Graphite taper hole combined machining system and process

Abstract

The invention belongs to the field of graphite material precision machining, and particularly relates to a graphite taper hole combined machining system and process, and the system comprises an automatic milling device which is used for automatically milling a graphite workpiece mounted in a clamp groove and machining a prefabricated taper hole with size allowance on the graphite workpiece; the secondary dust collection equipment is used for carrying out secondary dust collection on the interior of the clamp groove; the electric spark machining equipment is used for carrying out electric spark finish machining forming on the prefabricated taper hole; the workbench is used for supporting the clamp groove when the taper hole is machined, and is arranged across the automatic milling equipment, the secondary dust collection equipment and the electric spark machining equipment; the clamp groove is of a groove body structure, and a clamp used for clamping a graphite workpiece is installed in the clamp groove; the clamp groove walking mechanism drives the clamp groove to walk on the workbench, and automatic switching between equipment is achieved; and the liquid injection equipment injects a liquid medium for electric spark machining into the clamp groove. Full-process automation can be achieved through one-time clamping, the machining quality can be guaranteed, and pollution can be controlled.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of precision mechanical processing of graphite materials, and particularly relates to a composite processing system and process for high-precision and non-damage taper hole processing on a graphite material workpiece. BACKGROUND

[0002] Graphite is a non-metallic element with special 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 widely used in many fields, such as electronics, machinery, and chemical industry. Among them, graphite products with taper holes have an important position in specific industrial applications due to their unique structure and performance.

[0003] However, the existing graphite taper hole (such as funnel-shaped flow guide hole) processing technology has problems such as insufficient precision, low efficiency, and high cost, which seriously restricts the quality and market competitiveness of related products. The processing of such holes faces two major challenges: first, graphite has high brittleness, and traditional mechanical processing (especially milling) is prone to defects such as edge collapse and micro-cracks at the hole edge; second, for composite-shaped taper holes (such as the upper part being a tapered shape with the bottom edge facing up and the lower part being a circular straight hole), a single processing technology cannot simultaneously ensure shape accuracy, surface quality, and non-damage requirements.

[0004] The current mainstream solution is step-by-step processing, which first uses a single or combined tool head on a numerical control milling machine for rough and semi-precision machining, leaving a margin, then disassembles, cleans, and re-clamps the workpiece to an electric discharge (EDM) machine, and uses a shaped electrode for precision machining. Although this solution can ensure the final quality, it has positioning errors caused by multiple clamping, low efficiency, and environmental and health hazards of graphite dust during transfer.

[0005] Therefore, there is an urgent need for an automated solution that integrates multiple processes, completes all processing with one clamping, and effectively solves environmental and efficiency problems. SUMMARY

[0006] The present application aims to overcome the shortcomings of the prior art and provide a graphite taper hole composite processing system and process that integrates milling, secondary dust collection, and electric discharge machining to achieve high-precision, high-efficiency, and pollution-free graphite taper hole processing.

[0007] The technical solution of the present application is as follows: A graphite taper hole composite processing system, comprising: An automatic milling device for automatically milling a graphite workpiece installed in a clamp slot to process a preformed taper hole with a size margin on the graphite workpiece; Secondary dust suction equipment for secondary dust suction inside the jig groove; Electric spark machining equipment for electric spark finishing forming of the prefabricated tapered hole; Workbench for supporting the jig groove when machining the tapered hole, which is arranged across the automatic milling equipment, the secondary dust suction equipment and the electric spark machining equipment; The jig groove is a groove structure, and a jig for clamping the graphite workpiece is arranged inside the jig groove. The jig groove walking mechanism is used to drive the jig groove to walk on the workbench and automatically switch between the automatic milling equipment, the secondary dust suction equipment and the electric spark machining equipment. Liquid injection equipment for injecting liquid medium for electric spark machining into the jig groove.

[0008] Further, the automatic milling equipment of the graphite tapered hole composite machining system is a numerical control milling machine or a numerical control machining center.

[0009] Further, the automatic milling equipment is provided with a synchronous dust suction assembly.

[0010] Further, the graphite tapered hole composite machining system, the secondary dust suction equipment is an automatic three-dimensional dust suction equipment.

[0011] Further, the graphite tapered hole composite machining system, the jig groove is integrated with a circulating filtration assembly capable of moving together with the jig groove, which is used for circulating purification of the liquid medium in the jig groove during electric spark machining.

[0012] Further, the graphite tapered hole composite machining system, the jig groove bottom is provided with a liquid discharge port, and the liquid discharge port is provided with an automatic valve.

[0013] Further, the graphite tapered hole composite machining system, the liquid injection equipment is arranged on one side of the electric spark machining equipment.

[0014] The application also provides a graphite tapered hole composite machining process, which adopts the composite machining system introduced above, and comprises the following steps: S1, clamping the graphite workpiece to be machined to the jig in the jig groove; S2, using the automatic milling equipment to automatically mill the graphite workpiece installed in the jig groove to process a prefabricated tapered hole with a size allowance on the graphite workpiece; S3, starting the jig groove walking mechanism to drive the jig groove to walk on the workbench, switching to the secondary dust suction station, and using the secondary dust suction equipment to perform secondary dust suction inside the jig groove; S4, starting the jig groove walking mechanism to drive the jig groove to walk on the workbench, switching to the electric spark machining station, and using the electric spark machining equipment to perform electric spark finishing forming on the prefabricated tapered hole; Wherein, before the electric spark finishing forming, the liquid medium is injected into the fixture groove through the liquid injection equipment; S5, after the electric spark finishing forming, the liquid medium in the fixture groove is emptied, the graphite workpiece is taken out, the fixture groove walking mechanism is started to drive the fixture groove to walk on the workbench, and the automatic milling station is returned; S6, repeat steps S1-S5 to process the next graphite workpiece.

[0015] Further, the graphite taper hole composite machining process, the taper hole comprises upper and lower two parts, the upper part is a taper with the bottom edge upward, and the lower part is a circular straight hole. Further, in step S4 of the above-mentioned graphite taper hole composite machining process, the liquid medium is injected into the fixture groove through the liquid injection equipment located on one side of the electric spark machining equipment before the electric spark finishing forming. When the fixture groove switches to the electric spark machining station, the liquid medium is injected into the fixture groove through the liquid injection equipment located on one side of the electric spark machining equipment.

[0016] The beneficial effects of the present application are: Compared with the prior art, the present application has the advantages of: By adopting the scheme of the present application, full automation can be realized through one clamping, the movable fixture groove and the walking mechanism realize the whole process of milling, secondary dust collection and electric spark machining of the workpiece under one clamping, eliminate repeated clamping errors, ensure high machining precision (especially the coaxiality of the upper and lower holes), and greatly improve the production efficiency.

[0017] By adopting the scheme of the present application, environmental pollution is effectively controlled, the integrated milling synchronous dust collection and secondary dust collection strictly limit the diffusion of graphite dust within the system, greatly improve the operating environment, protect the health of personnel, and meet the requirements of green manufacturing.

[0018] By adopting the scheme of the present application, the ultimate machining quality can be guaranteed, which combines the high efficiency of milling and the stress-free and high-precision advantages of electric spark machining, and is especially suitable for machining complex graphite material holes prone to edge collapse, and can stably obtain undamaged and high-quality surfaces and edges.

[0019] By adopting the scheme of the present application, intensification and intelligentization can be realized, a variety of equipment and functions are integrated into one system, the floor area is reduced, and the process automation is realized, which lays a foundation for digital and intelligent production. BRIEF DESCRIPTION OF DRAWINGS

[0020] In the drawings: Figure 1 It is a cross-sectional view of a graphite workpiece to be machined in the embodiment of the present application.

[0021] Figure 2 The flow chart of the graphite taper hole composite machining scheme of the embodiment of the present application.

[0022] Figure 3 The structure schematic diagram of the graphite taper hole composite machining system of the embodiment of the present application Figure 1 (the fixture groove is in the automatic milling station).

[0023] Figure 4 The structure schematic diagram of the fixture groove of the embodiment of the present application.

[0024] Figure 5 The structure schematic diagram of the flexible door of the embodiment of the present application.

[0025] Figure 6 The structure schematic diagram of the graphite taper hole composite machining system of the embodiment of the present application Figure 2 (the fixture groove is in the secondary dust collection station).

[0026] Figure 7 The structure principle of the graphite taper hole composite machining system of the embodiment of the present application Figure 3 (the fixture groove is in the electric spark machining station).

[0027] The components represented by the reference numerals in the figures are as follows: Automatic milling equipment 1, secondary dust collection equipment 2, electric spark machining equipment 3, workbench 4, fixture groove 5, fixture groove walking mechanism 6, liquid injection equipment 7, circulating filtration assembly 8, liquid discharge port 9, temperature control drying assembly 10, synchronous dust collection assembly 11, sealing cover 12, fixture 13, graphite workpiece 14, taper hole 15, milling cutter head 16, electrode head 17, liquid injection port 18, emptying box 19, flexible door 20. DETAILED DESCRIPTION

[0028] Exemplary embodiments of the present disclosure will be described in greater detail below with reference to the accompanying drawings. Embodiment 1

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

[0030] Figure 1 The taper hole 15 in the graphite workpiece 14 comprises two parts, the upper part is a taper with the bottom edge facing upward, and the lower part is a circular straight hole. There can be one or more such taper holes 15 on one graphite workpiece 14. Such a taper hole 15 can be used as a guide hole for fluid passage on some precision graphite products.

[0031] Next, refer to Figures 2 to 7The embodiment provides a graphite taper hole composite machining system, which firstly comprises an automatic milling device 1 used for automatic milling machining of a graphite workpiece 14 installed in a clamp groove 5 to process a prefabricated taper hole with a size allowance on the graphite workpiece 14.

[0032] The automatic milling device 1 in the embodiment is a numerical control milling machine, which is provided with a synchronous dust collection assembly 11, and the automatic milling work is performed in a closed sealing cover 12 to prevent air pollution under dry milling conditions, and a flexible door 20 is arranged on the side of the sealing cover 12 for the clamp groove 5 to enter and exit, as shown in the figure, the flexible door 20 is provided with a flexible material at an opening edge to prevent collision when the clamp groove 5 enters and exits. Figure 5

[0033] The composite machining system further comprises a secondary dust collection device 2 used for secondary dust collection inside the clamp groove 5 to completely remove residual graphite dust, and the main purpose of this step is to provide a good liquid medium injection environment for subsequent electric spark machining, therefore, the secondary dust collection device 2 is specially provided with an automatic three-dimensional dust collection device with a multi-joint dust collection arm, and the multi-joint dust collection arm can deeply enter the inside of the clamp groove 5 to perform intensive and omnidirectional cleaning.

[0034] The composite machining system further comprises an electric spark machining device 3 used for electric spark finishing forming of the prefabricated taper hole, and the electric spark machining device 3 is provided with an electrode head 17 designed for the target taper hole, and a liquid injection device 7 is arranged on one side of the work station.

[0035] In order to realize one-time clamping from milling to secondary dust collection and then to electric spark machining and automation, the composite machining system is specially provided with the clamp groove 5 and a clamp groove walking mechanism 6, and as a supporting basis, a workbench 4 of the composite machining system is arranged across the automatic milling device 1, the secondary dust collection device 2 and the electric spark machining device 3 to support the clamp groove 5 when the taper hole is machined.

[0036] Specifically, referring to Figure 3 , Figure 4 , Figure 6 , Figure 7 ​The clamp groove 5 is a groove body, which is internally provided with a clamp 13 for clamping the graphite workpiece 14 and is connected with the pulse power supply of the electric spark machining device 3 through a special conductive path (not shown in the figure). The groove body of the clamp groove 5 is made of stainless steel and is electrically isolated from the clamp groove running mechanism 6 and the workbench 4 through an insulating support, so that the electric potential of the clamp groove 5 is approximately equal to the electric potential of the workpiece during electric spark machining, thereby preventing stray discharge. The clamp groove 5 is integrated with a small circulating filtration assembly 8, which is internally provided with a micro oil pump and a filter for circulating and purifying the liquid medium in the clamp groove 5 during electric spark machining, thereby maintaining the cleanliness of the liquid medium. The bottom of the circulating filtration assembly 8 is provided with a liquid discharge port 9 with an automatic valve, which is used for quickly emptying the liquid medium after the machining is completed.

[0037] In this embodiment, the circulating filtration assembly 8 is installed on the right side of the clamp groove 5 and has an installation height equal to or slightly higher than the upper edge of the clamp groove 5 and a width equal to or slightly wider than the clamp groove 5. The advantages of this arrangement are as follows. Figure 5 As shown in the figure, the flexible door 20 provided 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 filtration assembly 8 has an installation height and a width not lower than the clamp groove 5, as shown in the figure, when the clamp groove 5 is accurately positioned during milling machining, the circulating filtration assembly 8 is in a position extending to the right into the flexible door 20 by a certain size. Therefore, the opening can be closed by the cooperation of the circulating filtration assembly 8 and the flexible door 20. Figure 3

[0038] The clamp groove running mechanism 6 is a special mechanism for driving the clamp groove 5 to run on the workbench 4, which ensures that the clamp groove 5 can be automatically switched between the automatic milling device 1, the secondary dust collection device 2 and the electric spark machining device 3 and accurately positioned.

[0039] Figure 3 As shown in the figure, the clamp groove running mechanism 6 can adopt a servo lead screw module. It can also be seen that the workbench 4 is provided with an internally recessed moving guide rail. The insulating support of the clamp groove 5 can be limitingly guided and cooperated with the moving guide rail and driven by the servo lead screw module to accurately move on the workbench 4. Embodiment 2

[0040] Next, this embodiment further illustrates the advantages of the present application by introducing the composite machining process.

[0041] Specifically, the composite machining is carried out by using the composite machining system introduced in the above embodiment 1, which includes the following steps: S1, clamping the graphite workpiece 14 to be machined to the clamp 13 in the clamp groove 5.

[0042] ​S2, the automatic milling equipment 1 is used to automatically mill the graphite workpiece 14 installed in the clamp groove 5 according to the set program, and a preformed tapered hole with a size allowance is processed on the graphite workpiece 14.

[0043] As an alternative, the milling tool head 16 in this embodiment can be a ball nose end mill, and the machining process is divided into two steps. First, the upper tapered cavity is rough milled. The ball nose end mill starts from the upper surface of the graphite workpiece 14, and uses a layered milling strategy to process downward along the Z axis. After each layer is lowered, the XY cutting profile is retracted inward by one step, until the bottom depth of the tapered cavity is reached, forming a rough tapered blank with a stepped bottom edge facing upward. Then, the lower circular straight hole is machined. The ball nose end mill is positioned at the bottom of the tapered cavity, and continues to use a drilling type milling strategy to process downward along the Z axis, while performing a fixed diameter circular motion in the XY plane, to machine the circular straight hole to the final depth.

[0044] If a multi-spindle numerical control milling machine or a numerical control machining center with a tool magazine and a tool changing mechanism is used, a flat bottom end mill or a twist drill can first be used to machine the circular straight hole, and then a ball nose end mill can still be used 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 program for the tapered hole 15. Depending on the type of milling equipment selected, the tool, and the rough machining accuracy, other programs can also be used to machine the tapered hole 15 without departing from the spirit of the present application. The entire machining process is performed with the continuous operation of the synchronous dust collection assembly 11.

[0046] When multiple tapered holes 15 need to be machined on a graphite workpiece 14, only one positioning is generally required, and the milling tool head 16 processes each tapered hole one by one. After all the tapered holes 15 are machined, the next process is entered.

[0047] S3, the clamp groove running mechanism 6 is started to drive the clamp groove 5 to run on the workbench 4, and the second dust collection position is switched to. The second dust collection equipment 2 is used to perform secondary dust collection on the inside of the clamp groove 5, and to thoroughly clean and remove all residual dust inside.

[0048] S4, the clamp groove running mechanism 6 is started to drive the clamp groove 5 to run on the workbench 4, and after precise positioning at the electric spark machining position, the liquid medium kerosene (or other electric spark machining liquid) is injected into the clamp groove 5 through the liquid injection equipment 7 located on one side of the electric spark machining equipment 3 until the graphite workpiece 14 is submerged, and then the electric spark machining equipment 3 can be used to perform electric spark finishing on the preformed tapered hole.

[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, repeating steps S1-S5, processing 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). 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 the graphite workpiece (14) is installed inside. 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); The liquid injection device (7) is used to inject liquid medium for electrical discharge machining into the fixture groove (5).

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 2, characterized in that, The automatic milling equipment (1) is equipped with a synchronous dust collection component (11).

4. 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.

5. The graphite tapered hole composite machining system as described in claim 1, characterized in that, 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.

6. The graphite tapered hole composite machining system as described in claim 1, characterized in that, The bottom of the clamp groove (5) is provided with a drain port (9), and the drain port is provided with an automatic valve.

7. 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).

8. A composite machining process for graphite tapered holes, employing the composite machining system described in any one of claims 1-7, 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).

9. The composite processing technology for graphite tapered holes as described in claim 8, 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.

10. The composite processing technology for graphite tapered holes as described in claim 8, 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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