Paper tube machine slitting double side blade flat round knife tube
trimming skd-11/HSS
Industrial tool material and its selection: tool material mainly
refers to the material of the cutting part of the tool. The cutting
performance of the tool directly affects the production efficiency,
processing quality and production cost. The cutting performance of
the tool depends first on the material of the cutting part;
secondly, whether the selection and design of the geometry and tool
structure are reasonable.
1. Basic requirements for tool materials
In the cutting process, the cutting part of the tool must not only
bear a large cutting force, but also withstand the high temperature
caused by chip deformation and friction. To maintain the cutting
ability of the tool, the tool should have the following cutting
performance.
1. High hardness and wear resistance
The hardness of the tool material must be higher than the hardness
of the workpiece material. It should be above HRC60 at room
temperature. Generally speaking, the higher the hardness of the
tool material, the better the wear resistance.
2. Sufficient strength and toughness
The cutting part of the tool must bear a lot of cutting force and
impact force. Therefore, the tool material must have sufficient
strength and toughness.
3. Good heat resistance and thermal conductivity
The heat resistance of the tool material means that it can still
maintain its hardness and strength at high temperatures. The better
the heat resistance, the stronger the tool material's ability to
resist plastic deformation and wear resistance at high
temperatures. The better the thermal conductivity of the tool
material, the easier the heat generated during cutting is conducted
out, thereby reducing the temperature of the cutting part and
reducing tool wear.
4. Good workmanship
In order to facilitate manufacturing, the tool material is required
to have good machinability. Including hot workability
(thermoplasticity, weldability, hardenability) and mechanical
workability.
5. Good economy
2. Common tool materials
There are many types of tool materials. Commonly used tool steels
include: carbon tool steel, alloy tool steel and high-speed steel,
cemented carbide, ceramics, diamond and cubic boron nitride.
Carbon tool steel and alloy tool steel are only suitable for hand
tools because of their poor heat resistance.
Ceramics, diamonds, and cubic boron nitride are only used in a
relatively small range due to brittleness, poor manufacturability,
and high prices.
The most commonly used tool materials are high-speed steel and
cemented carbide.
1. High speed steel
It is a high-alloy tool steel with more alloy elements such as
tungsten, molybdenum, chromium, vanadium added to alloy tool steel.
It has high strength, toughness and heat resistance, and is
currently the most widely used tool material. Because it is easy to
get a sharp edge when sharpening, it is also called "Front Steel".
According to different uses, high speed steel can be divided into
ordinary high speed steel and high performance high speed steel.
1) Ordinary high-speed steel Ordinary high-speed steel has a
certain hardness (62 ~ 67 HRC) and wear resistance, high strength
and toughness, the cutting speed when cutting steel is generally
not higher than 50 ~ 60m/min, not suitable for high-speed cutting
And cutting of hard materials. Common grades are W18Cr4V,
W6Mo5Cr4V2.
2) High-performance high-speed steel Increase the content of carbon
and vanadium in ordinary high-speed steel or add some other alloy
elements to obtain new steel grades with higher heat resistance and
wear resistance. But the overall performance of this type of steel
is not as good as ordinary high-speed steel. Commonly used grades
are 9W18Cr4V, 9W6Mo5Cr4V2, W6Mo5Cr4V3, etc.
2. Cemented carbide
Cemented carbide is a powder metallurgy product sintered by
carbides with high hardness and melting point, sintered with Co,
Mo, Ni as a binder. Its normal temperature hardness can reach 78~82
HRC, can withstand high temperature of 850~1000℃, cutting speed can
be 4~10 times higher than high speed steel. However, its impact
toughness and flexural strength are far worse than high-speed
steel, so it is rarely made into a monolithic tool. In actual use,
the cemented carbide blade is often fixed to the blade body by
welding or mechanical clamping.
The cemented carbide currently produced in my country is mainly
divided into three categories:
1) Class K (YG)
Namely tungsten cobalt, composed of tungsten carbide and cobalt.
This kind of cemented carbide has good toughness, but poor hardness
and wear resistance, and is suitable for processing brittle
materials such as cast iron and bronze. Commonly used grades are:
YG8, YG6, YG3, and the tools they make are suitable for roughing,
semi-finishing and finishing. The number indicates the percentage
of Co content. YG6 contains 6% Co. The more Co, the better the
toughness.
2) Class P (YT)
That is tungsten cobalt titanium, which consists of tungsten
carbide, titanium carbide and cobalt. This kind of cemented carbide
has good heat resistance and wear resistance, but poor impact
resistance and is suitable for processing tough materials such as
steel. Commonly used grades are: YT5, YT15, YT30, etc., where the
numbers indicate the percentage of titanium carbide content, the
higher the content of titanium carbide, the better the wear
resistance and the lower the toughness. These three grades of
carbide tools are suitable for roughing, semi-finishing and
finishing.
3) Type M (YW)
That is tungsten cobalt titanium tantalum niobium. It is composed
of a small amount of rare metal carbide (TaC or NbC) added to
tungsten cobalt titanium cemented carbide. It has the advantages of
the first two types of cemented carbide. The tools made with it can
process both brittle materials and tough materials. At the same
time, it can also process difficult materials such as
high-temperature alloys, heat-resistant alloys and alloy cast iron.
Commonly used grades are YW1, YW2.
3. Introduction to other tool materials
1. Coated Carbide
This material is coated on the hard alloy substrate with good
toughness and strength or high speed steel substrate by chemical
vapor deposition (CVD) method or physical vapor deposition (PVD)
method. Tool material obtained from extremely high refractory metal
compounds. By this method, the cutter has both the strength and
toughness of the matrix material and high wear resistance. Common
coating materials are TiC, TiN, Al2O3, etc. TiC has good toughness
and wear resistance; TiN has good resistance to oxidation and
adhesion; Al2O3 has good heat resistance. The coating material can
be selected according to different needs during use.
2. Ceramic
The main component is Al2O3, the blade hardness can reach 78 HRC or
more, can withstand high temperatures of 1200 ~ 1450 ℃, so it can
withstand higher cutting speeds. But the bending strength is low,
the impact toughness is poor, and it is easy to fall. Mainly used
for finishing of steel, cast iron, high hardness materials and high
precision parts.
3. Diamond
There are two kinds of diamonds, man-made and natural. The
materials used for cutting tools are mostly man-made diamonds,
whose hardness is extremely high, up to 10,000 HV (cemented carbide
is only 1300 ~ 1800 HV). Its wear resistance is 80 to 120 times
that of cemented carbide. But the edge is poor, and it has a great
affinity for iron family materials. Therefore, it is generally not
suitable for processing ferrous metals, mainly used for high-speed
finishing of hard alloys, glass fiber plastics, hard rubber,
graphite, ceramics, non-ferrous metals and other materials.
4. Boron nitride (CNB)
This is a synthetic super-hard tool material, its hardness can
reach 7300 ~ 9000HV, second only to the hardness of diamond.
However, it has good thermal stability, can withstand high
temperature of 1300~1500℃, and has little affinity with iron group
materials. But the strength is low and the weldability is poor. At
present, it is mainly used for processing hardened steel, chilled
cast iron, high-temperature alloys and some difficult-to-machine
materials.
The choice of tool materials should be comprehensively considered
in terms of performance, process performance, price and other
factors, so as to make reasonable choices. For example, when
turning 45 steel and free forging gear blanks, due to the irregular
surface of the workpiece and oxide scales, the impact force during
cutting is large, and the K type (tungsten cobalt type) with good
toughness is better than the P type (tungsten cobalt titanium type)
favorable. Another example is the use of YT when turning shorter
steel threads. However, because the turning tool is subject to
impact at the cutting point of the workpiece, it is easy to jump,
so it is generally advantageous to use YG. Although its thermal
rigidity is not as good as YT, but the workpiece is short, the heat
dissipation is easy, and the thermal rigidity is not the main
contradiction.