was 2 hours, and the diamond thickness removed was 287 nm. Under the same conditions, after grinding with a conventional cast iron disc without a grinding slurry system for 2 hours, the thickness removed from the polycrystalline diamond was 263 nm. Compared with the conventional cast iron disc grinding process without a grinding slurry system, the grinding removal rate of the grinding apparatus of the present invention is improved by approximately 9%. After grinding, the surface was observed under a 50x optical microscope, and the surface was uniform overall with no obvious uneven grinding marks.

[0043] The above results demonstrate that this invention effectively solves the problems of surface scratches and low catalytic efficiency when grinding diamond with cast iron discs by converting solid iron-based particles into liquid iron ions online, thus achieving low-damage and high-efficiency grinding processing.

[0044] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A diamond grinding device, characterized in that, include: A grinding system, comprising a grinding disc, rotating components, a grinding fluid circulation device, and a control system; The grinding fluid circulation device has a recovery pipeline and a discharge pipeline; A grinding slurry preparation system (1) is connected in series between the recovery pipeline and the outlet pipeline of the grinding slurry circulation device. The grinding slurry preparation system (1) includes an acid storage tank (103) and a reaction tank (105). A double channel is arranged between the acid storage tank (103) and the reaction tank (105). The double channel includes channel A (104) and channel B (102). One end of channel A (104) is connected to the outlet of the acid storage tank (103), and the other end is connected to the inlet of the reaction tank (105). It is used to transfer the acid from the acid storage tank to the outlet of the reaction tank (105). The acid in (103) is unidirectionally transported to the reaction tank (105); one end of the B channel (102) is connected to the gas outlet of the reaction tank (105), and the other end is connected to the return port of the acid storage tank (103). A condensing device is arranged on the B channel (102) to condense the acid vapor that evaporates from the reaction tank (105) into liquid acid and then unidirectionally return it to the acid storage tank (103); the reaction tank (105) is a heatable container, its inlet is connected to the recovery pipeline of the grinding slurry circulation device, and its outlet is connected to the outlet pipeline of the grinding slurry circulation device. The grinding fluid circulation device is also equipped with an oxidant dripping pipeline for replenishing the oxidant in the grinding fluid; the grinding disc is a cast iron disc.

2. The diamond grinding apparatus according to claim 1, characterized in that, The acid stored in the acid storage tank (103) is hydrochloric acid, with a mass concentration range of 1% to 30%.

3. The diamond grinding apparatus according to claim 1, characterized in that, An ultrasonic disperser is arranged inside the reaction vessel (105).

4. The diamond grinding apparatus according to claim 1, characterized in that, The reaction vessel (105) is provided with a vent for discharging the hydrogen gas produced by the reaction.

5. The diamond grinding apparatus according to claim 1, characterized in that, The grinding slurry preparation system (1) further includes a concentration tank (107) and a dilution tank (101); the concentration tank (107) is connected in series between the recovery pipeline and the inlet of the reaction tank (105), that is, the inlet of the concentration tank (107) is connected to the outlet end of the recovery pipeline, and the outlet of the concentration tank (107) is connected to the inlet of the reaction tank (105); the dilution tank (101) is connected in series between the outlet of the reaction tank (105) and the outlet pipeline, that is, the inlet of the dilution tank (101) is connected to the outlet of the reaction tank (105), and the outlet of the dilution tank (101) is connected to the inlet end of the outlet pipeline.

6. The diamond grinding apparatus according to claim 5, characterized in that, The concentration tank (107) is equipped with a filter membrane to remove some of the water from the grinding liquid; the concentration tank (107) is provided with a water outlet pipe and a one-way valve (106) to discharge the separated water.

7. The diamond grinding apparatus according to claim 5, characterized in that, The grinding fluid preparation system (1) also includes a delivery pump and / or a one-way valve, which are respectively arranged between the A channel (104), the concentration tank (107) and the reaction tank (105), and the reaction tank (105) and the dilution tank (101) to realize the directional delivery of liquid between the components.

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