Drill bit matrix working layer, drill teeth, drill bit and preparation method and application thereof based on 3D printing

Abstract

The present invention provides a drill bit matrix working layer, drill teeth, drill bits and their preparation methods and applications based on 3D printing. Metal powder is laid on a metal substrate to generate a strength retention layer, and then metal powder is laid on the strength retention layer, diamond particles are sprinkled in the metal powder, and the surface selectively scans the powder bed. The metal powder in some areas is not acted upon by the laser to generate a pore-forming and flow channel layer, thereby constructing artificially controllable micropores and microchannels. After the drill bit provided by the present invention interacts with the rock formation, it gradually wears out the drill bit matrix working layer, and its micropores and microchannels provide channels for the flow of cuttings and drilling fluid. The fine cuttings are washed by the drilling fluid and flow out of the bottom of the well with the circulation of the drilling fluid, and will not stay on its surface for too long, which is conducive to the maintenance of the mechanical drilling speed and reduces the harm caused by the "slipping" of the drill bit. The circulation of the drilling fluid in the microchannel can take away more heat from the surface of the drill teeth, reducing the probability of underground accidents such as drill burning.

Description

Technical Field

[0001] The present invention belongs to the technical field of diamond tool manufacturing, and in particular relates to a drill bit matrix working layer, drill teeth, a drill bit and a preparation method and application thereof based on 3D printing. Background Art

[0002] Diamond drill bits are widely used in many fields such as geological drilling and mineral development. In industry, sintering, welding or electroplating methods are often used to prepare diamond drill bits. By changing the shape of the mold before sintering, changing the matching method of the electroplated insulating area and the conductive area, or changing the movement trajectory of the brazing material during welding, the working layer of the diamond drill bit with diverse appearance can be manufactured. These products are suitable for crushing a large number of rock formations of different properties and can meet the process performance requirements of different application scenarios.

[0003] Among many types of diamond drill bits, impregnated diamond drill bits are suitable for crushing hard rocks with a drillability grade of 6 or above. This type of product plays a great role in deep geological drilling. However, as the footage of geological drilling gradually increases, the hardness of the rock may continue to increase. If the particle size of the rock-forming minerals in the rock shows a decreasing trend, the wear of the metal matrix of the diamond drill bit working layer by the worn rock cuttings will be greatly reduced, and the diamond blade speed will slow down, which will reduce the mechanical drilling speed of the drilling. When the rock cuttings are too small and have a certain viscosity, the drilling fluid cannot effectively wash the rock cuttings. The rock cuttings are easy to stick to the lip of the drill bit, causing the drill to stick and the drill bit to "slip". Therefore, the failure to discharge the rock cuttings in time is one of the important factors that lead to the reduction of the mechanical drilling rate. The existing traditional diamond tool manufacturing process generally only designs and transforms the shape or structure of the drill teeth on the working layer of the impregnated diamond drill bit. The microstructures such as the bonding structure of the diamond and the metal matrix inside the drill teeth and the metal matrix structure have not changed, and the drill teeth are still a whole without flow channels. Therefore, although the special-shaped tooth drill bit can solve the problem of cuttings discharge to a certain extent, it still cannot effectively deal with underground problems such as excessive cuttings residue on the drill teeth, drill sticking, and "slipping". At the same time, due to the limitations of the forming principle, such as the manufacturing of hot pressing and sintering molds, the setting of electroplating insulation areas, and brazing accuracy, the manufacturing difficulty of special-shaped tooth drill bits has increased dramatically.

[0004] Therefore, it is urgent to explore a method to change the internal structure of the drill bit matrix so that the drill teeth contain channels for the circulation of tiny rock cuttings or drilling fluid, ensure the normal cutting of the diamonds in the drill teeth, and improve the efficiency of the drill bit in drilling special rock formations. Summary of the invention

[0005] The purpose of the present invention is to provide a drill bit matrix working layer, drill teeth, drill bit and preparation method and application thereof based on 3D printing in view of the above-mentioned deficiencies in the prior art.

[0006] To achieve the above object, the present invention adopts the following technical solution:

[0007] The present invention provides a drill bit matrix working layer based on 3D printing, which includes the following specific steps:

[0008] Step S1, constructing a 3D model of a drill bit matrix working layer, slicing and layering the 3D model of the drill bit matrix working layer, and importing the data into a 3D printing forming device; the drill bit matrix working layer is composed of a strength retaining layer and a pore-forming and flow channel-forming layer stacked in a loop in sequence, and the pore-forming and flow channel-forming layer is provided with micropores and microchannels;

[0009] Step S2, loading the metal powder of the drill bit matrix working layer into the powder dropping tank of the 3D printing forming device, installing a metal substrate in the forming cavity of the 3D printing forming device, laying the metal powder on the metal substrate, and forming a powder bed to be processed of the strength retention layer;

[0010] Step S3, forming by a selective laser melting process, performing selective laser melting on the strength-retaining layer to-be-processed powder bed obtained in step S2, to generate a strength-retaining layer metal substrate;

[0011] Step S4, lowering the height of the strength-retaining layer metal substrate, laying the metal powder on the strength-retaining layer metal substrate, and then evenly sprinkling diamond particles into the metal powder to form a powder bed to be processed for the pore-forming and flow channel-forming layer;

[0012] Step S5, forming by a selective laser melting process, performing selective laser melting on the powder bed of the pore-forming and flow channel layer to be processed obtained in step S4, to generate a metal substrate of the pore-forming and flow channel layer, wherein during the melting-solidification process, the laser does not scan the position of the preset micropores of the microchannel;

[0013] Step S6, cyclically repeating steps S2-S5, i.e., laying metal powder, laser scanning to form a strength retention layer, laying metal powder, sprinkling diamonds, scanning to form a hole-making and flow channel-making layer, to generate several layers of single-layer substrates stacked in sequence to form a drill bit matrix working layer of micropores and microchannels.

[0014] Furthermore, the sphericity of the metal powder is ≥95%, the oxygen content is ≤800ppm, the Hall flow rate is ≤18s / 50g, and the particle size is 15~53μm; the crystal form of the diamond particles is a regular dodecahedron, and the average particle size ranges from 240μm to 300μm; in the powder bed to be processed, the volume ratio of diamond is 10%~25%, and the volume ratio of metal powder is 75%~90%.

[0015] Furthermore, the process of selective laser melting forming includes: introducing a protective gas to reduce the oxygen content in the forming cavity to below 300 ppm, raising the substrate temperature in the forming cavity to 100°C~200°C, the protective gas includes at least one of argon and nitrogen, the metal powder layer thickness of the powder bed is set to 40~60μm, the filling spacing is 120~160μm, the laser scanning speed is 550~1550mm / s, the laser power is 100~500w, the scanning strategy is strip XY scanning, and the laser commutation angle is 60~70°.

[0016] Furthermore, each time the current layer of substrate is processed, the metal substrate is lowered by a certain height, and the height is the total thickness of the strength retention layer and the pore-forming and flow channel-forming layer; the thickness of the single-layer substrate is 50μm~300μm.

[0017] The second object of the present invention is to provide a drill bit matrix working layer based on 3D printing technology, which is prepared by the above-mentioned preparation method.

[0018] Furthermore, the drill bit matrix working layer is composed of a strength retaining layer and a pore-forming and flow channel forming layer which are stacked in a loop from bottom to top, the strength retaining layer is a metal substrate formed by metal powder being melted by a selected laser full scanning, the pore-forming and flow channel forming layer is a metal substrate formed by metal powder being melted by a selected laser partial scanning, the top of the drill bit matrix working layer is the pore-forming and flow channel forming layer, the outer surface of the pore-forming and flow channel forming layer is provided with a plurality of protrusions, the pore-forming and flow channel forming layer includes a plurality of groups of diamond structural units, each group of the diamond structural units includes a diamond, a flow channel boundary and a plurality of microchannels, and the plurality of the diamond structural units include a diamond, a flow channel boundary and a plurality of microchannels. The diamond part is exposed on the outer surface of the pore-making and flow channel layer to form a plurality of protrusions, the flow channel boundary wraps the diamond, and a plurality of microchannels are evenly spaced around the flow channel boundary. The ends of each microchannel are connected to a micropore, and two adjacent diamond structure units are connected through at least one micropore. When the flow channel boundary is square, the diamond structure unit is square; when the flow channel boundary is circular, the diamond structure unit is circular, and the side length and diameter of the diamond structure unit are 7 to 9 times the average particle size of the diamond.

[0019] The third object of the present invention is to provide a drill tooth, which is formed by cutting the above-mentioned drill bit matrix working layer into a preset shape.

[0020] The fourth object of the present invention is to provide a drill bit, comprising a drill bit rigid body and drill teeth arranged on the drill bit rigid body, and the drill teeth are the above-mentioned drill teeth.

[0021] Furthermore, the drill bit includes a drill body and a plurality of drill teeth, the end of the drill body is provided with water inlets evenly spaced around its circumference, a diameter guard is provided between two adjacent water inlets, the bottom outer surface of the drill body is provided with a thread, each of the diameter guard upper surfaces is provided with the drill teeth, and the drill teeth correspond one-to-one to the diameter guard.

[0022] A fifth object of the present invention is to provide the application of the above-mentioned drill bit in the construction process of geological drilling engineering.

[0023] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0024] (1) The present invention provides a method for preparing a drill bit matrix working layer based on 3D printing technology, which comprises laying metal powder on a metal substrate to generate a strength retention layer, and then laying metal powder on the strength retention layer, sprinkling diamond particles in the metal powder, and selectively scanning the powder bed on the surface. The metal powder in some areas is not acted upon by the laser, and the metal melting-solidification process does not occur in these areas, resulting in the missing of some areas in the drill teeth after forming, thereby constructing artificially controllable micropores and microchannels. Compared with traditional diamond tool manufacturing technologies such as sintering, electroplating and welding, it is difficult to orderly form micropores and microchannels inside the drill bit working layer. 3D printing technology processes the powder bed layer by layer, so that the drill bit matrix working layer is stacked and formed layer by layer. Therefore, 3D printing technology is combined with diamond tool manufacturing technology, and the unique advantages of 3D printing technology, such as high forming freedom, high forming accuracy and selectivity of processing area, are utilized to change the process of drill tooth manufacturing, reduce three-dimensional manufacturing to two-dimensional manufacturing, facilitate operation, and help save costs.

[0025] (2) The quality of the drill teeth provided by the present invention will not be significantly reduced due to the presence of micropores and microchannels. Because in the process of 3D printing, the partial area loss caused by laser selective melting will not have a significant impact on the forming quality of the single layer, and the laser provides instantaneous high-intensity energy to the powder bed, and the metal powder undergoes a very fast melting-solidification process. This rapid cooling processing method has the effect of strengthening the material and can effectively improve the strength of the drill teeth.

[0026] (3) The drill bit provided by the present invention includes the drill teeth provided by the present invention. After the drill bit interacts with the rock formation, it gradually wears out to expose the drill tooth working layer. The micropores and microchannels formed in the 3D printing manufacturing process provide channels for the flow of rock cuttings and drilling fluid on the working layer. The fine rock cuttings will not stay on the surface of the drill tooth working layer for too long and will be washed away by the drilling fluid and flow out of the bottom of the well with the circulation of the drilling fluid, which is conducive to the maintenance of the mechanical drilling speed and reduces the adverse effects caused by the effects such as the "slipping" of the drill bit. At the same time, the circulation of the drilling fluid in the microchannel can take away more heat from the surface of the drill teeth, reducing the probability of underground accidents such as drill burning. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The process flow chart of the drill bit matrix working layer preparation of the present invention

[0028] Figure 2 This is a photo of the pore-forming and flow channel layer printed by 3D printing of the present invention;

[0029] Figure 3 An enlarged perspective view of a diamond structural unit in a working layer of a drill bit matrix printed by 3D printing according to the present invention;

[0030] Figure 4 It is a schematic diagram of the working layer structure of the drill bit matrix of the present invention;

[0031] Figure 5 It is a schematic diagram of the drill tooth structure of the present invention;

[0032] Figure 6 A schematic diagram of the overall structure of a drill bit in an embodiment of the present invention;

[0033] Figure 7 Schematic diagram of a top view of a diamond structure unit in Example 1 of the present invention;

[0034] Figure 8 Schematic diagram of a top view of a diamond structure unit according to Example 2 of the present invention.

[0035] In the figure: 1. drill bit matrix working layer; 11. strength retention layer; 12. hole-making and flow channel layer; 13. diamond structural unit; 131. diamond; 132. flow channel boundary; 133. microchannel; 134. micropores; 2. drill bit rigid body; 21. water inlet; 22. diameter protection; 23. thread; 3. drill teeth; 4. drill bit. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the present invention clearer, the embodiments of the present invention will be further described below in conjunction with the accompanying drawings. The following is a preferred embodiment of the present invention, which is intended to provide a basic understanding of the present invention, but is not intended to confirm the key or decisive elements of the present invention or to limit the scope of protection.

[0037] The 3D printing equipment used in the present invention is: laser selective melting rapid prototyping equipment HK-M125.

[0038] The hot pressing and sintering equipment used in the present invention is: a medium frequency induction hot pressing and sintering furnace.

[0039] The drill bit rigid body in the present invention is obtained by mechanical processing of a circular steel pipe, which is a common drill bit rigid body in the art. The inner and outer diameters of the drill bit rigid body are determined by the target aperture size of the drilling construction. The sprues, diameter guards and threads processed on the drill bit rigid body are set according to national standards and with reference to the aperture size of the drill bit rigid body.

[0040] The drill bit structure in the embodiment of the present invention is as follows: Figure 6 As shown, the drill bit 4 includes a drill body 2 and a plurality of drill teeth 3. The end of the drill body 2 is provided with water inlets 21 evenly spaced around its circumference, and a diameter guard 22 is provided between two adjacent water inlets 21. A thread 23 is provided on the bottom outer surface of the drill body 2, and a drill tooth 3 is provided on the upper surface of each diameter guard 22. The drill teeth 3 correspond to the diameter guards 22 one by one, and the number of drill teeth is 4 to 8.

[0041] The method for preparing the drill bit matrix working layer with micropores and microchannels provided by the present invention has a process flow chart as shown in FIG. Figure 1 As shown, the following steps are included:

[0042] Step S1, constructing a 3D model of a drill bit matrix working layer with micropores and microchannels in a 3D modeling software (such as Solidworks, Magics, etc.), and outputting the 3D model in STL format; then, importing the STL format file into a 3D printing device, and having a model information processing system in the device slice and layer the model to be processed.

[0043] Step S2, install a metal substrate in the forming cavity of the 3D printing device, and adjust the upper surface of the metal substrate to be at the same horizontal plane as the lower inner wall of the forming cavity. Load the metal matrix powder of the drill bit body working layer into the powder dropping tank in the 3D printing device, and the powder dropping tank drops the powder in front of the powder spreading scraper in the forming cavity of the 3D printing device. The powder spreading scraper moves back and forth to reserve a layer of metal matrix powder on the metal substrate to form a powder bed to be processed with a strength retention layer. The metal matrix powder is spherical, with a sphericity of ≥95%, a particle size of 15~53μm, and an oxygen content of ≤800ppm.

[0044] Step S3, forming by a selective laser melting process, selectively laser melting the strength-retaining layer powder bed to be processed obtained in step S2, to generate a strength-retaining layer metal substrate.

[0045] Step S4, the strength-retaining layer is lowered by a layer thickness, the same metal powder as in step S2 is laid on the strength-retaining layer, and then diamond particles are evenly sprinkled on the above metal powder to form a powder bed to be processed for the pore-forming and flow channel-forming layer;

[0046] The mechanical arm in the 3D printing device delivers the diamond particles to the designated position on the metal matrix powder layer. The diamond can be arranged at the preset position of the current layer of the drill tooth model of the drill bit working layer under artificial control. In this embodiment, the crystal form of the diamond is a regular dodecahedron with a particle size of 180-300 μm. The metal powder and the diamond particles are combined to form the current layer of the powder bed to be processed. In each layer of the powder bed to be processed, the diamond accounts for 10%-25% by volume, and the metal powder accounts for 75%-90% by volume.

[0047] Step S5, forming by a selective laser melting process, performing selective laser melting on the powder bed of the pore-forming and flow channel layer to be processed obtained in step S4, to generate a metal substrate of the pore-forming and flow channel layer, wherein during the melting-solidification process, the laser does not scan the position of the preset micropores of the microchannel;

[0048] The process of selective laser melting in steps S3 and S5 includes introducing protective gas (argon or nitrogen) to reduce the oxygen content in the forming cavity to below 300ppm, and raising the substrate temperature in the forming cavity to 100℃~200℃. Set the parameters for selective laser melting: the thickness of the powder bed metal powder layer is set to 40~60μm, the filling spacing is 120~160μm, the laser scanning speed is 550~1550mm / s, the laser power is 100~500w, the scanning strategy is strip XY scanning, and the laser reversing angle is 60~70°. After the laser is emitted, according to the slice model data of the drill tooth and the diamond structure unit in the drill tooth model, the laser selectively scans the powder bed in the form of a laser beam, provides heat energy to the powder bed, melts the metal on the powder bed, and then rapidly cools and solidifies.

[0049] Step S6, turn on the laser and scanning system, the laser scans the powder bed layer by layer according to the structure of the model slice, and repeats steps S2-S5 in a cycle, that is, laying metal powder, laser scanning to form a strength retention layer, laying metal powder, sprinkling diamonds, scanning to form a hole-making and flow channel layer, until the last layer of the model slicing task is completed, and a drill bit matrix working layer with micropores and microchannels is obtained.

[0050] like Figure 2-4As shown, the drill bit matrix working layer 1 is composed of a strength retaining layer 11 and a hole-forming and flow-forming channel layer 12 which are sequentially stacked from bottom to top in a cycle. The strength retaining layer 11 is a metal substrate formed by metal powder being fully melted by a selected laser scanning. The hole-forming and flow-forming channel layer 12 is a metal substrate formed by metal powder being partially melted by a selected laser scanning. The top of the drill bit matrix working layer 1 is the hole-forming and flow-forming channel layer 12. The outer surface of the hole-forming and flow-forming channel layer 12 is provided with a plurality of protrusions. The hole-forming and flow-forming channel layer 12 includes a plurality of groups of diamond structure units 13, each of which is Each diamond structure unit 13 includes a diamond 131, a flow channel boundary 132 and a plurality of microchannels 133. Parts of the plurality of diamonds 131 are exposed on the outer surface of the pore-forming flow channel layer 12 to form a plurality of protrusions. The flow channel boundary 132 wraps the diamond 131. The plurality of microchannels 133 are evenly spaced around the flow channel boundary 132. The ends of each microchannel 133 are connected to a micropore 134. Two adjacent diamond structure units 13 are connected via at least one micropore 134.

[0051] The method for preparing the drill teeth with micropores and microchannels provided by the present invention is to cut the drill bit matrix working layer from the forming cavity metal substrate according to a preset shape by an electric spark cutting machine.

[0052] like Figure 5 The drill teeth shown have diamond protrusions 131 on their top outer surfaces. In some embodiments, the profile of the drill teeth may be fan-shaped, with a central angle of 45° to 90°, and the spacing between two adjacent drill teeth is equal.

[0053] It should be noted that the drill teeth in the present invention are also equivalent to being manufactured through 3D printing technology. The 3D printing technology is laser selective melting technology. The forming process of this technology is: laying the material to be formed on a metal substrate, using a high-energy laser beam to selectively scan the powder on the metal substrate, so that the material after the laser scanning undergoes a melting-solidification process, and finally a three-dimensional object is obtained by scanning layer by layer and stacking.

[0054] The drill teeth are also obtained by cyclically stacking the strength retention layer and the pore-forming and flow-forming channel layer from top to bottom; each diamond is inlaid with a strength retention layer and a pore-forming and flow-forming channel layer; the thickness of the strength retention layer and the pore-forming and flow-forming channel layer are both half of the average diamond particle size; there are no micropores and microchannels on the strength retention layer to ensure the strength of the drill teeth and improve the holding force of the metal matrix on the diamond; the bottom plane of the diamond is on the same horizontal plane as the bottom of the strength retention layer; the microchannel in the pore-forming and flow-forming channel layer, the diamond, and the surrounding metal matrix form a group of diamond structural units, and two adjacent groups of diamond structural units can share at least one group of micropores, and each group of diamond structural units is square or circular, and the side length and diameter of the diamond structural unit are 7 to 9 times the average diamond particle size;

[0055] The size, quantity and arrangement of the micropores and microchannels on the pore-forming and flow-forming channel layer can be designed according to actual geological drilling needs.

[0056] In some embodiments, the formation rock is soft, the rock-forming mineral particles are large, and the degree of cementation is poor, so the speed of cuttings discharge should be faster, and the drilling fluid is not easy to stay on the lip of the drill bit working layer for a long time. It is advisable to use a straight flow channel and set larger micropores to temporarily accommodate cuttings in the diamond-free area. When the drilling fluid flushes the micropores, it is conducive to the discharge of cuttings.

[0057] In some embodiments, the formation rock texture is harder, the rock-forming mineral particles are smaller, and the degree of cementation is high, so the flow channel should be arc-shaped, the drilling fluid fully lubricates and cools the drill bit lip surface, and the extended flow channel accommodates the increased volume of rock cuttings to avoid "slipping" of the drill bit due to repeated wear of the rock cuttings.

[0058] It should be noted that if the diamond structure unit is a square, the microchannel is a rectangular direct flow channel, which is set along the square flow channel boundary area 1.5 times the average diamond particle size from the center point of the diamond, and 5 to 9 microchannels are set on each square flow channel boundary. The microchannel width is 40 to 80 μm, the length is 2 times the average diamond particle size (the microchannel extends to the boundary of the diamond structure unit), and the depth is half of the average diamond particle size. The spacing between microchannels on the same boundary is equal;

[0059] If the diamond structure unit is circular, the microchannel is semicircular, and is set along the circular flow channel boundary area that is 1.5 times the average diamond particle size from the center point of the diamond. The microchannel extends to the boundary of the diamond structure unit, and the radius is equal to the average diamond particle size. Each diamond structure unit contains 10 to 20 microchannels, the width of the microchannel is 40 to 80 μm, the depth is half of the average diamond particle size, and the spacing between adjacent microchannels is equal.

[0060] In some embodiments, outside the boundary of each diamond structure unit, there are circular micropores equal to the number of microchannels, with a diameter twice the width of the microchannel and a depth of one-half the average diamond particle size. The micropores are connected to the microchannel, and two adjacent groups of diamond structure units can share at least one group of micropores.

[0061] The method for preparing a drill bit with micropores and microfluidic channels provided by the present invention comprises the following steps:

[0062] Step S1, processing the drill bit rigid body

[0063] The drill bit body is a commercial steel round tube. The selected round tube diameter is determined by the drill bit design size. The threads, diameter protection, sprue, etc. on the drill bit body are obtained through mechanical processing methods such as lathes and milling machines according to the drill bit design specifications.

[0064] Step S2, connecting the drill teeth and the drill bit rigid body

[0065] In some embodiments, the drill bit can be obtained by combining the machined drill bit rigid body and the drill teeth formed by laser selective melting by hot pressing and sintering.

[0066] The process of hot pressing sintering can be: the hot pressing sintering temperature range is 400~1000℃; the temperature change curve of the sintering process is heating-up-highest temperature insulation-cooling down, the highest sintering temperature is set according to the melting point of the metal matrix alloy, the insulation time of hot pressing sintering to the highest temperature of the preset temperature curve is 2~15min, the pressure range of hot pressing sintering is 0~20MPa; the cooling method after hot pressing sintering is furnace cooling.

[0067] The drill bit with micropores and microchannels provided by the present invention is used in the construction process of geological drilling engineering. The drill bit is connected to a drill rod for use in the construction of geological drilling engineering.

[0068] In order to better illustrate the drill bit matrix working layer, drill teeth, drill bit and preparation method and application thereof based on 3D printing of the present invention, specific embodiments are used for description below.

[0069] Example 1

[0070] The diameter of the drill bit rigid body to be manufactured is 36mm, the drill bit matrix working layer is composed of 4 drill teeth, the drill tooth height is 6mm, it is arc-shaped, the outer circle radius is 18.25mm, the inner circle radius is 12.25mm, the center angle is 61.65°, and the 4 drill teeth are evenly spaced around the end of the drill bit rigid body.

[0071] 1. Preparation of drill bit matrix working layer

[0072] Step S1, constructing a 3D model of a drill bit carcass working layer, slicing and layering the 3D model of the drill bit carcass working layer, and importing the data into a 3D printing device;

[0073] The designed model is: Figure 7As shown in the figure, the drill bit matrix working layer is composed of a strength retention layer and a pore-forming and flow channel layer which are stacked in sequence from bottom to top. The thickness of the strength retention layer is 120 μm, and the thickness of the pore-forming and flow channel layer is 120 μm. The strength retention layer is not provided with micropores and microchannels to ensure that the diamond is sufficiently held by the metal matrix. The bottom plane of the diamond is in contact with the bottom plane of the strength retention layer. A group of microchannels in the pore-forming and flow channel layer, the diamond and the surrounding metal matrix form a group of diamond structural units. Two adjacent groups of diamond structural units share a group of micropores. Each group of diamond structural units is square and has a size of 1. The size is 1920μm×1920μm; the microchannel is a rectangular direct flow channel, which is set along the square flow channel boundary area 240μm away from the center point of the diamond. Five microchannels are set on the boundary of each square flow channel. The width of the microchannel is 40μm, the length is 480μm (extending to the end of the diamond structure unit boundary), and the depth is 120μm. The spacing between microchannels on the same boundary is 70μm; outside the boundary of each diamond structure unit, there are 5 circular micropores with a diameter of 80μm and a depth of 120μm, and the micropores are connected to the microchannel.

[0074] Step S2, loading the metal powder of the drill bit matrix working layer into the powder dropping tank of the 3D printing forming device, installing a metal substrate in the forming cavity of the 3D printing forming device, laying the metal powder on the metal substrate, and forming a powder bed to be processed of the strength retention layer;

[0075] Step S3, forming by a selective laser melting process, performing selective laser melting on the strength-retaining layer to-be-processed powder bed obtained in step S2, to generate a strength-retaining layer metal substrate;

[0076] Step S4, lowering the height of the strength-retaining layer metal substrate, laying the metal powder on the strength-retaining layer metal substrate, and then evenly sprinkling diamond particles into the metal powder to form a powder bed to be processed for the pore-forming and flow channel-forming layer;

[0077] Step S5, forming by a selective laser melting process, performing selective laser melting on the powder bed of the pore-forming and flow channel layer to be processed obtained in step S4, to generate a metal substrate of the pore-forming and flow channel layer, wherein during the melting-solidification process, the laser does not scan the position of the preset micropores of the microchannel;

[0078] In order to be more suitable for slipping, creeping and other formations, bronze alloy is used as the metal powder, and the mass content of the alloy elements is 90% copper and 10% tin; the bronze alloy powder is spherical, the sphericity is ≥95%, the oxygen content is ≤300ppm, and the Hall flow rate is ≤18s / 50g.

[0079] Load the metal substrate into the forming cavity of the 3D printing equipment, adjust the upper surface of the metal substrate to the same level as the lower inner wall of the forming cavity, the metal substrate is made of 316 stainless steel, and the size is 125mm×125mm×30mm. The powder dropping tank drops the bronze alloy powder into the forming cavity in front of the rubber scraper. The metal substrate drops 120μm, and the rubber scraper moves to lay the bronze alloy powder on the metal substrate.

[0080] After the metal powder is laid, the robotic arm in the 3D printing equipment starts to execute the movement command according to the imported three-dimensional model data, and sends the diamond to the specified position; the average particle size of the diamond is 240μm, with a relatively complete regular tetradecahedron crystal form, and the upper and lower surfaces are regular hexagons or nearly regular hexagons; after the diamonds of the current processing layer reach the preset position, the current layer of powder bed to be processed is formed.

[0081] Step S6, cyclically repeating steps S2-S5, i.e., laying metal powder, laser scanning to form a strength retention layer, laying metal powder, sprinkling diamonds, scanning to form a hole-making and flow channel-making layer, to generate several layers of single-layer substrates stacked in sequence to form a drill bit matrix working layer of micropores and microchannels.

[0082] The specific process of forming the drill bit matrix working layer of micropore microchannel is as follows:

[0083] (1) Preheat the 3D printing equipment to a temperature of 120°C for the metal substrate;

[0084] (2) starting the gas circulation system to allow argon gas to flow into the forming chamber of the 3D printing device, so that the oxygen content in the forming chamber is ≤200 ppm;

[0085] (3) Turn on the laser, and execute the scanning command according to the 3D model data after the drill tooth slice processing; the laser power is 200w, the scanning speed is 1000mm / s, the scanning interval is 60um, and the energy provided by the laser satisfies the Gaussian distribution; the thickness of the first layer of powder bed metal powder is 120μm, and all of it is scanned by the laser. At this time, the metal matrix forms the first layer of strength retention layer;

[0086] (4) After the first layer of powder bed is processed, the metal substrate is lowered by 120 μm, and the forming cavity scraper lays metal powder again, and the thickness of the metal powder layer is 120 μm;

[0087] (5) Laser scanning of metal powder to cause it to melt and solidify. The laser does not scan the position of the preset microchannel micropores. After the current layer scanning command is executed, the pore-forming and channel-forming layer is obtained, and the processing task in this cycle is completed.

[0088] (6) Execute the processing tasks of the next cycle, namely, laying metal powder, arranging diamonds, scanning and forming a strength retention layer, laying metal powder and scanning and forming a hole-making and flow channel layer;

[0089] (7) Continuously execute the processing task in a loop until all model data is processed;

[0090] (8) After the 3D printing process is completed, the laser and the gas circulation system are turned off, and the forming cavity is allowed to cool naturally to 25°C to obtain a drill bit matrix working layer with micropores and microchannels.

[0091] 2. Preparation of drill teeth

[0092] The drill tooth structure prepared in this embodiment is as follows: the drill tooth is arc-shaped, the drill tooth height is 6 mm, the outer arc radius is 18.25 mm, the inner arc radius is 12.25 mm, and the center angle is 61.65°.

[0093] The drill teeth can be obtained by cutting the drill bit matrix working layer according to the above-mentioned designed size using an electric spark wire cutting machine.

[0094] 3. Preparation of drill bit

[0095] (1) Processing of drill bit rigid body

[0096] The raw material of the drill bit body is a commercial steel round tube with a radius of 18mm and a thickness of 4mm. The drill tooth installation slots are cut by machine tools. There are 4 slots in total, which are consistent with the drill tooth size obtained by 3D printing. Water outlets are processed at the intervals between the steel pipe slots. There are four water outlets in total with a depth of 2mm. The external thread is machined at the other end of the steel pipe slot. The drill bit body is polished and rust-proofed.

[0097] (2) Hot-pressed sintered drill bits with micropores and microchannels

[0098] The machined drill bit rigid body and the drill teeth formed by laser selective melting are combined together by hot pressing and sintering to obtain a complete micro-hole micro-channel drill bit.

[0099] The maximum temperature of hot pressing sintering is 800℃, and the heating rate is 50℃ / min. The pressure range of hot pressing sintering is 10MPa. The holding time after reaching the maximum temperature of hot pressing sintering of 800℃ is 10min. The cooling method after hot pressing sintering is furnace cooling, and the gas environment is air. After the hot pressing sintering furnace is cooled, take out the drill with micropores and microchannels.

[0100] The application process of the drill bit with micropores and microchannels prepared in this embodiment in the construction process of geological drilling engineering is as follows: the micropore and microchannel drill bit is installed with the drill rod, and after the geological drilling rig is turned on, the active drill rod rotates to drive the drill rod and the micropore and microchannel drill bit to rotate, and the micropore and microchannel drill bit interacts with the rock formation. The impact / rotation action of the drill bit ensures that the diamond cuts into / presses into the rock to break it. After the generated rock cuttings are peeled off from the rock formation, part of them are directly washed back to the mud pool by the drilling fluid, and part of them remain on the drill bit lip surface, enter the micropores outside the boundary of the diamond structure unit through the microchannel, and are taken away from the drill bit lip surface as the drilling fluid is washed away.

[0101] The drill bit with micropores and microchannels prepared in this embodiment has the following benefits for geological drilling engineering construction: artificially controllable microchannels are arranged on the drill bit lip surface, and the drill bit lip surface is cooled during the circulation of drilling fluid in the microchannels to prevent the accumulation of large amounts of frictional heat and the occurrence of drill burning; when the rock or rock-forming mineral has strong adhesion, it is easy to stick to the surface of the drill bit and cause the drill to become sticky, which reduces the mechanical drilling speed and greatly reduces the geological drilling efficiency. Microchannels and micropores are buried inside the drill teeth to increase the liquid flow on the drill bit lip surface and reduce the accumulation of rock chips on the drill bit lip surface, which can protect the diamond from repeated wear by rock chips and prevent the phenomenon of sticking and "slipping", thereby increasing the mechanical drilling speed by more than 10%.

[0102] Example 2

[0103] The drill bit rigid body to be manufactured has a diameter of 75mm, and the working layer of the drill bit is composed of 6 drill teeth. The drill tooth height is 8mm, and it is arc-shaped. The outer circle radius is 37.75mm, the inner circle radius is 29.75mm, and the central angle is 30°. The 6 drill teeth are evenly spaced around the end of the drill bit rigid body.

[0104] 1. Preparation of drill bit matrix working layer

[0105] Step S1, constructing a 3D model of a drill bit carcass working layer, slicing and layering the 3D model of the drill bit carcass working layer, and importing the data into a 3D printing device;

[0106] The designed model is: Figure 8As shown in the figure, the drill bit matrix working layer is composed of a strength retention layer and a pore-forming and flow channel layer which are cyclically stacked in sequence. The strength retention layer is 80 μm thick, and the pore-forming and flow channel layer is 80 μm thick. The strength retention layer is not provided with micropores and microchannels to ensure that the diamond is sufficiently held by the metal matrix. The bottom plane of the diamond is in contact with the bottom plane of the strength retention layer. A group of microchannels in the pore-forming and flow channel layer, together with the diamond and the surrounding metal matrix, form a group of diamond structural units. Two adjacent groups of diamond structural units have two micropores connected and interpenetrating with each other. Each group of diamond structural units is in the shape of The microchannel is circular with a diameter of 1120μm. The microchannel is an arc-shaped channel, which is set along the circular channel boundary area 240μm away from the center point of the diamond. There are 12 microchannels evenly distributed on each circular channel boundary. The microchannel width is 40μm, the arc radius is 320μm (extending to the end of the diamond structure unit boundary), and the depth is 80μm. The spacing between microchannels on the same boundary is equal. Outside the boundary of each diamond structure unit, there are 12 circular micropores with a diameter of 80μm and a depth of 120μm. The micropores are connected to the microchannel.

[0107] Step S2, loading the metal powder of the drill bit matrix working layer into the powder dropping tank of the 3D printing forming device, installing a metal substrate in the forming cavity of the 3D printing forming device, laying the metal powder on the metal substrate, and forming a powder bed to be processed of the strength retention layer;

[0108] Step S3, forming by a selective laser melting process, performing selective laser melting on the strength-retaining layer to-be-processed powder bed obtained in step S2, to generate a strength-retaining layer metal substrate;

[0109] Step S4, lowering the height of the strength-retaining layer metal substrate, laying the metal powder on the strength-retaining layer metal substrate, and then evenly sprinkling diamond particles into the metal powder to form a powder bed to be processed for the pore-forming and flow channel-forming layer;

[0110] Step S5, forming by a selective laser melting process, performing selective laser melting on the powder bed of the pore-forming and flow channel layer to be processed obtained in step S4, to generate a metal substrate of the pore-forming and flow channel layer, wherein during the melting-solidification process, the laser does not scan the position of the preset micropores of the microchannel;

[0111] In order to be more suitable for hard formations with smaller rock-forming mineral particles, the metal powder is cobalt-chromium-molybdenum alloy, and the mass content of the alloy elements is 66% cobalt, 28% chromium, and 6% molybdenum; the cobalt-chromium-molybdenum alloy powder is spherical, with a sphericity of ≥95%, an oxygen content of ≤500ppm, and a Hall flow rate of ≤21s / 50g;

[0112] Load the metal substrate into the forming cavity of the 3D printing equipment, adjust the upper surface of the metal substrate to the same level as the lower inner wall of the forming cavity, the metal substrate is made of 316 stainless steel, and the size is 125mm×125mm×30mm. The powder dropping tank drops the bronze alloy powder into the forming cavity in front of the rubber scraper. The metal substrate drops 80μm, and the rubber scraper moves to lay the bronze alloy powder on the metal substrate.

[0113] After the metal powder is laid, the robotic arm in the 3D printing equipment starts to execute the movement command according to the imported three-dimensional model data, and sends the diamond to the specified position; the average particle size of the diamond is 160μm, with a relatively complete regular tetradecahedron crystal form, and the upper and lower surfaces are regular hexagons or nearly regular hexagons; after the diamonds of the current processing layer reach the preset position, the current layer of powder bed to be processed is formed.

[0114] Step S6, cyclically repeating steps S2-S5, i.e., laying metal powder, laser scanning to form a strength retention layer, laying metal powder, sprinkling diamonds, scanning to form a hole-making and flow channel-making layer, to generate several layers of single-layer substrates stacked in sequence to form a drill bit matrix working layer of micropores and microchannels.

[0115] The specific process of forming the drill bit matrix working layer of micropore microchannel is as follows:

[0116] (1) Preheat the 3D printing equipment to make the temperature of the metal substrate reach 180°C;

[0117] (2) starting the gas circulation system to allow argon gas to flow into the forming chamber of the 3D printing device, so that the oxygen content in the forming chamber is ≤300 ppm;

[0118] (3) Turn on the laser, and execute the scanning command according to the 3D model data after the drill tooth slice processing; the laser power is 220w, the scanning speed is 750mm / s, the scanning interval is 120μm, and the energy provided by the laser satisfies the Gaussian distribution; the thickness of the first layer of powder bed metal powder is 80μm, and all of it is scanned by the laser. At this time, the metal matrix forms the first layer of strength retention layer;

[0119] (4) After the first layer of powder bed is processed, the metal substrate is lowered by 80 μm, and the forming cavity scraper lays metal powder again, and the thickness of the metal powder layer is 80 μm;

[0120] (5) Laser scanning of metal powder to cause it to melt and solidify. The laser does not scan the position of the preset microchannel micropores. After the current layer scanning command is executed, the pore-forming and channel-forming layer is obtained, and the processing task in this cycle is completed.

[0121] (6) Execute the processing tasks of the next cycle, namely, laying metal powder, arranging diamonds, scanning and forming a strength retention layer, laying metal powder and scanning and forming a hole-making and flow channel layer;

[0122] (7) Continuously execute the processing task in a loop until all model data is processed;

[0123] (8) After the 3D printing process is completed, the laser and the gas circulation system are turned off, and the forming cavity is allowed to cool naturally to 25°C to obtain a drill bit matrix working layer with micropores and microchannels.

[0124] 2. Preparation of drill teeth

[0125] The drill tooth structure prepared in this embodiment is as follows: the drill tooth is arc-shaped, the drill tooth height is 8 mm, the outer arc radius is 37.75 mm, the inner arc radius is 29.75 mm, and the center angle is 30°.

[0126] The drill teeth can be obtained by cutting the drill bit matrix working layer according to the above-mentioned designed size using an electric spark wire cutting machine.

[0127] 3. Preparation of drill bit

[0128] (1) Processing of drill bit rigid body

[0129] The raw material of the drill bit body is a commercial steel round tube with a radius of 37.5mm and a thickness of 5mm. The drill tooth installation slots are cut by machine tools, with a total of 6 slots, which are consistent with the drill tooth size obtained by 3D printing. Water outlets are processed at the intervals of the steel pipe slots, with a total of 6 outlets and a depth of 3mm. The external thread is machined at the other end of the steel pipe slot. The drill bit body is polished and rust-proofed.

[0130] (2) Hot-pressed sintered drill bits with micropores and microchannels

[0131] The machined drill bit rigid body and the drill teeth formed by laser selective melting are combined together by hot pressing and sintering to obtain a complete micro-hole micro-channel drill bit.

[0132] The maximum temperature of hot pressing sintering is 1000℃, and the heating rate is 50℃ / min. The pressure range of hot pressing sintering is 15MPa. The holding time after reaching the maximum temperature of hot pressing sintering of 1000℃ is 15min. The cooling method after hot pressing sintering is furnace cooling, and the gas environment is air. After the hot pressing sintering furnace is cooled, the drill with micropores and microchannels is taken out.

[0133] The application process of the drill bit with micropores and microchannels prepared in this embodiment in the construction process of geological drilling engineering is as follows: the micropore and microchannel drill bit is installed with the drill rod, and after the geological drilling rig is turned on, the active drill rod rotates to drive the drill rod and the micropore and microchannel drill bit to rotate, and the micropore and microchannel drill bit interacts with the rock formation. The impact / rotation action of the drill bit ensures that the diamond cuts into / presses into the rock to break it. After the generated rock cuttings are peeled off from the rock formation, part of them are directly washed back to the mud pool by the drilling fluid, and part of them remain on the drill bit lip surface, enter the micropores outside the boundary of the diamond structure unit through the microchannel, and are taken away from the drill bit lip surface as the drilling fluid is washed away.

[0134] The drill bit with micropores and microchannels prepared in this embodiment has the following benefits for geological drilling engineering construction: artificially controllable microchannels are arranged on the drill bit lip surface, and the drill bit lip surface is cooled during the circulation of drilling fluid in the microchannels to prevent the accumulation of large amounts of frictional heat and the occurrence of drill burning; when the rock or rock-forming mineral has strong adhesion, it is easy to stick to the surface of the drill bit and cause the drill to become sticky, which reduces the mechanical drilling speed and greatly reduces the geological drilling efficiency. Microchannels and micropores are buried inside the drill teeth to increase the liquid flow on the drill bit lip surface and reduce the accumulation of rock chips on the drill bit lip surface, which can protect the diamond from repeated wear by rock chips and prevent the phenomenon of sticking and "slipping", thereby increasing the mechanical drilling speed by more than 15%.

[0135] In the absence of conflict, the above embodiments and features in the embodiments may be combined with each other.

[0136] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A drill bit matrix working layer based on 3D printing, characterized in that: The drill bit matrix working layer (1) is composed of a strength retaining layer (11) and a pore-forming and flow channel-forming layer (12) which are sequentially stacked in a cyclic manner from bottom to top. The strength retaining layer (11) is a metal substrate formed by melting metal powder by full-area laser scanning, and the pore-forming and flow channel-forming layer (12) is a metal substrate formed by melting metal powder by partial-area laser scanning. The top of the drill bit matrix working layer (1) is the pore-forming and flow channel-forming layer (12). The outer surface of the pore-forming and flow channel-forming layer (12) is provided with a plurality of protrusions. The pore-forming and flow channel-forming layer (12) includes a plurality of groups of diamond structural units (13). Each group of the diamond structural units (13) includes a diamond (131), a flow channel boundary (132) and a plurality of microchannels (133). The plurality of diamond (131) portions A plurality of protrusions are formed on the outer surface of the pore-forming and flow-forming channel layer (12), the flow-forming channel boundary (132) wraps the diamond (131), and a plurality of microchannels (133) are evenly spaced around the flow-forming channel boundary (132). The ends of each microchannel (133) are connected to a micropore (134), and two adjacent diamond structure units (13) are connected through at least one micropore (134). When the flow-forming channel boundary (132) is square, the diamond structure unit (13) is square; when the flow-forming channel boundary (132) is circular, the diamond structure unit (13) is circular, and the diameter of the diamond structure unit (13) is 7 to 9 times the average particle size of the diamond (131).

2. The method for preparing a drill bit matrix working layer based on 3D printing according to claim 1, characterized in that: The specific steps include: S1, constructing a 3D model of a drill bit matrix working layer, slicing and layering the 3D model of the drill bit matrix working layer, and importing the data into a 3D printing forming device; the drill bit matrix working layer is composed of a strength retaining layer and a pore-forming and flow channel-forming layer which are sequentially stacked in a circular manner, and the pore-forming and flow channel-forming layer is provided with micropores and microchannels; S2, loading the metal powder of the drill bit matrix working layer into the powder dropping tank of the 3D printing forming equipment, installing a metal substrate in the forming cavity of the 3D printing forming equipment, laying the metal powder on the metal substrate, and forming a powder bed to be processed of the strength retention layer; S3, forming by a selective laser melting process, performing selective laser melting on the strength-retaining layer to-be-processed powder bed obtained in step S2, to generate a strength-retaining layer metal substrate; S4, lowering the height of the strength-retaining layer metal substrate, laying the metal powder on the strength-retaining layer metal substrate, and then evenly sprinkling diamond particles into the metal powder to form a powder bed to be processed for the pore-forming and flow channel-forming layer; S5, forming by a selective laser melting process, performing selective laser melting on the powder bed of the pore-forming and flow channel layer to be processed obtained in step S4, to generate a metal substrate of the pore-forming and flow channel layer, wherein during the melting-solidification process, the laser does not scan the position of the preset micropores of the microchannel; S6, repeating steps S2-S5 in a loop, i.e., laying metal powder, laser scanning to form a strength retention layer, laying metal powder, sprinkling diamonds, scanning to form a hole-making and flow channel-making layer, to generate several layers of single-layer substrates stacked in sequence to form a drill bit matrix working layer of micropores and microchannels.

3. The preparation method according to claim 2, characterized in that The sphericity of the metal powder is ≥95%, the oxygen content is ≤800ppm, the Hall flow rate is ≤18s / 50g, and the particle size is 15~53μm; the crystal form of the diamond particles is a regular dodecahedron, and the average particle size ranges from 240μm to 300μm; in the powder bed to be processed, the volume ratio of diamond is 10%~25%, and the volume ratio of metal powder is 75%~90%.

4. The preparation method according to claim 2, characterized in that: The selective laser melting forming process includes: introducing a protective gas to reduce the oxygen content in the forming cavity to below 300 ppm, and raising the temperature of the substrate in the forming cavity to 100° C. to 200° C.

5. The preparation method according to claim 4, characterized in that: The protective gas includes at least one of argon and nitrogen, the metal powder layer thickness of the powder bed is set to 40~60μm, the filling spacing is 120~160μm, the laser scanning speed is 550~1550mm / s, the laser power is 100~500w, the scanning strategy is strip XY scanning, and the laser commutation angle is 60°~70°.

6. The preparation method according to claim 2, characterized in that: Each time the current layer of substrate is processed, the metal substrate is lowered to a certain height, where the height is the total thickness of the strength retention layer and the pore-forming and flow channel-forming layer; the thickness of the single-layer substrate is 50 μm to 300 μm.

7. A drill tooth, characterized in that: The drill bit matrix working layer as claimed in claim 1 is cut into a preset shape.

8. A drill bit, comprising a drill bit rigid body and drill teeth arranged on the drill bit rigid body, characterized in that: The drill tooth is the drill tooth as claimed in claim 7.

9. The drill bit according to claim 8, characterized in that The drill bit (4) comprises a drill bit rigid body (2) and a plurality of drill teeth (3); the end of the drill bit rigid body (2) is provided with water inlets (21) evenly spaced around its circumference; a gauge guard (22) is provided between two adjacent water inlets (21); a thread (23) is provided on the bottom outer surface of the drill bit rigid body (2); the upper surface of each gauge guard (22) is provided with the drill teeth (3); and the drill teeth (3) correspond to the gauge guards (22) one by one.

10. Use of the drill bit according to any one of claims 8 to 9 in a geological drilling engineering construction process.

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