CN107937700A - A kind of high-rate laser defocus quenching strengthening method for miniature shaving tool - Google Patents

Abstract

The invention discloses a high-speed laser defocus quenching strengthening method aimed at micro razors. The invention utilizes the characteristics of laser divergence after defocusing, expands the laser spot to the width of the blade, and selects the appropriate focal length of the field mirror according to the quenching depth required by the blade, and uses the high-speed vibrating mirror to output the laser according to the path, and completes the quenching of the workpiece at one time. The method has the characteristics of no need for repeated focusing, fast quenching speed, good strengthening effect, and consideration of performance and economic benefits.

Description

A high-speed laser defocus quenching strengthening method for micro razors

technical field

The invention relates to the field of mechanical processing, in particular to a high-speed laser defocus quenching strengthening method for a micro shaver.

Background technique

Shavers represented by brands such as Philips and Flyco widely use rotary micro-shavers as the core components of their cutter heads. The cutters are small in size and have complex geometric shapes. The processing method is usually stamping and forming of thin plate molds. In order to ensure the machinability of stamping forming, the tool is often processed with tempered martensitic stainless steel strip as raw material. Due to the long-term frictional contact between the blade and the knife net during use, and the tempered stainless steel material has low hardness and is prone to wear and tear, it is necessary to perform subsequent quenching and strengthening treatment on the formed tool in actual use.

Laser quenching is a strengthening process that has developed rapidly in recent years. It uses high-energy laser beams to scan the workpiece, so that the temperature of the laser irradiation area rises rapidly above the phase transition temperature. At the same time, it uses the heat conduction of the workpiece matrix to achieve self-cooling and quenching. phase change strengthening. Compared with the traditional surface quenching technology, laser quenching has the characteristics of fast processing speed, high efficiency, no need for quenching medium, energy saving, and environmental protection. At the same time, the obtained hardened layer has a finer structure and a higher hardness than conventional quenching. Although the existing laser quenching process has the above-mentioned advantages, there are still many deficiencies in processing micro-shavers with complex shapes, small sizes, and thin thicknesses. The three-dimensional inclination angle structure, in order to ensure the effective edge quenching depth of the blade needs to reach more than 2mm, the existing laser focus quenching process needs to repeat multiple scanning and multiple focusing to complete the quenching of the blade; 2. Due to the small size of the tool and the relatively large material Thin, the repeated scanning steps of the existing laser quenching process will cause serious heat accumulation effect, resulting in poor process consistency, self-cooling and quenching effect phase is not obvious, and the phase change strengthening effect is not obvious; 3. Due to the low unit value of the micro razor , the cost of the existing laser quenching process is relatively high, so it cannot be promoted in the market.

Contents of the invention

Aiming at the deficiencies of the existing laser quenching technology, the invention provides a laser defocus quenching method for micro razors. Using the characteristics of laser divergence after defocusing, the laser spot is expanded to the width of the blade, and the appropriate field lens focal length is selected according to the quenching depth required by the blade, and the high-speed galvanometer is used to output the laser according to the path to complete the quenching of the workpiece at one time. The method has the characteristics of no need for repeated focusing, fast quenching speed, good strengthening effect, and consideration of performance and economic benefits.

In order to achieve the above object, the method of the present invention is based on the following laser defocus quenching strengthening device, including a vibrating mirror fiber laser, an X-axis vibrating mirror, a Y-axis vibrating mirror, and a zoom field mirror; The mirror is reflected to the Y-axis galvanometer, and the laser is reflected by the Y-axis galvanometer to the zoom field lens and output to the workpiece to be quenched; the method includes the following steps:

Step (1), analyze the morphology and structure of the miniature razor tool workpiece to be quenched, set the laser output path in the CAD system of the laser defocus quenching strengthening device according to the Z-axis space projection position of the quenching area, and set the The geometric center of the workpiece is aligned to the optical axis center of the zoom field lens;

Preferably, the micro shaver workpiece is a rotary micro shaver;

Step (2), selecting appropriate optical path parameters according to the width of the workpiece blade and the required quenching depth, and setting the optimum field lens focal length and field lens height.

The empirical formula of the focal length of the field lens is: Formula 1)

Among them, f is the focal length of the field lens, and the unit is cm; c is the quenching depth required by the blade, and the unit is cm; d is the width of the blade, and the unit is cm;

The empirical formula for the field mirror height is: L≈1.3×f Formula (2)

Among them, L is the height of the field lens, in cm; f is the focal length of the field lens, in cm; c is the quenching depth required by the blade, in cm;

Step (3), setting the laser energy density.

The selection of laser energy density follows the best principle. When the laser energy density is too high, it will cause local melting of the blade, and it is necessary to reduce the laser power or increase the scanning speed; when the laser energy density is too low, the blade cannot be effectively quenched. It is necessary to increase the laser power or reduce the scanning speed; when the laser energy density is in the appropriate range, the obtained energy can not only drive the phase transformation transformation but also avoid the melting of the blade, and at the same time use the heat conduction of the workpiece matrix to achieve self-cooling and quenching, then use This is the optimal laser energy density setting value;

The formula for calculating the laser energy density is: P _D =P/dv Equation (3)

Where _PD is the energy density of the laser, in J/cm ² ; P is the output power of the laser, in w; d is the width of the blade, in cm; v is the scanning speed of the laser, in cm/s.

In the experiment, the output power of the laser is fixed at 500W, the width of the blade is a certain value, and the laser energy density is adjusted by changing the scanning speed of the laser.

Step (4), place the workpiece to be quenched and turn on the laser. After one scan, turn off the laser equipment, take out the quenched workpiece, and analyze its metallographic and hardness changes after quenching.

The present invention has the following beneficial effects:

The invention provides a method for performing high-speed laser out-of-focus quenching on a micro tool by using a vibrating mirror fiber laser as a quenching device. This method overcomes the complex reciprocating scanning and focusing process of the traditional laser quenching process, as well as the defects of poor quenching effect on micro-thin-walled tools. Small size, strong process stability and so on. When it is used for quenching the rotary micro shaver, it shows obvious quench hardening phenomenon, and has the characteristics of simple process, low production cost and taking into account benefits.

Description of drawings

Fig. 1 is the principle comparison diagram of out-of-focus laser hardening of the present invention and traditional laser hardening; Wherein (1) is traditional laser hardening, (2) is out-of-focus laser hardening of the present invention;

Fig. 2 is a structural diagram of a quenching device according to the present invention;

Fig. 3 is the schematic diagram of optical path parameter of the present invention; Wherein (1) is optical path, (2) is blade;

Fig. 4 is a schematic diagram of the laser quenching path of the present invention;

Fig. 5 is the metallographic diagram before the cutter head is not quenched;

Figure 6 is the photo of the microstructure of the quenched cutter head under the process parameters of the laser energy density of 420kJ/cm ² , in which (a) 50 times the micro heat-affected area, (b) 1000 times the micro quenching area, (c) 1000 times the microstructure Micro-transition region, (d) 1000X microscopic unquenched region;

Figure 7 is the photo of the microstructure of the quenched cutter head under the laser energy density of 840kJ/cm ² process parameters, in which (a) 50 times the micro heat-affected area, (b) 1000 times the micro quenching area, (c) 1000 times the microstructure Micro-transition region, (d) 1000X micrograph of the unquenched region.

Detailed ways

The present invention is further analyzed below in conjunction with specific examples.

The high-speed laser defocus quenching method of the present invention is adopted to strengthen the stainless steel (4Cr13) rotary shaver head.

A. Pretreatment of the cutter head to be quenched: Clean the cutter head with absolute ethanol, dry it with a hair dryer, and place it on the sample stage of the laser quenching device.

B. Setting of optical path parameters: Select optical path parameters according to the cutter head parameter setting. The blade width selected in this embodiment is 0.9mm, and the depth of quenching is 2mm. The focal length and height of the field lens are calculated by entering the formula, and placed on the quenching equipment. The focal length of the field lens and the height of the field lens are set to 30.5mm and 39.5mm, respectively, as shown in Figure 3.

C. Laser output path setting: As shown in Figure 4, set the ring-shaped laser output path according to the Z-axis geometric projection of the blade; align the geometric center of the workpiece to the optical axis center of the field mirror.

D. Laser quenching of the cutter head: Turn on the laser and output the laser according to the preset path. In this experiment, a fiber laser with a laser wavelength of 1060-1080nm was selected, and the frequency of the laser was 20kHZ. The two groups of samples were quenched with laser energy densities of 420kJ/cm ² and 830kJ/cm ² respectively.

E. After quenching and before quenching, compare and observe the shape, analyze the metallographic composition, and the change of hardness value.

As shown in Fig. 5, the material of the rotary shaver head before quenching is stainless steel (4Cr13), the original hardness is 506±6HV, and the material thickness is 0.4mm. Since the raw material has been tempered, its metallographic structure shows less martensite structure, and shows a more obvious phase interface with the matrix ferrite.

The metallographic structure of different regions of the blade after quenching with a laser energy density of 420kJ/cm ² is shown in Figure 6. Through the analysis of the metallographic structure of the side of a single blade, the quenching depth of the blade reaches 1.6mm (Figure 6a). By analyzing and comparing the microstructures of the laser quenching area (Figure 6b), the heat-affected zone (Figure 6c) and the unquenched area (Figure 6d), the martensite structure is further precipitated after laser quenching, and the precipitate particles are long. A large phenomenon, with a clear phase interface with the ferrite matrix. The hardness of the blade after treatment with a laser energy density of 420kJ/cm ² is 643±29HV, which is significantly improved compared with the original sample.

When the cutter head is quenched by the laser energy density of 840kJ/cm ² , the quenching depth can reach 2.0mm (Fig. 7a). By analyzing and comparing the microstructure between the laser quenching area (Figure 7b), the heat-affected zone (Figure 7c) and the unquenched area (Figure 7d), after laser quenching, due to factors such as faster cooling speed, high carbon A large amount of martensite is precipitated, and the structure is further refined and densified, and a large amount of martensite is dispersed in the ferrite matrix structure. The hardness of the blade after treatment with a laser energy density of 840kJ/cm ² reached 666±18HV, which was significantly improved compared with the original sample, further proving the feasibility of the quenching process.

The above embodiments do not limit the present invention, and the present invention is not limited to the above embodiments, as long as the requirements of the present invention are met, they all belong to the protection scope of the present invention.

Claims (2)

1. a kind of high-rate laser defocus quenching strengthening method for miniature shaving tool, following laser defocus quenching strengthening dress Put, including mirror-vibrating optical fiber laser, X-axis galvanometer, Y-axis galvanometer, zoom field lens；The laser warp that mirror-vibrating optical fiber laser is sent X-axis vibration mirror reflected to Y-axis galvanometer, laser is exported to workpiece to be quenched through Y-axis vibration mirror reflected to zoom field lens again；It is characterized in that This method comprises the following steps：

The appearance structure of step (1), analysis miniature shaving tool workpiece to be quenched, projects according to the Z- shaft spaces of hardened area are needed Position, sets laser outgoing route in the CAD system of laser defocus quenching strengthening device, and the geometric center of workpiece is alignd To the optical axis center of zoom field lens；

Step (2), choose suitable light path parameter according to the width dimensions of workpiece blade and the required depth of quenching, and setting is optimal Field lens focal length and field lens height；

The empirical equation of the field lens focal length is：

Wherein f is field lens focal length, unit cm；C is the required depth of quenching of blade, unit cm；D is blade width, single Position is cm；

The empirical equation of the field lens height is：L 1.3 × f of ≈ formulas (2)

Wherein L for field lens height, unit cm；F is field lens focal length, unit cm；C is the required depth of quenching of blade, single Position is cm；

Step (3), according to formula (3), set laser energy density：

P_D=P/dv formulas (3)

Wherein P_DIt is the energy density of laser, unit J/cm²；P is laser output power, unit W；D is the width of blade, Unit is cm；V is the sweep speed of laser, unit cm/s；

Open laser after step (4), placement workpiece to be quenched, after the completion of run-down, close laser equipment, completion is once swept Retouch taking-up quenching workpiece.

2. a kind of high-rate laser defocus quenching strengthening method for miniature shaving tool as claimed in claim 1, its feature It is rotary miniature shaving tool to be miniature shaving tool workpiece.