Mechanical electrolysis composite pre-grinding device and method for metallographic specimen

Abstract

The invention discloses a mechanical electrolysis composite pre-grinding device for a metallographic specimen and a using method thereof.The device comprises a polishing disc rotating mechanism, an electrolyte circulating system unit and a supporting frame, a polishing disc is arranged above the supporting frame, the polishing disc rotating mechanism is rotationally connected with the polishing disc, and the center of the polishing disc is in threaded connection with a center pin shaft; the center pin shaft is sleeved with a middle slotted hole cushion plate, a spiral groove with the trapezoidal section from the center to the edge is machined in one face of the middle slotted hole cushion plate, polishing cloth covers the other face of the middle slotted hole cushion plate in a pressed mode, a collecting ring is installed at the upper end of the center pin shaft, and a stator output line of the collecting ring is connected with a cathode of an electrolysis power source. An anode of the electrolytic power supply is connected with a sample clamp for clamping a sample, the sample is in contact with the polishing cloth above the middle slotted hole pad, and a nozzle of the electrolyte circulating system unit is arranged on the side edge of the sample. The problems that when a metallographic specimen of a conventional wear-resistant metal material is pre-ground, consumption of metallographic abrasive paper is large, and time is consumed are solved.

Description

Technical Field

[0001] The invention relates to the field of material detection, in particular to a mechanical electrolytic composite pre-grinding device and method for a metallographic sample. Background Art

[0002] The process of metallographic inspection of metal materials generally requires pre-grinding the inspection surface to achieve the required flatness and roughness before polishing. Conventional pre-grinding of highly wear-resistant materials such as high-speed tool steel requires multiple passes of grinding from coarse to fine using metallographic sandpaper. Especially for some large-surface specimens, the consumption of pre-grinding sandpaper is large, and often several sheets of sandpaper of the same particle size are required to remove the traces of the previous pass, which is very time-consuming and costly.

[0003] Conventional static electrolytic corrosion will cause phase-selective corrosion for high-alloy multiphase materials, and due to the unequal current between the two electrodes, the corrosion depth and surface roughness are difficult to control, and it is difficult to achieve the flatness and roughness requirements before polishing. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a mechanical electrolytic composite pre-grinding device for metallographic samples and a method for using the same, which adopts a high-speed rotating polishing cloth to remove corrosion products, thereby achieving the purpose of rapid pre-grinding and solving the problem of large consumption of metallographic sandpaper and long time consumption during pre-grinding of metallographic samples of conventional wear-resistant metal materials.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a mechanical electrolytic composite pre-grinding device for metallographic samples, including a polishing disc rotating mechanism and an electrolyte circulation system unit, and also including a support frame, a polishing disc is arranged above the support frame, the polishing disc rotating mechanism is rotatably connected to the polishing disc, a threaded hole is drilled in the center of the polishing disc and a center pin is threadedly connected at the threaded hole, an intermediate slot hole pad is sleeved on the center pin, one side of the intermediate slot hole pad is machined with a trapezoidal cross-section spiral groove from the center to the edge and equidistant through holes are machined at the bottom of the spiral groove, the groove surface of the spiral groove fits the polishing disc, and the other side of the intermediate slot hole pad is pressed with a polishing cloth, a collector ring is installed on the upper end of the center pin, the stator output line of the collector ring is connected to the cathode of the electrolytic power supply, the anode of the electrolytic power supply is connected to the sample fixture that clamps the sample, the sample is in contact with the polishing cloth above the intermediate slot hole pad, and the nozzle of the electrolyte circulation system unit is arranged on the side of the sample.

[0006] A further improvement of the technical solution of the present invention is that the electrolysis power supply adopts an isolated transformer DC output power supply.

[0007] A further improvement of the technical solution of the present invention is that a radial threaded hole is drilled in the middle of the upper end of the center pin shaft, and the radial threaded hole is used to install a fixed terminal, and the rotor output line of the collector ring is installed on the terminal.

[0008] A further improvement of the technical solution of the present invention is that the thickness of the middle slot hole pad is any one of 2 mm, 4 mm, 6 mm, 8 mm and 10 mm.

[0009] A further improvement of the technical solution of the present invention is that a buckle ring for fixing the polishing cloth is provided on the outer edge of the polishing disc.

[0010] A further improvement of the technical solution of the present invention is that the outer circle edge of the polishing disc and the inner circle edge of the retaining ring are both processed with a taper, and the inner diameter and taper of the retaining ring match the outer diameter and taper of the polishing disc.

[0011] A further improvement of the technical solution of the present invention is that the polishing disc rotating mechanism includes a three-phase asynchronous motor, a driving pulley, a V-belt, a driven pulley and a main shaft, and the three-phase asynchronous motor drives the polishing disc installed on the main shaft to rotate through the driving pulley, the V-belt and the driven pulley.

[0012] A further improvement of the technical solution of the present invention is that the electrolyte circulation system unit includes a liquid collecting tank, and a filter, an acid-resistant pump, a flow regulating valve and a nozzle are sequentially arranged on the outlet pipe of the liquid collecting tank, a splash guard is arranged around the polishing disk on the support frame, and the height of the splash guard is higher than the sample, and a reflux pipe is arranged at the bottom of the splash guard, and the outlet of the reflux pipe after passing through the support frame is arranged above the liquid collecting tank.

[0013] A further improvement of the technical solution of the present invention is: a mechanical electrolytic composite pre-grinding method for a metallographic sample, using the above-mentioned mechanical electrolytic composite pre-grinding device, the specific process is as follows: During pre-grinding, the electrolytic power supply is turned on, and the three-phase asynchronous motor drives the polishing disc installed on the main shaft to rotate through the driving pulley, V-belt, and driven pulley. At the same time, the electrolyte in the liquid collection tank is sprayed through the nozzle at the contact entrance of the sample and the polishing cloth. The electrolyte flows to the polishing disc through the through hole of the middle slot hole pad. The current passes through the anode of the electrolytic power supply, the sample, the electrolyte, the polishing disc, the center pin shaft, and the collector ring, and flows back to the cathode of the electrolytic power supply. The electrolytic current is controlled by adjusting the thickness of the middle slot hole pad, the pitch of the spiral groove, and the angle between the through hole and the center of the polishing disc. The sample acts as an anode and loses electrons to be corroded. The polishing disk acts as a cathode. The electrolyte obtains electrons and reduces to gas, which is centrifugally thrown out along the spiral grooves of the middle slot pad. The electrolytic corrosion products are thrown away by the polishing cloth, some of which adhere to the polishing cloth, and some of which are centrifugally thrown out and thrown onto the splash shield, and then flow back to the collection tank through the reflux pipe. The electrolyte in the collection tank is filtered (9-2) to remove the precipitate of the electrolytic corrosion products, and then it is drawn by an acid-resistant pump and sprayed again at the polishing inlet of the sample through a flow regulating valve and a nozzle. After a period of time, the sample reveals a fresh surface and the pre-grinding is completed.

[0014] The further improvement of the technical solution of the present invention is that the specific process of controlling the electrolytic current by adjusting the thickness of the middle slotted pad, the pitch of the spiral groove and the angle between the through hole and the center of the polishing disk is as follows: A series of intermediate slot hole pads are manufactured, with a thickness adjustment range of 2mm, 4mm, 6mm, 8mm or 10mm; the pitch of the spiral groove is 5mm, 10mm or 15mm, and the angle adjustment range of adjacent through holes relative to the center of the polishing disk is 5°, 10°, 15°, 20°, 25° or 30°. The electrolysis current is reduced by increasing the thickness of the intermediate slot hole pad, the pitch of the spiral groove, and the angle between adjacent through holes and the center of the polishing disk, and the electrolysis current is increased by reducing the thickness of the intermediate slot hole pad, the pitch of the spiral groove, and the angle between adjacent through holes and the center of the polishing disk.

[0015] Due to the adoption of the above technical solution, the technical progress achieved by the present invention is: During pre-grinding, the present invention sprays electrolyte at the contact entrance between the sample and the polishing cloth, and the electrolyte flows to the polishing disk through the through hole of the middle slotted pad in the middle, and the current flows back to the cathode of the electrolytic power source through the anode of the electrolytic power source, the sample, the electrolyte, the polishing disk, the center pin, and the collector ring. The electrolytic current is controlled by adjusting the thickness of the middle slotted pad, the pitch of the spiral groove, and the angle between the through hole and the center of the polishing disk. The sample loses electrons and is corroded as the anode. The polishing disk serves as the cathode, and the electrolyte obtains electrons, reduces gas, and is centrifugally thrown out along the spiral groove of the middle slotted pad. The corrosion product is thrown away by the polishing cloth, part of it adheres to the polishing cloth, and part of it is centrifugally thrown out, and the sample exposes a fresh surface. The present invention uses a high-speed rotating polishing cloth to take away the corrosion product, so as to achieve the purpose of rapid pre-grinding, and solves the problem that the metallographic sandpaper consumption is large and the time-consuming process is long when the metallographic sample of conventional wear-resistant metal materials is pre-grinded. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall structure of the mechanical electrolytic composite pre-grinding device for metallographic samples of the present invention; Figure 2 yes Figure 1 Schematic diagram of some structures in ; Figure 3 This is a schematic diagram of the structure of the middle slotted pad of the present invention; Among them, 1. sample, 2. sample fixture, 3. electrolytic power supply, 4. center pin, 5. collector ring, 6. middle slotted plate, 6-1. spiral groove, 6-2. through hole, 6-3. center hole, 7. buckle, 8. polishing plate, 9-1. liquid collecting tank, 9-2. filter, 9-3. acid-resistant pump, 9-4. flow regulating valve, 9-5. nozzle, 9-6. splash guard, 9-7. reflux pipe, 10-1. three-phase asynchronous motor, 10-2. driving pulley, 10-3. V-belt, 10-4. driven pulley, 10-5 spindle. DETAILED DESCRIPTION

[0017] The present invention is further described in detail below in conjunction with embodiments: like Figures 1 to 3 As shown, a mechanical electrolytic composite pre-grinding device for metallographic samples includes a polishing disc rotating mechanism, an electrolyte circulation system unit and a support frame 11. A polishing disc 8 is arranged above the support frame 11. The polishing disc 8 is made of a metal material with good conductivity and corrosion resistance. The polishing disc rotating mechanism includes a three-phase asynchronous motor 10-1, a driving pulley 10-2, a V-belt 10-3, a driven pulley 10-4 and a main shaft 10-5. The three-phase asynchronous motor 10-1 drives the polishing disc 8 installed on the main shaft 10-5 to rotate through the driving pulley 10-2, the V-belt 10-3 and the driven pulley 10-4.

[0018] A threaded hole is processed in the center of the polishing disc 8 for installing the pin 4. The center pin 4 is covered with an intermediate slotted pad 6, and the thickness of the intermediate slotted pad 6 is any one of 2mm, 4mm, 6mm, 8mm and 10mm. Specifically, a circular hole is processed in the center of the intermediate slotted pad 6 so as to pass the center pin 4. The intermediate slotted pad 6 is made of an electrically insulating material, which separates the sample 1 from the polishing disc 8 to prevent the sample 1 and the polishing disc 8 from short-circuiting after the polishing cloth is damaged, thereby burning the sample 1 and the equipment. One side of the intermediate slotted pad 6 is processed with a trapezoidal cross-section spiral groove 6-1 from the center to the edge, and the bottom of the spiral groove 6-1 is processed with equidistant through holes 6-2, and the groove surface fits the polishing disc 8, and the other side of the intermediate slotted pad 6 is pressed with a polishing cloth, and a buckle 7 for fixing the polishing cloth is provided on the outer edge of the polishing disc 8. The outer edge of the outer circle of the polishing disc 8 and the inner edge of the buckle 7 are both processed with tapers, and the inner diameter and taper of the buckle 7 match the outer diameter and taper of the polishing disc 8. After the polishing cloth is cut in the center, it passes through the center pin 4 and is pressed on the middle slotted pad 6. After smoothing, the edge of the polishing cloth is pressed on the outer circle of the polishing disc 8 with a buckle 7 to ensure that the polishing cloth is not wrinkled. The electrolyte circulation system unit includes a liquid collecting tank 9-1, and the outlet pipe of the liquid collecting tank 9-1 is sequentially provided with a filter 9-2, an acid-resistant pump 9-3, a flow regulating valve 9-4 and a nozzle 9-5. A splash shield 9-6 is provided around the polishing disc 8 on the support frame 11, and the height of the splash shield 9-6 is higher than the sample 1. A reflux pipe 9-7 is provided at the bottom of the splash shield 9-6, and the outlet of the reflux pipe 9-7 after passing through the support frame 11 is provided above the liquid collecting tank 9-1. During polishing, the electrolyte enters from the through hole 6-2, contacts with the polishing disc 8, forms a loop, and is then thrown out from the spiral groove 6-1 and returns to the liquid collecting tank 9-1.

[0019] The center pin 4 is used to connect the polishing disc 8 and the collector ring 5. The lower end is threaded, the upper end diameter matches the aperture of the collector ring 5, and the middle diameter is slightly larger than the upper end diameter. A radial threaded hole is drilled in the middle of the center pin 4 to install the terminal for fixing the collector ring 5 rotor output line. The collector ring 5 adopts a low-voltage and high-current type. The stator output line is connected to the cathode of the electrolytic power supply 3, and the rotor output line is installed on the terminal of the center pin. The anode of the electrolytic power supply 3 is connected to the sample fixture 2 that clamps the sample 1, and the sample 1 is in contact with the polishing cloth above the middle slot pad 6. The electrolytic power supply 3 adopts an isolated transformer DC output power supply, which can adjust the output voltage.

[0020] The sample 1 is mounted on the sample fixture 2. The sample fixture 2 is a prior art and can be clamped in various ways such as a ball screw linear guide rail module and a robot arm to achieve self-aligning loading.

[0021] A mechanical electrolytic composite pre-grinding method for metallographic samples, using the above-mentioned mechanical electrolytic composite pre-grinding device, the specific process is as follows: During pre-grinding, the electrolytic power supply 3 is turned on, and the three-phase asynchronous motor 10-1 drives the polishing disc 8 installed on the main shaft 10-5 to rotate through the driving pulley 10-2, the V-belt 10-3, and the driven pulley 10-4. At the same time, the electrolyte in the liquid collecting tank 9-1 is sprayed on the contact entrance of the sample 1 and the polishing cloth through the nozzle 9-5, and the electrolyte flows to the polishing disc 8 through the through hole 6-2 of the middle slot hole pad 6. The current passes through the anode of the electrolytic power supply 3, the sample 1, the electrolyte, the polishing disc 8, the center pin 4, and the collector ring 5, and flows back to the cathode of the electrolytic power supply 3. By adjusting the thickness of the middle slot hole pad 6 and the pitch of the spiral groove 6-1 and the through hole 6-2 relative to the center of the polishing disc, the electrolytic power supply 3 is adjusted. The angle controls the electrolytic current. Specifically, a series of middle slot hole pads 6 are made, and the thickness adjustment range is 2mm, 4mm, 6mm, 8mm or 10mm; the pitch of the spiral groove 6-1 is 5mm, 10mm or 15mm, and the angle adjustment range of adjacent through holes 6-2 relative to the center of the polishing disk is 5°, 10°, 15°, 20°, 25° or 30°. The electrolytic current is reduced by increasing the thickness of the middle slot hole pad 6, the pitch of the spiral groove 6-1, and the angle of adjacent through holes 6-2 relative to the center of the polishing disk, and the electrolytic current is increased by reducing the thickness of the middle slot hole pad 6, the pitch of the spiral groove 6-1, and the angle of adjacent through holes 6-2 relative to the center of the polishing disk.

[0022] The sample 1 acts as an anode and loses electrons to be corroded, the polishing disc 8 acts as a cathode, the electrolyte obtains electrons, reduces gas, and is centrifugally thrown out along the spiral groove 6-1 of the middle slot hole pad 6, the electrolytic corrosion product is thrown away by the polishing cloth, part of it adheres to the polishing cloth, and part of it is centrifugally thrown out and thrown onto the splash shield 9-6, and flows back to the liquid collecting tank 9-1 through the reflux pipe 9-7, the electrolyte in the liquid collecting tank 9-1 is removed by the filter 9-2 after the precipitate of the electrolytic corrosion product is removed, and then it is drawn by the acid-resistant pump 9-3 and sprayed again at the polishing inlet of the sample 1 through the flow regulating valve 9-4 and the nozzle 9-5, and after a period of time, the sample 1 exposes a fresh surface, and the pre-grinding is completed. The present invention adopts a high-speed rotating polishing cloth to take away the corrosion products, so as to achieve the purpose of rapid pre-grinding, and solves the problem that the metallographic sandpaper consumption is large and the time-consuming process is long when the metallographic sample of conventional wear-resistant metal materials is pre-grinded.

Claims

1. A mechanical electrolytic composite pre-grinding device for metallographic samples, comprising a polishing disc rotating mechanism and an electrolyte circulation system unit, characterized in that: It also comprises a support frame (11), a polishing disc (8) is arranged above the support frame (11), the polishing disc rotating mechanism is rotatably connected to the polishing disc (8), a threaded hole is drilled in the center of the polishing disc (8) and a center pin (4) is threadedly connected to the threaded hole, an intermediate slotted hole pad (6) is sleeved on the center pin (4), a trapezoidal cross-section spiral groove (6-1) from the center to the edge is machined on one side of the intermediate slotted hole pad (6), and equidistant through holes (6-2) are machined at the bottom of the spiral groove (6-1), and the spiral groove (6-1) is provided with a plurality of spiral holes (6-2) extending from the center to the edge of the spiral groove (6). The groove surface of the groove (6-1) fits the polishing disk (8), the other surface of the middle slot hole pad (6) is pressed with a polishing cloth, the upper end of the center pin (4) is installed with a collector ring (5), the stator output line of the collector ring (5) is connected to the cathode of the electrolytic power supply (3), the anode of the electrolytic power supply (3) is connected to the sample clamp (2) clamping the sample (1), the sample (1) is in contact with the polishing cloth above the middle slot hole pad (6), and the nozzle (9) of the electrolyte circulation system unit is arranged on the side of the sample (1).

2. The mechanical electrolytic composite pre-grinding device for metallographic samples according to claim 1, characterized in that: The electrolysis power supply (3) adopts an isolated transformer DC output power supply.

3. The mechanical electrolytic composite pre-grinding device for metallographic samples according to claim 1, characterized in that: A radial threaded hole is drilled in the middle of the upper end of the center pin shaft (4), and the radial threaded hole is used to install a fixed wiring terminal, and the rotor output line of the collector ring (5) is installed on the wiring terminal.

4. The mechanical electrolytic composite pre-grinding device for metallographic samples according to claim 1, characterized in that: The thickness of the middle slotted hole pad (6) is any one of 2 mm, 4 mm, 6 mm, 8 mm and 10 mm.

5. The mechanical electrolytic composite pre-grinding device for metallographic samples according to claim 1, characterized in that: A buckle ring (7) for fixing the polishing cloth is provided on the outer edge of the polishing disc (8).

6. The mechanical electrolytic composite pre-grinding device for metallographic samples according to claim 5, characterized in that: The outer circular edge of the polishing disc (8) and the inner circular edge of the buckle ring (7) are both processed with a taper, and the inner diameter and taper of the buckle ring (7) match the outer diameter and taper of the polishing disc (8).

7. The mechanical electrolytic composite pre-grinding device for metallographic samples according to claim 1, characterized in that: The polishing disc rotating mechanism comprises a three-phase asynchronous motor (10-1), a driving pulley (10-2), a V-belt (10-3), a driven pulley (10-4) and a main shaft (10-5); the three-phase asynchronous motor (10-1) drives the polishing disc (8) mounted on the main shaft (10-5) to rotate via the driving pulley (10-2), the V-belt (10-3) and the driven pulley (10-4).

8. The mechanical electrolytic composite pre-grinding device for metallographic samples according to claim 1, characterized in that: The electrolyte circulation system unit comprises a liquid collecting tank (9-1), wherein a filter (9-2), an acid-resistant pump (9-3), a flow regulating valve (9-4) and a nozzle (9-5) are sequentially arranged on an outlet pipe of the liquid collecting tank (9-1), a splash shield (9-6) is arranged around the polishing disc (8) on the support frame (11), and the height of the splash shield (9-6) is higher than the sample (1), and a return pipe (9-7) is arranged at the bottom of the splash shield (9-6), and the outlet of the return pipe (9-7) after passing through the support frame (11) is arranged above the liquid collecting tank (9-1).

9. A mechanical electrolytic composite pre-grinding method for metallographic samples, characterized in that: The mechanical electrolytic composite pre-grinding device of any one of claims 1 to 8 is adopted, and the specific process is as follows: During pre-grinding, the electrolytic power supply (3) is turned on, and the three-phase asynchronous motor (10-1) drives the polishing disc (8) mounted on the main shaft (10-5) to rotate through the driving pulley (10-2), the V-belt (10-3), and the driven pulley (10-4). At the same time, the electrolyte in the liquid collecting tank (9-1) is sprayed through the nozzle (9-5) on the contact entrance of the sample (1) and the polishing cloth. The electrolyte flows to the polishing disc (8) through the through hole (6-2) of the middle slot hole pad (6). The current flows back to the cathode of the electrolytic power supply (3) through the anode of the electrolytic power supply (3), the sample (1), the electrolyte, the polishing disc (8), the center pin (4), and the collector ring (5). By adjusting the thickness of the middle slot hole pad (6) and the pitch of the spiral groove (6-1) and the through hole (6-2), the current is adjusted. 2) The angle relative to the center of the polishing disk controls the electrolytic current. The sample (1) acts as an anode and loses electrons to be corroded. The polishing disk (8) acts as a cathode. The electrolyte obtains electrons and reduces to gas. The gas is centrifugally ejected along the spiral groove (6-1) of the middle slot hole pad (6). The electrolytic corrosion products are thrown away by the polishing cloth, part of which adheres to the polishing cloth, and part of which is centrifugally ejected and thrown onto the splash shield (9-6). The electrolytic corrosion products flow back to the liquid collecting tank (9-1) through the reflux pipe (9-7). The electrolyte in the liquid collecting tank (9-1) is filtered (9-2) to remove the sediment of the electrolytic corrosion products. The electrolyte is then drawn by the acid-resistant pump (9-3) and sprayed again at the polishing inlet of the sample (1) through the flow regulating valve (9-4) and the nozzle (9-5). After a period of time, the sample (1) reveals a fresh surface, and the pre-grinding is completed.

10. The method for mechanical electrolytic composite pre-grinding of a metallographic sample according to claim 8, characterized in that: The specific process of controlling the electrolytic current by adjusting the thickness of the middle slotted pad (6), the pitch of the spiral groove (6-1), and the angle between the through hole (6-2) and the center of the polishing disk is as follows: A series of intermediate slot hole pads (6) are manufactured, wherein the thickness is adjusted within a range of 2 mm, 4 mm, 6 mm, 8 mm or 10 mm; the pitch of the spiral groove (6-1) is 5 mm, 10 mm or 15 mm; the angle between adjacent through holes (6-2) and the center of the polishing disk is adjusted within a range of 5°, 10°, 15°, 20°, 25° or 30°; the electrolysis current is reduced by increasing the thickness of the intermediate slot hole pad (6), the pitch of the spiral groove (6-1) and the angle between adjacent through holes (6-2) and the center of the polishing disk; and the electrolysis current is increased by reducing the thickness of the intermediate slot hole pad (6), the pitch of the spiral groove (6-1) and the angle between adjacent through holes (6-2) and the center of the polishing disk.

Images