A hydrogel injection device and a drilling method

Abstract

The present invention belongs to the technical field of electro-discharge - electro-chemical compound hole drilling, and particularly relates to a hydrogel injection device and a drilling method. The device consists of an electrode sleeve, a fixture, a push rod and an electrode. The electrode sleeve includes an outer sleeve tube and a guide sleeve concentrically arranged therein, and the two are fixedly connected by rib plates; the electrode positioning section is threadedly connected with the guide sleeve, and the cylindrical electrode section is axially movably disposed through one end of the rib plate of the guide sleeve; the push rod is a tubular body disposed in the annular space between the outer sleeve tube and the guide sleeve, and the lower part of the annular space is filled with hydrogel. The end of the cylindrical electrode section performs electro-discharge drilling on the workpiece, and then uses hydrogel as an electrolyte to perform electro-chemical machining on the workpiece. The device of the present invention has a simple structure. The fixture only needs to be fed once, and without replacing the equipment and interrupting the machining, electro-discharge - electro-chemical compound drilling can be carried out, overcoming the stray corrosion of electro-chemical machining, improving the localization of electro-chemical machining, and enabling the drilling with good surface quality and high precision to be obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of electric discharge - electrolytic composite hole - making, and particularly relates to a hydrogel injection device and a drilling method. Background Art

[0002] The material removal mechanism of electric discharge machining is that the material is removed after melting or vaporization at high temperature. Therefore, after electric discharge drilling, the molten material that has not been discharged from the machining area on the hole wall surface will re - solidify under the cooling of the working fluid to form a so - called recast layer, which not only results in low surface quality of the hole wall, but also affects the fatigue strength of the hole and reduces the service life. In order to improve the surface quality and material properties of the hole, currently, an electrolytic machining method is adopted after electric discharge drilling to remove the recast layer, forming an electric discharge - electrolytic composite drilling method.

[0003] The disadvantage of electrolytic machining is the existence of stray corrosion. Stray corrosion refers to the secondary corrosion of the machined surface of the workpiece or the corrosion of the non - machining area by stray current during electrolytic machining, which is the main reason for the low precision of electrolytic machining. The reasons for the occurrence of stray corrosion are as follows: the working fluid used in electrolytic machining is liquid electrolytes such as NaCl, NaNO3, NaClO3, etc. The liquid electrolyte will flow around during machining, and the electric field cannot be completely confined in the machining area. At the same time, there will be stray current distributions of varying degrees in the non - machining area, resulting in the non - machining surface also participating in the electrochemical reaction, occurring pitting corrosion and stray corrosion. Therefore, there is a problem of poor machining localization. Summary of the Invention

[0004] The present invention aims to provide a hydrogel injection device and a drilling method to solve the problems of stray corrosion, low precision of electrolytic machining, and poor localization in the existing electrolytic machining technology.

[0005] To achieve the object of the present invention, the technical solution provided by the present invention is: a hydrogel injection device, which is composed of an electrode sleeve, a push rod, a fixture, and an electrode;

[0006] The electrode sleeve includes an outer sleeve and a guide sleeve arranged concentrically. The outer sleeve is slightly longer than the guide sleeve, and their upper parts are flush. The lower part of the outer sleeve and the bottom end of the guide sleeve are fixedly connected by a rib plate, and the surface of the electrode sleeve below the lower surface of the rib plate is coated with an insulating coating;

[0007] The electrode is a variable - diameter electrode. The positioning section with a thicker diameter is processed with an external thread and is connected in cooperation with the internal thread arranged on the inner wall of the guide sleeve. Its end is provided with a groove, and the thinner - diameter part is a cylindrical electrode section. The cylindrical electrode section can axially move through one end of the rib plate of the guide sleeve; the lower end of the outer sleeve tapers, and the reduced hole diameter is slightly larger than the diameter of the cylindrical electrode section;

[0008] The push rod is a tubular body and is arranged in an interference fit in the annular space between the outer sleeve and the guide sleeve;

[0009] A clamp is provided at the upper end of the push rod;

[0010] The annular space between the outer sleeve and the guide sleeve is filled with hydrogel.

[0011] Furthermore, an annular groove is provided on the outer wall of the push rod, and a rubber ring is embedded in the annular groove.

[0012] Furthermore, the above includes the following steps:

[0013] Step one: Inject hydrogel into the annular space between the outer sleeve and the guide sleeve in the electrode sleeve, and then install the push rod. The workpiece is arranged below the cylindrical electrode section of the electrode. According to the drilling depth and the degree of electrode wear, use a screwdriver to rotate the groove on the electrode to adjust the position of the electrode;

[0014] Step two: Perform electrical discharge machining: The clamp holds the push rod and drives the entire hydrogel injection device to move downward. Deionized water in the deionized water tank is sprayed as the working fluid onto the machining area. The electrode sleeve and the workpiece are respectively connected to the cathode and anode of the pulse power supply. The electrode approaches the workpiece to start electrical discharge drilling machining. When the bottom of the electrode sleeve and the workpiece come into contact with each other, the electrical discharge drilling machining ends;

[0015] Step three: The clamp holds the push rod and continues to move downward. Since the bottom of the electrode sleeve and the workpiece have come into contact, the electrode sleeve cannot move downward. At this time, the push rod squeezes the hydrogel, and the hydrogel is injected into the gap between the electrode and the hole wall through the gap at the bottom of the electrode sleeve, and electrolytic machining starts.

[0016] Compared with the prior art, the beneficial effects and advantages of the present invention are as follows:

[0017] 1. The hydrogel injection device of the present invention has a simple structure. The clamp drives the hydrogel injection device to only feed downward once, without the need to replace equipment or interrupt machining, and can combine electrical discharge drilling and electrolytic machining with hydrogel as the electrolyte to perform composite drilling machining.

[0018] 2. Hydrogel is composed of a three-dimensional cross-linked network formed by polymer molecules interconnected with each other and a liquid medium filled in the network structure, and is an elastic semi-solid material that can maintain a certain shape. Introducing hydrogel into a conductive medium can make a conductive hydrogel, which combines the two characteristics of a conductive substance and hydrogel, and the conductivity at room temperature can reach 10 - 4S / cm, only one order of magnitude smaller than that of organic liquid electrolytes. Based on the characteristics of conductive hydrogels, when the present invention uses hydrogels as electrolytes to replace traditional liquid electrolytes in electrolytic machining, as a semi-solid material, the hydrogel cannot flow freely. Therefore, the electric field is completely confined within the hydrogel, and no electrochemical reaction will occur in places not covered by the hydrogel, effectively improving the localization of electrolytic machining, greatly overcoming the stray corrosion in electrolytic machining, and improving the accuracy of electrolytic machining.

[0019] 3. The drilling method of the present invention, when performing electro-discharge - electrolytic composite drilling, creatively uses this semi-solid material of hydrogel to replace the traditional liquid working fluid for electrolytic machining. While overcoming stray corrosion, it effectively improves the localization of electrolytic machining, improves the accuracy of electrolytic machining, and can obtain drill holes without recast layer, with good surface quality and high accuracy. Brief Description of the Drawings

[0020] Figure 1 is the hydrogel injection device of the present invention;

[0021] Figure 2 is the schematic structural diagram of the electrode sleeve of the present invention;

[0022] Figure 3 is the schematic structural diagram of the electrode of the present invention;

[0023] Figure 4 is the schematic structural diagram of the electrode sleeve and the electrode of the present invention;

[0024] Figure 5 is the schematic structural diagram of the push rod of the present invention;

[0025] Figure 6 is the drilling process and machining principle diagram of the present invention.

[0026] Explanation of the reference numerals in the drawings is as follows: 1 outer sleeve; 2 guide sleeve; 3 push rod; 4 fixture; 5 groove; 6 electrode; 7 rubber ring; 8 hydrogel; 9; gap between rib plates, 10 machining part of the electrode. Detailed Description of the Embodiment

[0027] The following will describe the present invention in detail with reference to the drawings and specific embodiments.

[0028] See Figures 1-6 , a hydrogel injection device, which is composed of an electrode sleeve, a push rod 3, a fixture 4 and an electrode 6. The electrode sleeve includes an outer sleeve 1 and a guide sleeve 2 arranged concentrically. The outer sleeve 1 is slightly longer than the guide sleeve 2, and the upper parts are flush. The lower part of the outer sleeve 1 and the bottom end of the guide sleeve 2 are fixedly connected by rib plates, and the surface of the electrode sleeve below the lower surface of the rib plates is coated with an insulating coating.

[0029] The electrode 6 is a variable-diameter electrode. The positioning section with a thicker diameter is processed with an external thread and is connected in a mating manner with the internal thread provided on the inner wall of the guide sleeve 2. A groove 5 is provided at its end. The section with a thinner diameter is a cylindrical electrode section, and the cylindrical electrode section is axially movably inserted through one end of the rib plate of the guide sleeve. The lower end of the outer sleeve 1 tapers, and the reduced aperture is slightly larger than the diameter of the cylindrical electrode section.

[0030] After the positioning section of the electrode 6 is screwed into the guide sleeve 2, the part of the lower cylindrical electrode section extending out of the electrode sleeve is the machining part 10 of the electrode. By rotating the groove 5 above the electrode 6, the electrode 6 can move up and down in the guide sleeve 2, and the length of the machining part 10 of the electrode can be changed according to the drilling depth and the wear degree of the electrode 6 to meet the drilling requirements.

[0031] The push rod 3 is a tubular body and is disposed in an interference fit in the annular space between the outer sleeve 1 and the guide sleeve 2. The hydrogel 8 is injected into the annular space at the lower part of the electrode sleeve. The push rod 3 is inserted into the electrode sleeve, and the push rod 3 presses the hydrogel 8 against the bottom of the electrode sleeve. Since the hydrogel 8 is a semi-solid material with a certain mechanical strength, it will not fall out of the gap below the electrode sleeve without external force.

[0032] In this embodiment, grooves are provided on the outer wall of the tubular body of the push rod 3, and rubber rings 7 are embedded in the grooves. The main function of the rubber rings 7 is to increase the friction between the push rod 3 and the electrode sleeve and prevent the electrode sleeve from sliding downward under the action of gravity and disengaging from the push rod 3.

[0033] In this embodiment, a clamp 4 is provided at the upper end of the push rod 3. The clamp 4 can be connected to the machine tool. The clamp 4 clamps above the push rod 3 and drives the push rod 3 to perform up and down feeding movements.

[0034] A drilling method for a hydrogel injection device, as Figure 6 shown, includes the following steps:

[0035] Step 1: As shown in 6(a), inject the hydrogel 8 into the annular space between the outer sleeve 1 and the guide sleeve 2, then install the push rod 3. The workpiece is arranged below the cylindrical electrode section of the electrode 6. According to the drilling depth and the electrode wear degree, use a screwdriver to rotate the groove 5 on the electrode 6 to adjust the position of the electrode 6.

[0036] Step 2: Perform electrical discharge machining: The clamp 4 clamps the push rod 3 and drives the entire hydrogel injection device to move downward. Deionized water in the deionized water tank is sprayed as the working fluid onto the machining area. The electrode sleeve and the workpiece are respectively connected to the cathode and anode of the pulse power supply. The electrode 6 approaches the workpiece and starts electrical discharge drilling machining, as Figure 6As shown in (b), when the entire hydrogel injection device drives the electrode 6 to drill into the workpiece, and the bottom of the electrode sleeve contacts the workpiece, the electrode sleeve cannot move downward any further. At this time, the deionized water working fluid stops spraying, and the electrical discharge drilling process ends. Due to the material removal mechanism of electrical discharge machining, there will be a certain gap between the electrode 6 and the hole wall of the drilled hole. At the same time, the surface of the hole wall is covered with a recast layer, which affects the surface quality and material properties of the workpiece.

[0037] Step Three: As Figure 6 shown in (c), since the electrode sleeve and the workpiece have already made contact and the electrode sleeve cannot move downward, but the fixture 4 holds the push rod 3 and moves it downward. At this time, the push rod 3 moves downward between the outer sleeve 1 and the guide sleeve 2 and squeezes the hydrogel 8. The hydrogel 8 will be injected into the gap between the electrode 6 and the hole wall through the gap at the end of the electrode sleeve (the gap 9 between the rib plates). At this time, the hydrogel 8 acts as an electrolyte and electrolytic machining begins. Since the hydrogel 8 is a semi-solid elastic material and cannot flow freely, although there is hydrogel 8 in the enclosed space below the electrode sleeve, due to the presence of the insulating coating on the lower part of the electrode sleeve, an electrochemical reaction cannot occur. Therefore, the scope of electrolytic machining is strictly limited to the hole wall. After a certain period of electrolytic machining, the recast layer left by the electrical discharge machining can be completely removed, and finally a drilled hole with good surface quality and high precision is obtained, as Figure 6 shown in (d), and the drilling process ends.

[0038] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. A hydrogel injection device, comprising an electrode sleeve and an electrode (6), characterized in that: It also includes a push rod (3), a fixture (4), an electrode (6) and a rubber ring (7). The electrode sleeve includes a concentrically arranged outer sleeve (1) and a guide sleeve (2). The outer sleeve (1) is slightly longer than the guide sleeve (2), and their upper parts are flush. The lower part of the outer sleeve (1) and the bottom end of the guide sleeve (2) are fixedly connected by a rib plate. The surface of the electrode sleeve below the lower surface of the rib plate is coated with an insulating coating. The electrode (6) is a stepped electrode. The thicker positioning section is machined with an external thread and is connected in a mating manner with the internal thread provided on the inner wall of the guide sleeve (2). A groove (5) is provided at its end. The thinner part is a cylindrical electrode section, which is axially movably inserted through one end of the rib plate of the guide sleeve (2). The lower end of the outer sleeve (1) tapers, and the reduced aperture is slightly larger than the diameter of the cylindrical electrode section. The push rod (3) is a tubular body and is disposed in an interference fit in the annular space between the outer sleeve (1) and the guide sleeve (2). A fixture (4) is provided at the upper end of the push rod (3). The annular space between the outer sleeve (1) and the guide sleeve (2) is filled with a hydrogel (8).

2. The hydrogel injection device according to claim 1, characterized in that: An annular groove is provided on the outer wall of the push rod (3), and a rubber ring (7) is embedded in the annular groove.

3. The drilling method of a hydrogel injection device according to claim 1, characterized in that: It includes the following steps: Step 1: Inject the hydrogel (8) into the annular space between the outer sleeve (1) and the guide sleeve (2) of the electrode sleeve, and then install the push rod (3). The workpiece is disposed below the cylindrical electrode section of the electrode (6). According to the drilling depth and the wear degree of the electrode (6), use a screwdriver to rotate the upper electrode groove (5) on the electrode (6) to adjust the position of the electrode (6). Step 2: Perform electrical discharge machining. The fixture (4) clamps the push rod (3) and drives the entire hydrogel injection device to move downward. Deionized water in the deionized water tank is sprayed as the working fluid onto the machining area. The electrode sleeve and the workpiece are respectively connected to the cathode and anode of the pulse power supply. The electrode (6) approaches the workpiece to start electrical discharge drilling machining. When the bottom of the electrode sleeve and the workpiece come into contact with each other, the electrical discharge drilling machining ends. Step 3: The fixture (4) clamps the push rod (3) and continues to move downward. Since the bottom of the electrode sleeve and the workpiece have come into contact, the electrode sleeve cannot move downward. At this time, the push rod (3) squeezes the hydrogel (8), and the hydrogel (8) is injected into the gap between the electrode (6) and the hole wall through the gap at the bottom of the electrode sleeve, and electrolytic machining starts.

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