Micro electric spark inner flushing liquid main shaft and deep micropore machining method

Abstract

The invention provides a micro electric spark inner flushing liquid main shaft and a deep micropore machining method, and belongs to the technical field of non-traditional machining. The micro electric spark inner flushing liquid main shaft comprises a rotary joint, a gland, a liquid adapter, a locking nut, a sleeve, a bearing end cover, a main shaft seat, a bearing, a sealing ring, a main shaft, a belt wheel, a chuck and a porous microelectrode; working oil is conveyed between a porous microelectrode and a machined workpiece at a certain speed and pressure, accumulation of electric corrosion particles at the bottoms of micropores in the machined workpiece is slowed down, and the working oil is used for flushing, so that the chip removal efficiency is improved, and the complexity of a machining system is not increased; in conclusion, the micro electric spark inner flushing liquid main shaft and the deep micropore machining method effectively solve the problem that electric corrosion particles are difficult to discharge in the electric spark micropore machining technology.

Description

Technical Field

[0001] The invention belongs to the technical field of special processing, and in particular relates to a micro-electro-spark internal liquid-flushing spindle and a deep micro-hole processing method. Background Art

[0002] At present, EDM micro-hole machining technology plays an important role in the field of micro-hole machining of high-end equipment such as aerospace, precision machine tools, and optical machinery. EDM micro-hole machining technology has the characteristics of non-contact, high machining accuracy, easy adjustment of hole diameter and hole depth, and is not restricted by cutting conditions such as hardness and strength of the workpiece material. However, when facing deep micro-hole machining, especially micro-hole machining with extreme size characteristics, EDM micro-hole machining technology has the problem of difficulty in discharging electro-erosion particles. If electro-erosion particles cannot be discharged in time, it will also cause abnormal discharge phenomena such as secondary discharge and short circuit, which will lead to problems such as low micro-hole hole accuracy, serious electrode loss, and a sharp drop in processing speed or even stop.

[0003] Due to the small size of the micro-electrode itself, changing the shape or movement of the electrode itself has limited effect. Although the use of ultrasound, magnetic field or electrochemistry and other means for composite processing with electric sparks is relatively effective, it will make the processing system complicated.

[0004] Therefore, there is an urgent need for a micro-electro-spark internal liquid-flushing spindle and a deep micro-hole processing method to solve the problem that the electro-erosion particles are difficult to discharge. Summary of the invention

[0005] In order to solve the shortcomings and deficiencies of the prior art, a micro-electro-spark internal liquid flushing spindle and a deep micro-hole machining method are provided, thereby solving the problem that the electro-erosion particles in the electro-spark micro-hole machining technology are difficult to discharge.

[0006] A micro-spark internal liquid-flushing spindle is provided to achieve the purpose of the present invention, comprising a rotary joint, the bottom end of the rotary joint is threadedly connected to the top end of the liquid transfer tube, the bottom end of the liquid connecting tube is inserted into the inner cavity of the spindle, a pulley is threadedly fixed below the outer wall of the spindle, a bearing is sleeved on the outer wall of the spindle, the bottom of the spindle is threadedly connected to the mounting end of a chuck, and the chuck holds a porous microelectrode.

[0007] As a further improvement of the above scheme, an annular step is provided on the outer wall of the main shaft, the bottom of the bearing is in close contact with the upper surface of the annular step, and a sleeve is also sleeved on the outer wall of the main shaft, the bottom of the sleeve is in close contact with the top of the bearing, and a locking nut is threadedly connected to the outer wall of the main shaft, and the locking nut is located above the sleeve. The locking nut rotates downward around the main shaft so that the bearing is tightened by the sleeve.

[0008] As a further improvement of the above scheme, a pressure cover is threadedly connected to the upper part of the outer wall of the main shaft, and a avoidance hole is opened in the center of the pressure cover. The diameter of the avoidance hole is smaller than the outer diameter of the liquid transfer tube. The pressure cover rotates downward around the main shaft to press the liquid transfer tube and the main shaft.

[0009] As a further improvement of the above solution, a spindle seat is provided on the outer side of the bearing to improve the convenience of fixing the spindle, and a bearing end cover is threadedly connected to the top of the spindle seat to achieve compression of the bearing.

[0010] As a further improvement of the above solution, the diameter of the porous microelectrode is ≤100 μm.

[0011] As a further improvement of the above solution, the bearing end cover and the center hole at the bottom of the main shaft seat are both provided with sealing rings to prevent foreign matter from entering the bearing.

[0012] A micro-electro-spark deep micro-hole machining method comprises the following steps:

[0013] Step 1, fix the spindle seat, clamp the porous microelectrode with a chuck, put a belt on the outer wall of the pulley and connect the belt to the motor;

[0014] Step 2, connecting the top of the rotary joint to the oil pipe, so that the working oil flows from the rotary joint through the liquid transfer pipe and the main shaft to the porous microelectrode, and then the working oil flows out from the porous structure inside the porous microelectrode;

[0015] Step 3, after observing that the working oil flows out of the porous microelectrode, start the motor to pull the belt to drive the pulley to rotate;

[0016] Step 4, driving the porous microelectrode to feed the workpiece to be processed. When sparks are generated between the porous microelectrode and the workpiece to be processed, the EDM process is considered to have started; when a short circuit occurs between the porous microelectrode and the workpiece to be processed, the porous microelectrode is retracted; when the porous microelectrode is frequently retracted and the processing depth is almost no longer deepened, the EDM process is considered to have ended;

[0017] Step 5, repeat the above steps, measure the hole depth of the workpiece being processed and take the average value, and calculate the limit depth-to-diameter ratio of the deep microhole to be 20.

[0018] As a further improvement of the above solution, in step 4, the feeding speed of the porous microelectrode to the workpiece being processed is 2 μm / s.

[0019] As a further improvement of the above solution, in step 4, the retraction speed of the porous microelectrode and the workpiece being processed is 12 μm / s.

[0020] As a further improvement of the above solution, in step 4, the retraction step length of the porous microelectrode and the workpiece being processed is 12 μm.

[0021] The beneficial effects of the present invention are:

[0022] Compared with the prior art, the present invention provides a micro-electro-spark internal liquid flushing spindle and a deep micro-hole processing method, which delivers working oil between the porous micro-electrode and the workpiece being processed at a certain speed and pressure, slowing down the accumulation of electro-erosion particles at the bottom of the micro-holes in the workpiece being processed, and using the working oil for flushing to improve the chip removal efficiency, without increasing the complexity of the processing system.

[0023] In summary, the above-mentioned micro-EDM internal liquid-flushing spindle and deep micro-hole machining method effectively solve the problem of difficulty in discharging electro-erosion particles in EDM micro-hole machining technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the liquid-injection spindle in the micro-EDM of the present invention;

[0025] Figure 2 It is a schematic diagram of the micro-EDS deep micro-hole machining method of the present invention.

[0026] Among them, 1-rotating joint, 2-pressure cover, 3-liquid transfer tube, 4-locking nut, 5-sleeve, 6-bearing end cover, 7-spindle seat, 8-bearing, 9-sealing ring, 10-spindle, 11-pulley, 12-chuck, 13-porous microelectrode, 14-processed workpiece. DETAILED DESCRIPTION

[0027] The specific embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings:

[0028] according to Figure 1 As shown, the present invention provides a micro-spark internal liquid flushing spindle, including a rotary joint 1, the bottom end of the rotary joint 1 is connected to the top of the liquid transfer tube 3 by a thread, the bottom end of the liquid connecting tube 3 is inserted into the inner cavity of the spindle 10, a pulley 11 is threadedly fixed below the outer wall of the spindle 10, the outer wall of the spindle 10 is sleeved with a bearing 8, the outer side of the bearing 8 is sleeved with a spindle seat 7 for improving the convenience of fixing the spindle 10, the top of the spindle seat 7 is threadedly connected with a bearing end cover 6 for achieving the compression of the bearing 8, the bottom of the spindle 10 is threadedly connected to the mounting end of the chuck 12, the chuck 12 clamps a porous microelectrode 13, and the diameter of the porous microelectrode 13 is ≤100μm.

[0029] Among them, an annular step is provided on the outer wall of the main shaft 10, and the bottom of the bearing 8 is close to the upper surface of the annular step. The outer wall of the main shaft 10 is also sleeved with a sleeve 5, and the bottom of the sleeve 5 is close to the top of the bearing 8. A locking nut 4 is threadedly connected to the outer wall of the main shaft 10, and the locking nut 4 is located above the sleeve 5. The locking nut 4 rotates downward around the main shaft 10 so that the bearing 8 is pressed by the sleeve 5.

[0030] A gland 2 is threadedly connected to the upper part of the outer wall of the main shaft 10, and a relief hole is opened in the center of the gland 2. The diameter of the relief hole is smaller than the outer diameter of the liquid transfer tube 3. The gland 2 rotates downward around the main shaft 10 to press the liquid transfer tube 3 and the main shaft 10. The center holes at the bottom of the bearing end cover 6 and the main shaft seat 7 are both provided with sealing rings 9 to prevent foreign matter from entering the bearing 8.

[0031] A micro-electro-spark deep micro-hole machining method comprises the following steps:

[0032] Step 1, fix the spindle seat 7, clamp the porous microelectrode 13 with the chuck 12, put a belt on the outer wall of the pulley 11 and connect the belt to the motor;

[0033] Step 2, connect the top of the rotary joint 1 to the oil pipe, so that the working oil flows from the rotary joint 1 through the liquid transfer tube 3 and the main shaft 10 to the porous microelectrode 13, and then the working oil flows out from the porous structure inside the porous microelectrode 13;

[0034] Step 3, after observing that the working oil flows out of the porous microelectrode 13, the motor is started to pull the belt to drive the pulley 11 to rotate;

[0035] Step 4, driving the porous microelectrode 13 to feed the workpiece 14 to be processed, the feeding speed is 2μm / s, when the porous microelectrode 13 and the workpiece 14 to be processed sparks are generated, the EDM is considered to start; when the porous microelectrode 13 and the workpiece 14 are short-circuited, they are retracted, the retraction speed is 12μm / s, and the retraction step is 12μm; when the porous microelectrode 13 is frequently retracted and the processing depth is almost no longer deepened, the EDM process is considered to be finished, wherein the material of the workpiece 14 to be processed is 18CrNi8, as shown in detail Figure 2 As shown;

[0036] Step 5, repeat the above steps, measure the hole depth of the workpiece 14 to obtain the average value, and calculate the limit depth-to-diameter ratio of the deep microhole to be 20.

[0037] The above embodiments are not limited to the technical solutions of the embodiments themselves, and the embodiments can be combined with each other to form new embodiments. The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Any modification or equivalent replacement that does not deviate from the spirit and scope of the present invention shall be included in the scope of the technical solutions of the present invention.

Claims

1. A micro-electro-spark internal liquid-flushing spindle, characterized in that: The invention comprises a rotary joint (1), the bottom end of the rotary joint (1) is connected to the top end of a liquid transfer tube (3) by a thread, the bottom end of the liquid connection tube (3) is inserted into the inner cavity of a main shaft (10), a pulley (11) is threadedly fixed below the outer wall of the main shaft (10), a bearing (8) is sleeved on the outer wall of the main shaft (10), the bottom of the main shaft (10) is threadedly connected to the mounting end of a chuck (12), and the chuck (12) clamps a porous microelectrode (13).

2. A micro-EDM internal liquid-flushing spindle according to claim 1, characterized in that: An annular step is arranged on the outer wall of the main shaft (10), the bottom of the bearing (8) is in close contact with the upper surface of the annular step, a sleeve (5) is also sleeved on the outer wall of the main shaft (10), the bottom of the sleeve (5) is in close contact with the top of the bearing (8), a locking nut (4) is threadedly connected to the outer wall of the main shaft (10), the locking nut (4) is located above the sleeve (5), and the locking nut (4) rotates downward around the main shaft (10) so as to press the bearing (8) with the sleeve (5).

3. A micro-EDM internal liquid-flushing spindle according to claim 2, characterized in that: A pressure cover (2) is threadedly connected to the upper part of the outer wall of the main shaft (10), and a relief hole is opened at the center of the pressure cover (2). The diameter of the relief hole is smaller than the outer diameter of the liquid transfer tube (3). The pressure cover (2) rotates downward around the main shaft (10) to press the liquid transfer tube (3) and the main shaft (10) together.

4. A micro-EDM internal liquid-flushing spindle according to claim 3, characterized in that: The outer side of the bearing (8) is sleeved with a main shaft seat (7) for improving the convenience of fixing the main shaft (10); the top of the main shaft seat (7) is threadedly connected with a bearing end cover (6) for achieving the compression of the bearing (8).

5. A micro-EDM internal liquid-flushing spindle according to claim 4, characterized in that: The diameter of the porous microelectrode (13) is ≤100 μm.

6. A micro-EDM internal liquid-flushing spindle according to claim 5, characterized in that: The central holes of the bearing end cover (6) and the bottom of the main shaft seat (7) are both provided with sealing rings (9) to prevent foreign matter from entering the bearing (8).

7. A micro-electro-spark deep micro-hole machining method, characterized in that: The following steps are involved: Step 1, fix the spindle seat (7), clamp the porous microelectrode (13) with a chuck (12), put a belt on the outer wall of the pulley (11) and connect the belt to the motor; Step 2, connecting the top of the rotary joint (1) to the oil pipe, so that the working oil flows from the rotary joint (1) through the liquid transfer pipe (3) and the main shaft (10) to the porous microelectrode (13), and then the working oil flows out from the porous structure inside the porous microelectrode (13); Step 3, after observing that working oil flows out of the porous microelectrode (13), the motor is started to pull the belt to drive the pulley (11) to rotate; Step 4, driving the porous microelectrode (13) to feed toward the workpiece (14) to be processed. When sparks are generated between the porous microelectrode (13) and the workpiece (14), the electrospark machining is considered to have started; when a short circuit occurs between the porous microelectrode (13) and the workpiece (14), the porous microelectrode (13) is retracted; when the porous microelectrode (13) is frequently retracted and the machining depth is almost no longer deepened, the electrospark machining process is considered to have ended; Step 5, repeat the above steps, measure the hole depth of the workpiece (14) to obtain the average value, and calculate the limit depth-to-diameter ratio of the deep micro-hole to be 20.

8. A micro-electro-spark deep micro-hole machining method according to claim 6, characterized in that: In the step 4, the feeding speed of the porous microelectrode (13) toward the workpiece (14) being processed is 2 μm / s.

9. A micro-electro-spark deep micro-hole machining method according to claim 6, characterized in that: In the fourth step, the retraction speed of the porous microelectrode (13) and the workpiece (14) is 12 μm / s.

10. A micro-electro-spark deep micro-hole machining method according to claim 6, characterized in that: In the fourth step, the retraction step length of the porous microelectrode (13) and the workpiece (14) being processed is 12 μm.

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