欧美人妻精品一区二区三区99,中文字幕日韩精品内射,精品国产综合成人亚洲区,久久香蕉国产线熟妇人妻

Tools with positive or negative rake angle are fundamental cutting instruments whose geometric angle design directly affects machining outcomes. Among these, the rake angle (the angle between the tool’s front face and a reference plane perpendicular to the cutting plane) is one of the most critical parameters. Based on the direction of the rake angle, turning tools can be classified into two main types: positive rake angle tools and negative rake angle tools. This article will systematically introduce the structural characteristics, working principles, and applicable scenarios of these two types of tools.

What Are Positive and Negative Rake Angle Cutting Tools? 2

Basic Definitions of Positive and Negative Rake Angle Tools

Positive Rake Angle Tool

A positive rake angle tool refers to a turning tool where the front face is inclined toward the interior of the workpiece relative to the cutting point, resulting in a positive rake angle (typically +5° to +15°). Its structural characteristic is a relatively sharp cutting edge, with a smaller contact area between the front face and the chip.

Negative Rake Angle Tool

A negative rake angle tool, on the other hand, has a front face inclined outward from the workpiece relative to the cutting point, resulting in a negative rake angle (typically -5° to -10°). Its structural feature is a blunter cutting edge, with a thicker and more robust tooltip.

 

Advantages and Disadvantages of Positive and Negative Rake Tools

Positive Rake Angle Tool

Advantages:

Lower Cutting Forces: A positive rake angle allows smoother chip flow and reduces deformation, decreasing main cutting forces by 15–25%.

Better Chip Evacuation: Shorter chip-tool contact length reduces built-up edge formation.

Suitable for Finishing: Minimizes vibration, enabling better surface finish (Ra < 1.6 μm).

Dezavantajlar?:

Lower Tooltip Strength: The positive geometry reduces material support, making the tool prone to chipping in interrupted cuts or hard materials.

Poor Heat Dissipation: Smaller chip-tool contact area limits heat transfer, accelerating crater wear at high speeds.

Shorter Tool Life: Typically 60–70% of negative rake tools under the same conditions.

 

Negative Rake Angle Tool

Advantages:

High Tooltip Strength: The negative angle creates a “support wedge,” improving impact resistance by >50%.

Superior Heat Dissipation: Larger chip-tool contact area enhances heat conduction, reducing cutting temperatures by 15–30°C.

Multi-Sided Usability: Often designed with double-negative angles, allowing flipping for extended use.

Limitations:

Higher Cutting Forces: Negative rake increases chip deformation, raising main cutting forces by 20–30%.

Greater Power Demand: Requires 15–20% more motor power from the machine tool.

Vibration Risk: Prone to chatter in long overhang machining due to increased cutting forces.

Rake Angle?tool

Experimental Comparison

The following systematic experiment compares the performance of carbide positive and negative rake tools under different machining conditions, providing practical insights for tool selection.

 

Experimental Design

1.Materials & Equipment:

Positive rake tool (+8° rake angle)

Negative rake tool (-6° rake angle)

Both use YG8 karbit substrate with TiAlN coating and 0.4 mm nose radius.

2.Workpiece:45# steel (Φ50×200 mm), quenched and tempered to HRC 28–32.

3.Machine:CA6140 lathe with 3-jaw chuck and tailstock center.

4.Measurement Instruments:

Surface roughness tester (Mitutoyo SJ-210)

Electron microscope (OLYMPUS DSX510)

Cutting force dynamometer (Kistler 9257B)

Infrared thermometer (Fluke Ti400)

5.Parameters

Fixed: Depth of cut (ap = 1 mm), feed rate (f = 0.15 mm/rev).

Variable: Cutting speed (v = 60–180 m/min).

Three repetitions per condition for reliability.

 

Results & Analysis

Tool Wear & Life Comparison

Using flank wear VB = 0.3 mm as the failure criterion:

What Are Positive and Negative Rake Angle Cutting Tools? 3

Negative rake angle tools demonstrate significantly longer service life, exceeding positive rake tools by an average of 50-70%. Analysis of wear patterns reveals that positive rake tools primarily fail through crater wear on the rake face and tooltip chipping, whereas negative rake tools exhibit more uniform flank wear, demonstrating superior fracture resistance.

Cutting Force Comparison

What Are Positive and Negative Rake Angle Cutting Tools? 4

The data shows that under all tested cutting speeds, negative rake tools generate significantly higher principal cutting forces than positive rake tools, with an average increase of approximately 17%. This is attributed to the negative rake design’s larger contact area between the tool’s rake face and chips, as well as intensified cutting deformation. Notably, while cutting forces for both tool types decrease with increasing cutting speed, the difference ratio remains essentially stable.

 

Cutting Temperature Comparison

Results indicate that negative rake tools maintain consistently lower cutting temperatures than positive rake tools, typically by 15-25°C. This thermal advantage primarily stems from the negative rake design’s enhanced tooltip strength and improved heat dissipation capacity. The temperature difference becomes particularly pronounced during high-speed cutting (v>120m/min), reaching approximately 30°C.

 

Surface Quality Evaluation

Surface roughness serves as a critical indicator of machining quality. At a feed rate of f=0.15mm/rev, measurements show:

Positive rake tool surface roughness (Ra): 1.6-2.0μm

Negative rake tool surface roughness (Ra): 1.2-1.5μm

Electron microscope observations reveal that surfaces machined with negative rake tools exhibit more uniform texture patterns with fewer burrs and vibration marks. This improvement results from the negative rake design’s enhanced system rigidity that reduces cutting vibrations. Furthermore, negative rake tools maintain more stable tooltip geometry during machining, avoiding the surface quality degradation caused by micro-chipping that often occurs with positive rake tools.

 

Conclusions

1.While carbide negative rake tools show slightly inferior performance in cutting force, they demonstrate clear advantages in cutting temperature control, surface quality, and tool life.

2.The performance advantages of negative rake tools become more pronounced at higher cutting speeds, making them particularly suitable for modern high-speed machining requirements.

3.Positive rake tools excel in reducing cutting forces and are better suited for machining systems with limited rigidity.

4.Optimal tool angle selection should comprehensively consider multiple factors including workpiece material, machine tool conditions, and specific machining stages.

Bir cevap yaz?n

E-posta hesab?n?z yay?mlanmayacak. Gerekli alanlar * ile i?aretlenmi?lerdir

免费男人和女人黄片| 福利国产第一视频| 国产成人精品免费视频全| 国产精品久久一区二区三区夜色| 亚洲国产嫩草18久久久| 亚洲天堂av一区二区在线观看| 鸡巴插骚逼视频欧美风格| 国产日韩精品v一区二区| 国产亚洲一区白丝在线观看| 高颜值情侣鸡巴插插淫叫| 熟妇丰满大阴户熟妇啪啪| 成人黄色网破处在线播放| 深插巴西美女的逼| 国产精品久久久久妇| 三级片在线无码播放| 欧美一区二区高清视频在线观看| 中文国产成人精品久久久| 人妻少妇精品视频12p| 蜜臀AV无码国产精品尤物| 亚洲av午夜一区二区| 日本精品高清在线观看| 欧美男女舔逼舔鸡巴视频| 99热这里有精品在线观看| 欧美 日韩 激情 在线| 久久精品一区二区三区免费看| 日本一区二区三区四区五| 中文字幕在线精品的视频| 色噜噜人妻丝袜中文字幕| 韩国无玛黄片毛片| 18岁以下禁看美女的胸| 精品一区二区三区女性色| 91在线一区二区| 高颜值情侣鸡巴插插淫叫| 国产品无码一区二区三区在线| 亚洲欧美日韩中文v在线| 男人添女人下面免費视頻| 国产精品一区二区三区涩涩av| 新视觉亚洲三区二区一区理伦| 欧美人人做人人爽人人喊| 一区二区三区四区五六区| 精品少妇一区二区三区中文字幕|