Electric hair cutter moving cutter blade blank and production process and injection molding die thereof

Abstract

The invention discloses an electric hair cutter moving cutter blade blank and a production process and an injection molding mold thereof. The production process comprises the following steps: S1, manufacturing a set of injection molding mold; s2, preparing a composite raw material; s3, manufacturing a movable cutter blade blank through an injection molding process; s4, performing in-mold glue sealing treatment to form a glue sealing layer; s5, degreasing in a degreasing furnace; s6, high-temperature sintering is conducted in a sintering furnace, and the shrinkage rate during sintering is 16.5 + / -0.5%; s7, heat treatment hardening is conducted; and S8, a sliding movable cutter edge is formed through a grinding technology, and a finished product of the movable cutter blade blank is obtained. The production process provided by the invention not only can solve the problems that ceramic is easy to break, but also can solve the problems that stainless steel temperature rise is high and tooth punching is difficult when the stainless steel blade is machined by a traditional punching machine, and also can solve the problem that an acute angle punching die of a punching blade is difficult to manufacture. The method is simple in process, extremely high in production efficiency and suitable for mass production, and the development cost and the production cost can be greatly reduced.

Description

Technical Field

[0001] The invention relates to a blade blank for a movable blade of an electric hair clipper and a production process and an injection molding die. Background Art

[0002] As a commonly used hairdressing tool, hair clippers are well known to people. They are mainly used to trim human hair or animal hair. The hair clippers include a shell and a motor arranged in the shell. A fixed blade is fixed at the front end of the shell. A movable blade is fixed at the front end of a swing head through a swing frame. The motor drives the swing head to swing left and right, thereby driving the movable blade to move left and right relative to the fixed blade to achieve the hair trimming function. The motor is divided into a rotary motor and a swing motor. The rotary motor is a rotary electromagnetic machine that operates on the principle of electromagnetic induction and is used to realize the mutual conversion of mechanical energy and electrical energy. At the same time, the rotary motor converts the rotary motion into reciprocating swing with the help of a transmission mechanism. Common transmission mechanisms include cam mechanisms and eccentric connecting rod structures.

[0003] The razor blade is the main working part of a shaver or a hair shaving device. Existing shavers or hair shaving devices mainly include rotary and reciprocating types. The razor blade rotates or swings on the head of the shaver or hair shaving device, so that the razor blade moves relative to the fixed blade net to cut off the hair between the razor blade and the fixed blade net. The cutting end of the razor blade is usually provided with a plurality of cutting teeth at intervals. The sharpness of the cutting edge of the cutting teeth and the shape of the cutting teeth will greatly affect the hair cutting effect.

[0004] The mainstream moving blades on the market are still ceramic, which is difficult to process and has poor toughness, making it easy to have defects such as broken teeth. Some moving blades are made by stamping stainless steel and then slotting with special slotting equipment. However, since the slotting equipment is special, the price is high; it is difficult to remove burrs after slotting, and it is difficult to make sharp angles, resulting in poor sharpness. At the same time, during use, the temperature of stainless steel moving blades rises high and they are easy to get hot, which gives consumers a poor experience. Summary of the invention

[0005] In order to overcome the above-mentioned shortcomings of the prior art, the present invention provides a production process for a blade blank of an electric hair clipper.

[0006] The technical solution of the present invention to solve the technical problem is: a production process of a movable blade blank, comprising:

[0007] S1. Make a set of injection molding molds;

[0008] S2, preparing the composite raw material, mixing and kneading at 170±5°C and pelletizing and drying to obtain 5±2mm composite raw material particles;

[0009] S3. Place the injection molding die into a precision injection molding machine. Then, add the composite raw material particles into the precision injection molding machine to manufacture a moving blade blank through an injection molding process. The moving blade blank includes an upper fixed section and a lower sliding section, and a tooth-shaped part is provided at the lower sliding section. The tooth-shaped part includes a plurality of unit teeth, and tooth spaces are formed between adjacent unit teeth;

[0010] S4. Perform in-mold sealing on the lower sliding section of the moving blade blank to form a sealing layer;

[0011] S5. Place the moving blade blank on a ceramic plate and then put the whole into a debinding furnace for debinding;

[0012] S6. Put the debound moving blade blank into a sintering furnace for high-temperature sintering. The shrinkage rate during sintering is 16.5 ± 0.5%;

[0013] S7. Put the sintered moving blade blank into a heat treatment furnace for heat treatment hardening;

[0014] S8. Form a sliding moving blade edge on the tooth-shaped part through a grinding and lapping process to obtain a finished product of the moving blade blank;

[0015] In step S2, the composite raw material is a combination of metal powder and binder, and the weight ratio of the metal fusion powder to the binder is 10.6:1;

[0016] Among them, the metal fusion powder, by weight percentage, includes the following components: 85% - 95% of metal powder of 440C stainless steel or M2 steel, 15% - 5% of alumina powder or zirconia powder;

[0017] Among them, the binder, by weight percentage, includes the following components: polyoxymethylene accounts for 81.2% ± 1%: high-density polyethylene accounts for 7.1% ± 1%: styrene-acrylonitrile copolymer accounts for 4.6% ± 1%; antioxidant 1010 accounts for 7.1% ± 1%.

[0018] Optionally, in step S3, the thickness dimension of the obtained moving blade blank is less than or equal to 3mm ± 1‰.

[0019] Optionally, in step S4, the thickness T of the sealing on the lower sliding section of the moving blade blank is T > 0.25mm, and the depth H of the tooth space after sealing is H ≥ 0.15mm.

[0020] Optionally, in step S5, the debinding temperature is 90 - 120°C, the debinding medium is oxalic acid, and the debinding time is 6 - 10h.

[0021] Optionally, in step S6, the sintering temperature in the first stage rises from room temperature to 600°C, and the sintering time in the first stage lasts for 5 - 6h;

[0022] The sintering temperature in the second stage rises from 600 °C to 1050 °C, and the sintering time in the second stage lasts for 6 - 8 h;

[0023] The sintering temperature in the third stage rises from 1050 °C to 1300 °C, and the sintering time in the third stage lasts for 8 - 10 h;

[0024] The sintering temperature in the fourth stage drops from 1300 °C to 1100 °C, and the sintering time in the fourth stage lasts for 5 - 6 h;

[0025] The sintering temperature in the fifth stage drops from 1100 °C to room temperature, and the sintering time in the fifth stage lasts for 3 - 5 h.

[0026] Optionally, in step S7, the heat treatment temperature is set at 1045 - 1055 °C, and the hardness of the moving blade blank after heat treatment is HRC61 - 65; then the moving blade blank is subjected to tempering treatment, and the hardness of the moving blade blank after tempering treatment is HRC57 - 60.

[0027] Optionally, in step S8, the angle of the moving blade edge formed by the grinding and polishing process is 45° - 55°, and there is an arc chamfer R at the moving blade edge, and the radius of the arc chamfer R is 0.10 - 0.20 mm.

[0028] Another important solution of the present invention is a moving blade blank for an electric hair clipper, which is made by using the production process of the moving blade blank for an electric hair clipper as described above. The moving blade blank has the upper fixed section and the lower sliding section as described above. The upper fixed section also has a positioning groove and an assembly hole. The upper end surface of the lower sliding section is formed with the unit teeth, and the lower end surface of the lower sliding section has an acute angle groove adapted to the unit teeth.

[0029] Another important solution of the present invention is an injection molding die for molding a moving blade blank, which includes a male die and a female die. The male die has a parting core and a main runner. The female die has a cavity adapted to the parting core;

[0030] The male die has a first protrusion, a square column insert for forming a positioning groove, and a cylindrical insert for forming an assembly hole;

[0031] The female die has a second protrusion.

[0032] Preferably, the injection molding die further has a sealant runner, and the sealant runner includes a feed section, a bypass section, a main discharge section, and a plurality of discharge branch sections that are connected in sequence from front to back;

[0033] The feed section is located at the middle position of the lower side area of the male die, and the feed section has a secondary runner;

[0034] The described bypass section is located on the master mold, and there are two bypass sections symmetrically distributed on both sides of the cavity;

[0035] The described main glue outlet section is located in the upper area of the male mold;

[0036] The described glue outlet branch section is located on the male mold, and the glue outlet branch section corresponds to the unit teeth of the moving knife blade blank one by one.

[0037] The beneficial effects of the present invention are as follows:

[0038] First, the process is simple, the production efficiency is extremely high, it is suitable for mass production, and the development cost and production cost can be greatly reduced.

[0039] Second, the production process provided by the present invention can not only solve the problem of easy chipping of ceramics, but also solve the problems of high temperature rise and difficult tooth opening of traditional machined stainless steel blades, and can also solve the problem of difficult production of acute angle stamping dies for stamping blades.

[0040] Third, the mold forming can be facilitated in design by replacing the mold inserts. Description of the Drawings

[0041] Figure 1 is the flow chart of the production process in the present invention.

[0042] Figure 2 is the structural schematic diagram of the moving knife blade blank in the present invention.

[0043] Figure 3 is Figure 2 the enlarged schematic diagram of part A in

[0044] Figure 4 is the schematic diagram of the sealing glue layer on the front and back sides of the moving knife blade blank.

[0045] Figure 5 is the front view of the moving knife blade blank and the enlarged view of its partial structure.

[0046] Figure 6 is the schematic diagram when the injection molding die is closed in the present invention.

[0047] Figure 7 is the structural exploded view of the injection molding die in the present invention.

[0048] Figure 8 is the partial structural schematic diagram of the upper male mold of the injection molding die in the present invention.

[0049] Figure 9 is the partial structural schematic diagram of the upper female mold of the injection molding die in the present invention.

[0050] Figure 10 It is a schematic diagram of the sealant flow channel on the injection molding die.

[0051] In the figure: 1. Moving knife blade blank; 11. Upper fixed section; 111. Positioning groove; 112. Assembly hole; 12. Lower sliding section; 13. Tooth-shaped part; 131. Unit tooth; 132. Tooth gap; 133. Acute angle groove; 14. Sealant layer; 2. Male mold; 21. Parting core; 22. Main feed groove; 23. First protrusion; 24. Square column insert; 25. Cylindrical insert; 3. Female mold; 31. Cavity; 32. Second protrusion; 4. Sealant flow channel; 41. Feed section; 411. Auxiliary feed groove; 42. Bypass section; 43. Main discharge section; 44. Discharge branch section; H. Depth of tooth gap; R. Arc chamfer. Specific embodiments

[0052] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0053] Embodiment 1

[0054] Refer to Figures 1 to 10 , a production process of a moving knife blade blank 1, including:

[0055] S1. Manufacture a set of injection molding dies. The specific tooth shape and pattern required for the moving knife blade blank can be customized according to customer needs. The die is convenient for replacing inserts, and the pattern can be diamond-shaped, triangular, etc., all of which can be formed through the die. The die is simple to process, and the acute angle that is difficult to edge in machining can be easily obtained by electrical discharge machining of the die. The minimum size of the tooth-shaped structure can be as small as 0.20 mm.

[0056] S2. Manufacture a composite raw material, mix and knead it at 170 ± 5 °C and then pelletize and dry it to obtain particles of the composite raw material with a size of 5 ± 2 mm. During the injection molding process, it can be quickly and evenly melted, reducing the risk of unmelted particles or local overheating; avoiding agglomeration caused by too large particles or dust problems caused by too small particles; and the feeding is smooth, reducing blockage or "bridging" phenomena, improving the stability of continuous production; the tolerance range of ±2 mm has low requirements for the pelletizing process, is suitable for large-scale production, and at the same time reduces the raw material processing cost.

[0057] S3. Place the injection molding die into a precision injection molding machine (an externally purchased component, such as an injection molding machine of Haitian brand, etc.). Then add the composite raw material particles into the precision injection molding machine to manufacture the moving blade blank 1 through the injection molding process. By selecting the injection molding die, the moving blade of the required shape can be molded. Specifically, the moving blade blank 1 includes an upper fixed section 11 and a lower sliding section 12, and there is a toothed portion 13 at the lower sliding section 12. The toothed portion 13 includes a number of unit teeth 131, and tooth spaces 132 are formed between adjacent unit teeth 131.

[0058] S4. Perform in-mold sealing on the lower sliding section 12 of the moving blade blank 1 to form a sealing layer 14. The sealing material can be selected as engineering plastics, TPE, etc. After the sealing coating, the stress generated during the cutting of the toothed portion 13 is dispersed, reducing the risk of tooth breakage or fracture; moreover, the colloid absorbs vibration and impact energy, extending the service life of the blade during high-frequency use; on the other hand, the colloid completely wraps the joint between the front teeth and the blank, preventing moisture and chemical substances from infiltrating and avoiding metal oxidation or corrosion; at the same time, the sealing can cover the sharp edge, reducing the risk of accidental cuts.

[0059] S6. Place the moving blade blank 1 on a ceramic plate and then put the whole into a debinding furnace for debinding. During the debinding process, the ceramic plate (such as alumina, silicon carbide) can withstand the high-temperature environment required for debinding (usually 200 - 600 °C), avoiding deformation of the support plate or release of harmful gases. Moreover, the ceramic plate has extremely small dimensional changes at high temperatures. The flat surface of the ceramic plate enables the workpiece to be heated evenly, reducing cracking or warping caused by thermal stress, ensuring the stable placement of the product during debinding, and reducing workpiece displacement or deformation caused by the deformation of the support; on the other hand, the ceramic does not react with the debinding solvent (such as water-based, solvent-based or catalytic debinding agent) or decomposition products (such as acids, hydrocarbons), avoiding contamination of the workpiece; at the same time, the thermal conductivity of the ceramic is between that of metal and refractory bricks, which can not only avoid uneven debinding caused by local overheating but also prevent rapid heat dissipation, improving the debinding efficiency.

[0060] S6. Put the debound moving blade blank 1 into a sintering furnace for high-temperature sintering. The shrinkage rate during sintering is 16.5 ± 0.5%. The strict limitation of the shrinkage rate during sintering is to ensure that the product achieves the expected dimensional accuracy during the high-temperature densification process, optimize the material properties and structural uniformity, improve the process stability and yield, support complex structure design and adapt to special-shaped parts. For example, before high-temperature sintering, the width dimension of the moving blade blank 1 is 11.65 mm. After the high-temperature sintering in step S6, the width dimension of the moving blade blank 1 is 10 mm.

[0061] S7. Place the sintered blank 1 of the moving blade into a heat treatment furnace for heat treatment hardening, so as to regulate the microstructure and phase composition of the material through heat treatment, and further improve its mechanical properties, dimensional stability and service life.

[0062] S8. Form a sliding cutting edge of the moving blade through the grinding and polishing process on the tooth-shaped part 13 to obtain the finished product of the blank 1 of the moving blade; a good cutting edge of the moving blade can quickly cut off hair with the least resistance, reduce the pulling feeling, and avoid pain and skin irritation.

[0063] In step S2, the composite raw material is a combination of metal powder and binder, and the weight ratio of the metal fusion powder to the binder is 10.6:1. The advantages of the composite raw material under this ratio are at least as follows: First, it optimizes the green body strength and structural stability. 8.6% of the binder is sufficient to form a physical bridge between the powder particles, endowing the green body (before sintering) with basic mechanical strength, preventing the collapse of complex structures (such as thin walls, fine features) during handling or debinding, and at the same time avoiding excessive softening. That is, compared with a high binder ratio (such as more than 30%), a low binder content can reduce the risk of green body deformation caused by binder softening; Second, it reduces the debinding difficulty and residual risk. The low binder content shortens the debinding time (such as thermal debinding or solvent debinding), reduces energy consumption, and at the same time reduces the risk of pores or cracks caused by binder residue. Moreover, the pollutants generated after the decomposition of the low ratio binder are less, meeting the environmental protection requirements; Third, it improves the sintering efficiency and material densification, reduces the porosity. The pores left after the binder burns out are small and evenly distributed. The metal powder is more likely to fill the pores through solid-phase or liquid-phase sintering during sintering, improving the material density, and can inhibit grain coarsening. That is, a small amount of binder decomposition products inhibit the excessive growth of metal grains, refine the microstructure, and enhance the material strength; Fourth, it balances cost and performance. Reducing the binder usage directly reduces the raw material cost, and at the same time shortens the debinding and sintering time, improving the production efficiency, and the low binder residue has little impact on the electrical conductivity, thermal conductivity or corrosion resistance of the metal material.

[0064] Among them, the metal fusion powder, by weight percentage, includes the following components: 85% - 95% of metal powder of 440C stainless steel or M2 steel (powder grade D50 is 8 - 10μm), and 15% - 5% of alumina powder or zirconia powder. The products processed with the metal fusion powder of the above ratio have the following advantages: First, they have a ceramic strengthening effect. That is, adding 15% - 5% of alumina powder or zirconia powder can significantly improve the surface hardness of the composite material, reduce the wear rate, and the chemical properties of alumina / zirconia are stable, which can form a dense barrier on the metal surface to delay oxidation or chemical corrosion. Second, the metal matrix provides toughness, and the ceramic particles are embedded as hard phases to form a "metal-ceramic composite structure", which is suitable for high-speed friction or strong wear scenarios. Third, a stainless steel substrate is used. If 440C stainless steel itself contains 16% - 18% chromium, it has good corrosion resistance. If M2 steel has slightly weaker corrosion resistance, the corrosive medium can be further isolated through a ceramic coating. Fourth, the complementarity of metal and ceramic. The heat-resistant temperature of 440C stainless steel is about 800°C, and that of M2 steel can reach 600°C, while the melting points of alumina / zirconia are 2054°C and 2715°C respectively. The composite material can withstand higher temperatures (such as above 1000°C) and is suitable for wear-resistant components in high-temperature environments. Fifth, lightweight is achieved, that is, the density of alumina (3.9 g / cm 3 ) and zirconia (6.0 g / cm 3 ) is lower than that of steel (7.8 g / cm 3 ), and adding them can reduce the overall material density. Sixth, it is beneficial to the sintering process. The ceramic particles can inhibit the excessive growth of metal grains, refine the microstructure, and improve the material strength.

[0065] Among them, the binder, by weight percentage, includes the following components: polyoxymethylene accounts for 81.2% ± 1%: high-density polyethylene accounts for 7.1% ± 1%: styrene-acrylonitrile copolymer accounts for 4.6% ± 1%; antioxidant 1010 accounts for 7.1% ± 1%. With the binder of the above ratio, through the synergistic modification of POM and HDPE / SAN, optimization is achieved among strength, toughness, processability, and debinding compatibility, which is especially suitable for the field of metal powder forming with high requirements for comprehensive performance.

[0066] Optionally, in step S3, the thickness dimension of the moving knife blade blank 1 obtained is less than or equal to 3mm ± 1‰. At this stage, the thickness dimension of the moving knife blade blank 1 will be slightly larger than the actual size, providing a suitable size for the subsequent finishing process.

[0067] Optionally, in step S4, the thickness T of the sealant on the lower sliding section 12 of the moving blade blank 1 is > 0.25 mm. On the other hand, after sealing, the depth H of the inter-tooth groove 132 is ≥ 0.15 mm. Sufficient sealant thickness can play many roles. For example: First, it prevents oxidation and corrosion. The sealant layer 14 can isolate air, moisture, or corrosive media, protecting the surface of the blade blank (such as the metal cutting edge) from oxidation or chemical erosion and extending the tool life. Second, it resists impact and provides buffering. The relatively thick sealant layer 14 can absorb minor impacts or vibrations, reducing chipping or wear of the blade blank edge caused by external forces. Third, it enhances the anti-deformation ability. For ultra-thin or easily deformable blade blanks (such as ceramic blades), the sealant layer 14 can provide additional support to prevent bending deformation caused by thermal expansion and contraction or external forces. Fourth, it distributes stress evenly. After sintering or heat treatment, the sealant layer 14 can relieve the residual stress inside the blade blank and reduce the risk of cracking. Fifth, the outermost sealant can serve as a sacrificial layer. In subsequent grinding or polishing processes, the sealant can be used as a temporary protective layer to avoid damaging the non-working area of the blade blank during processing.

[0068] Optionally, in step S5, the degreasing medium is oxalic acid. Among them, oxalic acid, as an acidic degreasing agent, can undergo saponification or hydrolysis reactions with the organic binder on the surface of the blade blank, destroying the organic structure and making it dissolve or disperse in the solution. And oxalic acid slightly etches the metal or ceramic surface, removing the oxide layer or contaminants, providing a clean interface for subsequent sintering. The degreasing temperature is 90 - 120 °C. The decomposition temperature of oxalic acid is about 150 °C, but it can stably play its role at 90 - 120 °C, increasing the molecular kinetic energy and shortening the decomposition time of organic substances. The degreasing time is 6 - 10 h. First, it meets the requirement of sufficient degreasing. Thick blade blanks or complex structures require enough time for oxalic acid to penetrate and dissolve deep organic substances. Second, it balances efficiency and cost. Too short a time will result in incomplete degreasing, affecting subsequent sintering (such as pores caused by residual carbides). Too long will increase energy consumption and equipment occupancy. Third, it meets the material stability requirement. Prolonged action of oxalic acid may cause excessive roughness or phase changes on the surface of the blade blank.

[0069] One of the core process points of the present invention is the control of the temperature and time of the sintering process in step S6, which is specifically as follows:

[0070] In the first stage, the sintering temperature rises from room temperature to 600 °C, and the first-stage sintering time lasts for 5 - 6 h. The main effects of the first stage are as follows: First, the residual organic substances decompose, further removing a small amount of decomposition products (such as CO 2 、H 2 2O, etc.) remaining after the degreasing process, avoiding pores or cracks caused by gas expansion during high-temperature sintering. Second, the moisture evaporates, removing the moisture adsorbed by the blade blank and preventing the destruction of the blank structure by the vapor pressure at high temperatures. Third, the stress is slowly released. Slowly raising the temperature in the low-temperature section (about 100 - 120 °C / h) can reduce the internal stress caused by uneven thermal expansion and avoid cracking of the blank.

[0071] The sintering temperature in the second stage rises from 600 °C to 1050 °C, and the sintering time in the second stage lasts for 6 - 8 h. The main effects of the second stage are as follows: First, it is preliminary sintering. Necks are formed between particles through diffusion, and the density gradually increases (about 50% - 70% of the theoretical density), and the green body begins to have mechanical strength. Second, gas expulsion is strengthened. Higher temperatures accelerate the expulsion of residual gases (such as CO, NH 3 ) and promote the decomposition of the metal complexes remaining after oxalic acid degreasing. Third, it activates the grain boundaries and provides an active interface for subsequent high-temperature sintering. For example, grain rearrangement or glass phase softening begins in ceramic materials.

[0072] The sintering temperature in the third stage rises from 1050 °C to 1300 °C, and the sintering time in the third stage lasts for 8 - 10 h. The main effects of the third stage are as follows: First, it is complete sintering (liquid-phase sintering). The temperature is close to the melting point of the material (such as about 1400 °C for steel-based materials and about 1600 °C for ceramics), and high density (>95% of the theoretical density) is achieved through grain rearrangement and dissolution-precipitation mechanisms. Second, pore closure occurs. At high temperatures, the pores are filled with the liquid phase or eliminated through diffusion, forming a dense structure and improving the hardness and wear resistance of the cutting tool. Third, the microstructure is optimized, and the grain size is controlled (such as fine grain strengthening). For example, the excessive growth of grains is inhibited by adding inhibitors (such as carbide particles).

[0073] The sintering temperature in the fourth stage drops from 1300 °C to 1100 °C, and the sintering time in the fourth stage lasts for 5 - 6 h. The main effects of the fourth stage are as follows: First, phase transformation regulation. Some materials (such as tool steel) undergo austenite decomposition near 1100 °C. By holding the temperature, the martensite transformation rate is controlled to reduce quenching stress. Second, residual stress release. The temperature is slowly cooled below the phase transformation point to avoid microcracks caused by differences in thermal shrinkage. Third, pre-cooling protection. It reduces the requirements for the subsequent cooling rate and prevents surface cracking caused by direct rapid cooling.

[0074] The sintering temperature in the fifth stage drops from 1100 °C to room temperature, and the sintering time in the fifth stage lasts for 3 - 5 h. The main effects of the fifth stage are as follows: First, slow cooling. The cooling rate is controlled (about 200 - 300 °C / h) to reduce the concentration of thermal stress, which is especially suitable for ceramic or composite material cutting tools. Second, final structure stabilization. It ensures that the metal material completes solid-state phase transformation (such as pearlite formation) or the glass phase of the ceramic material is fully cured. Third, dimensional accuracy maintenance. It avoids warping deformation caused by rapid cooling and meets the accuracy requirement of ±1‰ for the blank thickness of the cutting tool mentioned in step three.

[0075] The key logics in the above sintering process are as follows: 1. Temperature control in stages: The heating-holding-cooling rhythm takes into account densification and structural stability, avoiding grain coarsening or stress accumulation caused by a single high-temperature stage. 2. Time matching: The high-temperature stage (the third stage) has the longest time to ensure sufficient diffusion; the low-temperature stages (the first, fourth, and fifth stages) focus on safe transitions. 3. Material adaptation: Since the tool blank contains ceramics, it is necessary to pay attention to avoiding grain boundary oxidation near 1300°C; at the same time, the tool blank also belongs to the stainless steel metal matrix, so it is necessary to balance the carbide distribution and hardness.

[0076] During the actual operation process, it is necessary to predict abnormal situations, mainly including two points. One is insufficient stage time: too short in the first stage → high porosity after sintering due to residual gas; too short in the third stage → insufficient density, and the tool is prone to chipping. The other is too fast cooling rate: rapid cooling in the fifth stage → through cracks appear in the ceramic tool, and a quenched martensite brittle layer is generated in the metal tool.

[0077] Optionally, in step S7, the heat treatment temperature is set at 1045 - 1055°C, and the hardness of the moving blade blank 1 after heat treatment is HRC61 - 65; then the moving blade blank 1 is subjected to tempering treatment to achieve the purposes of stress release, toughness improvement, and dimensional stabilization. Among them, the hardness of the moving blade blank 1 after tempering treatment is HRC57 - 60, and the tempering temperature is set at 200 - 300°C as required. The hardness after treatment is maintained at HRC57 - 60, while ensuring the sharpness of the cutting edge and avoiding the brittleness risk brought by a hardness above HRC60. In summary, through this quenching-tempering process, the moving blade blank 1 can achieve the mechanical properties of "hard but not brittle, tough but not soft", meeting the comprehensive requirements of cutting tools for strength, wear resistance, and impact resistance.

[0078] Optionally, in step S8, the angle of the moving blade cutting edge formed by the grinding and polishing process is 45° - 55°. The cutting edge angles of conventional cutting tools (such as turning tools) are mostly 20° - 30°, while 45° - 55° belongs to a large-angle design, which adapts to the processing requirements of the ceramic-stainless steel composite material. If the angle < 45°, the cutting edge is too thin and prone to cracking under impact load; if the angle > 55°, the cutting resistance increases significantly, and the sharpness of the cutting edge decreases. Therefore, by increasing the cutting edge strength to resist chipping, the large angle can disperse the cutting force and avoid plastic deformation of the cutting edge.

[0079] On the other hand, a sharp cutting edge (R < 0.05 mm) is prone to stress concentration during cutting (local stress can reach 3 times the tensile strength of the material), leading to the initiation of microcracks. Therefore, in the present invention, the moving cutting edge has a circular arc chamfer RR, and the radius of the circular arc chamfer RR is 0.10 - 0.20 mm. According to the test data, the fatigue life of the cutting edge with R = 0.15 mm is 40% higher than that with R = 0.05 mm. After machining, the cutting performance is more optimized. The circular arc chamfer R can promote chip curling and reduce the formation of built-up edge; at the same time, the surface quality is improved. The R value of 0.10 - 0.20 mm can avoid the plowing effect of the cutting edge on the workpiece surface, reducing the surface roughness Ra by 0.5 - 1.0 μm. Considering the feasibility of the machining process, if R < 0.10 mm, a grinding wheel with a grit size > #2000 needs to be used and the feed rate needs to be reduced (< 0.01 mm / r), resulting in a 50% decrease in machining efficiency; if R > 0.20 mm, the effective thickness of the cutting edge increases, weakening the sharpness (for example, when R = 0.3 mm, the cutting force increases by 15%).

[0080] Actual Case 1: When the 45° cutting edge is paired with R = 0.15 mm, the comprehensive performance is the best (the strength is increased by 20% and the cutting force is increased by 8%);

[0081] Actual Case 2: For a 55° cutting edge, if R > 0.20 mm, the cutting resistance exceeds the yield strength of the material, resulting in increased work hardening.

[0082] Actual Case 3: If R < 0.10 mm and the angle < 45°, the crack risk index of the tested cutting edge exceeds the critical value of 1.5.

[0083] Actual Case 4: If R > 0.20 mm and the angle > 55°, the tool wear mechanism changes from abrasive wear to adhesive wear, and the life is shortened by 60%.

[0084] In summary, in step S8, adopting a "gradual change in cutting edge angle + gradual change in R value" structure (such as transitioning from 45° to 55°, and R transitioning from 0.10 mm to 0.20 mm) can further improve the anti-fatigue performance. At the same time, when performing PVD coating (such as TiAlN) on the cutting edge, R = 0.15 mm can increase the coating adhesion by 30%, effectively suppressing spalling failure.

[0085] Example Two

[0086] Refer to Figures 2 to 5, Another important solution of the present invention is a moving blade blank 1 of an electric hair clipper to be produced by using the production process of Embodiment 1. The moving blade blank 1 has the upper fixed section 11 and the lower sliding section 12. The upper fixed section 11 also has a positioning groove 111 and an assembly hole 112. The upper end surface of the lower sliding section 12 is formed with the unit teeth 131, and the lower end surface of the lower sliding section 12 has an acute angle groove 133 adapted to the unit teeth 131.

[0087] Embodiment 3

[0088] Refer to Figures 6 to 10 , An injection molding die is used to mold the moving blade blank 1 and meets the requirements in step S1 of Embodiment 1. The injection molding die includes a male mold 2 and a female mold 3. The male mold 2 has a parting core 21 and a main runner 22. The female mold 3 has a cavity 31 adapted to the parting core 21. The male mold 2 has a first protrusion 23, a square column insert 24 for forming the positioning groove 111, and a cylindrical insert 25 for forming the assembly hole 112. The female mold 3 has a second protrusion 32. The first protrusion 23 and the second protrusion 32 cooperate with each other to form the unit teeth 131, the inter-tooth grooves 132 and the acute angle grooves 133, so that the injection molding die can directly mold the moving blade blank in its initial form.

[0089] It should be particularly emphasized that the injection molding die also has a sealant runner 4. The sealant runner 4 is physically separated from the main runner 22 in the spatial structure and is used for injecting sealant materials (optionally engineering plastics, TPE). The sealant runner 4 includes a feeding section 41, a bypass section 42, a main discharging section 43 and a plurality of discharging branch sections 44 that are connected in sequence from front to back. The feeding section 41 is located at the middle position of the lower side area of the male mold 2, and the feeding section 41 has a secondary runner 411. The bypass section 42 is located on the female mold 3, and there are 2 sections of the bypass section 42 which are symmetrically distributed on both sides of the cavity 31 to bypass the cavity 31 of the product. The main discharging section 43 is located in the upper side area of the male mold 2. The discharging branch sections 44 are located on the male mold 2, and the discharging branch sections 44 correspond to the unit teeth 131 of the moving blade blank 1 one by one.

[0090] The sealant runner 4 is designed with a four-stage structure of "single-point feeding → symmetric bypassing → secondary splitting → precise filling", combined with temperature control, exhaust optimization and die movement coordination, to achieve high-precision sealing of the unit teeth 131 of the moving blade blank 1.

[0091] The above are only the preferred embodiments of the present invention, and do not impose any limitations on the present invention. Any simple modifications, changes, and equivalent structural changes made to the above embodiments based on the technical essence of the invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. The production process of the movable blade blank is characterized by: Included are: S1. Make a set of injection molding molds; S2, preparing the composite raw material, mixing and kneading at 170±5°C and pelletizing and drying to obtain 5±2mm composite raw material particles; S3, placing the injection molding mold into a precision injection molding machine, then adding the particles of the composite raw material into the precision injection molding machine to manufacture a movable blade blank (1) through an injection molding process, wherein the movable blade blank (1) comprises an upper fixed section (11) and a lower sliding section (12), and the lower sliding section (12) has a tooth-shaped portion (13), the tooth-shaped portion (13) comprises a plurality of unit teeth (131), and inter-tooth grooves (132) are formed between adjacent unit teeth (131); S4, performing an in-mold sealing treatment on the lower sliding section (12) of the movable blade blank (1) to form a sealing layer (14); S5, placing the movable blade blank (1) on a ceramic plate, and then placing the entire blade blank into a degreasing furnace for degreasing; S6. The degreased movable blade blank (1) is placed in a sintering furnace for high-temperature sintering, and the shrinkage rate during sintering is 16.5±0.5%; S7, placing the sintered movable blade blank (1) into a heat treatment furnace for heat treatment and hardening; S8, forming a sliding movable blade edge by grinding the toothed portion (13) to obtain a finished movable blade blank (1); In step S2, the composite raw material is a combination of metal powder and a binder, and the weight ratio of the metal fusion powder to the binder is 10.6:1; The metal fusion powder comprises the following components by weight percentage: 85% to 95% of 440C stainless steel or M2 steel metal powder, and 15% to 5% of aluminum oxide powder or zirconium oxide powder; The binder comprises the following components by weight percentage: polyoxymethylene accounts for 81.2%±1%; high-density polyethylene accounts for 7.1%±1%; styrene-acrylonitrile copolymer accounts for 4.6%±1%; and antioxidant 1010 accounts for 7.1%±1%.

2. The production process of the movable blade blank (1) according to claim 1, characterized in that: In step S3, the thickness of the obtained movable blade blank (1) is less than or equal to 3 mm ± 1‰.

3. The production process of the movable blade blank (1) according to claim 1, characterized in that: In step S4, the thickness T of the sealant on the lower sliding section (12) of the movable blade blank (1) is greater than 0.25 mm, and the depth H of the inter-tooth groove (132) after the sealant is greater than or equal to 0.15 mm.

4. The production process of the movable blade blank (1) according to claim 1, characterized in that: In step S5, the degreasing temperature is 90-120° C., the degreasing medium is oxalic acid, and the degreasing time is 6-10 hours.

5. The production process of the movable blade blank (1) according to claim 1, characterized in that: In step S6, the first stage sintering temperature is increased from room temperature to 600°C, and the first stage sintering time lasts for 5 to 6 hours; The second stage sintering temperature rises from 600°C to 1050°C, and the second stage sintering time lasts for 6 to 8 hours; The sintering temperature in the third stage increases from 1050°C to 1300°C, and the sintering time in the third stage lasts for 8 to 10 hours; The sintering temperature in the fourth stage drops from 1300°C to 1100°C, and the sintering time in the fourth stage lasts for 5 to 6 hours; The sintering temperature in the fifth stage drops from 1100° C. to room temperature, and the sintering time in the fifth stage lasts for 3 to 5 hours.

6. The production process of the movable blade blank (1) according to claim 1, characterized in that: In step S7, the heat treatment temperature is set at 1045-1055° C., and the hardness of the movable blade blank (1) obtained after the heat treatment is HRC61-65; the movable blade blank (1) is then tempered, and the hardness of the movable blade blank (1) obtained after the tempering treatment is HRC57-60.

7. The production process of the movable blade blank (1) according to claim 1, characterized in that: In step S8, the angle of the moving blade edge formed by the grinding process is 45° to 55°, and the moving blade edge has a circular chamfer (R) R, and the radius of the circular chamfer (R) R is 0.10-0.20 mm.

8. A blade blank (1) for a movable blade of an electric hair clipper, characterized in that: The movable blade blank (1) is manufactured by the production process of any one of claims 1 to 6, wherein the movable blade blank (1) comprises an upper fixed section (11) and a lower sliding section (12), the upper fixed section (11) also comprises a positioning groove (111) and an assembly hole (112), the upper end surface of the lower sliding section (12) is formed with the unit teeth (131), and the lower end surface of the lower sliding section (12) comprises an acute-angle groove (133) matched with the unit teeth (131).

9. An injection molding mold for molding the movable blade blank (1) according to claim 8, characterized in that: It comprises a male mold (2) and a female mold (3), wherein the male mold (2) has a parting core (21) and a main glue feeding groove (22), and the female mold (3) has a cavity (31) adapted to the parting core (21); The male mold (2) has a first protrusion (23), a square column insert (24) for forming a positioning groove (111), and a cylindrical insert (25) for forming an assembly hole (112); The female mold (3) has a second protrusion (32).

10. The injection molding die according to claim 9, characterized in that: The injection molding die also has a sealing glue flow channel (4), and the sealing glue flow channel (4) includes a glue inlet section (41), a bypass section (42), a glue outlet trunk section (43) and a plurality of glue outlet branch sections (44) which are sequentially connected from front to back; The glue feeding section (41) is located in the middle of the lower area of ​​the male mold (2), and the glue feeding section (41) has a secondary glue feeding groove (411); The detour section (42) is located on the female mold (3), and the detour section (42) has two sections and is symmetrically distributed on both sides of the mold cavity (31); The glue outlet trunk section (43) is located in the upper area of ​​the male mold (2); The glue outlet diverging section (44) is located on the male mold (2), and the glue outlet diverging section (44) corresponds one to one with the unit teeth (131) of the movable blade blank (1).

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