Diamond drill bit for punching mobile phone backboard and preparation method of diamond drill bit

Abstract

The diamond drill bit comprises a steel base body and a diamond tool bit, the steel base body comprises a cylindrical section and a conical section which are integrally formed, the diamond tool bit is welded to the outer end of the conical section, the taper of the conical section is 25-35 degrees, the outer diameter of the diamond tool bit is 3-8 mm, the outer diameter of the cylindrical section is 3-8 mm, and the outer diameter of the conical section is 3-8 mm. Raw materials of the diamond tool bit comprise metal alloy powder and diamond, the metal alloy powder specifically comprises, by weight, 30%-40% of copper powder, 5%-10% of tin powder, 20%-30% of copper-tin pre-alloyed powder and 20%-40% of superfine cobalt powder, the volume fraction of the diamond is 50%-80% (prepared according to 400%), and the particle size of the diamond is 65-90 microns. Comprising the steps of material mixing, granulation, powder loading and sintering, demolding, welding, electric spark machining and the like. By selecting the raw materials and the weight percentage of the diamond tool bit, the concentricity of the diamond tool bit and the steel substrate is ensured to be less than or equal to 0.02 mm, and the method has the advantages of being good in diamond exposure, high in punching speed, large in punching number, high in reaming precision and the like.

Description

Technical Field

[0001] The invention relates to the field of drill bits, and in particular to a diamond drill bit used for drilling holes in a mobile phone back plate and a preparation method thereof. Background Art

[0002] In recent years, the development of Internet technology, the improvement of the manufacturing level of consumer electronic products, and the increase in residents' income levels have gradually led to the integration of consumer electronic products and the Internet becoming a trend, and the use of consumer electronic products has gradually become a part of residents' daily lives. Mobile phones, digital products, home appliances and their ancillary products are still the fastest growing products in the consumer electronics market. At the same time, tablet computers, smart appliances, digital TVs and other products are also rapidly maturing and becoming new growth points in the consumer electronics market. At the same time, China's consumer electronics industry will gradually grow into a large-scale industry with mature independent supporting capabilities. In the future, the growth rate of China's consumer electronics industry output value and sales will remain stable.

[0003] The sales of consumer electronic materials, especially smartphones, remain high all year round, and each mobile phone needs to grind the back panel to open steps and punch holes in the cover for assembly protection, so the corresponding grinding and drilling tools are in great demand. The main problems of mobile phone drilling and hole expansion drills are product performance assurance and product precision control. At present, domestic drills are prone to broken teeth when expanding holes, and the drilling life is far less than that of imported products. Summary of the invention

[0004] The purpose of the invention is to provide a diamond drill bit for drilling holes in a mobile phone back plate, so as to solve the problems of easy tooth breakage and short service life of the drill bit when expanding the hole.

[0005] In order to solve the above technical problems, the present invention is implemented by the following technical solutions:

[0006] A diamond drill bit for punching holes in a back panel of a mobile phone comprises a steel matrix and a diamond bit, wherein the steel matrix comprises an integrally formed cylindrical section and a conical section, the diamond bit is welded to the outer end of the conical section, the taper of the conical section is 25°-35°, the outer diameter of the diamond bit is 3mm-8mm, the outer diameter of the cylindrical section is 3mm-8mm, the raw materials of the diamond bit comprise metal alloy powder and diamond, the metal alloy powder specifically comprises the following raw materials in weight percentage: 30%-40% copper powder, 5%-10% tin powder, 20%-30% copper-tin pre-alloy powder and 20%-40% ultrafine cobalt powder, the volume fraction of diamond is 50%-80% (based on 400%), and the particle size is 65-90um.

[0007] Preferably, the outer diameter of the diamond bit is 1 mm-3 mm, the outer diameter of the steel substrate is 6 mm, and the height of the diamond bit is 4 mm-10 mm.

[0008] Preferably, the copper powder has a particle size of 30-35um, the tin powder has a particle size of 25-30um, the copper-tin pre-alloy powder has a particle size of 15-20um, the ultrafine cobalt powder has a particle size of 5-8um, and the weight percentage of tin in the copper-tin pre-alloy powder is 30%, and the rest is copper.

[0009] A method for preparing a diamond drill bit specifically comprises the following steps:

[0010] Step 1: For the production of diamond segments, weigh the following raw materials in weight proportion: 30-40 parts of copper powder, 5-10 parts of tin powder, 20-30 parts of copper-tin pre-alloyed powder, and 20-40 parts of ultrafine cobalt powder, wherein the volume fraction of diamond is 50%-80% (based on 400%), and the particle size is 65-90um. Put the above raw materials into a three-dimensional mixer for mixing, and add a granulating agent at the same time. The mixing time is not less than 2 hours. After mixing evenly, granulation treatment is carried out, and the mixture is placed in a drying oven for drying for 60 minutes to obtain a mixture of metal powder and diamond particles, and the particle size of the mixture particles is 30#~80#;

[0011] Step 2: powder filling and sintering, the mixture particles obtained in step 1 are transferred into a graphite mold, and then the graphite mold is placed in a hot press for hot pressing and sintering, the sintering temperature is 800-950°C, the sintering pressure is 10-20MPa, the heat preservation time is 5-8min, and the sintering is naturally cooled after the sintering is completed, and the demolding treatment is performed after cooling to obtain a diamond cutter head;

[0012] Step 3: Deburr and sandblast the diamond cutter head obtained in step 2, then polish the sandblasted diamond cutter head welding surface, clean the oil stains on the steel substrate welding surface, and apply a certain amount of silver solder paste, install the steel substrate on the spindle of the engraving machine, and then place the diamond cutter head welding surface on the steel substrate welding surface for high-frequency welding, first heat for about 2s-4s, wait for the solder paste to completely melt, cool it, and then demold it to obtain the semi-finished drill bit;

[0013] Step 4: For the semi-finished drill bit welded in step 3, firstly finish turning the outer circle of the steel base to the required tolerance size, then use the electro-discharge method to process the end face of the drill bit and the outer circle of the diamond cutter head, diamond grind the top of the diamond cutter head to the required size, then process the taper of the steel base, and finally use the three-coordinate to detect the accuracy of the drill bit to obtain the finished drill bit.

[0014] Preferably, the graphite mold described in the above step 2 comprises an outer frame, an upper pressure head and a lower pressure head. When loading the powder, the lower pressure head is first loaded into the graphite mold, then the mixture particles are loaded, and finally the upper pressure head is placed.

[0015] The present invention has the following beneficial effects: by selecting the raw materials and weight percentage of the diamond bit, the present invention can form a diamond bit with a sharp cutting edge through hot pressing and sintering, and after welding, subsequent electric spark trimming is performed to ensure that the concentricity of the diamond bit and the steel substrate is ≤0.02mm, and the diamond bit has the advantages of good diamond blade, fast drilling speed, large number of holes, high hole expansion accuracy, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the present invention.

[0017] In the figure: 1- steel substrate; 2- diamond bit;. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] Example 1

[0020] like Figure 1 As shown, a diamond drill bit for punching holes in a back panel of a mobile phone comprises a steel substrate 1 and a diamond bit 2. The steel substrate 1 comprises an integrally formed cylindrical section and a conical section. The diamond bit 2 is welded to the outer end of the conical section. The taper of the conical section is 25°-35°. The outer diameter of the diamond bit 2 is 3mm-8mm, and the outer diameter of the cylindrical section is 3mm-8mm. The raw materials of the diamond bit 2 comprise metal alloy powder and diamond. The metal alloy powder specifically comprises the following raw materials in weight percentage: 30%-40% copper powder, 5%-10% tin powder, 20%-30% copper-tin pre-alloy powder and 20%-40% ultrafine cobalt powder. The volume fraction of diamond is 50%-80% (based on 400%), and the particle size is 65-90um. The preparation method of the diamond drill bit specifically comprises the following steps:

[0021] Step 1: For the production of diamond segments, the following raw materials in weight proportion are weighed: 35 parts of copper powder, 5 parts of tin powder, 25 parts of copper-tin pre-alloyed powder, and 35 parts of ultrafine cobalt powder, wherein the volume fraction of diamond is 55% (based on 400%), and the particle size is 65-90um. The above raw materials are put into a three-dimensional mixer for mixing, and a granulating agent is added at the same time. The mixing time is not less than 2 hours. After mixing evenly, granulation treatment is performed, and the mixture is placed in a drying oven for drying for 60 minutes to obtain a mixture of metal powder and diamond particles, and the particle size of the mixture particles is 30# to 80#;

[0022] Step 2: powder filling and sintering, the mixture particles obtained in step 1 are transferred into a graphite mold, and then the graphite mold is placed in a hot press for hot pressing and sintering, the sintering temperature is 800-950°C, the sintering pressure is 10-20MPa, the heat preservation time is 5-8min, and the sintering is naturally cooled after the sintering is completed, and the demolding treatment is performed after cooling to obtain a diamond cutter head;

[0023] Step 3: Deburr and sandblast the diamond cutter head obtained in step 2, then polish the sandblasted diamond cutter head welding surface, clean the oil stains on the steel substrate welding surface, and apply a certain amount of silver solder paste, install the steel substrate on the spindle of the engraving machine, and then place the diamond cutter head welding surface on the steel substrate welding surface for high-frequency welding, first heat for about 2s-4s, wait for the solder paste to completely melt, cool it, and then demold it to obtain the semi-finished drill bit;

[0024] Step 4: For the semi-finished drill bit welded in step 3, first fine-turn the outer circle of the steel base to the required tolerance size, then use the electro-discharge method to process the end face of the drill bit and the outer circle of the diamond cutter head, diamond-grind the top of the diamond cutter head to the required size, and then process the taper of the steel base body. Finally, use the three-coordinate system to detect the accuracy of the drill bit to obtain the finished drill bit. During the processing, pay attention to the fact that the discharge current should not be too large, which is easy to cause pits, and then process the taper of the base body.

[0025] Example 2

[0026] This embodiment is the same as embodiment 1, except that 40 parts of copper powder, 6 parts of tin powder, 22 parts of copper-tin pre-alloyed powder, and 32 parts of ultrafine cobalt powder are weighed, wherein the volume fraction of diamond accounts for 60% (based on 400%).

[0027] Example 3

[0028] This embodiment is the same as embodiment 1, except that 30 parts of copper powder, 106 parts of tin powder, 20 parts of copper-tin pre-alloyed powder, and 40 parts of ultrafine cobalt powder are weighed, wherein the volume fraction of diamond accounts for 50% (based on 400%).

[0029] Example 4

[0030] This embodiment is the same as embodiment 1, except that 40 parts of copper powder, 106 parts of tin powder, 30 parts of copper-tin pre-alloyed powder, and 20 parts of ultrafine cobalt powder are weighed, wherein the volume fraction of diamond accounts for 80% (based on 400%).

[0031] The diamond drill bits prepared in the above-mentioned embodiments 1-4 have an outer diameter of the diamond bit 2 of 1 mm-3 mm, an outer diameter of the steel substrate 1 of 6 mm, and a height of the diamond bit 2 of 4 mm-10 mm.

[0032] Specifically, the copper powder has a particle size of 30-35um, the tin powder has a particle size of 25-30um, the copper-tin pre-alloy powder has a particle size of 15-20um, the ultrafine cobalt powder has a particle size of 5-8um, and the weight percentage of tin in the copper-tin pre-alloy powder is 30%, and the rest is copper.

[0033] The diamond drill bits prepared in Examples 1-4 differ slightly in the weight percentage of the raw materials of the diamond segments 2 in each example. By testing various properties of the diamond drill bits formed therefrom, it is found that the differences in the properties are not large, as shown in Table 1 below:

[0034] Table 1

[0035]

[0036]

[0037] It can be seen from the above table that the present invention can form a diamond cutter head with a sharp cutting edge by hot pressing and sintering through the selection of the raw materials and weight percentage of the diamond cutter head. After welding, subsequent electric spark trimming is performed to ensure that the concentricity of the diamond cutter head and the steel substrate is ≤0.02mm. The diamond cutter head has the advantages of good diamond cutting edge, fast drilling speed, large number of holes, and high hole expansion accuracy.

[0038] The above are only preferred embodiments of the present invention, and are not intended to limit the implementation methods and protection scope of the present invention. Those skilled in the art should be aware that all solutions obtained by equivalent substitutions and obvious changes made using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A diamond drill bit for drilling holes in a mobile phone back panel, comprising a steel substrate and a diamond bit, characterized in that: The steel substrate includes an integrally formed cylindrical section and a conical section, the diamond bit is welded to the outer end of the conical section, the taper of the conical section is 25°-35°, the outer diameter of the diamond bit is 3mm-8mm, the outer diameter of the cylindrical section is 3mm-8mm, the raw material of the diamond bit includes metal alloy powder and diamond, the metal alloy powder specifically includes the following raw materials in weight percentage: copper powder 30%-40%, tin powder 5%-10%, copper-tin pre-alloy powder 20%-30% and ultrafine cobalt powder 20%-40%, the volume fraction of diamond is 50%-80% (based on 400%), and the particle size is 65-90um.

2. A diamond drill bit for punching holes in a mobile phone back panel according to claim 1, characterized in that: The outer diameter of the diamond bit is 1mm-3mm, the outer diameter of the steel substrate is 6mm, and the height of the diamond bit is 4mm-10mm.

3. The diamond drill bit for drilling a hole in a mobile phone back panel according to claim 1, characterized in that: The copper powder has a particle size of 30-35um, the tin powder has a particle size of 25-30um, the copper-tin pre-alloy powder has a particle size of 15-20um, the ultrafine cobalt powder has a particle size of 5-8um, and the weight percentage of tin in the copper-tin pre-alloy powder is 30%, and the rest is copper.

4. A method for preparing a diamond drill bit as claimed in claim 1, characterized in that: The specific steps include: Step 1: For the production of diamond segments, weigh the following raw materials in weight proportion: 30-40 parts of copper powder, 5-10 parts of tin powder, 20-30 parts of copper-tin pre-alloyed powder, and 20-40 parts of ultrafine cobalt powder, wherein the volume fraction of diamond is 50%-80% (based on 400%), and the particle size is 65-90um. Put the above raw materials into a three-dimensional mixer for mixing, and add a granulating agent at the same time. The mixing time is not less than 2 hours. After mixing evenly, granulation treatment is carried out, and the mixture is placed in a drying oven for drying for 60 minutes to obtain a mixture of metal powder and diamond particles, and the particle size of the mixture particles is 30#~80#; Step 2: powder filling and sintering, the mixture particles obtained in step 1 are transferred into a graphite mold, and then the graphite mold is placed in a hot press for hot pressing and sintering, the sintering temperature is 800-950°C, the sintering pressure is 10-20MPa, the heat preservation time is 5-8min, and the sintering is naturally cooled after the sintering is completed, and the demolding treatment is performed after cooling to obtain a diamond cutter head; Step 3: Deburr and sandblast the diamond cutter head obtained in step 2, then polish the sandblasted diamond cutter head welding surface, clean the oil stains on the steel substrate welding surface, and apply a certain amount of silver solder paste, install the steel substrate on the spindle of the engraving machine, and then place the diamond cutter head welding surface on the steel substrate welding surface for high-frequency welding, first heat for about 2s-4s, wait for the solder paste to completely melt, cool it, and then demold it to obtain the semi-finished drill bit; Step 4: For the semi-finished drill bit welded in step 3, firstly finish turning the outer circle of the steel base to the required tolerance size, then use the electro-discharge method to process the end face of the drill bit and the outer circle of the diamond cutter head, diamond grind the top of the diamond cutter head to the required size, then process the taper of the steel base, and finally use the three-coordinate to detect the accuracy of the drill bit to obtain the finished drill bit.

5. The method for preparing a diamond drill bit according to claim 4, characterized in that: The graphite mold described in step 2 includes an outer frame, an upper pressure head, and a lower pressure head. When loading powder, first load the lower pressure head into the graphite mold, then load the mixture particles, and finally put the upper pressure head on.

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