Precision tool manufacturing high speed stamping tool continuous stamping Mold
Stamping die is a special process equipment that processes materials (metal or non-metal) into parts (or semi-
finished products) in cold stamping processing. It is called cold stamping die (commonly known as cold stamping
die). Stamping is a pressure processing method that uses a die mounted on a press to exert pressure on a material
at room temperature to produce separation or plastic deformation, so as to obtain the required parts.
According to the nature of the process
a. Die where the blanking die separates the material along a closed or open profile. Such as blanking die, punching
die, cutting die, incision die, cutting die, cutting die, etc.
b. Bending die A die that causes the blank or other blank to bend and deform along a straight line (bending line)
to obtain a workpiece of a certain Angle and shape.
c. Deep drawing die is a die that makes the blank of sheet metal into open hollow parts, or makes the hollow parts
further change shape and size.
d. Forming die is the blank or semi-finished workpiece according to the shape of the convex and concave die
directly copied forming, and the material itself only produces local plastic deformation of the die. Such as
bulging die, shrinking die, flanging die, flanging die and so on.
e. Riveting die is to use external forces to connect or lap the participating parts together in a certain order and
way, and then form a whole
Classification according to the degree of process combination
a. Single process die only one stamping process die is completed in one stroke of the press.
b. The compound die has only one station. In one stroke of the press, two or more stamping processes can be
completed at the same station at the same time.
c. The progressive die (also known as continuous die) has two or more stations in the feeding direction of the
blank. In one stroke of the press, two or more stamping processes are completed successively at different stations.
d. Transfer mold integrated the characteristics of single-process mold and progressive mold, the use of manipulator
transfer system, to achieve rapid in-mold transfer of products, can greatly improve the production efficiency of
products, reduce production costs, save material costs, and stable and reliable quality.
Mold material selection
The materials produced by stamping are steel, hard alloy, steel-bonded hard alloy, zinc-based alloy, low melting
point alloy, aluminum bronze, polymer materials and so on. Most of the materials used for manufacturing stamping
dies are steel. The commonly used types of materials for working parts of dies are: carbon tool steel, low alloy
tool steel, high carbon and high chromium or medium chromium tool steel, medium carbon alloy steel, high speed
steel, matrix steel, hard alloy, steel-bonded hard alloy and so on.
In the process of stamping die production, various metal and non-metal materials are used, mainly carbon steel,
alloy steel, cast iron, cast steel, hard alloy, low melting point alloy, zinc base alloy, aluminum bronze,
synthetic resin, polyurethane rubber, plastic, laminated birch wood and so on.
The materials for manufacturing molds are required to have high hardness, high strength, high wear resistance,
appropriate toughness, high hardenability, no deformation (or little deformation) during heat treatment and no
cracking during quenching.
Basic classification
a. Carbon tool steel
T8A, T10A and so on are the most widely used carbon tool steels in the mold. Their advantages are good machining
performance and low price. But hardenability and hardness is poor, heat treatment deformation is large, bearing
capacity is low.
b. Low alloy tool steel
Low alloy tool steel is based on carbon tool steel with appropriate alloying elements. Compared with carbon tool
steel, it reduces the tendency of quenching deformation and cracking, improves the hardenability of steel and has
better wear resistance. The low-alloy steels used for mold manufacturing are CrWMn, 9Mn2V, 7CrSiMnMoV(code CH-1),
6CrNiSiMnMoV(code GD), etc.
c. High carbon and high chromium tool steel
Commonly used high carbon and high chromium tool steels are Cr12 and Cr12MoV, Cr12Mo1V1 (code D2), SKD11, they have
good hardenability, hardenability and wear resistance, heat treatment deformation is small, high wear resistance
micro deformation die steel, bearing capacity second only to high speed steel. However, the carbide segregation is
serious, so it must be upset repeatedly (axial upsetting, radial upsetting) to reduce the inhomogeneity of the
carbide and improve the service performance.
d. High carbon medium chrome tool steel
High carbon medium chromium tool steels used for die include Cr4W2MoV, Cr6WV, Cr5MoV, etc., their chromium content
is low, eutectic carbide is less, carbide distribution is uniform, heat treatment deformation is small, and they
have good hardenability and dimensional stability. Compared with the high carbon and high chromium steels with more
serious carbide segregation, the properties are improved.
e. High speed steel
High speed steel has the highest hardness, wear resistance and compressive strength of die steel, and high load
capacity. Commonly used molds are W18Cr4V (code 8-4-1) and W6Mo5 Cr4V2 (code 6-5-4-2, U.S. brand name M2) with less
tungsten content, as well as carbon and vanadium reducing high speed steel 6W6Mo5 Cr4V (code 6W6 or Low carbon M2)
developed to improve toughness. High speed steel also needs to be forged to improve its uniform carbide
distribution.
f. Matrix steel
A small amount of other elements are added to the basic composition of high speed steel, and the carbon content is
increased or decreased appropriately to improve the performance of the steel. Such steels are collectively referred
to as matrix steels. They not only have the characteristics of high speed steel, with certain wear resistance and
hardness, but also have better fatigue strength and toughness than high speed steel. They are high strength and
toughness cold working die steel, but the material cost is lower than high speed steel. The matrix steels commonly
used in die are 6Cr4W3Mo2VNb (code 65Nb), 7Cr7Mo2V2Si (code LD), 5Cr4Mo3SiMnVAL (code 012AL), etc.
g. Cemented carbides and steel cemented carbides
The hardness and wear resistance of hard alloy are higher than any other kind of die steel, but the bending
strength and toughness are poor. The hard alloy used as the mold is tungsten and cobalt. For the mold with small
impact and high wear resistance, the hard alloy with low cobalt content can be selected. Hard alloy with higher
cobalt content can be used for mold with high impact.
Steel-bonded cemented carbide is sintered by powder metallurgy with iron powder and a small amount of alloying
element powder (such as chromium, molybdenum, tungsten, vanadium, etc.) as binder, titanium carbide or tungsten
carbide as hard phase. The matrix of steel-bonded cemented carbide is steel, which overcomes the shortcomings of
poor toughness and difficult processing of cemented carbide, and can be cut, welded, forged and heat treated.
Steel-bonded cemented carbides contain a lot of carbides. Although the hardness and wear resistance are lower than
cemented carbides, they are still higher than other steels. The hardness can reach 68 ~ 73HRC after quenching and
tempering.
h. New materials
The material used in stamping die belongs to cold working die steel, which is the most widely used die steel with
large dosage. The main performance requirements are strength, toughness and wear resistance. The development trend
of cold working die steel is based on the performance of high alloy steel D2, which can be divided into two
categories:
1) One is to reduce the carbon content and alloying element content, improve the distribution uniformity of carbide
in steel, and improve the toughness of the die. Such as the United States vanadium Alloy Steel Company 8CrMo2V2Si,
Japan Datong Special Steel Company DC53(Cr8Mo2SiV) and so on.
2) The other powder high speed steel is developed for the main purpose of improving wear resistance and adapting to
high-speed, automatic and mass production. Such as Germany's 320CrVMo13, etc.
Principle of selection
Reasonable selection of die materials and correct heat treatment process are the key to ensure die life. For
different uses of the die, should be based on its working state, stress conditions and the performance of the
processed material, production batch and productivity of the factors such as comprehensive consideration, and the
above requirements of the performance of some emphasis, and then make the corresponding choice of steel and heat
treatment process.
When the production batch of stamping parts is large, the punch and die materials of the working parts of the die
should be selected with high quality and good wear resistance of the die steel. For the mold of other process
structure part and auxiliary structure part of the parts material, also should be improved accordingly. In the
batch is not large, should be appropriate to relax the material performance requirements, to reduce the cost.
When the material processed by stamping is hard or the deformation resistance is large, the convex and concave die
of the punching die should be selected with good wear resistance and high strength. When drawing stainless steel,
aluminum bronze die can be used, because it has better adhesion resistance. The guide column guide sleeve requires
wear resistance and good toughness, so the surface carburization of low carbon steel is used. For example, the main
shortcoming of carbon tool steel is poor hardenability. When the section size of die parts is large, the hardness
of the center is still low after quenching. However, when working on the press with a large number of trips, its
good impact resistance becomes an advantage instead. For the fixed plate, discharge plate parts, not only to have
enough strength, and require small deformation in the process of work. In addition, cold treatment and
cryotreatment, vacuum treatment and surface strengthening can be used to improve the performance of die parts. For
cold extrusion dies with poor working conditions of convex and concave dies, die steel with good comprehensive
mechanical properties such as sufficient hardness, strength, toughness and wear resistance should be selected, and
it should have certain red rigidity and thermal fatigue strength.
The cold and hot working properties of the material and existing plant conditions should be considered.
Attention should be paid to the use of micro-deformed die steel to reduce machining costs.
The die steel with special properties should be developed and applied for the die with special requirements
The selection of die materials should be determined according to the use conditions of die parts. On the premise of
meeting the main conditions, low-cost materials should be selected to reduce costs.
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