Discussion on the edge passivation technology of t

Discussion on the passivation technology of cutting edge

I. Introduction

name and importance of cutting edge passivation

the name of a process after fine grinding and before coating of a cutting tool or blade is not unified at home and abroad at present. It is called "cutting edge passivation", "cutting edge strengthening", "cutting edge honing", "cutting edge preparation" or "Er treatment". This paper adopts the name of "cutting edge passivation"

the passivation technology of cutting edge is a very important problem, which has not been widely valued by people. Therefore, it is important that the passivated tool can effectively improve the edge strength, improve the tool life and the stability of the cutting process. We all know that cutting tools are the "teeth" of machine tools, and the main factors that affect the cutting performance and service life of cutting tools. In addition to the optimization of tool materials, tool geometric parameters, tool structure, cutting parameters, etc., through a large number of tool edge passivation practices, we realize that a good edge type and edge passivation quality are also the premise of whether the tool can be cut faster, better and less. Therefore, the condition of the cutting edge of the tool is also a factor that cannot be ignored

why do we need to passivate the cutting edge?

the cutting edge of the tool grinded by ordinary grinding wheel or diamond grinding wheel does have micro notches of different degrees (i.e. micro chipping and saw edge). The former can be observed with the naked eye and ordinary magnifying glass, while the latter can be observed with a 100x (with 0.010mm scribed) microscope, and its micro notch is generally 0 05mm, more than 0.1mm in severe cases. In the cutting process, the micro notch of the tool edge is easy to expand, which accelerates the tool wear and damage

modern high-speed machining and automatic machine tools put forward higher requirements for tool performance and stability, especially coated tools must be passivated before coating, so as to ensure the firmness and service life of the coating

the cutting edges of CNC machine tools and cutting tools used in production lines imported from abroad have been passivated. A lot of information shows that the passivation of the cutting edge of the tool can effectively prolong the service life of the tool by 200% or more, greatly reduce the cost of the tool, and bring great economic benefits to users

therefore, it is very important to deeply study and practice the knowledge of tool counterpart passivation. This topic should start from the following two aspects: one is to select the blade type and parameters; the other is to explore the blade passivation technology and parameters, so as to achieve a close combination of the two

II. Blade type and blade passivation shape

common blade type: (see Figure 1)

sharp blade

chamfered blade

vibration damping edge

white blade

rounding edge

several commonly used blade types in Figure 1

sharp edge: Tax edge naturally formed by the intersection of front and rear blade surfaces, whose edge is sharp, poor strength and easy to wear. Generally used for finishing tools

chamfering edge: on the rake face near the edge, the edge grinds out a very narrow negative rake edge, which greatly improves the strength of the edge. Used for rough machining and semi finishing tools

vibration elimination edge: its importance is self-evident on the flank near the edge. Grind a very narrow negative back corner edge, increase the contact area between the tool and the workpiece during cutting, and eliminate the vibration in the cutting process. It is used for single edge tools when the rigidity of the process system is insufficient

white edge: there is a narrow edge or edge belt with a back angle of 0 ° on the back surface near the edge, which can play the role of support, guidance and extrusion finishing. It is used for reamers, Broaches and other multi edge tools

rounding edge: it is an indexable tool used for various rough machining and semi precision machining, which grinds or passivates the edge into rounded corners with certain parameters to increase the strength of the edge and improve the service life of the tool

edge passivation shape: (see Figure 2)

arc edge

waterfall edge

Figure 2 two edge passivation shapes

edge passivation geometry have a great impact on tool life: one is arc edge, which forms a symmetrical arc at the corner of the edge, which is used by more than 80% of the tools, and is suitable for rough and fine machining. One is a waterfall cutting edge. The ratio of top surface to side surface at the corner of the cutting edge is generally 2:1. It is an asymmetric arc, which is suitable for harsh impact processing

the purpose of the tool edge passivation technology is to solve the defects of the micro notch of the tool edge after grinding, so as to reduce or eliminate its sharp value, so as to achieve the purpose of smoothness, sharpness, firmness and durability. According to different processing conditions, reasonably select the blade type and parameters, and closely combine them with the selection of counterpart passivation parameters, and correctly handle the relationship between "sharp" and "solid" of the tool. "Sharp" is a necessary feature of tool cutting. At the same time, considering the "solid" of the blade is also for more effective cutting, improving tool life and reducing tool consumption

III. Development Trend of knife passivation methods

manual passivation:

the earliest passivation tools began with leather and oil. For example, when shaving in a barber's shop, barbers cut on leather, making the blade sharper and more durable. Our predecessors have a lot of rich experience in cutting tools used in machining, and the effect is very remarkable. Examples are as follows:

during rough machining, a tool with a new edge can reduce the wear value in the primary wear stage. In the later stage of the normal wear stage, the tool can still extend the normal wear stage, and the service life of the general tool can be increased by more than 0.5 times

when reamers are used for finish machining, the inner hole surface sometimes cannot meet the requirements of the drawing without reaming, and the surface roughness can be stabilized ra1 after careful reaming 8 m, and the tool life can be increased by about 1 time

the guide rail of the precision planing machine tool adopts a negative front angle wide edge calendering knife, and its front and rear knife surfaces must be carefully ground by a flat plate. Only by improving the surface quality can the sharp and straight edge be guaranteed, and the surface roughness of the guide rail can be stabilized below Ra0.8 M

the broaching knife used in a factory to process the incoming and outgoing lines of the inner hole of a large barrel, because the processed material has high toughness and strength, the knife wears fast, and even the chips are stuck, causing accidents, so it is necessary to specially arrange experienced old workers to sharpen the knife in order to complete this critical processing

the floating boring cutter is used for the fine hole processing of the wall panel of the printing machine. There is a feeding trace. After the development of a knife tool with a magnifying glass, the cutting edge is sharp and straight. The feed rate is increased from 1mm/r to 4mm/r

the equipment and cutting tools for processing internal combustion engine crankshafts in a factory are imported from abroad. The original knife can process parts, but only parts can be processed after using domestic blades. After the blade is passivated and reasonable passivation parameters are selected, a knife can also process parts

mechanical passivation

in order to improve the efficiency and quality of passivation, efficient mechanical passivation methods are mostly used. Such as vibration passivation, medium passivation, grinding slurry passivation, rubber wheel passivation with abrasive, dry or wet sand blasting passivation, rolling passivation and nylon brush passivation with abrasive, etc

high efficiency and high intelligence passivation equipment

ixm-50 cone passivation machine newly developed by Congress Technologies LLC in the United States is controlled by CNC program, and the operator inputs several simple commands. It can passivate into different sizes on different surfaces of the same tool. It can passivate slotting knife and thread comb knife, etc. From the blade production lines introduced by several domestic companies, it can be seen that both coated and uncoated blade production lines are equipped with blade edge passivator, which has become an indispensable and important process in blade production, which is also one of the reasons why foreign tools have good performance and high service life

IV. development of small blade edge passivation machine and passivation parameters

development of small blade edge passivation machine

at present, most of the indexable blades widely used in China are sharpened by small and medium-sized tool factories, and there is no applicable blade edge passivation machine product in China, while the price of foreign blade edge passivation machine is very expensive (100 to hundreds of thousands of dollars), so the blade edge without passivation is in poor condition, poor performance and low service life, Compared with similar blades abroad, there is a big gap in performance and service life. How to narrow this gap and solve the problem of blade edge passivation? It is necessary to develop a small indexable blade edge passivation machine, which is more suitable for national conditions. Therefore, after more than a year of efforts to develop and improve eight times, our institute has been successful. Patent number: 4. Passivator model: 2mq6712d, overall dimension: 400x400x600 (mm), which is suitable for products popularized by small and medium-sized tool factories and machining workshops

principle of small indexable blade edge passivator; The planetary mechanism driven by gear reduction electronic speed regulation motor makes the blade rotate and revolve, and the blade edge is passivated by the high-speed rotating nylon disk brush containing abrasive. The passivation machine consists of five parts; Disk brush head and sliding seat part, blade turntable transmission part, frame and box part, detection part and electrical part. The machine has the following characteristics: 1. The function of the reducer in the tension machine

the structure is compact and reasonable, and the use is flexible and reliable

the rotating speed of blade turntable and turntable is stepless and adjustable

the passivation time can be controlled

blade edge passivation parameters can be measured on the machine

passivation containers with different blade shapes and specifications can be replaced

it has been proved by relevant manufacturers that the blade edge passivator meets the design requirements, has reliable performance, and has good passivation effect. Beijing Man Machine Co., Ltd. has increased the service life of cemented carbide blades by more than 0.2 times on average after passivation, and that of individual tools by times. Shandong Laiwu huashunmeng Ceramic New Material Co., Ltd. has increased the service life of ceramic blades by more than 0.5 times after passivation, and that of individual cutters by times. The increase of service life is related to the specific processing conditions, the selected mating type and the edge passivation parameters

selection of passivation parameters through the development and production practice of blade edge passivation machine, some laws have been preliminarily mastered. According to different processing conditions, it is very important to select blade type and passivation parameters. Due to different blade materials, first of all, according to the experimental requirements, the corresponding bending mandrel, bending sleeve and work roll are correctly installed on the work plate. The processing conditions are different, and the selected blade type and passivation parameters are also different, otherwise the expected effect of prolonging the tool life cannot be achieved. See the following parameter recommendation table:

compared with the foreign edge passivation parameters, the passivation value of 70% of the tools is 0 Between 0762. Maximum: 0 2032mm。 Minimum value: 1/6 of 0.0762mm of a hair, i.e. 0.0127mm. Even if the passivation is so small, it obviously strengthens the cutting edge of the tool

from a large number of practical experience of counterpart passivation, it is confirmed that the sharper the edge is, the better, and the duller the edge is, the better. It is best to determine different passivation values for different processing conditions

the combination of edge passivation and matching type is the most common and effective measure to improve the matching strength, improve the tool life and reduce the tool cost

when grinding negative inverted core with micro powder grinding wheel, its micro notch is small (up to 0..010mm), plus small passivation parameters (0.010-0.030mm), making the edge sharp, firm and durable. Some data show that it is widely used abroad

v. effect and economy of blade mouth to mouth passivation

here, taking the cemented carbide and ceramic square indexable blades widely used in China as an example, the actual use effect after mouth to mouth passivation is comprehensively counted and calculated respectively for reference

saving value of blade passivation

cemented carbide indexable blade: Square D = 15.875, s=4.76, rear angle a0=11 °, single-sided passivation, the price of each blade is 8 yuan, and if the average service life is increased by 25%, the saving value of each blade is 2 yuan