Graphite taper hole composite processing system and process

Abstract

The present application belongs to the field of graphite material precision machining, and particularly relates to a graphite taper hole compound machining system and process. The system comprises: an automatic milling device, which performs automatic milling machining on graphite workpieces installed in a clamp groove to process a prefabricated taper hole with a size allowance on the graphite workpiece; a secondary dust collection device, which performs secondary dust collection on the inside of the clamp groove; an electric spark machining device, which performs electric spark precision machining forming on the prefabricated taper hole; a workbench, which supports the clamp groove when machining the taper hole and is arranged across the automatic milling device, the secondary dust collection device and the electric spark machining device; a clamp groove, which is a groove body structure and internally installed with a clamp for clamping the graphite workpiece; a clamp groove walking mechanism, which drives the clamp groove to walk on the workbench and automatically switch between the devices; and a liquid injection device, which injects liquid medium for electric spark machining into the clamp groove. The present application can realize full automation through one-time clamping and can guarantee machining quality and control pollution.

Description

Technical Field

[0001] This invention belongs to the field of precision machining of graphite materials, and specifically relates to a composite machining system and process for machining high-precision, non-destructive tapered holes on graphite workpieces. Background Technology

[0002] Graphite is a non-metallic element with unique physical and chemical properties. Due to its conductivity, high-temperature stability, chemical stability, and corrosion resistance, it is widely used in many fields. With the continuous development of modern industry, graphite products are increasingly used in numerous sectors, such as electronics, machinery, and chemicals. Among these, graphite products with tapered pores hold an important position in specific industrial applications due to their unique structure and properties.

[0003] However, existing processing techniques for graphite tapered holes (such as funnel-shaped guide holes) suffer from insufficient precision, low efficiency, and high cost, severely restricting the quality and market competitiveness of related products. The processing of such holes faces two major challenges: First, graphite is highly brittle, and traditional machining methods (especially milling) easily produce defects such as chipping and micro-cracks at the hole edges; second, for tapered holes with composite shapes (such as a tapered upper part with an upward-facing bottom edge and a circular straight hole at the bottom), a single processing technique cannot simultaneously guarantee shape accuracy, surface quality, and damage-free operation.

[0004] The current mainstream approach is step-by-step machining. First, roughing and semi-finishing are performed on a CNC milling machine using a single or combination of cutting heads, leaving a margin for machining. Then, the workpiece is disassembled, cleaned, and re-clamped onto an electrical discharge machining (EDM) machine for finishing using a shaped electrode. While this approach ensures final quality, it suffers from positioning errors due to multiple clamping operations, low efficiency, and the environmental and health hazards posed by graphite dust during transfer cannot be ignored.

[0005] Therefore, there is an urgent need for an automated solution that can integrate multiple processes, complete all processing in a single setup, and effectively address environmental and efficiency issues. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a graphite tapered hole composite machining system and process that integrates milling, secondary dust collection and electrical discharge machining, so as to achieve high-precision, high-efficiency and pollution-free graphite tapered hole machining.

[0007] The technical solution of the present invention is as follows: A composite machining system for graphite tapered holes, comprising: Automatic milling equipment is used to automatically mill graphite workpieces mounted in a fixture slot to machine pre-fabricated tapered holes with dimensional allowances on the graphite workpieces. Secondary dust collection equipment is used for secondary dust collection inside the fixture slot; Electrical discharge machining equipment is used to perform electrical discharge finishing on pre-made tapered holes. A worktable, used to support the fixture slot when machining tapered holes, is set across the automatic milling equipment, secondary dust extraction equipment and electrical discharge machining equipment; The fixture slot is a groove structure with fixtures for holding graphite workpieces installed inside. The fixture slot traveling mechanism is used to drive the fixture slot to travel on the worktable and automatically switch between automatic milling equipment, secondary dust collection equipment and electrical discharge machining equipment. Liquid injection equipment is used to inject liquid media for electrical discharge machining into the fixture slot.

[0008] Furthermore, in the above-mentioned graphite tapered hole composite machining system, the automatic milling equipment is a CNC milling machine or a CNC machining center.

[0009] Furthermore, the automatic milling equipment is equipped with a synchronous dust extraction component.

[0010] Furthermore, in the above-mentioned graphite tapered hole composite processing system, the secondary dust collection device is an automatic three-dimensional dust collection device.

[0011] Furthermore, in the aforementioned graphite tapered hole composite machining system, the fixture groove integrates a circulating filter assembly that can move with it, used to circulate and purify the liquid medium in the fixture groove during electrical discharge machining.

[0012] Furthermore, in the above-mentioned graphite tapered hole composite machining system, the bottom of the fixture groove is provided with a drain port, and the drain port is equipped with an automatic valve.

[0013] Furthermore, in the aforementioned graphite tapered hole composite machining system, the liquid injection device is located on one side of the electrical discharge machining equipment.

[0014] This invention also provides a composite machining process for graphite tapered holes, employing the composite machining system described above, and includes the following steps: S1. A fixture that clamps the graphite workpiece to be processed into the fixture slot; S2. An automatic milling machine is used to automatically mill the graphite workpiece installed in the fixture slot to machine a pre-fabricated tapered hole with dimensional allowance on the graphite workpiece. S3. Start the fixture slot walking mechanism to drive the fixture slot to move on the workbench, switch to the secondary dust collection station, and use the secondary dust collection equipment to perform secondary dust collection inside the fixture slot. S4. Start the fixture slot traveling mechanism to drive the fixture slot to travel on the worktable, switch to the EDM station, and use the EDM equipment to perform EDM finishing on the pre-made tapered hole. In this process, a liquid medium is injected into the fixture groove using a liquid injection device before the electrical discharge machining is performed. S5. After the electrical discharge machining is completed, drain the liquid medium in the fixture slot, remove the graphite workpiece, start the fixture slot traveling mechanism to drive the fixture slot to travel on the worktable, and return to the automatic milling station. S6. Repeat steps S1-S5 to process the next graphite workpiece.

[0015] Furthermore, in the above-mentioned graphite tapered hole composite processing technology, the tapered hole comprises two parts: the upper part is a cone with the bottom edge facing upward, and the lower part is a circular straight hole. Furthermore, in the above-mentioned composite processing technology for graphite tapered holes, step S4, the injection of a liquid medium into the fixture groove via a liquid injection device before electrical discharge machining (EDM) finishing is: After the fixture slot is switched to the electrical discharge machining (EDM) station, a liquid medium is injected into the fixture slot through the liquid injection device located on one side of the EDM equipment.

[0016] The beneficial effects of this invention are as follows: Compared with the prior art, the advantages of the present invention are as follows: By adopting the solution of the present invention, the entire process can be automated in one clamping. Through the movable fixture slot and the traveling mechanism, the entire process of milling, secondary dust collection and EDM is completed in one clamping, eliminating repeated clamping errors, ensuring high machining accuracy (especially the coaxiality of the upper and lower holes), and greatly improving production efficiency.

[0017] The solution of this invention effectively controls environmental pollution. The integrated milling synchronous dust collection and secondary dust collection strictly limit the diffusion of graphite dust within the system, greatly improving the operating environment, protecting personnel health, and meeting the requirements of green manufacturing.

[0018] The solution of this invention can guarantee the final machining quality, combining the high efficiency of milling with the stress-free and high-precision advantages of electrical discharge machining. It is particularly suitable for machining complex holes in graphite materials that are prone to chipping, and can stably obtain undamaged, high-quality surfaces and edges.

[0019] The solution of this invention can achieve intensification and intelligence, integrating multiple devices and functions into one system, reducing the floor space required, and laying the foundation for digital and intelligent production through process-oriented automatic control. Attached Figure Description

[0020] In the attached diagram: Figure 1 This is a schematic cross-sectional view of a graphite workpiece with a tapered hole to be processed in an embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram of the graphite tapered hole composite processing scheme according to an embodiment of the present invention.

[0022] Figure 3 This is a schematic diagram of the graphite tapered hole composite machining system according to an embodiment of the present invention. Figure 1 (The fixture slot is in the automatic milling station).

[0023] Figure 4 This is a schematic diagram of the fixture groove structure according to an embodiment of the present invention.

[0024] Figure 5 This is a schematic diagram of a flexible door structure according to an embodiment of the present invention.

[0025] Figure 6 This is a schematic diagram of the graphite tapered hole composite machining system according to an embodiment of the present invention. Figure 2 (The fixture slot is located at the secondary dust collection station).

[0026] Figure 7 The structural principle of the graphite tapered hole composite machining system according to an embodiment of the present invention. Figure 3 (The fixture slot is located at the electrical discharge machining station).

[0027] The components represented by the various reference numerals in the diagram are: 1. Automatic milling equipment, 2. Secondary dust collection equipment, 3. Electrical discharge machining equipment, 4. Workbench, 5. Fixture slot, 6. Fixture slot traveling mechanism, 7. Liquid injection equipment, 8. Circulating filter assembly, 9. Drain outlet, 10. Temperature control drying assembly, 11. Synchronous dust collection assembly, 12. Sealing cover, 13. Fixture, 14. Graphite workpiece, 15. Tapered hole, 16. Milling cutter head, 17. Electrode head, 18. Liquid injection port, 19. Emptying box, 20. Flexible door. Detailed Implementation

[0028] Exemplary embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings. Example 1

[0029] like Figure 1 As shown, this embodiment takes the machining of a tapered hole 15 on a graphite workpiece 14 as an example to introduce a graphite tapered hole composite machining system and process.

[0030] Figure 1 The tapered hole 15 in the graphite workpiece 14 comprises two parts, an upper part being a tapered shape with the bottom edge facing upwards and a lower part being a circular straight hole. A graphite workpiece 14 may have one or more such tapered holes 15. For example, such tapered holes 15 can be used as flow guide holes for fluid passage in some precision graphite products.

[0031] See next. Figures 2 to 7This embodiment provides a graphite tapered hole composite machining system. The composite machining system first includes an automatic milling machine 1, which is used to automatically mill a graphite workpiece 14 installed in a fixture slot 5 to machine a prefabricated tapered hole with dimensional allowance on the graphite workpiece 14.

[0032] In this embodiment, the automatic milling equipment 1 is a CNC milling machine, equipped with a synchronous dust extraction component 11. Automatic milling is performed within a closed sealing cover 12 to prevent air pollution under dry milling conditions. The sealing cover 12 has a flexible door 20 on its side for the fixture slot 5 to enter and exit. Figure 5 As shown, the flexible door 20 has a flexible material along its opening edge to prevent collisions when the clamping slot 5 enters or exits.

[0033] The composite machining system also includes a secondary dust collection device 2, which is used to perform secondary dust collection inside the fixture slot 5 to thoroughly remove residual graphite dust. The main purpose of this step is to provide a good liquid medium injection environment for the subsequent electrical discharge machining. Therefore, the secondary dust collection device 2 is specially equipped with an automatic three-dimensional dust collection device with a multi-joint dust collection arm. Its multi-joint dust collection arm can go deep into the fixture slot 5 to perform powerful and all-round cleaning.

[0034] The composite machining system also includes an electrical discharge machining (EDM) device 3, which is used to perform EDM finishing on pre-made tapered holes. The spindle of the EDM device 3 is equipped with an electrode head 17 designed for the target tapered hole, and a liquid injection device 7 is located on one side of this station.

[0035] To achieve automated operation from milling to secondary dust collection and then to EDM in a single clamping process, the composite machining system is specially equipped with a fixture slot 5 and a fixture slot traveling mechanism 6. As a supporting foundation, the worktable 4 of the composite machining system spans across the aforementioned automatic milling equipment 1, secondary dust collection equipment 2 and EDM equipment 3, and is used to support the fixture slot 5 when machining tapered holes.

[0036] Specifically, see Figure 3 , Figure 4 , Figure 6 , Figure 7The fixture slot 5 is a tank containing a fixture 13 for clamping the graphite workpiece 14. It is connected to the pulse power supply of the electrical discharge machining (EDM) equipment 3 via a dedicated conductive path (not shown in the figure). The tank body is made of stainless steel and is electrically isolated from the fixture slot traveling mechanism 6 and the worktable 4 by an insulating bracket, ensuring that its potential is approximately the same as the workpiece potential during EDM to prevent stray discharge. The fixture slot 5 integrates a small circulating filter assembly 8, which contains a miniature oil pump and filter. This assembly circulates and purifies the liquid medium within the fixture slot 5 during EDM, maintaining its cleanliness. A drain port 9 with an automatic valve is located at the bottom for quickly draining the liquid medium after machining.

[0037] In this embodiment, the circulating filter assembly 8 is installed on the right side of the clamp slot 5, with an installation height equal to or slightly higher than the upper edge of the clamp slot 5. Its width is the same as, or slightly wider than, the clamp slot 5. The advantage of this arrangement is that... Figure 5 As shown, the flexible door 20 on the side of the sealing cover 12 of the automatic milling station can be an open opening without the need for automatic opening and closing, since the circulating filter assembly 8 is not lower than the fixture slot 5 in both the installation height and width directions. Figure 3 As shown, during milling, after the fixture slot 5 is precisely positioned, the circulating filter assembly 8 is positioned on the right side, extending into the flexible door 20 by a certain dimension. In this way, the opening can be closed by the cooperation between the circulating filter assembly 8 and the flexible door 20.

[0038] The fixture slot traveling mechanism 6 is a dedicated mechanism for driving the fixture slot 5 to travel on the worktable 4, ensuring that the fixture slot 5 can automatically switch and accurately position itself between the automatic milling equipment 1, the secondary dust collection equipment 2, and the electrical discharge machining equipment 3.

[0039] Figure 3 The diagram illustrates that the fixture slot traveling mechanism 6 can use a servo screw module. It can also be seen that the worktable 4 is equipped with a recessed moving guide rail. The insulating support of the fixture slot 5 can form a limiting and guiding cooperation with the moving guide rail and be driven by the servo screw module to move precisely on the worktable 4. Example 2

[0040] The following embodiment further illustrates the advantages of the present invention by introducing the composite processing technology.

[0041] Specifically, the composite processing system described in Example 1 above is used for composite processing, including the following steps: S1. The graphite workpiece 14 to be processed is clamped into the fixture 13 in the fixture slot 5.

[0042] S2. The graphite workpiece 14 installed in the fixture slot 5 is automatically milled using an automatic milling machine 1 according to a set program, and a pre-made tapered hole with dimensional allowance is machined on the graphite workpiece 14.

[0043] As an optional solution, in this embodiment, the milling cutter head 16 can be a ball end mill. The machining process is divided into two steps. First, the upper conical cavity is rough milled. The ball end mill starts from the upper surface of the graphite workpiece 14 and uses a layer milling strategy to process downward along the Z-axis. Each time it descends a layer, the XY cutting contour shrinks inward by one step until it reaches the bottom depth of the conical cavity, forming a microscopically stepped conical blank with the bottom edge facing upward. Then, the lower circular straight hole is machined. At the bottom of the conical cavity, the ball end mill continues to use a drilling milling strategy to process downward along the Z-axis, while making a fixed diameter circular motion in the XY plane to machine the circular straight hole to the final depth.

[0044] If a multi-spindle CNC milling machine or a CNC machining center with a tool magazine and tool changing mechanism is used, you can first use a flat-end mill or twist drill to machine the circular straight hole, and then use a ball end mill to rough mill the tapered cavity according to the layered milling strategy of the CAM software program.

[0045] The above should be regarded as an example of the machining procedure for the tapered hole 15. Depending on the type of milling equipment, cutting tool, and roughing accuracy selected, other procedures can also be used to machine the tapered hole 15 without departing from the spirit of the present invention. The dust collection component 11 works continuously throughout the entire machining process.

[0046] When multiple tapered holes 15 need to be machined on a graphite workpiece 14, generally only one positioning is needed, and the milling cutter head 16 processes them one by one. After all the tapered holes 15 have been machined, the next process can be started.

[0047] S3. Start the clamp slot walking mechanism 6 to drive the clamp slot 5 to move on the workbench 4, switch to the secondary dust collection station, and use the secondary dust collection equipment 2 to perform secondary dust collection on the inside of the clamp slot 5 to thoroughly clean it and remove all residual dust.

[0048] S4. Start the fixture groove traveling mechanism 6 to drive the fixture groove 5 to travel on the worktable 4. After switching to the EDM station and accurately positioning, inject liquid medium kerosene (or other EDM fluid) into the fixture groove 5 through the liquid injection device 7 located on one side of the EDM equipment 3 until the graphite workpiece 14 is submerged. Then the pre-made tapered hole can be precision shaped by EDM using the EDM equipment 3.

[0049] In this embodiment, the injection device 7 is an injection tank with a metering valve. The height of its injection port 18 is higher than that of the fixture slot. This installation method simplifies the power injection pipeline. It should be noted that although the injection device 7 is set on one side of the EDM equipment 3 in this embodiment, this is only a preferred layout. It facilitates injection after the fixture slot 5 is in place and also facilitates subsequent working cooperation with the drain tank 19. The liquid medium in the drain tank 19 is purified and pumped back to the injection device 7 for reuse. If there are other considerations, the liquid medium can also be injected at other positions or times between the completion of the secondary dust extraction and the EDM finishing process. Such modifications should be within the scope of protection of this patent.

[0050] The liquid injection device 7 of the present invention has necessary controls such as flow sensor and liquid level sensor. The main control PLC further integrates a counter that records the frequency of the liquid medium pumped back to the liquid injection device 7 in the empty box 19 and a timer that records the running time of the circulating filter component 8. The main control system provides monitoring and early warning of the effective use status of the liquid medium based on the pumping frequency and pumping volume data of the liquid medium and the running time of the circulating filter component 8, combined with the empirical contamination model preset for the liquid medium.

[0051] In this embodiment, the shape of the electrode head 17 is complementary to the cavity required by the graphite workpiece 14. It is an integral electrode, with the lower cylindrical part used for finishing the straight hole section, and the cone angle of the upper tapered part consistent with the cone angle of the target tapered cavity. After the fixture groove 5 is filled with kerosene, the spindle of the EDM equipment 3 drives the electrode head 17 to rotate and feed downward. EDM is performed by servo feed controlled by the CNC system, ultimately obtaining a smooth, precise, and chipped composite tapered hole. The circulating filter assembly 8 integrated on the fixture groove 5 works continuously throughout the process to keep the liquid medium clean.

[0052] S5. After the electrical discharge machining is completed, the electrode head 17 is lifted, the automatic valve of the drain port 9 is opened, the kerosene in the fixture slot 5 is drained into the drain box 19 set below the drain port 9, the machined graphite workpiece 14 is taken out, the fixture slot traveling mechanism 6 is started to drive the fixture slot 5 to travel on the worktable 4 and return to the automatic milling station.

[0053] In addition, such as Figure 4 As shown, in this embodiment, the sidewall and bottom of the fixture slot 5 (or only the sidewall or bottom) are provided with a temperature-controlled drying component 10, which is used to quickly dry the fixture slot after draining the liquid to prepare for the next cycle of milling. In step S5, during the process of the fixture slot 5 returning to the automatic milling station and / or after the fixture slot 5 returns to the automatic milling station, the temperature-controlled drying component 10 is used to dry the fixture slot 5 by temperature control. In this embodiment, the temperature-controlled drying component 10 is preferably an electric heating component, which can control the temperature more precisely than hot air.

[0054] S6. Repeat steps S1-S5 to process the next graphite workpiece 14.

Claims

1. A composite machining system for graphite tapered holes, characterized in that, include: An automatic milling machine (1) is used to automatically mill a graphite workpiece (14) installed in a fixture slot (5) to produce a prefabricated tapered hole with dimensional allowance on the graphite workpiece (14). The automatic milling machine (1) is equipped with a synchronous dust collection assembly (11). Secondary dust collection equipment (2) is used to perform secondary dust collection inside the clamping slot (5); Electrical discharge machining equipment (3) is used to perform electrical discharge finishing on pre-made tapered holes; A worktable (4) is used to support a fixture slot (5) when machining tapered holes, and is set across the automatic milling equipment (1), the secondary dust collection equipment (2) and the electrical discharge machining equipment (3); The clamping groove (5) is a groove structure, and a clamp (13) for clamping graphite workpiece (14) is installed inside. A drain port (9) is provided at the bottom of the clamping groove (5), and an automatic valve is provided at the drain port. The fixture slot traveling mechanism (6) is used to drive the fixture slot (5) to travel on the worktable (4) and automatically switch between the automatic milling equipment (1), the secondary dust collection equipment (2) and the electrical discharge machining equipment (3); Liquid injection device (7) is used to inject liquid medium for electrical discharge machining into fixture groove (5); The fixture groove (5) is integrated with a circulating filter assembly (8) that can move with it, which is used to circulate and purify the liquid medium in the fixture groove (5) during electrical discharge machining. The fixture (13) is connected to the pulse power supply of the electrical discharge machining equipment (3) through a conductive path; Automatic milling is performed inside a closed sealing cover (12), and a flexible door (20) is provided on the side of the sealing cover (12), with an opening provided in the flexible door (20); During milling, once the fixture slot (5) is precisely positioned, the circulating filter assembly (8) is positioned at a certain size extending into the flexible door (20) on the right side. In this way, the opening can be closed by the cooperation between the circulating filter assembly (8) and the flexible door (20).

2. The graphite tapered hole composite machining system as described in claim 1, characterized in that, The automatic milling equipment (1) is a CNC milling machine or a CNC machining center.

3. The graphite tapered hole composite machining system as described in claim 1, characterized in that, The secondary vacuuming device (2) is an automatic three-dimensional vacuuming device.

4. The graphite tapered hole composite machining system as described in claim 1, characterized in that, The liquid injection device (7) is located on one side of the electrical discharge machining device (3).

5. A composite machining process for graphite tapered holes, employing the composite machining system described in any one of claims 1-4, characterized in that, Including the following steps: S1. The graphite workpiece (14) to be processed is clamped into the fixture (13) in the fixture slot (5). S2. The graphite workpiece (14) installed in the fixture slot (5) is automatically milled using an automatic milling machine (1) to produce a prefabricated tapered hole with dimensional allowance on the graphite workpiece (14). S3. Start the clamp slot walking mechanism (6) to drive the clamp slot (5) to walk on the workbench (4), switch to the secondary dust collection station, and use the secondary dust collection equipment (2) to perform secondary dust collection inside the clamp slot (5). S4. Start the fixture slot walking mechanism (6) to drive the fixture slot (5) to walk on the worktable (4), switch to the electrical discharge machining station, and use the electrical discharge machining equipment (3) to perform electrical discharge finishing on the pre-made tapered hole. Before the electrical discharge machining process, a liquid medium is injected into the fixture groove (5) through a liquid injection device (7); S5. After the electrical discharge machining is completed, drain the liquid medium in the fixture slot (5), take out the graphite workpiece (14), start the fixture slot walking mechanism (6) to drive the fixture slot (5) to walk on the worktable (4) and return to the automatic milling station. S6. Repeat steps S1-S5 to process the next graphite workpiece (14).

6. The composite processing technology for graphite tapered holes as described in claim 5, characterized in that, The tapered hole comprises two parts: the upper part is a cone with the bottom edge facing upwards, and the lower part is a circular straight hole.

7. The composite processing technology for graphite tapered holes as described in claim 5, characterized in that, In step S4, the process of injecting a liquid medium into the fixture groove (5) via the liquid injection device (7) before performing electrical discharge machining is as follows: When the fixture slot (5) is switched to the electrical discharge machining station, liquid medium is injected into the fixture slot (5) through the liquid injection device (7) located on one side of the electrical discharge machining equipment (3).

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